Magnetic nanoparticles of CoFe₂O₄ have been synthesized under an applied magnetic field through a co-precipitation method followed by thermal treatments at different temperatures, producing nanoparticles of varying size. The magnetic behavior of these nanoparticles of varying size was investigated. As-grown nanoparticles demonstrate superparamagnetism above the blocking temperature, which is dependent on the particle size. The anomalous magnetic behavior is attributed to the preferred Co ions and vacancies arrangements when the CoFe₂O₄ nanoparticles were synthesized under applied magnetic field. Furthermore, this magnetic property is strongly dependent on the high temperature heat treatments, which produce Co ions and vacancies disorder. We performed the fabrication of condensed and mesoporous silica coated CoFe₂O₄ magnetic nanocomposites. The CoFe₂O₄ magnetic nanoparticles were encapsulated with well-defined silica layer. The mesopores in the shell were fabricated as a consequence of removal of organic group of the precursor through annealing. The NiO nanoparticles were loaded into the mesoporous silica. The mesoporous silica coated magnetic nanostructure loaded with NiO as a final product may have potential use in the field of biomedical applications. Growth mechanism of ZnO nanorod arrays on ZnO seed layer investigated by electric and Kelvin probe force microscopy. Both electric and Kelvin force probe microscopy was used to investigate the surface potentials on the ZnO seed layer, which shows a remarkable dependence on the annealing temperature. The optimum temperature for the growth of nanorod arrays normal to the surface was found to be at 600 °C, which is in the range of right surface potentials and energy measured between 500 °C and 700 °C. We demonstrated from both EFM and Kelvin force probe microscopy studies that surface potential controls the growth of ZnO nanorods. This study will provide important understanding of growth of other nanostructures. ZnO nanolayers were also grown by atomic layer deposition techniques. These nanolayers of ZnO demonstrate remarkable optical and electrical properties. These nanolayers were patterned by the Electron Beam Lithography (EBL) technique. A major goal of nanotechnology is to couple the self-assembly of molecular nanostructures with conventional lithography, using either or both bottom-up and top-down fabrication methods, that would enable us to register individual molecular nanostructures onto the functional devices. However, combining the nanofabrication technique with high resolution Electron Beam Lithography, we can achieve 3D bimolecular or/and DNA origami that will be able to identify nucleic acid sequences, antigen targets, and other molecules, as for a perfect nano-biosensor. We have explored some of the nanopatterning using EBL in order to fabricate biomolecule sensing on a single chip with sub nm pitch. The applications are not limited for the bioactivity, but for enhancing immunoreactions, cell culture dishes, and tissue engineering applications.

Neural recording through microelectrodes requires biocompatibility and long term chronic usage. With a potential for various applications and effort to improve the performance of neural recording probes, consideration is taken to the tissue and cellular effects in these device designs. The degeneration of neurons due to brain tissue motion is an issue along with brain tissue inflammation in the insertion of the probes. To account for motion and irritation the material structure of the probes must be improved upon. This research presents the fabrication of neural probes on the microscale utilizing flexible polymers. Polyimide neural probes have been considered possibly to reduce degradation in their variability caused by brain motion. The microfabrication of the polyimide neural probe has an increased flexibility while accounting for biocompatibility and the needs for chronic use. Through microfabrication processes a needle probe is produced and tested for neural recording.

Carbon nanotubes dispersed in polymer matrix have been aligned in the form of fibers and interconnects and cured electrically and by UV light. Conductivity and effective semiconductor tunneling against reverse to forward bias field have been designed to have differentiable current-voltage response of each of the fiber/channel. The current-voltage response is a function of the strain applied to the fibers along axial direction. Biaxial and shear strains are correlated by differentiating signals from the aligned fibers/channels. Using a small doping of magnetic nanoparticles in these composite fibers, magneto-resistance properties are realized which are strong enough to use the resulting magnetostriction as a state variable for signal processing and computing. Various basic analog signal processing tasks such as addition, convolution and filtering etc. can be performed. These preliminary study shows promising application of the concept in combined analog-digital computation in carbon nanotube based fibers. Various dynamic effects such as relaxation, electric field dependent nonlinearities and hysteresis on the output signals are studied using experimental data and analytical model.

We report on the growth of vertically aligned Al:ZnO nanorod arrays synthesized by the hydrothermal technique at considerably low temperature on a sputtered Al:ZnO seed layer. The morphology demonstrates that the nanorod arrays maintain remarkable alignment along the c-axis over a large area. The optoelectronic properties of nanorod arrays on Al:ZnO/p-Si seed layer with SiO₂ have been illustrated. The photocurrent is significantly reduced in nanorod arrays on AZO/SiO2/p-Si heterojunction due to multiple scattering phenomena associated with the nanorod arrays. The optical properties of the AZO film with and without the AZO nanorod arrays were investigated. Also the effects of an intermediate layer in the AZO/P-Si heterojunction structure with and without the AZO nanorod array present were explored. All the various intermediate layers displayed photovoltaic effect behavior, especially with the AZO/SiO₂/P-Si heterojunction structure, which exhibited ideal diode behavior. The optoelectronic properties of nanorod arrays on AZO/P-Si seed layer with SiO₂ have been illustrated. The photocurrent is significantly reduced in nanorod arrays on AZO/SiO₂/P-Si heterojunction due to multiple scattering phenomena associated with the nanorod arrays. The results have tremendous impact for sensor fabrication, including glucose sensor.

A Titanium dioxide (TiO₂)/multi wall carbon nanotubes (MWCNTs) nanocomposite was synthesized by hydrothermal process. X-ray diffractometry, transmittance electron microscopy observation revealed this nanocompsite has high nanocrystral structure. After blending with regenerated cellulose, this hybrid nanocomposite was used as a room temperature ammonia (NH₃) gas sensor. The TiO₂/MWCNTs hybrid nanocomposite exhibited much higher response and faster response-recovery to NH3 gas of concentration ranging from 3000 ppm to 9000 ppm. The TiO₂/MWCNTs hybrid nanocomposite can be a flexible room temperature gas sensor. The gas sensing mechanism of this hybrid nanocomposite is also discussed in this paper.

This paper presents the design of glucose sensors that will be integrated with advanced nano-materials, bio-coatings and electronics to create novel devices that are highly sensitive, inexpensive, accurate, and reliable. In the work presented, a glucose biosensor and its fabrication process flow have been designed. The device is based on electrochemical sensing using a working electrode with bio-functionalized zinc oxide (ZnO) nano-rods. Among all metal oxide nanostructures, ZnO nano-materials play a significant role as a sensing element in biosensors due to their properties such as high isoelectric point (IEP), fast electron transfer, non-toxicity, biocompatibility, and chemical stability which are very crucial parameters to achieve high sensitivity. Amperometric enzyme electrodes based on glucose oxidase (GOx) are used due to their stability and high selectivity to glucose. The device also consists of silicon dioxide and titanium layers as well as platinum working and counter electrodes and a silver/silver chloride reference electrode. Currently, the biosensors are being fabricated using the process flow developed. Once completed, the sensors will be bio-functionalized and tested to characterize their performance, including their sensitivity and stability.

A miniaturized solid-state optical spectrometer chip was designed with a linear gradient-gap Fresnel grating which was mounted perpendicularly to a sensor array surface and simulated for its performance and functionality. Unlike common spectrometers which are based on Fraunhoffer diffraction with a regular periodic line grating, the new linear gradient grating Fresnel spectrometer chip can be miniaturized to a much smaller form-factor into the Fresnel regime exceeding the limit of conventional spectrometers. This mathematical calculation shows that building a tiny motionless multi-pixel microspectrometer chip which is smaller than 1mm³ of optical path volume is possible. The new Fresnel spectrometer chip is proportional to the energy scale (hc/λ), while the conventional spectrometers are proportional to the wavelength scale (λ). We report the theoretical optical working principle and new data collection algorithm of the new Fresnel spectrometer to build a compact integrated optical chip.

Simultaneous monitoring of physiological parameters- multi-lead Electrocardiograph (ECG), Heart rate variability, and blood pressure- is imperative to all forms of medical treatments. Using an array of signal recording devices imply that the patient will have to be confined to a bed. Textiles offer durable platform for embedded sensor and communication systems. The smart healthcare textile, presented here, is a mobile system for remote/wireless data recording and conditioning. The wireless textile system has been designed to monitor a patient in a non-obstructive way. It has a potential for facilitating point of care medicine and streamlining ambulatory medicine. The sensor systems were designed and fabricated with textile based components for easy integration on textile platform. An innovative plethysmographic blood pressure monitoring system was designed and tested as an alternative to inflatable blood pressure sphygmomanometer. Flexible dry electrodes technology was implemented for ECG. The sensor systems were tested and conditioned to daily activities of patients, which is not permissible with halter type systems. The signal quality was assessed for it applicability to medical diagnosis. The results were used to corroborate smart textile sensor system's ability to function as a point of care system that can provide quality healthcare.

The Electrocardiogram(ECG) signal is one of the bio-signals to check body status. Traditionally, the ECG signal was checked in the hospital. In these days, as the number of people who is interesting with periodic their health check increase, the requirement of self-diagnosis system development is being increased as well. Ubiquitous concept is one of the solutions of the self-diagnosis system. Zigbee wireless sensor network concept is a suitable technology to satisfy the ubiquitous concept. In measuring ECG signal, there are several kinds of methods in attaching electrode on the body called as Lead I, II, III, etc. In addition, several noise components occurred by different measurement situation such as experimenter's respiration, sensor's contact point movement, and the wire movement attached on sensor are included in pure ECG signal. Therefore, this paper is based on the two kinds of development concept. The first is the Zibee wireless communication technology, which can provide convenience and simpleness, and the second is motion artifact remove algorithm, which can detect clear ECG signal from measurement subject. The motion artifact created by measurement subject's movement or even respiration action influences to distort ECG signal, and the frequency distribution of the noises is around from 0.2Hz to even 30Hz. The frequencies are duplicated in actual ECG signal frequency, so it is impossible to remove the artifact without any distortion of ECG signal just by using low-pass filter or high-pass filter. The suggested algorithm in this paper has two kinds of main parts to extract clear ECG signal from measured original signal through an electrode. The first part is to extract motion noise signal from measured signal, and the second part is to extract clear ECG by using extracted motion noise signal and measured original signal. The paper suggests several techniques in order to extract motion noise signal such as predictability estimation theory, low pass filter, a filter including a moving weighted factor, peak to peak detection, and interpolation techniques. In addition, this paper introduces an adaptive filter in order to extract clear ECG signal by using extracted baseline noise signal and measured signal from sensor.

This paper presents research activities carried out at VTT Technical Research Centre of Finland in the field of hybrid integration of optics, electronics and mechanics. Main focus area in our research is the manufacturing of electronic modules and product structures with printed electronics, film-over-molding and polymer sheet lamination technologies and the goal is in the next generation of smart systems utilizing monolithic polymer packages. The combination of manufacturing technologies such as roll-to-roll -printing, injection molding and traditional component assembly is called Printed Hybrid Systems (PHS). Several demonstrator structures have been made, which show the potential of polymer packaging technology. One demonstrator example is a laminated structure with embedded LED chips. Element thickness is only 0.3mm and the flexible stack of foils can be bent in two directions after assembly process and was shaped curved using heat and pressure. The combination of printed flexible circuit boards and injection molding has also been demonstrated with several functional modules. The demonstrators illustrate the potential of origami electronics, which can be cut and folded to 3D shapes. It shows that several manufacturing process steps can be eliminated by Printed Hybrid Systems technology. The main benefits of this combination are small size, ruggedness and conformality. The devices are ideally suited for medical applications as the sensitive electronic components are well protected inside the plastic and the structures can be cleaned easily due to the fact that they have no joints or seams that can accumulate dirt or bacteria.

Printing technology enables continuous, high-speed fabrication of thermoelectric devices on both flexible and rigid substrates. The printing process, patterns, substrates and inks need to be investigated and optimized for the fabrication of these printable thermoelectric devices. Ink design in terms of physical properties like wettability and viscosity, choice of binder and filler materials is a critical part in the fabrication of printable thermoelectric devices, especially printable p-type materials and n-type materials to make p-n junctions. In this study, we described the mechanism of thermoelectric generator and synthetic method of thermoelectric materials for printing inks. And the Bi₂Te₃ / epoxy resin and Bi₂Te₃ / polystyrene printing inks were prepared with high energy ball milled Bi₂Te₃ powder.

In recent years, regenerated cellulose has received much attention due to its huge industrial potentials and its feasibility for many industrial applications such as sensors and actuators. However, due to its insulating property, few results used for potential electronic applications have been reported. By modification of cellulose itself, nano-sized electrical inner paths can be formed by chemical bonding of metallic or semiconducting nanowires to cellulose fibrils during regenerated process. Already our earlier result of the chemical bonding between carbon nanotubes and the regenerated cellulose has been reported as a novel electronic material for potential paper transistor. In this paper, we study the cellulose-gold nanowire (GNW) composite for electronic application due to its huge potential for paper transistor and other applications such as biosensors and strain sensors due to its electrical response sensitivity. The detailed material properties of GNW cellulose composite and its potential for electrical applications will be demonstrated.

This paper investigates the feasibility of conductometric glucose biosensor based on glucose oxidase (GOx) immobilized TiO₂-cellulose hybrid nanocomposite. TiO₂ nanoparticles were blended with cellulose solution prepared by dissolving cotton pulp with lithium chloride/N, N-dimethylacetamide solvent to fabricate TiO₂-cellulose hybrid nanocomposite. The enzyme (GOx) was immobilized into this hybrid material by physical adsorption method. The successful immobilization of GOx into TiO₂-cellulose hybrid nanocomposite via covalent bonding between TiO₂ and GOx was confirmed by X-ray photoelectron analysis. The linear response of our propose glucose biosensor is obtained in the range of 1-10mM with correlation coefficient of 0.93. Our study demonstrates TiO₂-cellulose hybrid material as a potential candidate for an inexpensive, flexible and disposable glucose biosensor.

Olivine-structured lithium iron phosphates are promising cathode materials in the development of high power lithium ion batteries for electric vehicles. However, the low electronic conductivity and ionic conductivity of lithium iron phosphates hinder their commercialization pace. This work aims to verify the approaches for improving the electrochemical properties of lithium iron phosphates. In this work, sol-gel method was used to synthesize carbon coated lithium iron phosphates and nickel doped lithium iron phosphates, and their particle sizes were controlled in the nanometer to sub-micrometer range. The crystalline structures of the synthesized lithium iron phosphates were characterized by X-ray diffraction, and their morphologies were analyzed by scanning electron microscopy. To study their electrochemical properties, prototype lithium ion batteries were assembled with the synthesized lithium iron phosphates as cathode active materials, and with lithium metal discs as the anodes, and the discharge / charge properties and cycling behaviors of the prototype batteries were tested at different rates. The synthesized lithium iron phosphate materials exhibited high capacity and high cycling stability. It was confirmed that particle size reduction, carbon coating and metal doping are three effective approaches for increasing the conductivity of lithium iron phosphates, and thus improving their electrochemical properties. Experimental results show that by combing the three approaches for improving the electrochemical properties, lithium iron phosphate composites with characteristics favorable for their applications in lithium ion batteries for electric vehicles can be developed, including high specific capacity, high rate capacity, flat discharge voltage plateau and high retention ratio.

Carbon nanotubes have exhibited excellent molecular adsorption properties and their dimensions are comparable to typical bio-molecules such as the DNA. Carbon nanotube field effect transistors (CNT-FETs) and integrated circuits are being explored for electrical sensing of bio-materials and gases. The adsorbed molecules by the carbon nanotube and the CNT-FET result in a change of the CNT conductance and electronic properties of the CNT-FET which can be easily monitored. It thus becomes very important to better understand electronic transport and model its behavior in relation to bio- and chemical sensing. Some of the recently developed compact analytical models for current transport in CNT-FETs are compatible with EDA tools for analysis and design of CNT-FET based integrated circuits but these are limited to applications in non-ballistic region. Since applications requiring a large number of bio-sensing using CNT-FETs are in 2- 20 nm range, in this work, the current transport model of CNT-FETs has been suitably modified for operation in the ballistic region for use in integrated circuit design and sensing applications. The surface potentials in a CNT-FET have been coupled with the current transport equations to obtain compact electronic current transport models for operation in the ballistic region. A p-type CNT-FET is considered for the analysis which can be easily applied in n-type CNT-FETs. The work is also compared with other electronic transport models and experimental measurements. A close agreement establishes the validity of our electronic transport model of the transistor operation in the ballistic region. It is also shown that two subbands in the valance band of CNT are sufficient for computation of current in CNT-FETs. The current transport model characterizing CNT-FET in the ballistic region is simple and compatible with EDA tools for bio-sensing chip design.

Music is a powerful elicitor of emotions. Emotions evoked by music, through autonomic correlates have been shown to cause significant modulation of parameters like heart rate and blood pressure. Consequently, Heart Rate Variability (HRV) analysis can be a powerful tool to explore evidence based therapeutic functions of music and conduct empirical studies on effect of musical emotion on heart function. However, there are limitations with current studies. HRV analysis has produced variable results to different emotions evoked via music, owing to variability in the methodology and the nature of music chosen. Therefore, a pragmatic understanding of HRV correlates of musical emotion in individuals listening to specifically chosen music whilst carrying out day to day routine activities is needed. In the present study, we aim to study HRV as a single case study, using an e-bra with nano-sensors to record heart rate in real time. The e-bra developed previously, has several salient features that make it conducive for this study- fully integrated garment, dry electrodes for easy use and unrestricted mobility. The study considers two experimental conditions:- First, HRV will be recorded when there is no music in the background and second, when music chosen by the researcher and by the subject is playing in the background.

Various wireless power transfer systems based on electromagnetic coupling have been investigated and applied in many biomedical applications including functional electrical stimulation systems and physiological sensing in humans and animals. By integrating wireless power transfer modules with wireless communication devices, electronic systems can deliver data and control system operation in untethered freely-moving conditions without requiring access through the skin, a potential source of infection. In this presentation, we will discuss a wireless power transfer module using magnetic resonance coupling that is specifically designed for neural sensing systems and in-vivo animal models. This research presents simple experimental set-ups and circuit models of magnetic resonance coupling modules and discusses advantages and concerns involved in positioning and sizing of source and receiver coils compared to conventional inductive coupling devices. Furthermore, the potential concern of tissue heating in the brain during operation of the wireless power transfer systems will also be addressed.

Nondestructive Structural health monitoring (SHM) system using wireless sensor network is the one of important issue for aerospace and civil engineering. Chipless passive wireless sensor system is one of novel methods for SHM which uses the electromagnetic wave characteristic change by geometrical change of electromagnetic resonators or impedance change of functional material sensing part without RFID chip. In this paper, the chipless passive wireless SHM sensor using frequency selective surface (FSS) is investigated. Electromagnetic characteristic change of FSS by mechanical strain or structural damage is investigated by simulation and experiment.

A brain-machine interface (BMI) links a user's brain activity directly to an external device. It enables a person to control devices using only thought. Hence, it has gained significant interest in the design of assistive devices and systems for people with disabilities. In addition, BMI has also been proposed to replace humans with robots in the performance of dangerous tasks like explosives handling/diffusing, hazardous materials handling, fire fighting etc. There are mainly two types of BMI based on the measurement method of brain activity; invasive and non-invasive. Invasive BMI can provide pristine signals but it is expensive and surgery may lead to undesirable side effects. Recent advances in non-invasive BMI have opened the possibility of generating robust control signals from noisy brain activity signals like EEG and EOG. A practical implementation of a non-invasive BMI such as robot control requires: acquisition of brain signals with a robust wearable unit, noise filtering and signal processing, identification and extraction of relevant brain wave features and finally, an algorithm to determine control signals based on the wave features. In this work, we developed a wireless brain-machine interface with a small platform and established a BMI that can be used to control the movement of a robot by using the extracted features of the EEG and EOG signals. The system records and classifies EEG as alpha, beta, delta, and theta waves. The classified brain waves are then used to define the level of attention. The acceleration and deceleration or stopping of the robot is controlled based on the attention level of the wearer. In addition, the left and right movements of eye ball control the direction of the robot.

Over time, a wide variety of Haptic actuator have been designed and implemented to apply for mobile devices. This paper addresses an electrostatic actuator composed of an active film and patterned polydimethylsiloxane (PDMS) columns. A cellulose acetate (CA) film charged with an electric potential can generate vibration under the potential. The motion of the actuator is a concave and the actuator performance was modulated by increasing the bias level of the electric potential. The performance was evaluated depending on various actuation conditions in terms of electrical potential, bias voltage and frequency. It was found that the induced displacement of the actuator is proportional to the bias level of electric potential. Fast rising and falling behavior of the proposed haptic actuator can allow the generation of a vibrotactile sensation over a wide frequency range. The CA haptic actuator has a potential to generate a wide variety of tactile sensations.

We present a review of different micropatterning technologies for flexible elastomeric functional nanocomposites with a particular emphasis on mold material and processes for production of large size substrates. The functional polymers include electrically conducting and magnetic materials developed at the Micro-instrumentation Laboratory at Simon Fraser University, Canada. We present a chart that compares many of these different conductive and magnetic functional nanocomposites and their measured characteristics. Furthermore, we have previously reported hybrid processes for nanocomposite polymers micromolded against SU-8 photoepoxy masters. However, SU-8 is typically limited to substrate sizes that are compatible with microelectronics processing as a microelectronics uv-patterning step is typically involved, and de-molding problems are observed. Recently, we have developed new processes that address the problems faced with SU-8 molds. These new technologies for micropatterning nanocomposites involve new substrate materials. A low cost Poly(methyl methacrylate) (PMMA) microfabrication technology has been developed, which involves fabrication of micromold via either CO₂ laser ablation or deep UV. We have previously reported this large-scale patterning technique using laser ablation. Finally, we compare the two processes for PMMA producing micromolds for nanocomposites.

The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV (±0.2eV) respectively. This is less than that of undoped ScN (2.5±0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (E_g), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM analysis. These results give an insight for future applications for the field-controlled spectrally active material

Electromagnetic characteristics like absorption and electric field distributions of metallic carbon nanotubes are simulated using the discrete dipole approximation. Absorption of electromagnetic energy over a range of frequencies are studied for both parallel and perpendicular incidence of light to the axis of carbon nanotube. Our simulations show 30% enhancement of electric field in the radial direction for nanotubes with axial strain of 0.2 when compared to unstrained nanotubes in case of parallel incidence of light. Simulations for perpendicular incidence of light show an oscillatory behavior for the electric field in the axial direction. Analysis of simulation results indicate potential applications in designing nanostructured antennae and electromagnetic transmission/shielding using CNT-composite.

We report on the successful covalent functionalization of carbon nanotube (CNT) forests, in situ grown on a silicon chip with thin metal contact film as the buffer layer between the CNT forests and the substrate. The CNT forests were successfully functionalized with active amine and azide groups, which can be used for further chemical reactions. The morphology of the CNT forests was maintained after the functionalization. We thus provide a promising foundation for a miniaturized biosensor arrays system that can be easily integrated with Complementary Metal-Oxide Semiconductor (CMOS) technology.

Printing method for electronics elements fabrication has attractive advantages such as low material consumption, high speed fabrication, and low temperature process. The stable conductive ink is the most important factor for the fabrication of printed electronics elements with high resolution. These materials are widely used as fillers in conductive inks; metal particles, conductive polymers, and carbon materials. Among these materials, the carbon nanotubes (CNTs) are extremely attractive filler for printed electronics due to its superior electrical properties, extra high mechanical properties, and excellent chemical stability. In this research, nano-composites which are composed of multi wall carbon nanotubes (MWCNTs) and polyaniline core-shell type particles were synthesized and formulated into electrically conductive colloidal inks. The poly(acrylonitrile-co-itaconic acid-co-methylacrylate) nanoparticles were used as cores. And this core was coated with polyaniline. The surface treatments for MWCNTs were applied to make the stable nano-composites. The experimental conditions were optimized to achieve high miscibility between MWCNTs and polyaniline coated particles. Their structure and surface morphology of the nanocomposites were characterized by Scanning Electron Microscopy. And four point probe automatic resistivity meter was used to measure the conductivities of the nanocomposites.

This paper presents the influence of reaction time for the thickness and particle density of ZnO layer. Paper-like ZnOCellulose hybrid nanocomposite was fabricated using a low temperature hydrothermal synthesis in the aqueous solution. This ZnO nanostructure on the cellulose as thin ZnO layer, utilized substrate via simple reaction including the alkaline hydrolysis, was composed by hydrothermal synthesis. It is revealed that growth mechanism of ZnO nano-rod of the ZnO-Cellulose hybrid nanocomposite is governed as the crystal orientation limited by structural and morphological analysis. As the reaction time of chemical process increases, the size of the ZnO nanostructure also increases. These composite materials can be used to smart materials for flexible electronic or electro-mechanical devices such as transistors and strain sensors.

Magnetic nanoparticles have been used in a wide array of industrial and biomedical applications due to their unique properties at the nanoscale level. They are extensively used in magnetic resonance imaging (MRI), magnetic hyperthermia treatment, drug delivery, and in assays for biological separations. Furthermore, superparamagnetic nanoparticles are of large interest for in vivo applications. However, these unmodified nanoparticles aggregate and consequently lose their superparamagnetic behaviors, due to high surface to volume ratio and strong dipole to dipole interaction. For these reasons, surface coating is necessary for the enhancement and effectiveness of magnetic nanoparticles to be used in various applications. In addition to providing increased stability to the nanoparticles in different solvents or media, stabilizers such as surfactants, organic/inorganic molecules, polymer and co-polymers are employed as surface coatings, which yield magnetically responsive systems. In this work we present the synthesis and magnetic characterization of Fe3O4 nanoparticles coated with 3-aminopropyltriethoxy silane (APS) and citric acid. The particles magnetic hysteresis was measured by a superconducting quantum interference device (SQUID) magnetometer with an in-plane magnetic field. The uncoated and coated magnetic nanoparticles were characterized by using fourier transform infrared (FTIR), UV-vis, X-ray diffraction, transmission electron microscopy, and thermo-gravimetric analysis.

Electroporation is the formation of reversible pores in cell membranes without rupturing the membrane using a high electric field. Electroporation is an important technique for various biomedical applications including drug delivery, gene transfection and therapeutic treatments. A microfluidic device was developed to investigate electroporation using single and multiple pulses. The device contained integrated electrodes inside microchannels. Stained cells were introduced inside the microchannels and excitation pulses were applied. Sequences of images were captured using an integrated-camera on an optical microscope in the bright-field mode. Stained pixel data from the sequences of images were extracted through image processing to detect and quantify electroporation. Flow Index of EP (FIEP) was computed from the normalized (wrt initial) stained pixel data. Multiple pulses increased FIEP when increased energy was delivered, but reduced FIEP when the same amount of energy was delivered. Mean FIEP using 20 V excitation for 1 pulse of 1 ms was 0.256, 10 pulses of 1 ms was 0.329 and 1 pulse of 10 ms was 0.422. These experimental results show that a single pulse is more effective to induce higher FIEP compared to multiple pulses. FIEP enables quantitative and systematic study towards optimization of pulse parameters for electroporation-based applications.

Microwave can be used as a power carrier to implanted medical devices wirelessly, which is regarded as one of the attractive features for medical applications. The loss mechanism of microwave transmission through lossy media often appears as a thermal effect due to the absorption of microwave. Such a thermal effect on human tissue has not rigorously studied yet. The thermal effect on living tissues was experimentally tested with animal skins to understand the absorption characteristics of microwave. In this paper, the frequency range of microwave used for the tests was from 6 GHz to 13 GHz.

Microfluidics is revolutionizing laboratory methods and biomedical devices, offering new capabilities and instrumentation in multiple areas such as DNA analysis, proteomics, enzymatic analysis, single cell analysis, immunology, point-of-care medicine, personalized medicine, drug delivery, and environmental toxin and pathogen detection. For many applications (e.g., wearable and implantable health monitors, drug delivery devices, and prosthetics) mechanically flexible polymer devices and systems that can conform to the body offer benefits that cannot be achieved using systems based on conventional rigid substrate materials. However, difficulties in implementing active devices and reliable packaging technologies have limited the success of flexible microfluidics. Employing highly compliant materials such as PDMS that are typically employed for prototyping, we review mechanically flexible polymer microfluidic technologies based on free-standing polymer substrates and novel electronic and microfluidic interconnection schemes. Central to these new technologies are hybrid microfabrication methods employing novel nanocomposite polymer materials and devices. We review microfabrication methods using these materials, along with demonstrations of example devices and packaging schemes that employ them. We review these recent developments and place them in the context of the fields of flexible microfluidics and conformable systems, and discuss cross-over applications to conventional rigid-substrate microfluidics.

This paper investigates a direct inkjet printing method for electrode patterning on cellulose Electro-Active Paper (EAPap). Flexibility and transparency of the EAPap are advantageous for a versatile substrate in flexible printable electronics. The effects of curing conditions are evaluated by electrical resistivity and morphological analysis. To fabricate EAPap device, inter-digital transducer (IDT) electrodes are printed on the EAPap with drop-on-demand inkjet printing method. Silver patterns are obtained from organometallic silver ink by jetting and heat treatment at 160°C in air. IDT patterns are made on cellulose for variety and extensive application of inkjet printing electronics.

In this research work, a phase modulation surface plasmon resonance (SPR) image detection system adapted timestepped quadrature phase shifting method as the phase retrieving technique has been developed. There are many techniques used to retrieve the phase from interference fringes, such as five steps phase shifting, rotating analyzer, etc. However, they need five fringes images or three rotating steps of the optical component for each phase retrieving. We chose the time-stepped quadrature phase shifting method to be the phase retrieving technique. Since this method is originally developed for electronic speckle pattern interferometry (ESPI), we have modified the algorithm and verified it with the simulated data. The path-independent phase unwrapping method was utilized to reconstruct the sample's phase distribution on the testing area. A previous built-up system, OBMorph, has been modified to complete the time-stepped quadrature phase shifting technique based phase modulation SPR image detection system. Some different concentration sodium chloride-water solution and Ethanol-water solution has been measured. The experimental results showed the trend of the phase variation was coincident to the concentration change. Hence, the system we developed can successfully obtain the phase changes while the sample varies.

To retrieve effective refractive indices, impedances, and material properties, such as electric permittivity (ε) and magnetic permeability (μ) of MMs, we propose a full extraction method allowing determination of properties over all frequencies of interest including the strong resonant band, where the results are unavailable by the well-known robust method proposed by Kong. The proposed method based on the material continuity can retrieve missing results in the strong resonant band where the imaginary part of permittivity or permeability is negative. Two optimization models proposed to determine effective boundaries of split-ring-resonator (SRR)-based and fishnet MMs are defined based on the assumption of effective medium theory and characteristic of homogeneous media. The results are then compared with the traditional definition proposed by Kong. Finally, the refractive index, impedance, permittivity, and permeability of two slabs composed of SRR-based and fishnet MMs, respectively, are retrieved by the proposed method.

The robustness and reliability of two nondestructive evaluation methods to assess dental prostheses stability is presented. The study aims at addressing an increasing need in the biomedical area where robust, reliable, and noninvasive methods to assess the bone-interface of dental and orthopedic implants are increasingly demanded for clinical diagnosis and direct prognosis. The methods are based on the electromechanical impedance method and on the propagation of solitary waves. Nobel Biocare® 4.3 x 13 mm implants were entrenched inside bovine rib bones that were immersed inside Normal Saline for 24 hours before test in order to avoid dehydration and simulating physiologic osmolarity of the corticocancellous bone and plasma. Afterwards the bones were immersed in a solution of nitric acid to allow material degradation, inversely simulating a bone-healing process. This process was monitored by bonding a Piezoceramic Transducer (PZT) to the abutment and measuring the electrical admittance of the PZT over time. On the other hand the bones calcium loss was calculated after immersing in acid by Atomic Absorption Spectroscopy over time for comparison. Moreover a novel transducer based on the generation and detection of highly nonlinear solitary waves was used to assess the stiffness of the abutment-implant bone. In these experiments it was found that the PZT's conductance and some of the solitary waves parameters are sensitive to the degradation of the bones and was correlated to the bone calcium loss over time.

Flat panels imagers based on amorphous silicon technology (a-Si) for digital radiography have been accepted by the medical community as having several advantages over film-based systems. Radiotherapy treatment planning systems employ computed tomographic (CT) data sets and projection images to delineate tumor targets and normal structures that are to be spared from radiation treatment. The accuracy of CT numbers is crucial for radiotherapy dose calculations. Conventional CT scanners operating at kilovoltage X-ray energies typically exhibit significant image reconstruction artifacts in the presence of metal implants in human body. Megavoltage X-ray energies have problems maintaining contrast sensitivity for the same dose as kV X-ray systems. We intend to demonstrate significant improvement in metal artifact reductions and electron density measurements using an amorphous silicon a-Si imager obtained with an X-ray source that can operate at energies up to 1 MeV. We will investigate the ability to maintain contrast sensitivity at this higher X-ray energy by using targets with lower atomic numbers and appropriate amounts of Xray filtration than are typically used as X-ray production targets and filters.

The performance of dipole rectenna for microwave power transmission is very critical to the size and configuration of the dipole rectenna. Thus, it is important to verify the performance of dipole rectenna by comparing its performance in terms of simulation and experiment. This paper reports an experimental and computational investigation of coplanar strip (CPS) dipole rectenna for microwave power transmission. Rectenna consists of an antenna and a rectifier that involves a Schottky diode. CPS dipole antenna and rectenna are simulated using commercial software, so called Ansoft's HFSS and Designer. CPS dipole antenna as well as rectenna is fabricated on a copper coated polyimide substrate using an etching process. The characteristics of CPS dipole antenna are tested by using a pulse analyzer and spectrum analyzer under a 1.2 W microwave power incidence. Comparison of the simulation results with the experiments is made. The verified simulation approach for the CPS dipole rectenna will bring an effective design approach of rectennas for microwave power transmission.

Brain cells located adjacent to an implantable electrode are susceptible to both insertion and mechanical damage due to micromotion as the tissue undergoes cyclic periods of pulsation and breathing. The brain cells inevitably interface with electrodes that are typically much lighter and stiffer in comparison. As a result, the brain's high sensitivity to deformation poses a great challenge in designing a neuron probe that is durable throughout time, as mechanical damage in the brain can reduce the usefulness of the electrode. A number of electrode design parameters need to be examined to determine how the brain's high susceptibility to deformation can be minimized, such as material properties and geometry. Objectively, a neuron probe may need to be designed such that it can conform to motion of the brain while electrical functionality is maintained during deformation. To better understand the design enhancements needed for the neuron probe, a series of dynamic simulations are conducted which represent the motion the brain is expected to undergo over time. This motion will, in turn, influence the motion of the neuron probe throughout time. Of interest is how the brain tissue deformation near the interface of the neuron probe will be affected by micromotion of the probe. The nonlinear transient explicit finite element code LS-DYNA is used to carry out the analyses.

Hematite nanoparticles are a type of promising electrode active materials for lithium ion batteries due to their low cost and high specific capacity. However, the cycling performances of hematite nanoparticles are not as good as those of the conventional electrode active materials for lithium ion batteries. This paper reports the study on the relationship between the electrochemical properties and the particle sizes and shapes, aiming to optimize the electrochemical properties of hematite nanoparticles for their applications in lithium ion batteries. Three types of hematite nanoparticles were compared, including hematite nanospheres with an average diameter of 200 nm, hematite nanoflakes with an average maximum dimension of 200 nm, and hematite nanospheres with an average diameter of 30 nm. Their crystalline structures were characterized by X-ray diffraction (XRD) and their particle morphologies were analyzed by scanning electron microscopy (SEM). Composite electrode materials were made from hematite nanoparticles with carbon black as the conducting material and PVDF as the binding material (hematite : carbon black : PVDF = 70 : 15 : 15). Prototype lithium ion batteries (CR2032 button cells) were assembled with the composite electrodes as cathodes, metal lithium as anodes, and Celgard 2400 porous membrane as separators. It was found that in the first few cycles, the specific discharge capacity of hematite nanospheres with an average diameter of 30 nm is higher than those of the other two, while after first seven cycles, the specific discharge capacity of hematite nanospheres with an average diameter of 30 nm is lower than those of the other two. Possible approaches for improving the cycling performance and rate capacity of hematite nanoparticles are discussed at the end of this paper.

Recent experiments with non-uniform plastic deformation have shown the size effects in micro/nano scale. But the classical continuum plasticity can't predict these size effects in micro/nano scale, since the constitutive equation of the classical mechanics doesn't include the internal length as a parameter for the deformation. The mechanism based strain gradient plasticity is one of the methods to analyze non-uniform deformation behavior in micro/nano scale. The MSG plasticity is the multi-scale analysis connecting the micro-scale notion of the statistically stored dislocations and the geometrically necessary dislocation to meso-scale deformation using the strain gradient. In this paper, modified strain gradient theory is proposed based on the nonhomogeneity of polycrystalline metallic materials and free surface effect. Consideration of the geometrically necessary dislocations on the grain boundary and the free surface effect suggests a relationship between the characteristic length, specimen size and grain size. This relationship can explain the size effects and flow stress in micro/nanoscale structures. We will propose a new model for bending tests using the modified strain gradient plasticity theory. Using the proposed model, bending behavior of polycrystalline materials in micron-scale structures is investigated, and compared with experimental results from other researchers.

Layered lithiated transition metal oxides have been extensively developed and investigated as a cathode materials for lithium ion batteries due to the following advantages, such as high output voltage of 3.6 V, high energy density larger than 450Wh/dm³, low self-discharge rate less than 10%, no memory effect resulting in long cycle lives for more than 1000 times charging and discharging, free maintenance and no environmental pollution. The cathode materials in lithium ion battery are generally in the form of LiMO2 (M= Co, Ni, Mn, etc). Currently, lithium vanadium oxides also were studied. It is well known that the synthetic condition and methods are closely related to the electrochemical properties of lithium ion batteries. In this work, the wet chemical sol gel techniques have been used to synthesize LiNiO₂ and LiV₃O₈. In this study, the LiNiO₂ particles and LiV₃O₈ nanorods were successfully synthesized by sol-gel wet chemical methods. Annealing heat treatment influence the crystallinity of the final product, which may be consequently affected their electrochemical performance.

We report here the investigation of Al-doped ZnO films fabricated by the RF magnetron deposition technique. The films show excellent crystalline quality with atomically smooth surface morphology. The Al-doped ZnO films have been characterized in detail using X-ray diffraction, X-ray photoelectron spectroscopy, atomic force microscopy UV-visible spectrophotometer and four probe technique. It was found that the morphological, structural, electrical and optical properties of Al-doped ZnO films are greatly dependent on substrate temperature. XRD patterns show that all the films are well crystallized with hexagonal wurtzite structure with preferred orientation along (0 0 2) plane. The electrical resistivity of Al-doped ZnO films decreases with increasing substrate temperature and was found to be close to 1.5 × 10^-3 ohm-cm and transmittance >85% in the visible region.

Non-invasive surgery techniques and drug delivery system with acoustic characteristics of ultrasound contrast agent have been studied intensively in recent years. Ultrasound contrast agent collapses easily under the blood circulating and the ultrasound irradiating because it is just a stabilized bubble without solid-shell by surface adsorption of surfactant or lipid. For improving the imaging stability, we proposed the fabrication method of the hollow microcapsule with polymer shell, which can be fabricated just blowing vapor of commonly-used instant adhesive (Cyanoacrylate monomer) into water as microbubbles. Therefore, the cyanoacrylate vapor contained inside microbubble initiates polymerization on the gasliquid interface soon after microbubbles are generated in water. Consequently, hollow microspheres coated by cyanoacrylate thin film are generated. In this report, we revealed that diameter distributions of microbubbles and microcapsules were approximately same and most of them were less than 10 μm, that is, smaller than blood capillary. In addition, we also revealed that hollow microcapsules enhanced the acoustic signal especially in the harmonic contrast imaging and were broken or agglomerated under the ultrasound field. As for the yield of hollow microcapsules, we revealed that sodium dodecyl sulfate addition to water phase instead of deoxycolic acid made the fabrication yield increased.