This PDF file contains the front matter associated with SPIE Proceedings Volume 6413, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Demands from the fields of bio-medical engineering and biologically-inspired robotics motivate a growing interest in actuators with properties similar to biological muscle, including ionic polymer-metal composites (IPMC), the focus of this study. IPMC actuators consist of an ion-conductive polymer membrane, coated with thin metal electrodes on both sides and bend when voltage is applied. Some of the advantages of IPMC actuators are their softness, lack of moving parts, easy miniaturization, light weight and low actuation voltage. When used in bio-mimetic robotic applications, such as a snake-like swimming robot, locomotion speed can be improved by increasing the bending amplitude. However, it cannot be improved much by increasing the driving voltage, because of water electrolysis. To enhance the bending response of IPMCs we created a "preferred" bending direction by anisotropic surface modification. Introduction of anisotropic roughness with grooves across the length of the actuator improved the bending response by a factor of 2.1. Artificially introduced cracks on the electrodes in direction, in which natural cracks form by bending, improved bending response by a factor of 1.6. Anisotropic surface modification is an effective method to enhance the bending response of IPMC actuators and does not compromise their rigidity under loads perpendicular to the bending plane.

Carbon possesses a number of properties that make it ideal for use in sensor and electrical applications. Using radio frequency plasma with various precursor gases it is possible to prepare carbon surfaces for further molecular attachment or functionalisation. Research in our laboratory has involved studies of plasma fluorination, hydrogenation and methanation of highly ordered pyrolytic graphite (HOPG) (as it serves as a highly ordered, single crystal, model substrate for other more complex forms of carbon), glassy carbon in the form of pyrolysed photoresist films (PPF) and single-walled carbon nanotubes (SWCNTs). Treated surfaces have been characterised using a variety of investigatory surface techniques. In this article we report on results obtained using X-ray Photoelectron Spectroscopy (XPS) for probing the chemical nature of the surface and hence the extent of treatment; Time of Flight Secondary-Ion Mass Spectrometry (ToFSIMS) has been utilised to examine the molecular surface structure and in particular, determine the extent of surface hydrogenation; Scanning Tunnelling Microscopy (STM) measurements provide information on the morphology of treated surfaces, in particular the damage and change in surface structures caused by various plasma treatments. We show in this work that the morphology, mechanisms and extent of modification of the plasma-modified surface obtained is strongly influenced by various experimental conditions. For instance, etching and/or nucleation and growth features are observed, with the type of features and their distribution strongly dependent on the precursor gas that is used to support the plasma. Other important parameters are operating pressure, RF power and exposure time.

We fabricated three dimensional networks of ZnO tetrapods on quartz substrates via a thermal oxidation reaction of Zn powder in air mixed with water vapor. The amount of water vapor in air was found to be a key parameter in controlling the yield of tetrapods and thus the formation of the network of tetrapods. The total oxygen amount was helpful in fine tuning the dimension of the tetrapods so as to obtain thin and long tetrapod legs which are essential in building the network of tetrapods. Tetrapod networks were tested as a gas sensing element by measuring changes in their electrical resistances upon exposure to ethanol vapor. The optimum operating temperature of the tetrapod network used as a gas sensing element was in the 400-500 °C range. Ethanol concentration as low as 500 ppb was detected with a response larger than 2, suggesting a high sensitivity to ethanol vapor for this novel structure. The response time to gas exposure of a dense tetrapod network consisting of tetrapods having thin and long legs was as fast as 10 sec, pointing to superior properties of the tetrapod network over standard gas sensing elements.

In order to demonstrate the feasibility of Active Fiber Composites (AFC) as sensors for detecting damage, a pretwisted strip made of AFC with symmetric free-edge delamination is considered in this paper. The strain developed on the top/bottom of the strip is measured to detect and assess delamination. Variational Asymptotic Method (VAM) is used in the development of a non-classical non-linear cross sectional model of the strip. The original three dimensional (3D) problem is simplified by the decomposition into two simpler problems: a two-dimensional (2D) problem, which provides in a compact form the cross-sectional properties using VAM, and a non-linear one-dimensional (1D) problem along the length of the beam. This procedure gives the non-linear stiffnesses, which are very sensitive to damage, at any given cross-section of the strip. The developed model is used to study a special case of cantilevered laminated strip with antisymmetric layup, loaded only by an axial force at the tip. The charge generated in the AFC lamina is derived in closed form in terms of the 1D strain measures. It is observed that delamination length and location have a definite influence on the charge developed in the AFC lamina. Also, sensor voltage output distribution along the length of the beam is obtained using evenly distributed electrode strip. These data could in turn be used to detect the presence of damage.

There is a growing demand for lightweight structures in aircraft systems for energy and cost savings. The authors have therefore continued development of the Highly Reliable Advanced Grid Structure (HRAGS) with the aim of application of the same to aircraft. HRAGS is provided with health monitoring functions that make use of Fiber Bragg Grating (FBG) sensors in advanced grid structures, which have been the focus of attention in recent years as lightweight structures. It is a new lightweight structural concept that enables lighter weight to be obtained while maintaining high reliability. This report describes the tests and evaluation of the Proto System conducted to verify experimentally the concept of the highly reliable advanced grid structure. The Proto System consists of a skin panel embedded with 29 FBG sensors and a wavelength detection system. The artificial damage to the skin panel of the specimen was successfully detected by comparing the strain distributions before and after the introduction of the damage measured by FBG sensors. Next, the application of HRAGS to the wing tip was studied. The results of the studies above are reported here.

Pb(Zr_xTi_1-x)O₃ (PZT) thin films were coated on Pt/Ti/SiO₂/Si substrates by a sol-gel method and then crystallized by 28 GHz microwave irradiation. The crystalline phases and microstructures as well as the electrical properties of the microwave-irradiated PZT films were investigated as a function of the elevated temperature generated by microwave irradiation. X-ray diffraction analysis indicated that the PZT films crystallized well into the perovskite phase at an elevated temperature of 480°C by microwave irradiation. Scanning electron microscopy images showed that the films had a granular grain structure and most of the grains were approximately 1.5 μm in size. With increasing the elevated temperature from 480°C to 600°C by microwave irradiation, the breadth of grain boundaries of the films became narrow and the remanent polarization of the films increased lightly. It is clear that microwave irradiation is effective for obtaining well-crystallized PZT films with good properties at low temperatures in a short time.

A three dimensional electro-mechanical continuum field model is developed to analyze the constrained boundary effects on the transduction performance of thin Piezoelectric films. The model proposed in this paper for Piezoelectric thin film is based on 3D continuum mechanics under plane-stress condition. The plane-stress condition is justifiable for the fact that the thickness of the piezoelectric film is of the order of microns(in 'z' direction); and hence, very small in comparison to the other two dimensions(in 'x' and 'y' directions) of the film. The film, and its proposed model, are intended to be used for Structural Health Monitoring of any structural component, such as, wing of an aircraft. The thin film is surface-mounted on this structural component, and this component will be termed as Host structure, henceforth. When the host structure is strained under the action of loads, the displacement vector field that is generated acts as an input to the thin film in this model. The performance of the thin film in terms of its voltage response, capacitance, and effect of residual stresses on capacitance and output voltage are studied here. The results show significant variation of the same as compared to conventional design and analysis based on electro-statics. The voltage distribution and its variation over the film when a crack is initiated in the host structure under mode-I and mode-II loadings are also presented. It has been observed that in microelectronic devices, various process-induced stresses such as intrinsic stress, epitaxial stress, thermal stress etc., play crucial role in the device performance. The model presented here is capable of handling such stresses while designing the sensor itself.

The evaluation of cell-material surface interactions is important for the design of novel biomaterials which are used in a variety of biomedical applications. While traditional in vitro test methods have routinely used samples of relatively large size, microarrays representing different biomaterials offer many advantages, including high throughput and reduced sample handling. Here, we describe the simultaneous cell-based testing of matrices of polymeric biomaterials, arrayed on glass slides with a low cell-attachment background coating. Arrays were constructed using a microarray robot at 6 fold redundancy with solid pins having a diameter of 375 μm. Printed solutions contained at least one monomer, an initiator and a bifunctional crosslinker. After subsequent UV polymerisation, the arrays were washed and characterised by X-ray photoelectron spectroscopy. Cell culture experiments were carried out over 24 hours using HeLa cells. After labelling with CellTracker^® Green for the final hour of incubation and subsequent fixation, the arrays were scanned. In addition, individual spots were also viewed by fluorescence microscopy. The evaluation of cell-surface interactions in high-throughput assays as demonstrated here is a key enabling technology for the effective development of future biomaterials.

Manipulating biomolecules at solid/liquid interfaces is important for the development of various biodevices including microarrays. Smart materials that enable both spatial and temporal control of biomolecules by combining switchability with patterned surface chemistry offer unprecedented levels of control of biomolecule manipulation. Such a system has been developed for the microscale spatial control over both DNA and cell growth on highly doped p-type silicon. Surface modification, involving plasma polymerisation of allylamine and poly(ethlylene glycol) grafting with subsequent laser ablation, led to the production of a patterned surface with dual biomolecule adsorption and desorption properties. On patterned surfaces, preferential electro-stimulated adsorption of DNA to the allylamine plasma polymer surface and subsequent desorption by the application of a negative bias was observed. The ability of this surface to control both DNA and cell attachment in four dimensions has been demonstrated, exemplifying its capacity to be used for complex biological studies such as gene function analysis. This system has been successfully applied to living microarray applications and is an exciting platform for any system incorporating biomolecules.

In this paper we propose the use of a RF controlled microvalve for implementation on a PZT substrate for biomedical applications. Such device has a huge range of applications such as parallel mixing of photo-lithographically defined nanolitre volumes, flow control in pneumatically driven microfluidic systems and lab-on-chip applications. The microvalve makes use of direct actuation mechanisms at the microscale level to allow its use in vivo applications. A number of acoustic propagation modes are investigated and their suitability for biomedical applications, in terms of the required displacement, device size and operation frequency. A theoretical model of the Surface Acoustic Wave (SAW) device is presented and its use in micro-valve application was evaluated using ANSYS tools. Furthermore, the wireless aspect of the device is considered through combining the RF antenna with the microvalve simulation by assuming a high carrier frequency with a small peak-to-peak signal. A new microvalve structure which uses a parallel type piezoelectric bimorph actuator was designed and simulated using ANSYS tools. Then, further optimization of the device was carried out to achieve a better coupling between electrical signal and mechanical actuation within the SAW device.

The physicochemical properties of biological membranes are crucial to understand membrane function, since their main role is to provide a barrier that divides electrolytic solutions into different compartments guaranteeing at the same time membrane mechanical stability. It is well-known that the chemical composition of the phospholipid molecules that compose the membrane greatly determine the architecture of such biological systems. Force Spectroscopy with AFM is a powerful tool able to study the nanomechanical properties of supported planar bilayers (SPBs). Force plots on lipid bilayers show a discontinuity in the approaching curve that is interpreted as the penetration of the AFM tip through the lipid bilayer. The force at which this discontinuity occurs is the maximum force the bilayer is able to withstand before breaking and it can be regarded as a "fingerprint" of the bilayer stability, just like force is the fingerprint for a protein to unfold or for a hard material surface to be indented. We report on an experimental quantitative Force Spectroscopy study on how both lipid bilayer stability and compactness depend on the solution ionic composition.

A capsid is the protein coat surrounding a virus' genome that ensures its protection and transport. The capsid of murine polyomavirus (muPy) consists of one major (VP1) and two minor (VP2/3) proteins, from which just VP1 is sufficient to form the capsid when expressed recombinantly (1). From a material engineering point of view, viral capsids are of interest because they present a paradigm for complex self-assembly on the nanometer scale. Understanding and controlling these assembly dynamics will allow the construction of nanoscale structures using a self-assembly process. The first step in this direction was the discovery that capsids of several viruses can be reversibly disassembled into their building blocks and reassembled using the same building blocks by simply changing the buffer conditions (2, 3). Such capsids already find applications as targeted in vivo delivery vectors for genes, proteins or small molecular drugs (4, 5), as optical probes for biomedical imaging and sensing purposes with unprecedented resolution and sensitivity and can potentially be used as templates for nanoelectronics (6, 7). Here we show the controlled incorporation of inorganic gold nanoparticles into the capsid shell of muPy. This incorporation is mediated by covalent sulfide bonds between the capsid proteins cysteine residues and the molecular gold. The number of incorporated gold particles can be controlled during the assembly process and the capsids retain their ability to transduce cells. These particles provide new tools for tracking of viral particles in cells, and simultaneously allow the delivery of genes packages in the hollow capsid.

We synthesize and investigate the swelling behavior of polyelectrolyte and polyampholyte grafted layers on planar substrates. The polymer brushes are prepared using the "grafting from" method with surface-initiated atom transfer radical polymerization (ATRP), which allows a good control of the chain length and a weak polydispersity of chains. Ellipsometry and neutron reflectivity are used to determine the swollen thickness and the monomer volume fraction profile. The scaling behavior of the neutral polymer brush and the strong polyelectrolyte brush is in good agreement with scaling laws predicted by mean-field theories. The swelling behavior of the pH-responsive polybase brush is between the situation of the neutral polymer brush in good solvent and the quenched polyelectrolyte. Polyampholyte brushes are contracted in the pH range of zero net charge. A barrier zone likely due to the attraction between positively and negatively charged monomer units is observed in the density profile. This barrier could prevent from a collective ionization of the chains and reduce the expected collapse of the brush.

We have fabricated silicon structure in silicate glass prepared with metallic aluminum in the starting material, using femtosecond laser irradiation and subsequent annealing. Small Si-rich structures such as oxygen-deficiency (O-deficiency) defects or Si clusters transform into nano-sized Si particles by the focusing irradiation of the laser. Then the Si-rich structures grow into micro-size particles due to the thermite reaction promoted by heat treatment. We determine the effect of focused laser pulse on the Si deposition process by using a time-resolved transient lens method with a sub-picosecond laser pulse. Localized high-temperature, high-pressure, and the generation of shock waves appear to be very important in forming the Si-rich structures that ultimately grow into Si particles. The diffusion of oxygen by shock waves and the existence of Al-rich structures help form Si-rich structures as Si-O bonds continuously break under high temperature. The focusing irradiation of femtosecond lasers is very useful for fabricating Si structures inside glass.

A couple of glass plates sandwiching the molten AgNO₃-KNO₃ mixture at the temperature of 250°C was irradiated by pulsed Nd:YAG laser with a wavelength of 1.06μm. The irradiation induced the color of transparent yellow and orange in the glasses with the irradiation time because of the deposition of silver nanoparticles. In the observations using FE-SEM and AFM, periodically aligned structures, stripes and circles, formed by silver nanoparticles were observed in the irradiated area. The stripes had the interval of 600-700nm, and the circles had the diameters more than 40μm, the latter of which were considered to be due to the Newton's ring interference of laser on bubbles in the molten salt. On the other hand, in the experiment of two-beam irradiation, we obtained strictly aligned stripes pattern with a periodic interval of 2.6μm and a height of 50nm on the glass surface. The observed interval gave a good agreement with the theoretical length that was calculated from the wavelength and the inter-crossing angle of the coherent lasers. Moreover, the stripes pattern showed the Bragg diffraction of visible light from violet to red. From these, it was found that the laser deposition method united with light interference was useful to prepare periodic pattern of nanoparticles on a transparent substrate.

We show a novel method of fabricating a periodic nanovoid structure inside commercial borosilicate glass using femtosecond laser irradiation. The aligned voids are formed spontaneously with a period of micrometer length along the propagation direction of the fs laser beam. In addition, structure parameters of the void array, i.e., the period between voids, the number of voids, and the entire length of the aligned structure, can be controlled by adjusting the laser irradiation conditions. In addition, cross-shaped pattern due to local dislocations can be formed spontaneously inside MgO single crystal using fs laser irradiation. The ability to easily fabricate such controllable periodic void or crossshaped pattern guarantees applicability in optoelectronics areas, such as 3D photonic crystals and polarizer.

We developed an AFM-based new apparatus with a photomultiplier in order to measure the weak light emission from a single microparticle induced by applying a micro force and measured the emission intensity as a function of the applied micro force and speed. The emission intensity was approximately proportional to the speed of the applied micro- force and the square of the micro stress.

Sintered materials formed by sub-micron powder have been attracting attention as next generation functional materials. Since the surface energy of sub-micron particles is high, the sintering temperature is relatively low. Once a sub-micron powder is sintered, its structure is stable in the used temperature range. Therefore, sintered body of sub-micron particles are expected to be alternatives to current interconnect materials that have reached the limits of miniaturization. However, the mechanisms of deformation and fracture in sintered body formed from sub-micron particles are unclear yet. Specially, low temperature sintered body consisting of clusters of sub-micron particles provide several interesting mechanical properties. In this study, mechanical response of low temperature sintered body was examined. The gold powder and solvent were mixed into a paste and that was then sintered. Tensile strength and elongation of the sintered body were evaluated experimentally. Because microstructure of sintered body affects several mechanical properties, cluster structure was simulated using DLA (diffusion-limited aggregation) model and tensile properties of cluster structure were extracted from finite element analysis. Comparing with experimental results, the validity of cluster model simulation was examined. Low temperature sintered body has lower tensile strength and elastic modulus because of network of clusters. Cluster structure depends on the porosity and the sintering temperature. Simulated elastic stiffness depends cluster structure and its value is lower than bulk. The fracture behavior of particles in clusters connects macroscopic tensile strength and elongation of sintered body. It agrees with the SEM observation of the fracture surface. Cluster of particles characterizes the macroscopic mechanical properties of sintered body.

Diatoms have the ability to generate highly ornamented nanostructured silicified cell walls under ambient conditions and without harsh chemicals, yet the molecular mechanisms underlying biosilification are still not well understood. The idea of this study is to mimic silica biomineralization of diatom cell walls that may provide the key to the development of new routes towards novel tailor-made silicas. Here the ability of R5 peptide, a peptide from the silaffin-1 protein derived from diatom species of Cylindrotheca fusiformis, to generate silica nanostructure in vitro was investigated. The R5 peptide was synthesized using Fmoc Solid-Phase Peptide Synthesis and purified using reverse phase high performance liquid chromatography. MALDI analysis showed that the peptide was successfully synthesis. With the application of silicic acid as a silica precursor and the peptide as catalyse, the formation of silica nanostructure was achieved. AFM analysis of the precipitated silica from the mixture of silicic acid and the peptide revealed the nanostructure of silica spheres ranging between 50 - 300 nm in diameter. Silica precipitate was not obtained in the absence of R5 (negative control) and when the silicic acid was mixed with poly-L-lysine (positive control), a network of large aggregates of uniform size of silica spheres of about 100 nm in diameter was observed.

Microarrays, high-throughput devices for genomic analysis, can be further improved by developing materials that are able to manipulate the interfacial behaviour of biomolecules. This is achieved both spatially and temporally by smart materials possessing both switchable and patterned surface properties. A system had been developed to spatially manipulate both DNA and cell growth based upon the surface modification of highly doped silicon by plasma polymerisation and polyethylene grafting followed by masked laser ablation for formation of a pattered surface with both bioactive and non-fouling regions. This platform has been successfully applied to transfected cell microarray applications with the parallel expression of genes by utilising its ability to direct and limit both DNA and cell attachment to specific sites. One of the greatest advantages of this system is its application to reverse transfection, whereupon by utilising the switchable adsorption and desorption of DNA using a voltage bias, the efficiency of cell transfection can be enhanced. However, it was shown that application of a voltage also reduces the viability of neuroblastoma cells grown on a plasma polymer surface, but not human embryonic kidney cells. This suggests that the application of a voltage may not only result in the desorption of bound DNA but may also affect attached cells. The characterisation of a DNA microarray by contact printing has also been investigated.

Plasma immersion ion implantation (PIII) offers an alternative to ion beam with the advantage of high implantation rate. However, problems inherent to the application of PIII to non-conducting materials such as polymers are due to surface charging. To overcome these difficulties and to have a controllable implantation depth, we sputtered a thin layer of gold before PIII is applied to the polymer substrate. The result is a controllable implantation dept and stronger adhesion between the metal-polymer interfaces. The extent of implantation depth can be correlated to tribological properties, electrical conductivity and Raman spectroscopy. While conductive AFM confirmed the conductivity of the embedded layer, the future applications, difficulties and limitations using this technique for fabrication of conductive embedded layer in polymers are also discussed.

Wound dressings and other types of wound healing technologies are experiencing fast-paced development and rapid growth. As the population ages, demand will continue to rise for advanced dressings used to treat chronic wounds, such as pressure ulcers, venous stasis ulcers, and diabetic ulcers. Moist wound dressings, which facilitate natural wound healing in a cost-effective manner, will be increasingly important. In commercially available hydrogel / gauze wound dressings the gel swells to adsorb wound excreta and provide an efficient non adhesive particle barrier. An alternative to hydrogels are microgels. Essentially discrete colloidal gel particles, as a result of their very high surface area to volume ratio compared to bulk gels, they have a much faster response to external stimuli such as temperature or pH. In response to either an increase or decrease in solvent quality these porous networks shrink and swell reversibly. When swollen the interstitial regions within the polymer matrix are available for further chemistry; such as the incorporation of small molecules. The reversible shrinking and swelling as a function of external stimuli provides a novel drug release system. As the environmental conditions of a wound change over its lifetime, tending to increase in pH if there is an infection combining these discrete polymeric particles with a substrate such as cotton, results in a smart wound dressing.

Colloidal microgels may be used for the absorption and controlled release of confirmationally sensitive molecules such as proteins and peptides. These monodisperse microgels are easily prepared in a single pot reaction from e.g. Nisopropylacrylamide, butyl acrylate and methacrylic acid in the presence of a cross-linking agent and a suitable free radical initiator. The resultant materials display dramatic conformational changes in aqueous dispersion in response to changes in e.g. environmental pH. Colloidal microgels are capable of absorbing a range of different proteins and peptides at one pH, affording them protection by changing the conformation of the microgel following a pH change. A further change in environmental pH will allow the microgel to adopt a more extended confirmation and therefore allow the release of the encapsulated material. In the case of e.g. insulin this would offer the possibility of an oral delivery route. At the pH of stomach the microgel adopts a compact conformation, "protecting" the protein from denaturation. As the pH increases passing into the GI tract, the microgel changes its conformation to a more expanded form and thereby allows the protein to be released. Colloidal microgels offer an opportunity for the controlled release of conformationally sensitive protein and peptide molecules via an oral route.

Tissue engineering and stem cell technologies have led to a rapidly increasing interest in the control of the behavior of mammalian cells growing on tissue culture substrates. Multifunctional polymer coatings can assist research in this area in many ways, for example, by providing low non-specific protein adsorption properties and reactive functional groups at the surface. The latter can be used for immobilization of specific biological factors that influence cell behavior. In this study, glass slides were coated with copolymers of glycidyl methacrylate (GMA) and poly(ethylene glycol) methacrylate (PEGMA). The coatings were prepared by three different methods based on dip and spin coating as well as polymer grafting procedures. Coatings were characterized by X-ray photoelectron spectroscopy, surface sensitive infrared spectroscopy, ellipsometry and contact angle measurements. A fluorescently labelled protein was deposited onto reactive coatings using a contact microarrayer. Printing of a model protein (fluorescein labeled bovine serum albumin) was performed at different protein concentrations, pH, temperature, humidity and using different micropins. The arraying of proteins was studied with a microarray scanner. Arrays printed at a protein concentration above 50 μg/mL prepared in pH 5 phosphate buffer at 10°C and 65% relative humidity gave the most favourable results in terms of the homogeneity of the printed spots and the fluorescence intensity.