This PDF file contains the front matter associated with SPIE Proceedings Volume 9668, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Both microchannels and nanofluids have shown promise to enhance convective heat transfer. However, the major drawback of these two technologies is their significant increase of pumping pressure due to increased frictional drag (for high surface area microchannels) or increased viscoelastic frictional drag (for nanofluids). It is possible to decrease frictional drag, and overcome this drawback, by implementing superhydrophobic surfaces to create slip with the channel wall. In this work, surface microstructures fabricated from the thermoset polyester (TPE) were used to create superhydrophobic surfaces which are capable of reducing the frictional drag in channel flow and thus, reduce the pumping pressure. Preliminary experimental results of superhydrophobic microchannels with rib-and-cavity microstructures aligned transversely and longitudinally to the flow direction were studied with both distilled water and water-based multi-walled carbon nanotube (MWCNT) nanofluid as the working fluids. While pressure drop reduction of superhydrophobic surfaces and heat transfer enhancement of nanofluids were shown, it was observed that heat transfer degradation occurred at higher flow rates with MWCNT nanofluid as the working fluid due to the precipitation of nanoparticles.

We report the fabrication of densely packed InGaN/GaN nanorods with high hexagonal periodicity. Nanosphere lithography and reactive ion etching were adopted to fabricate the nanorods from planar multiple quantum wells (MQWs). Compared to the planar MQWs, the nanorods exhibit significant luminescence enhancement. This is mostly attributed to the increased radiative recombination and light extraction efficiency. Both photoluminescence and Raman measurements confirmed in-plane strain relaxation in the MQWs after nanofabrication. A reduction in strain-induced quantum confined Stark effect in the nanorods increased radiative recombination. This work is most crucial to the understanding of optical properties with respect to the carrier transport and recombination in InGaN/GaN nanorods.

Several waveguide solutions based on technologies from both electronics and photonics have been proposed for guiding Terahertz (THz) radiation. Hollow-core dielectric waveguides are one of the best options for guiding THz radiation since the material absorption is almost zero in the air-core. However, these waveguides are usually multimode and have dimensions in the order of a few millimeters. Here we propose a hollow-core waveguide with sub-wavelength scale metallic wires in the cladding for THz guidance. The theoretical studies show that such a hybrid cladding reflects the transverse magnetic (TM) waves and transmits the transverse electric (TE) waves, leading to a waveguide structure that only confines TM modes. The numerical simulations show a pure single mode, single polarization operation window from 0.22 THz to 0.34 THz and 14.8 dB/m propagation loss at 0.29 THz. Compared to a metallic waveguide with similar dimension, the proposed waveguide more than doubles the single mode operation bandwidth with comparable losses. We discuss the effect of optical and structural parameters of the hybrid cladding on the single mode operating window and propagation losses, and suggest methods of fabrication of the waveguide. The design principle of the proposed waveguide can be extended to the mid-inferred spectrum.

In this work silicon pillar waveguides have been proposed to exploit the entire transparent window of silicon. These geometries posses a broad and at dispersion (from 2 to 6 μm) with four zero dispersion wavelengths. We calculate supercontinuum generation spanning over two octaves (2 to >8 μm) with long wavelengths interacting weakly with the lossy substrate. These structures have higher mode confinement in the silicon - away from the substrate, which makes them substrate independent and are promising for exploring new nonlinear phenomena and highly sensitive molecular sensing over the entire silicon's transparency range

It is well known that effective medium description of metamaterials requires much caution, even for strongly subwavelength systems. Boundary effects play a dramatic role in finite samples with discrete structure, making their observable properties quite different from the predictions of effective medium theory. We report some new findings regarding the distinction between a homogenised response and actual properties of discrete structures, looking into canonical shape of metamaterial objects. Even for large size (up to 20000 “meta-atoms”), we observe a difference between large discretised spheres and a continuous one, which is important for practical design and future development of metamaterials. Finally, we also provide the results for non-resonant discrete finite systems

We propose a hybrid metamaterial with embedded amorphous oxide thin-film transistor (TFT) arrays, which embraces the advantages of energy saving, low cost and high yields for tunable amplitude modulation in terahertz (THz) regime. The properties of this active metamaterial system are numerically investigated based on full-wave techniques and multipole theory. The calculation results attribute the modulation to a change in the damping rate of an electric dipoletype resonance mode caused by the increased conductivity of the transparent oxide layer. Such a device, expanding the horizon of oxide electronics into metamaterials, opens up many fascinating prospects for producing stable, uniform, and low-cost THz components.

We demonstrate humidity sensors based on optical resonances sustained in sub-wavelength thick dye-doped polymer coatings on reflecting surfaces. As a result of coupling between dye molecular absorption and Fabry-Perot resonances in the air-coating-surface cavity, the absorption spectra of such thin-film structures show a strong resonant peak under certain illumination conditions. These resonances are sensitive to the structural and material properties of the thin-film, metal underlayer and ambient conditions and hence can be used for gas and vapor sensing applications. Specifically, we present our proof of principle experimental results for humidity sensing using a thin-film structure comprising Rhodamine6G-doped polyvinyl alcohol (PVA) films on silver substrates. Depending on the PVA film thickness, dye-concertation and angle of incidence, the resonant absorption peak can undergo either red-shift or blue-shift as RH level increases in the range 20% to 60%. Also, the absorption magnitude at certain wavelengths near to resonance show almost linear reduction which can be used as the sensing signal. Our simulation studies show a very good agreement with the experimental data. The spectral and temporal sensitivity of this thin-film structure is attributed to the changes in the thickness of the PVA layer which swells by absorbing water molecules

Enhanced liquid water flows through carbon nanotubes reinvigorated the study of moisture permeation through membranes and micro- and nano-channels. The study of water vapour through micro-and nano-channels has been neglected even though water vapour is as important as liquid water for industry, especially for encapsulation of electronic devices. Here we measure moisture flow rates in silica microchannels and interdiffusive water vapour flows in anodic aluminium oxide (AAO) membrane channels for the first time. We construct theory for the flow rates of the dominant modes of water transport through four previously defined standard configurations and benchmark it against our new measurements. The findings show that measurements of leak behaviour made using other molecules, such as helium, are not reliable. Single phase water vapour flow is overestimated by a helium measurement, while Washburn or capillary flow is underestimated or for all channels when boundary slip applies, to an extent that depends on the slip length for the liquid phase flows.

The integration of microfluidics with living biological systems has paved the way to the exciting concept of “organson- a-chip”, which aims at the development of advanced in vitro models that replicate the key features of human organs. Glass based devices have long been utilised in the field of microfluidics but the integration of alternative functional elements within multi-layered glass microdevices, such as polymeric membranes, remains a challenge.
To this end, we have extended a previously reported approach for the low-temperature bonding of glass devices that enables the integration of a functional polycarbonate porous membrane. The process was initially developed and optimised on specialty low-temperature bonding equipment (μTAS2001, Bondtech, Japan) and subsequently adapted to more widely accessible hot embosser units (EVG520HE Hot Embosser, EVG, Austria). The key aspect of this method is the use of low temperatures compatible with polymeric membranes. Compared to borosilicate glass bonding (650 °C) and quartz/fused silica bonding (1050 °C) processes, this method maintains the integrity and functionality of the membrane (T_g 150 °C for polycarbonate). Leak tests performed showed no damage or loss of integrity of the membrane for up to 150 hours, indicating sufficient bond strength for long term cell culture. A feasibility study confirmed the growth of dense and functional monolayers of Caco-2 cells within 5 days.

An increasing demand in performance from electronic devices has resulted in continuous shrinking of electronic components. This shrinkage has demanded that the primary integration platform, the printed circuit board (PCB), follow this same trend. Today, PCB companies offer ~100 micron sized features (depth and width) which mean they are becoming suitable as physical platforms for Lab-on-a-Chip (LOC) and microfluidic applications. Compared to current lithographic based fluidic approaches; PCB technology offers several advantages that are useful for this technology. These include: Being easily designed and changed using free software, robust structures that can often be reused, chip layouts that can be ordered from commercial PCB suppliers at very low cost (1 AUD each in this work), and integration of electrodes at no additional cost. Here we present the application of PCB technology in connection with microfluidics for several biomedical applications. In case of commercialization the costs for each device can be even further decreased to approximately one tenth of its current cost.

Behavioral ecotoxicity tests are gaining an increasing recognition in environmental toxicology. Behavior of sensitive bioindicator species can change rapidly in response to an acute exposure to contaminants and thus has a much higher sensitivity as compared to conventional LC₅₀ mortality tests. Furthermore, behavioral endpoints seems to be very good candidates to develop early-warning biomonitoring systems needed for rapid chemical risk assessment. Behavioral tests are non-invasive, fast, do not harm indicator organisms (behavioural changes are very rapid) and are thus fully compatible with 3R (Replacement – Reduction – Refinement) principle encouraging alternatives to conventional animal testing. These characteristics are essential when designing improved ecotoxicity tests for chemical risk assessment.

In this work, we present a pilot development of miniaturized Lab-on-a-Chip (LOC) devices for studying toxin avoidance behaviors of small aquatic crustaceans. As an investigative tool, LOCs represent a new direction that may miniaturize and revolutionize behavioral ecotoxicology. Specifically our innovative microfluidic prototype: (i) enables convening “caging” of specimens for real-time videomicroscopy; (ii) eliminates the evaporative water loss thus providing an opportunity for long-term behavioral studies; (iii) exploits laminar fluid flow under low Reynolds numbers to generate discrete domains and gradients enabling for the first time toxin avoidance studies on small aquatic crustaceans; (iv) integrates off-the-chip mechatronic interfaces and video analysis algorithms for single animal movement analysis. We provide evidence that by merging innovative bioelectronic and biomicrofluidic technologies we can deploy inexpensive and reliable systems for culture, electronic tracking and complex computational analysis of behavior of bioindicator organisms.

A recent revolution in additive manufacturing technologies and access to 3D Computer Assisted Design (CAD) software has spurred an explosive growth of new technologies in biomedical engineering. This includes biomodels for diagnosis, surgical training, hard and soft tissue replacement, biodevices and tissue engineering. Moreover, recent developments in high-definition additive manufacturing systems such as Multi-Jet Modelling (MJM) and Stereolithography (SLA), capable of reproducing feature sizes close to 100 μm, promise brand new capabilities in fabrication of optical-grade biomicrofluidic Lab-on-a-Chip and MEMS devices.

Compared with other rapid prototyping technologies such as soft lithography and infrared laser micromachining in PMMA, SLA and MJM systems can enable user-friendly production of prototypes, superior feature reproduction quality and comparable levels of optical transparency. Prospectively they can revolutionize fabrication of microfluidic devices with complex geometric features and eliminate the need to use clean room environment and conventional microfabrication techniques.

In this work we demonstrate preliminary data on toxicity profiling of a panel of common polymers used in 3D printing applications. The main motivation of our work was to evaluate toxicity profiles of most commonly used polymers using standardized biotests according to OECD guidelines for testing of chemic risk assessment. Our work for the first time provides a multispecies view of potential dangers and limitation for building biocompatible devices using FDM, SLA and MJM additive manufacturing systems. Our work shows that additive manufacturing holds significant promise for fabricating LOC and MEMS but requires caution when selecting systems and polymers due to toxicity exhibited by some 3D printing polymers.

We design, develop and demonstrate the principle of a continuous, non-intrusive, low power microfluidics-based lab-ona- chip (LOC) structure for Circulating Tumor Cell (CTC) separation. Cell separation is achieved through 80 cascaded contraction and expansion microchannels of widths 60 μm and 300 μm, respectively, and depth 60 μm, which enable momentum-change-induced inertial forces to be exerted on the cells, thus routing them to desired destinations. The total length of the developed LOC is 72 mm. The LOC structure is simulated using the COMSOL multiphysics software, which enables the optimization of the dimensions of the various components of the LOC structure, namely the three inlets, three filters, three contraction and expansion microchannel segments and five outlets. Simulation results show that the LOC can isolate CTCs of sizes ranging from 15 to 30 μm with a recovery rate in excess of 90%. Fluorescent microparticles of two different sizes (5 μm and 15 μm), emulating blood and CTC cells, respectively, are used to demonstrate the principle of the developed LOC. A mixture of these microparticles is injected into the primary LOC inlet via an electronically-controlled syringe pump, and the large-size particles are routed to the primary LOC outlet through the contraction and expansion microchannels. Experimental results demonstrate the ability of the developed LOC to isolate particles by size exclusion with an accuracy of 80%. Ongoing research is focusing on the LOC design improvement for better separation efficiency and testing of biological samples for isolation of CTCs.

Homogeneous and fast mixing of samples at microscale is a critical requirement for successful applications of microfluidics in biochemical analysis, chemical synthesis, drug delivery and nanomaterial synthesis. This paper reports the optimisation of bubble-induced mixing in a microfluidic device in terms of voltage, driving frequency, piezo transducer position and PDMS thickness. The microfluidic device consists of a microwell (with the diameter of 1mm and volume of ~95 nL) with two rectangular bubble traps (400×400μm) on both sides of the well. After the injection of liquid, air bubbles were spontaneously trapped in two rectangular traps. When the frequency of a piezo was equal to the resonance frequency of air bubbles, strong liquid recirculation formed (so called acoustic microstreaming) in the vicinity of the interface of air bubbles and water. The acoustic induced flow of microbeads and mixing of water and fluorescence dye were imaged to study the mixing efficiency. For a given voltage and PDMS thickness, when the piezo was placed on top of the well, the mixing was most vigorous. For a given frequency, the mixing efficiency was directly proportional to the voltage (4-20V) and inversely proportional to the PDMS thickness (0.3-2mm). When the frequency driving the piezo was approaching the resonance frequency of air bubbles, the mixing efficiency was maximal, while when it was far away from the resonance frequency of air bubbles, the mixing efficiency was much lower. This work provides guidance to the design and the application of bubble-induced acoustic mixing in microfluidics.

An increased rigor in water quality monitoring is not only a legal requirement, but is also critical to ensure timely chemical hazard emergency responses and protection of human and animal health. Bioindication is a method that applies very sensitive living organisms to detect environmental changes using their natural responses. Although bioindicators do not deliver information on an exact type or intensity of toxicants present in water samples, they do provide an overall snapshot and early-warning information about presence of harmful and dangerous parameters. Despite the advantages of biotests performed on sentinel organisms, their wider application is limited by the nonexistence of high-throughput laboratory automation systems. As a result majority of biotests used in ecotoxicology require time-consuming and laborious manual procedures.

In this work, we present development of a miniaturized Lab-on-a-Chip (LOC) platform for automation and enhancement of acute ecotoxicity test based on immobilization of a freshwater crustacean Daphnia magna (Daphtoxkit-FTM). Daphnids’ immobilization in response to sudden changes in environment parameters is fast, unambiguous, and easy to record optically. We also for the first time demonstrate that LOC system enables studies of sub-lethal ecotoxic effects using behavioral responses of Daphnia magna as sentinels of water pollution.

The system working principle incorporated a high definition (HD) time-resolved video data analysis to dynamically assess impact of the reference toxicant on swimming behavior of D. magna. Our system design combined: (i) microfluidic device for caging of Daphnia sp.; (ii) mechatronic interface for fluidic actuation; (iii) video data acquisition; and (iv) algorithms for animal movement tracking and analysis.

Damage monitoring is the need of the hour in this age of infrastructure. Many methods are being used for damage monitoring in different mechanical and civil structures. Some of them are strain based methods in which abruptly increased strain signifies the presence of damage in the structure. This article focuses on crack monitoring of a fixedfixed beam using fiber optic sensors which can measure strain locally or globally. The two types of fiber optic sensors used in this research are fiber Bragg grating (FBG) and fiber optic polarimetric sensors (FOPS). FBG and FOPS are used for local strain monitoring (at one point only) and global strain monitoring (in the entire specimen) respectively. At the centre of the specimen, a piezoelectric wafer active sensor (PWAS) is also attached. PWAS is used to obtain electromechanical admittance (EMA) signatures. Further, these EMA signatures are analysed to access the damage state in the beam. These multiple smart materials together provide improved information on damages in the specimen which is very valuable for the structural health monitoring (SHM) of the specimen.

Engineered materials with feature sizes on the order of a few nanometres offer the potential for producing metamaterials with properties which may differ significantly from their bulk counterpart. Here we describe the production of plasmonic colour filters using periodic arrays of nanoscale cross shaped apertures fabricated in optically opaque silver films. Due to its relatively low loss in the visible and near infrared range, silver is a popular choice for plasmonic devices, however it is also unstable in wet or even ambient conditions. Here we show that ultra-thin layers of Diamond-Like Carbon (DLC) can be used to prevent degradation due to oxidative stress, ageing and corrosion. We demonstrate that DLC effectively protects the sub-micron features which make up the plasmonic colour filter under both atmospheric conditions and accelerated aging using iodine gas. Through a systematic study we confirm that the nanometre thick DLC layers have no effect on the device functionality or performance.

We show the first functional signal processing device based on forward stimulated Brillouin scattering from a silicon nanowire. We harness 1dB of SBS gain to create a high performance, energy efficient microwave photonic notch filter. The filter possess 48dB of suppression, 98 MHz linewidth, and is tunable within a 6 GHz bandwidth. This demonstration represents a significant advance in integrated microwave photonics with potential applications in on-chip microwave signal processing and establish the foundation towards the first CMOS-compatible high performance RF photonic filter.

Blended polymer electrolyte of methylcellulose (MC) / chitosan with ammonium triflate (NH₄TF) were prepared with different weight percentage of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) via solution casting technique. The film was characterized by impedance spectroscopy to measure its ionic conductivity. Samples with 45% of BMITFSI exhibit the highest conductivity of (3.98 ± 2.84) x 10^-4 Scm^-1 at ambient. Dielectric data were analyzed by using complex permittivity and complex electrical modulus for the sample with highest conductivity. Dielectric data proves that the increase in conductivity is mainly due to the increase in number of charge carriers.

Cold filters, which simultaneously reflect infrared light and transmit visible light, prevent overheating in charge-coupled device cameras, microscopes, and other heat-sensitive equipment. This study proposes a cold filter based on a two dimensional (2D) metal periodic grating structure. Conventional dielectric multilayer films with abrupt filtering characteristics are undesirably affected by incident angle, temperature, and polarization. To solve these problems, a 2D metal periodic grating structure, which does not depend on the polarization, was applied. The grating structure comprises an Au layer and an electron beam resist layer, and was fabricated by electron beam lithography. The optical characteristics of this structure in the visible light region were measured by a spectrometer, and the optical properties were related to structural parameters of the double-layer, 2D grating structure. In particular, the reflectance over the entire visible light spectrum decreased at periods of 800 nm and 1 μm. The wavelengths of minimum and maximum reflectance were shifted by changing the spacing between the upper and lower metal layers from 270 to 370 nm. Simulation results suggested that the interference between the upper and lower layers and the surface plasmon resonance between the metal and resist layers occur simultaneously. Therefore, in the visible light region, the reflectance and transmission spectra were controlled by altering the structure of the 2D metal periodic grating.

The excellent light harvesting properties and potentially low cost fabrication of organometal halide perovskites have attracted great attention in their application as solar cell device. Apart from the general advantages of organic-inorganic perovskite, CH₃NH₃PbBr₃ has a larger bandgap (~2.3eV) suitable to be the top cell in a tandem solar device. Here we use steady-state and time-resolved photoluminescence (PL) techniques to investigate the photophysical behaviour of CH₃NH₃PbBr₃ perovskite including its carrier dynamics under continuous illumination. Samples were studied under different illumination conditions and the following observations were made: (1) defect assisted recombination is dominant under low excitation under nano-second scale measurement, (2) bimolecular and Auger recombinations dominate under high excitation under the minute timescale measurement, (3) the magnitude PL decay traces decrease over time under continuous excitation. We propose that both the density of photo-generated free carriers and the density of mobile ions have an impact on the carrier dynamic of CH₃NH₃PbBr₃. This finding provides insights into the photophysical properties of perovskite materials.

Microfluidic technology has the potential to revolutionise blood-clotting diagnostics by incorporating key physiological blood flow conditions like shear rate. In this paper we present a customised dynamic microfluidic system, which evaluates the blood clotting response to multiple conditions of shear rate on a single microchannel. The system can achieve high-throughput testing through use of an advanced fluid control system, which provides with rapid and precise regulation of the blood flow conditions in the platform. We present experimental results that demonstrate the potential of this platform to develop into a high-throughput, low-cost, blood-clotting diagnostics device.

Advances in microfabrication technologies and manufacturing over last decade, allowed for inexpensive prototyping of microfluidic chip-based devices for biomedical studies in biocompatible and optically transparent elastomeric polymers such as poly(dimethylsiloxane) (PDMS) and thermoplastics such as poly(methyl methacrylate) (PMMA). More resently, advanced additive manufacturing technologies such as stereolithography (SLA), capable of reproducing feature sizes less than 50 μm, pave a way towards a new generation of microfabrication techniques. The latter promise new methods to enable accelerated design, validation and optimisation of optical-grade biomicrofluidic Lab-on-a-Chip (LOC) devices.

The main limitation, however, of virtually all polymers that are used to both manufacture LOC devices as well as to provide fluidic interconnects is their significant hydrophobicity. Conventionally the hydrophobic properties were postulated to impede wetting and priming of the polymeric chip-based devices and tubing interconnects. Such issues were often solved with plasma treatment or ethanol priming to help wet the polymeric substrata and also reduce the nucleation and persistence of air bubbles.

In this work, we present evidence that use of certain hydrophobic polymers is a significant impediment in performing ecotoxicity tests of organic chemicals on biomicrofluidic devices. We report on electrostatic interaction between polymers and toxicants that lead to non-covalent adsorption and rapid depletion of chemicals from the tested media. This introduces a significant bioanalytical bias irrespectively of the fact that microfluidic tests are preformed under continuous perfusion.

Recently, piezoelectric material has a very important potential for functional material which configure Bio-MEMS (Biological Micro Electro Mechanical Systems) actuator and sensor. Specifically, in implementation of piezoelectric material for Bio-MEMS, thin film fabrication by sputtering method is made from the viewpoint of miniaturization. Furthermore, in piezoelectric material, perovskite type material composed of ABO3 has a high piezoelectricity. Then, PZT (Lead Zirconate Titanate) as the perovskite type piezoelectric material is widely used since it is easy to produce and has high piezoelectricity. PZT has zirconium or titanium in the B site of ABO3 structure. PZT has the features such as physical properties to greatly change by change in the B site composition ratio of zirconium and titanium. Thus, the B site greatly influences physical properties and therefore function improvement by additive element is tried widely. However, experimental method to lack in economy and quantitativeness is mainstream. Therefore, application of the result is difficult and new evaluation method of B site additive element for sputtering fabrication is necessary. Accordingly, in this research, search of an additive element at low cost and quantitative from the viewpoint of energy by first-principles calculation. First of all, the additive elements which capable of substituting for a B site of PZT were searched. Next, change of piezoelectricity was evaluated by change of crystal structure in a PZT system was introduced an additive element that substitution of the B site was possible. As a result, additive elements for the PZT B site capable of improving piezoelectricity were determined.

Nanoscale dielectric resonator antennas (DRAs) are promising elements for constructing the next generation of efficient and compact optical devices. Their efficient light manipulation capability underpinned by electric and magnetic resonances at visible frequencies is appealing for optical metasurfaces with various functions such as anomalous re ection, polarization conversion and surface plasmon coupling. To realize these functions, the resonance properties of the individual DRA elements are of critical importance. In this paper, we study the resonance breakdown of nanoscale cylindrical DRAs on metallic substrates. By gradually increasing the relative permittivity of DRAs on a metallic ground plane from low to high values, we observe two types of resonance breakdown and on that basis we can define a permittivity range for efficient resonance. More specifically, the resonance breakdown occuring at low DRA permittivities is a result of weak confinement and excessive radiation loss. The resonance breakdown at high DRA permittivities is a result of an elevated plasmonic loss at the metal- dielectric interface when the negative permittivity of the metal and the positive permittivity of the dielectric material have matched in their absolute values. The latter breakdown can be avoided by inserting a thin dielectric spacer with a low permittivity between the metal and dielectric. This study suggests important considerations for designing dielectric resonator metasurfaces at the visible frequencies.

Paper presents a structure of a micro-mirror element driven by thermal micro-actuators. Micro-mirror dimensions are 100x100 um and it was manufactured by a surface micromachining using microelectronics technologies. Thermal microactuator is a bimorph structure consisting of aluminum and silicon dioxide layers with a polysilicon heater between them. The description of manufacturing process for micro-mirror element is given. The micro-mirror motion is achieved by passing an electric current through the heater. The actuator structure is heated and rotates the mirror. The processes of heating and cooling of thermal micro-actuator structure directly affects the characteristics of manufactured micro-mirror, thus the studying of these processes is essential. The report proposes a method for calculating the heating and cooling time, taking into account the influence of the structure geometry, electrical characteristics of external influence and the environment conditions. Also a method for the experimental determination of the dynamic characteristics is proposed, along with the method of electro-thermal analogy. The results of calculation are in good agreement with the experimental data, which allows one to use it to determine the dynamic characteristics of micro-devices based on thermal microactuators.

Butt-coupling of light into a surface plasmon is a simple and compact coupling method with a range of potential uses in photonic circuitry. Although butt-coupling has been successfully implemented in many coupling configurations, the coupling effectiveness is not fully understood. Here, we present a semi-analytical study which models the coupling efficiency of an incident beam into a surface plasmon on silver in the presence of loss using an projection method in one dimension. We find that the coupling efficiencies for silver between the wavelengths of 0:38 - 1:6 μm reach 77 - 88% with optimum incident beam parameters.

Organic light emitting diodes (OLEDs) are now widely commercialized in market due to many advantages such as possibility of making thin or flexible devices. Nevertheless there are still several things to obtain the high quality flexible OLEDs, one of the most important issues is the light extraction of the device. It is known that OLEDs have the typical light loss such as the waveguide loss, plasmon absorption loss and internal total reflection. In this paper, we demonstrate the one-step processed light scattering films with aluminum oxide nano-particles and polystyrene matrix composite to achieve highly efficient OLEDs. Optical characteristics and surface roughness of light scattering film was optimized by changing the mixing concentration of Al₂O₃ nano-particles and investigated with the atomic force microscopy and hazemeter, respectively.

This paper describes an efficient fiber to submicron silicon waveguide coupling based on an inversely tapered silicon waveguide embedded in a SiO₂ waveguide that is suspended in air. The inverse taper waveguide consist of a 50um long and 240nm thick silicon that linearly taper in width from 500nm to 120nm, which is embedded in SiO₂. The SiO₂ waveguide is 6um wide and 10um long. The simulation results show that the coupling loss of this new approach is 2.7dB including the interface loss at the input and output. The tolerance to fiber misalignment at the input of the coupler is 2um in both horizontal and vertical directions for only 1.5dB additional loss.

This paper presents the design and simulation of a novel piezoelectric actuator integrated with on-chip piezoresistive sensors for micro-lens actuation. COMSOL Multiphysics is used to perform and facilitate the design and simulation. The actuator consists of eight d31 mode unimorph piezoelectric actuators symmetrically attached to a lens holding frame through springs at one end, and to the silicon substrate at the other end. Diffused p-Si piezoresistors with doping of 1x10¹⁸cm^-3 are considered in the proposed design for displacement sensing of each micro-actuator. Results shows 3.2μm/V displacement sensitivity for the micro-lens actuator and piezoresistive sensitivity of 0.134mV/V/μm is obtainable with p-Si piezoresistors.

Photolithography is used in the important technologies of the device fabrication process in the semiconductor industry. However, photolithography has a pattern resolution limit because of the diffraction of light. Using surface plasmon (SP) is one of the ways to overcome this limit, which is a recently proposed nanolithography technology. Using SP, we developed a fabrication process using an Al grating structure on glass (glass/Al grating/PR structure). A perfect contact between the photoresist and the Al grating increased the effects of the SP because the contact gap was reduced in the photolithography process. The pattern pitch of lithography result was 120 nm (simulation results) and 115 nm (fabrication results). In surface plasmon interference lithography (SPIL) it is possible to use SP in the photolithography area. And we analyzed irregular pattern trends in the shape of random horizontal patterns and found that the patterns result from Al line edge roughness. Therefore, techniques that reduce the Al line edge roughness could enable clearer Al line patterns in SPIL.

The aim of the present work was to demonstrate the fabrication technique for semitransparent layers of nanoparticulated (~50 nm) LuPO₄:15%Eu phosphors. Furthermore, to present their basic luminescent properties and provide results regarding their performance in a planar imaging system incorporating a CMOS photodetector. Parameters such as the Detective Quantum Efficiency (DQE), the Normalized Noise Power Spectrum (NNPS) and the Modulation Transfer Function (MTF), were investigated.
The NNPS was found to present significantly higher values near the zero frequency for the 67 μm, 100 μm films, pointing on their higher non uniformities compared to the 220 and 460 μm films For the two thickest films (460 μm and 220 μm) the MTF curves practically do not differ, while MTFs for the thinner layers of 100 μm and 67 μm are higher as the layer’s thickness decreases. The higher DQE values observed for the 220 μm and 460 μm films up to medium frequencies, while at high frequencies the DQE values are comparable. Although the MTF values of these films are much lower than the thinner screens, the capability of the higher x-ray absorption, in conjunction with the low noise properties, lead to higher DQE values.
The LuPO₄:Eu semitransparent films seems to be a very promising scintillator for stationary x-ray imaging. The acquired data allow to predict that high-temperature sintering of our films under pressure may help to improve their imaging quality, since such a processing should increase the luminescence efficiency without significant growth of the grains, and thus without sacrificing their translucent character.

Surface plasmon resonance (SPR) biosensing has been successfully applied for the label-free detection of a broad range of bioanalytes ranging from bacteria, cell, exosome, protein and nucleic acids. When it comes to the detection of small molecules or analytes found at low concentration, amplification schemes are desirable to enhance binding signals and in turn increase sensitivity. A number of SPR signal amplification schemes have been developed and validated; however, little effort has been devoted to understanding the effect of the SPR sensor structures on the amplification of binding signals and therefore on the overall sensing performance. The physical phenomenon of long-range SPR (LRSPR) relies on the propagation of coupled surface plasmonic waves on the opposite sides of a nanoscale-thick noble metal film suspended between two dielectrics with similar refractive indices. Importantly, as compared with commonly used conventional SPR (cSPR), LRSPR is not only characterized by a longer penetration depth of the plasmonic waves in the analyzed medium but also by a greater sensitivity to bulk refractive index changes. In this work, an immunoassay signal amplification platform based on horseradish peroxidase (HRP) catalyzed precipitation was utilized to investigate the sensing performance with regards to cSPR and LRSPR. The enzymatic precipitation of 3, 3’-diaminobenzidine tetrahydrochloride (DAB)/H2O2 was used to amplify SPR signals. The structure-function relationship of cSPR and LRSPR sensors is presented for both standard refractometric measurements and the enzymatic precipitation scheme. Experimental data shows that despite its inherent higher sensitivity to bulk refractive index changes and higher figure of merit, LRSPR was characterized by a lower angular sensitivity in the model enzymatic amplification scheme used here.

We aimed to develop welfare devices for patients with phonation disorder. One of these devices is the electrical controltype speaking valve system. The conventional speaking valves have one-way valve architecture, they open when the user breathes in, and they close when user breathes out and produce voices. This type is very simple and tough, but some users feel closeness in case of exhalation without phonation. This problem is caused by its mechanism what can not be controlled by user’s will. Therefore, we proposed an electrical control-type speaking valve system to resolve this problem. This valve is controlled by neck myoelectric signal of sternohyoid muscle. From our previous report, it was clarified that this valve had better performance about easy-to-breath. Furthermore, we proposed the compact myoelectric control-type speaking valve system. The new-type speaking valve was enough small to attach the human body, and its opening area is larger than that of conventional one. Additionally, we described the improvement of flow channel shape by using of FEM analysis. According to the result of the analysis, it was clarified that the shape-improved speaking valve gets the low flow resistance channel in case of inspiration. In this report, we tried to make the flow resistance lower by the shape of current plates, in case of both inspiration and exhalation. From the result of FEM analysis, our speaking valve could get better flow channel than older one.

Luminescent solar concentrators (LSCs) offer the prospect of reducing the cost of solar energy, and are a promising candidate for building integrated photovoltaic (PV) structures. However, the realization of commercially viable efficiency of LSCs is currently hindered by reabsorption losses. In this work, a method is introduced for reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire length of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption, and directed by the seed laser towards a small target PV cell. A mathematical model of such a system is presented which identifies different physical parameters responsible for the power conversion efficiency and gives the net effective output power.

The aim of the work was to study the effect of various microelectronic structural and technological implementations to improve the field emission properties of the nano-carbon emitters. The field emission properties of vacuum diodes with nanodiamond-graphite emitters of different geometric shapes was researched. The nanodiamond-graphite layers deposition were carried out from ethanol vapor at low pressure using microwave plasma. Three series of experiments were studied. Researching of emission currents with flat cathodes on silicon wafer coated by nanodiamond-graphite layer were done in first series of experiments. In the second series of experiments, the electrical parameters of integrated field emission diodes with flat nanodiamond-graphite emitters was studied. In the third series of experiments, the electrical parameters of field emission with flat nanodiamond-graphite formed as a micro-sized needles or blades were studied. Vacuum emission studies were done at temperature 300K and pressure 1 × 10^-6 Torr.
Threshold voltage from10-50V per micron and current density about 0.2 A/cm² were obtained in the first series of experiments. In the second and third series of experiments, a threshold voltage from 1 to 10V/ μm and current density of 1.75 A/cm² were displayed. The greatest current density more than 20 A/cm² was obtained using a blade-type emitter.

Chemotherapy Induced Nausea and Vomiting (CINV) is a serious health concern in the treatment of cancer patients. Conventional routes for administering anti-emetics (i.e. oral and parenteral) have several drawbacks such as painful injections, poor patient compliance, dependence on skilled personnel, non-affordability to majority of population (parenteral), lack of programmability and suboptimal bioavailability (oral). Hence, we have developed a trans-epidermal antiemetic drug delivery patch using out-of-plane hollow silicon microneedle array. Microneedles are pointed micron-scale structures that pierce the epidermal layer of skin to reach dermal blood vessels and can directly release the drug in their vicinity. They are painless by virtue of avoiding significant contact with dermal sensory nerve endings. This alternate approach gives same pharmacodynamic effects as par- enteral route at a sparse drug-dose requirement, hence negligible side-effects and improved patient compliance. Microneedle design attributes were derived by systematic study of human skin anatomy, natural micron-size structures like wasp-sting and cactus-spine and multi-physics simulations. We used deep reactive ion etching with Bosch process and optimized recipe of gases to fabricate high-aspect-ratio hollow silicon microneedle array. Finally, microneedle array and polydimethylsiloxane drug reservoir were assembled to make finished anti-emetic patch. We assessed microneedles mechanical stability, physico-chemical properties and performed in-vitro, ex- vivo and in-vivo studies. These studies established functional efficacy of the device in trans-epidermal delivery of anti-emetics, its programmability, ease of use and biosafety. Thus, out-of-plane hollow silicon microneedle array trans-epidermal antiemetic patch is a promising strategy for painless and effective management of CINV at low cost in mainstream healthcare.

Zebrafish larvae are ideal for toxicology and drug screens due to their transparency, small size and similarity to humans on the genetic level. Using modern imaging techniques, cells and tissues can be dynamically visualised and followed over days in multiple zebrafish. Yet continued imaging experiments require specialized conditions such as: moisture and heat control to maintain specimen homeostasis. Chambers that control the environment are generally very expensive and are not always available for all imaging platforms. A highly customizable mounting configuration with built-in means of controlling temperature and media flow would therefore be a valuable tool for long term imaging experiments. Rapid prototyping using 3D printing is particularly suitable as a production method as it offers high flexibility in design, is widely available and allows a high degree of customizing. We study neural regeneration in zebrafish. Regeneration is limited in humans, but zebrafish recover from neural damage within days. Yet, the underlying regenerative mechanisms remain unclear.

We developed an agarose based mounting system that holds the embryos in defined positions along removable strips. Homeostasis and temperature control is ensured by channels circulating buffer and heated water. This allows to image up to 120 larvae simultaneously for more than two days. Its flexibility and the low-volume, high larvae ratio will allow screening of small compound libraries. Taken together, we offer a low cost, highly adaptable solution for long term in-vivo imaging.

Classical plasmonics has mostly focused on structures characterized by large dimension, for which the quantummechanical effects have nearly no impact. However, recent advances in technology, especially on miniaturized plasmonics devices at nanoscale, have made it possible to imagine experimental applications of plasmons where the quantum nature of free charge carriers play an important role. Therefore, it is necessary to use quantum mechanics to model the transport of charge carriers in solid state plasma nanostructures. Here, a non-local quantum model of permittivity is presented by applying the Wigner equation with collision term in the kinetic theory of solid state plasmas where the dominant electron scattering mechanism is the electron-lattice collisions. The surface plasmon resonance of ultra-small nanoparticles is investigated using this non-local quantum permittivity and its dispersion relation is obtained. The successful application of this theory in ultra-small plasmonics structures such as surface plasmon polariton waveguides, doped semiconductors, graphene, the metamaterials composed of alternating layers of metal and dielectric, and the quantum droplets is anticipated.

Zinc oxide tetrapods (ZnO-Ts) were synthesized by flame transport synthesis using Zn microparticles. This work herein reports a systematical study on the structural, optical and electrochemical properties of the ZnO-Ts. The morphology of the ZnO-Ts was confirmed by scanning electron microscopy (SEM) as joint structures of four nano-microstructured legs, of which the diameter of each leg is 0.7-2.2 μm in average from the tip to the stem. The ZnO-Ts were dispersed in glucose solution to study the luminescence as well as photocatalytic activity in a mimicked biological environment. The photoluminescence (PL) intensity in the ultraviolet (UV) region quenches with linear dependence to increased glucose concentration up to 4 mM. The ZnO-Ts were also attached with glucose oxidase (GOx) and over coated with a thin film of Nafion to form active layers for electrochemical glucose sensing. The attachment of GOx and coating of Nafion were confirmed by infrared spectroscopy (FT-IR). Furthermore, the current response of the active layers based on ZnO-Ts was investigated by cyclic voltammetry (CV) in various glucose concentrations. Stable current response of glucose was detected with linear dependence to glucose concentration up to 12 mM, which confirms the potential of ZnO-Ts for biomolecule sensing applications.

Two-dimensional (2D) materials have become very important building blocks for electronic, photonic, and phononic devices. The 2D material family has four key members, including the metallic graphene, transition metal dichalcogenide (TMD) layered semiconductors, semiconducting black phosphorous, and the insulating h-BN. Owing to the strong quantum confinements and defect-free surfaces, these atomically thin layers have offered us perfect platforms to investigate the interactions among photons, electrons and phonons. The unique interactions in these 2D materials are very important for both scientific research and application engineering. In this talk, I would like to briefly summarize and highlight the key findings, opportunities and challenges in this field. Next, I will introduce/highlight our recent achievements. We demonstrated atomically thin micro-lens and gratings using 2D MoS2, which is the thinnest optical component around the world. These devices are based on our discovery that the elastic light-matter interactions in highindex 2D materials is very strong. Also, I would like to introduce a new two-dimensional material phosphorene. Phosphorene has strongly anisotropic optical response, which creates 1D excitons in a 2D system. The strong confinement in phosphorene also enables the ultra-high trion (charged exciton) binding energies, which have been successfully measured in our experiments. Finally, I will briefly talk about the potential applications of 2D materials in energy harvesting.

One of the priority trend in electronics is the design of the imaging system in various spectral band of the electromagnetic waves. Multi-spectrum system is one of the critical technologies. It is principal to direct efforts for the creation multi-spectrum system in single block with simple regulation of the receiving band. First question in this field is to do the receiving pixel with tunable band for the matrix imaging system. Best candidate for this aim is Josephson Junction (JJ). The using of the JJ for this purpose can stay the new trend for the creation modern multi-spectrum passive terahertz imaging system. There proposed some analysis at the base of theoretical and experimental results of the possible noise parameters of the such pixel.

We study the radiation patterns produced by a dipole placed at the surface of a nanofiber and oriented perpendicular to it, either along the radial (r-oriented) or azimuthal (Φ-oriented) directions. We find that the dipole induces an effective circular cavity-like leaky mode in the nanofiber. The first radiation peak of the Φ-oriented dipole contributes only to TE radiation modes, while the radiation of the r-oriented dipole is composed of both TE and TM radiation modes, with relative contribution depending on the refractive index of the nanofiber. We reveal that the field pattern of the first resonance of a Φ-oriented dipole is associated with a magnetic dipole mode and strong magnetic response of an optical nanofiber.

By combining computational aided design with synthetic chemistry, we are able to identify core 2D polyaromatic small molecule templates with the necessary optoelectronic properties for p- and n-type materials. By judicious selection of the functional groups, we can tune the physical properties of the material making them amenable to solution and vacuum deposition. In addition to solubility, we observe that the functional group can influence the thin film molecular packing. By developing structure-property relationships (SPRs) for these families of compounds we observe that some compounds are better suited for use in organic solar cells, while others, varying only slightly in structure, are favoured in organic field effect transistor devices. We also find that the processing conditions can have a dramatic impact on molecular packing (i.e. 1D vs 2D polymorphism) and charge mobility; this has implications for material and device long term stability. We have developed small molecule p- and n-type materials for organic solar cells with efficiencies exceeding 2%. Subtle variations in the functional groups of these materials produces p- and ntype materials with mobilities higher than 0.3 cm²/Vs. We are also interested in using our SPR approach to develop materials for sensor and bioelectronic applications.

Recent studies [1-3] have demonstrated that nanotechnology, in the form of nanoparticles suspended in water and organic liquids, can be employed to enhance solar collection via direct volumetric absorbers. However, current nanofluid solar collector experimental studies are either relevant to low-temperature flat plate solar collectors (<100 °C) [4] or higher temperature (>100 °C) indoor laboratory-scale concentrating solar collectors [1, 5]. Moreover, many of these studies involve in thermal properties of nanofluid (such as thermal conductivity) enhancement in solar collectors by using conventional selective coated steel/copper tube receivers [6], and no full-scale concentrating collector has been tested at outdoor condition by employing nanofluid absorber [2, 6]. Thus, there is a need of experimental researches to evaluate the exact performance of full-scale concentrating solar collector by employing nanofluids absorber at outdoor condition.

As reported previously [7-9], a low profile (<10 cm height) solar thermal concentrating collector was designed and analysed which can potentially supply thermal energy in the 100-250 °C range (an application currently met by gas and electricity). The present study focuses on the design and experimental investigation of a nanofluid absorber employed in this newly designed collector. The nanofluid absorber consists of glass tubes used to contain chemically functionalized multi-walled carbon nanotubes (MWCNTs) dispersed in DI water. MWCNTs (average diameter of 6-13 nm and average length of 2.5-20 μm) were functionalized by potassium persulfate as an oxidant. The nanofluids were prepared with a MCWNT concentration of 50 ± 0.1 mg/L to form a balance between solar absorption depth and viscosity (e.g. pumping power). Moreover, experimentally comparison of the thermal efficiency between two receivers (a black chrome-coated copper tube versus a MWCNT nanofluid contained within a glass tubetube) is investigated.

Thermal experimentation reveals that while the collector efficiency reduced from 73% to 54% when operating temperature increased from ambient to 80 °C by employing a MWCNT nanofluid receiver, the efficiency decreased from 85% to 68% with same operating temperature range by employing black chrome-coated copper tube receiver. This difference can mainly be explained by the reflection optical loss off and higher thermal emission heat loss the front surface of the glass tube, yielding a 90% of transmittance to the MWCNT fluid and a 0.9 emissivity of glass pipe. Overall, an experimental investigation of the performance of a low profile solar collector with a direct volumetric absorber and conventional surface absorber is presented. In order to bring nanotechnology into industrial and commercial heating applications,

The optical properties of nanostructures control the performance of applications that are based on localized surface plasmon resonances. Here we use finite-difference time-domain calculations to explore the effect of geometry and material-of-construction on the transmission and near-field optical intensity of arrays of closely-spaced five-pointed nano-star shapes. We compared isolated solid star shapes to star-shaped nano-gaps set within a surrounding square metal shape. The materials investigated were silver, gold, copper and aluminum. The study showed that both the geometry and material chosen had a significant effect on the resulting transmittance spectra. Transmittance spectra of arrays of solid five-pointed nano-stars did not show any strong absorption peaks in the visible region whereas, in contrast, the arrays of star-shaped nano-gaps set within the metal squares did show strong absorption peaks. However, on closer examination it became obvious that the enhanced electric field of the latter was mostly on the corners of the square metal domains and not actually in or on the star-shaped nano-gaps. Therefore we deduce that arrays of simple metal squares will be more suitable as substrates for surface enhanced Raman spectroscopy than arrays of stars or star-shaped nano-gaps. Gold, silver and copper were suitable choices for the latter type of array. Aluminum was unsuitable, at least for applications in the visible part of the spectrum, because it was associated with relatively weak electric fields.

The optical and electrical responses of open, nanoscale, metal networks are of interest in a variety of technologies including transparent conducting electrodes, charge storage, and surfaces with controlled spectral selectivity. The properties of such nanoporous structures depend on the shape and extent of individual voids and the associated hyper-dimensional connectivity and density of the metal filaments. Unfortunately, a quantitative understanding of this dependence is at present only poorly developed. Here we address this problem using numerical simulations applied to a systematically designed series of prototypical sponges. The sponges are produced by a Monte Carlo simulation of the dealloying of Ag-Al alloys containing from 60% to 85% Al. The result is a series of Ag sponges of realistic morphology. The optical properties of the sponges are then calculated by the discrete dipole approximation and the results used to construct an 'effective medium' model for each sponge. We show how the resulting effective medium can be correlated with the associated morphological characteristics of each target and how the optical properties are primarily controlled by the density of the sponge and its state of percolation.

It has been well established that delta-like transport distribution of electron gives the best thermoelectric performance. On another front, it has been experimentally verified that graphene nano-ribbon with nano-break in the channel region exhibits tunnelling. Here, we utilize the tunnelling phenomena observed in graphene break junctions to achieve delta like transport distribution. Indeed our device exhibit record ZT ranging from 10 to 100. This high ZT can be attributed to complete blockage of phonon transport due to the break. The electrical conductance also goes very low, however, near the tunnelling energy it becomes significant, giving rise to an enhanced ZT value. In this report we investigate the effect edge orientation and the width of the ribbon on thermoelectric property. Moreover, we investigate the effect of temperature on tunnelling and how it affect thermoelectric performance. We find that there is an optimal temperature at which the device performs best. In the simulations, we assumed ballistic transport and used first principle approach to obtain the electrical properties. The phononic system was characterized by a Tersoff empirical potential model. The proposed device structure has potential applications as a two-dimensional nanoscale local cooler and as a thermoelectric power generator when connected in arrays.

Graphene nanoscrolls (GNSs) as a new category of quasi one dimensional belong to the carbon-based nanomaterials, which have recently captivated the attention of researchers. The latest discoveries of exceptional structural and electronic properties of GNSs like, high mobility, controllable band gap and tunable core size has become a new stimuli for nanotechnology researchers. Fundamental descriptions about structure and electronic properties of GNSs have been investigated in order to apply them in nanoelectronic applications like nanotransistors and nanosensors as a new semiconducting material. By utilizing a novel approach, the analytical conductance model (G) of GNSs with the effect of Hall quantum is derived. This letter introduces a geometrydependent model to analyze the conductance of GNSs. The conductance modeling of GNS in parabolic part of the band structure which displays minimum conductance near the charge neutrality point is calculated. Subsequently, the effect of temperature and physical parameters on GNS conductivity is studied. This study emphasized that the GNS is a promising candidate for new generation of nanoelectronic devices.

Nanoparticle-based delivery of drugs and contrast agents holds great promise in cancer research, because of the increased delivery efficiency compared to ‘free’ drugs and dyes. A versatile platform to investigate nanotechnology is the chick embryo chorioallantoic membrane tumour model, due to its availability (easy, cheap) and accessibility (interventions, imaging). In our group, we developed this model using several tumour cell lines (e.g. breast cancer, colon cancer). In addition, we have synthesized in-house silica coated photoluminescent upconversion nanoparticles with several functional groups (COOH, NH₂, PEG). In this work we will present the systematic assessment of their in vivo blood circulation times. To this end, we injected chick embryos grown ex ovo with the functionalized UCNPs and obtained a small amount of blood at several time points after injection to create blood smears The UCNP signal from the blood smears was quantified using a modified inverted microscope imaging set-up. The results of this systematic study are valuable to optimize biochemistry protocols and guide nanomedicine advancement in the versatile chick embryo tumour model.

Treatment of neurological anomalies, whether done invasively or not, places stringent demands on device functionality and size. We have developed a micro-spectrometer for use as an implantable neural probe to monitor neuro-chemistry in synapses. The micro-spectrometer, based on a NASA-invented miniature Fresnel grating, is capable of differentiating the emission spectra from various brain tissues. The micro-spectrometer meets the size requirements, and is able to probe the neuro-chemistry and suppression voltage typically associated with a neural anomaly. This neural probe-pin device (PPD) is equipped with wireless power technology (WPT) to enable operation in a continuous manner without requiring an implanted battery. The implanted neural PPD, together with a neural electronics interface and WPT, enable real-time measurement and control/feedback for remediation of neural anomalies. The design and performance of the combined PPD/WPT device for monitoring dopamine in a rat brain will be presented to demonstrate the current level of development. Future work on this device will involve the addition of an embedded expert system capable of performing semi-autonomous management of neural functions through a routine of sensing, processing, and control.

Fluorescence microscopy has emerged as a pivotal platform for imaging in the life sciences. In recent years, the overwhelming success of its different modalities has been accompanied by various efforts to carry out imaging deeper inside living tissues. A key challenge of these efforts is to overcome scattering and absorption of light in such environments. Multiple strategies (e.g. multi-photon, wavefront correction techniques) extended the penetration depth to the current state-of-the-art of about 1000μm at the resolution of approximately 1μm. The only viable strategy for imaging deeper than this is by employing a fibre bundle based endoscope. However, such devices lack resolution and have a significant footprint (1mm in diameter), which prohibits their use in studies involving tissues deep in live animals. We have recently demonstrated a radically new approach that delivers the light in/out of place of interest through an extremely thin (tens of microns in diameter) cylindrical glass tube called a multimode optical fibre (MMF). Not only is this type of delivery much less invasive compared to fibre bundle technology, it also enables higher resolution and has the ability to image at any plane behind the fibre without any auxiliary optics. The two most important limitations of this exciting technology are (i) the lack of bending flexibility and (ii) high demands on computational power, making the performance of such systems slow. We will discuss how to overcome these limitations.

Knowledge of optical properties (absorption coefficients, scattering Coefficients, and anisotropy) is necessary for understanding light tissue interactions. Optical parameters define the behavior of light in the tissues. Intralipid and Indian ink are well-established tissue body phantoms. Quantitative characterization of biological tissues in terms of optical properties is achieved with integrating sphere. However, samples having significantly higher scattering and absorption coefficients such as malignant tissues potentially reduce the signal to noise ratio (SNR) and accuracy of integrating sphere. We have measured the diffuse reflection and transmission of these phantoms by placing them in integrating sphere at 632.8 nm and then applied IAD method to determine the optical properties tissue phantoms composed of Indian ink (1.0%) and Intralipid (20%). We have fabricated a special sample holder with thin microscopic cover slips which can be used to measure signal from highly concentrated intralipid and Indian ink solutions. Experiments conducted with various phantoms reveal significant improvement of SNR for a wide range of optical properties. This approach opens up a field for potential applications in measurement of optical properties of highly diffusive biological tissues. For 20% intralipid μa =0.112±0.046 cm^-1 and μs =392.299±10.090 cm^-1 at 632.8 nm and for 1.0% Indian ink μa =9.808±0.490 cm^-1 and μs =1.258±0.063 cm^-1 at same wavelength. System shows good repeatability and reproducibility within 4.9% error. Work may have important biomedical applications in photo-diagnosis and Photodynamic therapy.

We studied the optical properties of polymer layers filled with phosphor particles in two aspects. First, we used two different polymer binders with refractive indices n = 1.46 and n = 1.61 (λ = 600 nm) to decrease Δn with the phosphor particles (n = 1.81). Second, we prepared two particle size distributions D50 = 12 μm and D50 = 19 μm. The particles were dispersed in both polymer binders in several volume concentrations and coated onto glass with thicknesses of 150 - 600 μm. We present further a newly developed optical model for simulation and optimization of such luminescent down-shifting (LDS) layers. The model is developed within the ray tracing framework of the existing optical simulator CROWM (Combined Ray Optics / Wave Optics Model), which enables simulation of standalone LDS layers as well as complete solar cells (including thick and thin layers) enhanced by the LDS layers for an improved solar spectrum harvesting. Experimental results and numerical simulations show that the layers of the higher refractive index binder with larger particles result in the highest optical transmittance in the visible light spectrum. Finally we proved that scattering of the phosphor particles in the LDS layers may increase the overall light harvesting in the solar cell. We used numerical simulations to determine optimal layer composition for application in realistic thin-film photovoltaic devices. Surprisingly LDS layers with lower measured optical transmittance are more efficient when applied onto the solar cells due to graded refractive index and efficient light scattering. Therefore, our phosphor-filled LDS layers could possibly complement other light-coupling techniques in photovoltaics.

Rear reflectors for solar cells comprised of metal films with periodic arrays of nanoscale features on their surface can provide significantly enhanced light trapping in the absorber layer. However these structures can also result in significantly increased parasitic absorption into the metal layer at various wavelengths of light. Conversely these highly absorbing resonances can also coincide with the wavelengths which display the largest enhancement to the cell’s photocurrent. As such it is important to understand the underlying causes for such photocurrent enhancements and losses in the metal in order to design the optimum structure for use. 3D Finite-difference-time-domain simulations have been used to model a variety of structures and analyze the spatial distribution of absorption within different materials which make up the structure, the angles at which light will be scattered from the rear surface, as well as the idealized short circuit current from each structure integrated across the AM1.5 spectrum. These reveal the properties of these modes at resonant wavelengths at which absorption into both materials is enhanced. Despite the enhanced coupling of light into the metal at these wavelengths, the amount of light scattered back into the absorber at large angles is also significantly boosted. For a large variety of geometries, the impact of this large angle scattering dominates leading to significant increases to a cell’s photocurrent. Our simulations allow us to understand the contributions of multiple plasmonic effects occurring in such structures, allowing selection of the most suitable geometries to achieve large-angle scattering in a desired wavelength range.

Thin film solar cells have been widely studied with the focus on how to improve light trapping mechanism and enhance the overall photon-electrons conversion efficiency. The effect of novel plasmonic materials based on wide bandgap semiconductors, such as metals heavily doped zinc oxides and metal nitrides, are here studied in relation to their potential use in thin film solar cells. Here, we show that metal nitrides can play similar roles as gold nanoparticles on a surface of a Si-thin film solar cell, possibly without introducing excessive dissipative absorption, while metals doped zinc oxide nanoparticles could significantly improve the efficiency of thin film solar cells.

Methylammonium Lead Bromide (CH₃NH₃PbBr₃) is a promising material for tandem solar cell due to its high band gap. Ultrafast optical techniques on a time scale of femto- and picosecond are used to investigate the carrier dynamics in CH₃NH₃PbBr₃. An ultrafast cooling of hot carriers occurs in sub-picoseconds in CH₃NH₃PbBr₃ by phonon scattering. Two ultrafast relaxation processes are attributed to optical phonon scattering and acoustic phonon scattering. The relaxation processes are evidently slower when CH₃NH₃PbBr₃ is in contact with compact TiO₂ (c-TiO₂) layer, suggesting better quality CH₃NH₃PbBr₃. when deposited on c-TiO₂. The nanosecond decay in CH₃NH₃PbBr₃ film is ascribed to electron-hole recombination. With the presence of c-TiO₂ layer, this process is accelerated due to electron transport across the CH₃NH₃PbBr₃/ c-TiO₂ interface.

Over the last decade, plasmonic nanoparticle arrays have been extensively studied for their light trapping potential in thin film solar cells. However, the commercial use of such arrays has been limited by complex and expensive fabrication techniques such as e-beam lithography. Nanosphere lithography (NSL) is a promising low-cost alternative for forming regular arrays of nanoscale features. Here, we use finite-difference time-domain (FDTD) simulations to determine the optical enhancement due to nanosphere arrays embedded at the rear of a complete thin film device. Array parameters including the nanosphere pitch and diameter are explored, with the FDTD model itself first validated by comparing simulations of Ag nanodisc arrays with optical measurements of pre-existing e-beam fabricated test structures. These results are used to guide the development of a nanosphere back-reflector for 20 μm thin crystalline silicon cells. The deposition of polystyrene nanosphere monolayers is optimized to provide uniform arrays, which are subsequently incorporated into preliminary, proof of concept device structures. Absorption and photoluminescence measurements clearly demonstrate the potential of nanosphere arrays for improving the optical response of a solar cell using economical and scalable methods.

Rationale: Tissue engineering (TE) is an emerging alternative approach to create models of human malignant tumors for experimental oncology, personalized medicine and drug discovery studies. Being the bottom-up strategy, TE provides an opportunity to control and explore the role of every component of the model system, including cellular populations, supportive scaffolds and signalling molecules.
Objectives: As an initial step to create a new ex vivo TE model of cancer, we optimized protocols to obtain organ-specific acellular matrices and evaluated their potential as TE scaffolds for culture of normal and tumor cells.
Methods and results: Effective decellularization of animals’ kidneys, ureter, lungs, heart, and liver has been achieved by detergent-based processing. The obtained scaffolds demonstrated biocompatibility and growthsupporting potential in combination with normal (Vero, MDCK) and tumor cell lines (C26, B16). Acellular scaffolds and TE constructs have been characterized and compared with morphological methods.
Conclusions: The proposed methodology allows creation of sustainable 3D tumor TE constructs to explore the role of organ-specific cell-matrix interaction in tumorigenesis.

Here we report the effect a metal grating on the light emission enhancement of a light emitting tunnel junction (LETJ). The device utilizes the finite probability of tunneling electrons to scatter inelastically, i.e. emit a photon over a phonon. Here a Fermi sea was electrically biased against the conduction band of a doped semiconductor. While functional, the external emission efficiency is low due to high absorption from the top metal. Here we experimentally show that introducing a grating to this top metal layer will enhance the emission intensity. Additional simulation results provide inside into the light-coupling process. Our result show a 12 times enhancement.

Accurate pH monitoring is crucial for many applications, such as, water quality monitoring, blood monitoring, chemical and biological analyses, environmental monitoring and clinical diagnostic. The most common technique for pH measurement is based on the use of conventional glass pH electrodes. Glass electrodes have several limitations, such as mechanical fragility, large size, limited shapes and high cost, making them impractical for implementation as Lab-onchips and pH sensor capsules. Various metal oxides, such as RuO₂, IrO₂, TiO₂, SnO₂, Ta₂O₅ and PdO have recently been proposed for the realization of pH sensing electrodes. Specifically, ruthenium oxide exhibits unique properties including thermal stability, excellent corrosion resistance, low hysteresis high sensitivity, and low resistivity. In this paper, we demonstrate the concept of a miniaturized ion selective electrode (ISE) based pH sensor for point-of-care urease monitoring. The sensor comprises a thin film RuO₂ on platinum sensing electrode, deposited using E-beam and R.F. magnetron sputtering, in conjunction with an integrated Ag/AgCl reference electrode. The performance and characterization of the developed pH/urea sensors in terms of sensitivity, resolution, reversibility and hysteresis are investigated. Experimental results show a linear potential-versus-urea-concentration response for urea concentrations in the range 0 - 180 mg/ml. Experimental results demonstrate super-Nernstian slopes in the range of 64.33 mV/pH - 73.83 mV/pH for RF sputtered RuO₂ on platinum sensing electrode using a 80%:20% Ar:O₂ gas ratio. The RuO₂ sensor exhibits stable operation and fast dynamic response, making it attractive for in vivo use, wearable and flexible biomedical sensing applications.

In this study, a high frequency piezoelectric energy harvester converted from the human low vibrated motion energy was newly developed. This hybrid energy harvester consists of the unimorph piezoelectric cantilever, the pendulum and a pair of permanent magnets. One magnet was attached at the edge of cantilever, and the counterpart magnet at the edge of pendulum. The mechanical energy provided through the human walking motion, which is a typical ubiquitous existence of vibration, is converted to the electric energy via the piezoelectric unimorph cantilever vibration. At first, we studied the energy convert mechanism and analyze the performance of novel energy harvester, where the resonance free vibration of unimorph piezoelectric cantilever generated a high electric power. Next, we equipped the counterpart permanent magnet at the edge of pendulum, which vibrates with a very low frequency caused by the human walking. Then the counterpart magnet was set at the edge of unimorph piezoelectric cantilever, which vibrated with a high frequency. This low-to-high frequency convert “dual vibration system” can be characterized as an enhanced energy harvester. We examined and obtained average values of voltage and power in this system, as 8.31 mV and 0.33 μW. Those results show the possibility to apply for the energy harvester in the portable and implantable Bio-MEMS devices.

Frequency reference and timing control devices are ubiquitous in electronic applications. There is at least one resonator required for each of this device. Currently electromechanical resonators such as crystal resonator, ceramic resonator are the ultimate choices. This tendency will probably keep going for many more years. However, current market demands for small size, low power consumption, cheap and reliable products, has divulged many limitations of this type of resonators. They cannot be integrated into standard CMOS (Complement metaloxide- semiconductor) IC (Integrated Circuit) due to material and fabrication process incompatibility. Currently, these devices are off-chip and they require external circuitries to interface with the ICs. This configuration significantly increases the overall size and cost of the entire electronic system. In addition, extra external connection, especially at high frequency, will potentially create negative impacts on the performance of the entire system due to signal degradation and parasitic effects. Furthermore, due to off-chip packaging nature, these devices are quite expensive, particularly for high frequency and high quality factor devices. To address these issues, researchers have been intensively studying on an alternative for type of resonator by utilizing the new emerging MEMS (Micro-electro-mechanical systems) technology. Recent progress in this field has demonstrated a MEMS resonator with resonant frequency of 2.97 GHz and quality factor (measured in vacuum) of 42900. Despite this great achievement, this prototype is still far from being fully integrated into CMOS system due to incompatibility in fabrication process and its high series motional impedance. On the other hand, fully integrated MEMS resonator had been demonstrated but at lower frequency and quality factor.
We propose a design and fabrication process for a low cost, high frequency and a high quality MEMS resonator, which can be integrated into a standard CMOS IC. This device is expected to operate in hundreds of Mhz frequency range; quality factor surpasses 10000 and series motional impedance low enough that could be matching into conventional system without enormous effort. This MEMS resonator can be used in the design of many blocks in wireless and RF (Radio Frequency) systems such as low phase noise oscillator, band pass filter, power amplifier and in many sensing application.

Force sensing in minimally invasive surgery (MIS) is a chronic problem since it has an intensive magnetic resonance (MR) operation environment, which causes a high influence to traditional electronic force sensors. Optical sensor is a promising choice in this area because it is immune to MR influence. However, the changing temperature introduces a lot of noise signals to them, which is the main obstacle for optical sensing applications in MIS. This paper proposes a miniature temperature-compensated optical force sensor by using Fabry-Perot interference (FPI) principle. It can be integrated into medical tools’ tips and the temperature noise is decreased by using a reference FPI temperature sensor. An injection needle with embedded temperature-compensated FPI force sensor has been fabricated and tested. And the comparison between temperature-force simulation results and the temperature-force experiment results has been carried out.

This paper reports the use of liquid marbles (LMs) as miniature bioreactors to produce three-dimensional (3D) spheroids including tumor-like spheriods from cancer cells and embryoid bodies (EBs) from stem cells. A liquid marble microbioreactor is prepared by placing a drop of cell suspension onto a polytetrafluoroethylene (PTFE) particle bed. Without the addition of growth factors, suspended EBs from liquid marbles exhibit spontaneous contraction. These results indicate that the liquid marble provides a suitable microenvironment to induce EB formation and spontaneous cardiac differentiation. The EBs were further plated onto gelatin-coated tissue culture dishes. Plated EBs express mature cardiomyocyte marker cardiac troponinT (cTnT), indicating that these EBs have differentiated into functional cardiomyocytes. The cardiomyocytes generated using this liquid marble approach could be useful for transplantation.

Chronic wounds, such as venous leg ulcers, can be monitored non-invasively by using modern sensing devices and wireless technologies. The development of such wireless diagnostic tools may improve chronic wound management by providing evidence on efficacy of treatments being provided. In this paper we present a low-power portable telemetric system for wound condition sensing and monitoring. The system aims at measuring and transmitting real-time information of wound-site temperature, sub-bandage pressure and moisture level from within the wound dressing.
The system comprises commercially available non-invasive temperature, moisture, and pressure sensors, which are interfaced with a telemetry device on a flexible 0.15 mm thick printed circuit material, making up a lightweight biocompatible sensing device. The real-time data obtained is transmitted wirelessly to a portable receiver which displays the measured values. The performance of the whole telemetric sensing system is validated on a mannequin leg using commercial compression bandages and dressings. A number of trials on a healthy human volunteer are performed where treatment conditions were emulated using various compression bandage configurations.
A reliable and repeatable performance of the system is achieved under compression bandage and with minimal discomfort to the volunteer. The system is capable of reporting instantaneous changes in bandage pressure, moisture level and local temperature at wound site with average measurement resolutions of 0.5 mmHg, 3.0 %RH, and 0.2 °C respectively. Effective range of data transmission is 4-5 m in an open environment.

Optical nano-antennas have become a hot topic in photonics research recently due to their ability to manipulate electromagnetic radiation on the subwavelength scale. Of particular interest is the application of optical nano-antennas to enhancement of quantum sources such as semiconductor Quantum Dots (QD) and Nitrogen Vacancy (NV) centers in nano-diamond. Much like their Radio Frequency (RF) cousins, optical nano-antennas are able to enhance and direct radiation from a localized source in the near-field of the antenna to the far-field. The work reported here exploits RF antenna designs by applying them to the development of optical nano-antennas for enhancement of multiple semiconductor QDs. In particular, the Vee antenna design, commonly used in improvised military RF applications, is utilized in this work as an optical nano-antenna to enable the selective excitation of two different color QDs via polarization control. The Vee antenna has two bright resonant modes in the visible spectrum, typically spectrally separated by approximately 50 nm, which are excited by orthogonal polarizations of the excitation field. Using these two resonant modes of the Vee antenna, two different color QDs can be selectively enhanced. The Vee antennas are fabricated with E-beam Lithography using aluminum as the antenna material on a multilayer SiO2/Al/glass substrate. The Vee antenna design consists of two dipole antennas, orientated at 90° to each other, where the gap between the antennas and the thickness of the SiO2 spacer layer is used to tune the spectral separation of the orthogonal resonances.

Strong Stokes and anti-Stokes one-photon luminescence from single gold nanorods is measured in experiments. It is found that the intensity and polarization of the Stokes and anti-Stokes emissions are in strong correlation. Our experimental observation discovered a coherent process in light emission from single gold nanorods. We present a theoretical mode, based on the concept of cavity resonance, for consistently understanding both Stokes and anti-Stokes photoluminescence. Our theory is in good agreement of all our measurements.

Silver is considered as one of the most desirable materials for plasmonic devices due to it having low loss, low epsilon₂, across the visible spectrum. In addition, silver nanotriangles can self-assemble into complex structures that can include tip-totip or base-to-base arrangements. While the optical properties of tip-to-tip dimers of nanotriangles have been quite intensively studied, the geometric inverse, the base-to-base configuration, has received much less attention. Here we report the results of a computational study of the optical response of this latter configuration. Calculations were performed using the discrete dipole approximation. The effect of gap size and substrate are considered. The results indicate that the base-to-base configuration can sustain a strong coupled dipole and various multimode resonances. The pairing of the parallel triangle edges produces a strongly capacitive configuration and very intense electric fields over an extended volume of space. Therefore, the base-to-base configuration could be suitable for a range of plasmonic applications that require a strong and uniform concentration of electric field. Examples include refractometeric sensing or metal-enhanced fluorescence.

Dynamic and rapid spectral shifts of whispering-gallery mode (WGM) from microdisk laser were studied. The microdisks with diameter about 100 μm were fabricated by ink-jet printing of Rhodamine 590 doped polymer. Sharper edge microdisk and rounder edge microdisk were pumped with Q-switched Nd:YAG laser(@532 nm). A spectral shift −3.77×10^-3 nm/(μJ·mm^-2) was occurred in the case of the rounder edge microdisk, which is smaller than the spectral shift −4.21×10^-3 nm/(μJ·mm^-2) in the case of the sharper edge microdisk. Expecting the anomalous dispersion and Rhodamine 590 degradation affect, under the same excitation condition, the WGM spatial modification can also led to the shifts. And the modification was caused by interaction between the sharpened-edge and the increased optical gain.

Titanium nitride is a golden-colored semiconductor with metallic optical properties. It is already widely used in room temperature spectrally-selective coatings. In contrast, aluminum nitride is a relatively wide-band gap, non-metallic material. Both nitrides have exceptional thermal stability, to over 1000 °C, but are susceptible to oxidation. We will show here that composite coatings consisting of these materials and their complex oxides have considerable potential for spectrally-selective applications, including at elevated temperatures. In particular, we examine the metastable materials produced by magnetron sputtering. The effective dielectric functions of these materials can be tuned over a wide range by manipulation of their microstructure. This provides a strategy to assemble materials with tunable dielectric functions using a 'bottom-up' approach. The results are compared to those achievable by conventional, 'top-down', planar optical stacks comprised of alternating layers of TiN_x and AlN.

The geometry of the Schottky contact electrode is important in the design of Schottky power diodes. This work focuses on the optimum shape of the Schottky contact geometry and uses finite element modeling to determine the effects of the shape on electrical characteristics of a diode. The investigation considers the typical situation where the contact is smaller than the substrate area. Simulations were run with different shapes ranging from perfect square to perfect circle with the size of the diode substrate (die) and the distance between the edge of the diode and edge of the Schottky contact as a constant. The different models were examined and compared with magnitude the occurrence of the maximum current density (for a particular output current) and hence the breakdown regions at current density approaching the critical value for breakdown (most likely destruction of a diode) due to high current density. There as an optimum geometry determined for the highest current that the given diode substrate could deliver. The results clearly show that the optimum geometry for the Schottky contact should be neither perfect square nor perfect circle, but an exact geometry in between. This optimum geometry gives the optimum distribution of current density around the edge of the Schottky contact. Investigation is done using Synopsys TCAD. The forward and reverse bias situations were investigated to optimize the electrode geometry.

Current ‘gold standard’ staging of breast cancer and melanoma relies on accurate in vivo identification of the sentinel lymph node. By replacing conventional tracers (dyes and radiocolloids) with magnetic nanoparticles and using a handheld magnetometer probe for in vivo identification, it is believed the accuracy of sentinel node identification in nonsuperficial cancers can be improved due to increased spatial resolution of magnetometer probes and additional anatomical information afforded by MRI road-mapping. By using novel iron core/iron oxide shell nanoparticles, the sensitivity of sentinel node mapping via MRI can be increased due to an increased magnetic saturation compared to traditional iron oxide nanoparticles. A series of in vitro magnetic phantoms (iron core vs. iron oxide nanoparticles) were prepared to simulate magnetic particle accumulation in the sentinel lymph node. A novel handheld magnetometer probe was used to measure the relative signals of each phantom, and determine if clinical application of iron core particles can improve in vivo detection of the sentinel node compared to traditional iron oxide nanoparticles. The findings indicate that novel iron core nanoparticles above a certain size possess high magnetic saturation, but can also be produced with low coercivity and high susceptibility. While some modification to the design of handheld magnetometer probes may be required for particles with large coercivity, use of iron core particles could improve MRI and magnetometer probe detection sensitivity by up to 330 %.

Plasma immersion ion implantation (PIII) is used here to improve the surface bioactivity of polyether ether ketone (PEEK) by modifying the chemical and mechanical properties and by introducing radicals. Modifications to the chemical and mechanical properties are characterised as a function of ion fluence (proportional to treatment time) to determine the suitability of the treated surfaces for biological applications. Radical generation increases with treatment time, where treatments greater than 400 seconds result in a high concentration of long-lived radicals. Radical reactions are responsible for oxidation of the surface, resulting in a permanent increase in the polar surface energy. The nano-scale reduced modulus was found to increase with treatment time at the surface from 4.4 to 5.2 GPa. The macromolecular Young’s modulus was also found to increase, but by an amount corresponding to the volume fraction of the ion implanted region. The treated surface layer exhibited cracking under cyclical loads, associated with an increased modulus due to dehydrogenation and crosslinking, however it did not show any sign of delamination, indicating that the modified layer is well integrated with the substrate – a critical factor for bioactive surface coatings to be used in-vivo. Protein immobilisation on the PIII treated surfaces was found to saturate after 240 seconds of treatment, indicating that there is room to tune surface mechanical properties for specific applications without affecting the protein coverage. Our findings indicate that the modification of the chemical and mechanical properties by PIII treatments as well as the introduction of radicals render PEEK well suited for use in orthopaedic implantable devices.

The high failure rate of the Yttria Partially Stabilized Zirconia (YPSZ)-porcelain interface in dental prostheses is influenced by the micro-scale mechanical property variation in this region. To improve the understanding of this behavior, micro-scale fracture toughness profiling by nanoindentation micropillar splitting is reported for the first time. Sixty 5 μm diameter micropillars were machined within the first 100 μm of the interface. Berkovich nanoindentation provided estimates of the bulk fracture toughness of YPSZ and porcelain that matched the literature values closely. However, the large included tip angle prevented precise alignment of indenter with the pillar center. Cube corner indentation was performed on the remainder of the pillars and calibration between nanoindentation using different tip shapes was used to determine the associated conversion factors. YPSZ micropillars failed by gradual crack propagation and bulk values persisted to within 15 μm from the interface, beyond which scatter increased and a 10% increase in fracture toughness was observed that may be associated with grain size variation at this location. Micropillars straddling the interface displayed preferential fracture within porcelain parallel to the interface at a location where nano-voiding has previously been observed and reported. Pure porcelain micropillars exhibited highly brittle failure and a large reduction of fracture toughness (by up to ~90%) within the first 50 μm of the interface. These new insights constitute a major advance in understanding the structure-property relationship of this important bi-material interface at the micro-scale, and will improve micromechanical modelling needed to optimize current manufacturing routes and reduce failure.

The epitaxial graphene-on-silicon carbide (SiC-G) has advantages of high quality and large area coverage owing to a natural interface between graphene and SiC substrate with dimension up to 100 mm. It enables cost effective and reliable solutions for bridging the graphene-based sensors/devices from lab to industrial applications and commercialization. In this work, the structural, optical and electrical properties of wafer-scale graphene grown on 2’’ 4H semi-insulating (SI) SiC utilizing sublimation process were systemically investigated with focus on evaluation of the graphene’s uniformity across the wafer. As proof of concept, two types of glucose sensors based on SiC-G/Nafion/Glucose-oxidase (GOx) and SiC-G/Nafion/Chitosan/GOx were fabricated and their electrochemical properties were characterized by cyclic voltammetry (CV) measurements. In addition, a few similar glucose sensors based on graphene by chemical synthesis using modified Hummer’s method were also fabricated for comparison.

In this paper, a proton conducting solid biopolymer electrolytes (SBE) comprises of carboxymethyl cellulose (CMC) as polymer host, ammonium thiocyanate (NH4SCN) as doping salt and ethylene carbonate (EC) as plasticizer has been prepared via solution casting technique. Electrical Impedance Spectroscopy (EIS) was carried out to study the conductivity and electrical properties of plasticized CMC-NH₄SCN SBE system over a wide range of frequency between 50 Hz and 1 MHz at temperature range of 303 to 353 K. Upon addition of plasticizer into CMC-NH₄SCN SBE system, the conductivity increased from 10^-5 to 10^-2 Scm^-1. The highest conductivity was obtained by the electrolyte containing 10 wt.% of EC. The conductivity of plasticized CMC-NH₄SCN SBE system by various temperatures obeyed Arrhenius law where the ionic conductivity increased as the temperature increased. The activation energy, E_a was found to decrease with enhancement of EC concentration. Dielectric studies for the highest conductivity electrolyte obeyed non-Debye behavior. The conduction mechanism for the highest conductivity electrolyte was determined by employing Jonsher’s universal power law and thus, can be represented by the quantum mechanical tunneling (QMT) model.

Zirconium-based alloys are promising materials for orthopedic prostheses due to their low toxicity, superb corrosion resistivity, and favorable mechanical properties. The integration of such bio-implantable devices with local host tissues can strongly be improved by the development of a plasma polymerized acetylene and nitrogen (PPAN) that immobilizes bio-active molecules. The surface chemistry of PPAN is critically important as it plays a key role in affecting the surface free energy that alters the functionality of bio-active molecules at the surface. The cross-linking degree of PPAN is another key property that directly influences the water-permeability and thus also the stability of films in aqueous media. In this study we demonstrate that by simply tuning the zirconium bias voltage, control over the surface chemistry and cross-linking degree of PANN is achieved.

Tamarisk usage as a new group of lignocelluloses material to produce fermentable sugars in bio ethanol process was studied. The overall aim of this work was to establish the optimum condition for acid hydrolysis of this new material and a mathematical model predicting glucose release as a function of operation variable. Sulfuric acid concentration in the range of 20 to 60%(w/w), process temperature between 60 to 95oC, hydrolysis time from 120 to 240 min and solid content 5,10,15%(w/w) were used as hydrolysis conditions. HPLC was used to analysis of the product. This analysis indicated that glucose was the main fermentable sugar and was increase with time, temperature and solid content and acid concentration was a parabola influence in glucose production. The process was modeled by a quadratic equation. Curve study and model were found that 42% acid concentration, 15 % solid content and 90oC were optimum condition.