The material properties of the nano-structured materials show remarkable improvement or deviation from the properties exhibited by the coarser grained material. These unique properties are attributed to the significant increase in grain boundary area due to the small grain size. The possibility to manipulate the properties of a nanosized thin film simply through annealing appears to be of widespread interest for material science. In the gas sensing field of application there is a great effort in reducing the grain dimension and increasing the surface area exposed to the interaction with gaseous species. One of the strategies used is the addition of a second element, which can inhibit the grain growth. Furthermore, there may be a coexistence of two phases and one phase can act as a receptor while the other can act as transducers and an effect on film porosity is also expected, depending on the extent of oxide segregation from the nanosized film. Thin films made of Mo-Ti, Mo-W, Ti-W, Ti-Nb mixed oxides were achieved by reactive sputtering, assisted by thermal treatments. These layers were characterized by means of the electrical measurements in presence of different pollutants and alcohols and with the Kelvin probe at different working temperatures; the good sensing capabilities registered with these mixed oxide compared to their single oxides have to be ascribed to the nanosized structure of these layers. In particular different p-type sensing materials were produced, the opposite behavior of these layer is attractive to ease data processing in sensors arrays.

Nano-size TiNi powder prepared by electro explosion of TiNi wire process as processed by spark plasma sintering for 5 minutes at variable temperatures between 700 and 1000°C. The shape memory effect and crystallagraphy of both the powder and the sintered TiNi specimens were extensively characterized. The specimen sintered at a temperature of 700° showed high porosity and partial densification, but with apparent shape memory effect. By contrast, the specimens sintered at higher sintering temperatures above 900°C showed high density, but experienced extensive oxidation with teh resulting loss of the shape memory effect. High temperature sintering resulted in significant solid-state inter-diffusion of atoms and thus the formation of different intermetallic phases, such as NiTi₂ and Ni₃Ti. The phase transformation temperatures and enthalpies for the samples sintered at 700 and 800°C increased with increasing temperature. In addition, the differences between the start and finish transformation temperatures for the sintered specimens appear to be significantly narrower compared to those of the nano-powder.

Formation behavior and photo-oxidation abilities of nanostructured TiO₂ powders were investigated through a direct crystallization from aqueous TiOCl₂ solutions containing various metal-chlorides at 100°C. The obtained TiO₂ powders without any additives and those added with Ni²⁺, Fe³⁺ and Nb⁵⁺ ions, which have a similar positive ionic radius to Ti⁴⁺, were mainly crystallized with rutile phase, whereas those added with Al³⁺ and Zr⁴⁺ ions, which have a quite different positive ionic radius, were mainly crystallized with anatase phase. On the other hand, the secondary particles in the TiO₂ powder consisted of acicular and spherical primary particles corresponding to rutile and anatase phases, respectively. From these results, it seems that the positive ionic radius of the additives would affect phase formation as well as morphology of TiO₂ precipitates. Among the TiO₂ powders prepared, Ni-added powder, which consisted mainly of rutile phase with a small amount of anatase phase, showed excellent photocatalytic ability in decomposition of 4-chlorophenol.

Photo decomposition ability of ultra-fine rutile TiO₂ powder was investigated using the photo-catalytic reaction in aqueous 1.0 mmol 4-chlorophenol (4CP) solutions with pH-controlled conditions. Its photo-catalytic characteristics were then compared with those of commercial P-25 powder having mainly anatase phase. When 4CP was completely decomposed by the photo-catalytic reaction, HPPLTed TiO₂ powder was more effective than the P-25 powder regardless of the crystalline structures. As the photo-catalytic reaction time increased, the decomposition of 4CP in the aqueous solution was accompanied with much consumption of OH^- ions. However, in the case of the aqueous solution at pH=4 naturally obtained by mixing of water and 4CP, the photo-catalytic reaction of the HPPLTed TiO₂ powder occurred more actively, compared with in the cases of the more acidic and caustic aqueous solutions. Therefore, it is thought that the decomposition of non-degradable 4CP would take place well at a certain amount of OH^- ion concentration in the aqueous solution, considering to show no difference in the adsorption of 4CP on the surface of TiO₂ particle with various pHs of the solution, when the HPPLTed TiO₂ powder with high surface areas more than 180 m²/g was used.

In this work, we have found that the charging of nc-Si in a thin gate oxide can induce a reduction in the total gate oxide capacitance. The capacitance can approach zero value if all the nanocrystals are charged up. The reduction of the gate oxide capacitance is attributed to the premature breakdown in the gate oxide due to the charging up in the nanocrystals, as the reduction of the gate oxide capacitance corresponds to a large decrease in the gate oxide leakage current. Here the breakdown caused by the charging in the nanocrystals is somewhat similar to the soft or hard breakdown in pure SiO₂ thin films that are related to the charge trapping in the oxide film. The breakdown caused by the charging in the nanocrystals is found to be fully recoverable under ultra-violet (UV) light illumination for 5 minutes and a thermal annealing at temperature of 100°C for 10 minutes. The reduction and recovery of the capacitance due to the charging and discharging in the nanocrystals is explained with an equivalent circuit model.

The Raman spectra for single-walled carbon nanotubes (SWNTs) at different temperatures are studied. We find that the G peak position shifts to low frequency with increasing temperature. The variation rate of the peak frequency as a function of temperature is a factor of 2~3 larger than the corresponding G peak frequency variation rates of multiwalled carbon nanotubes and highly ordered pyrolytic graphite from room temperature to 673 K. The line shapes of the RBM features are also found to be sensitive to temperature. The softening of the interatomic force constant due to thermal expansion of C-C bonds and the relaxation of the weak van der Waals interaction between the SWNTs in a bundle with increasing temperature are suggested to be the main origins of the reversible spectral variations.

Carbon nanotubes (CNTs) films are very efficient cathodes for used in field emission devices, such as field emission displays. In this paper, the randomly oriented carbon nanotubes film was grown on silicon substrate by chemical vapor deposition (CVD) using a gas mixture of nitrogen, hydrogen and acetylene, the catalyzer is Ni film which was electroplated in the solution of NiSO₄·6H₂O and H₃BO₄ ( NiSO₄•6H₂O:50g/L; H₃BO₄: 15g/L) in deion water with and without added the Si(OC₂H₅)₄. The SEM, TEM has been used in order to determine the structure of the films, which show that the diameter of the nanotubes would be decreased from about 100nm to 50~70nm when add the Si(OC₂H₅)₄. Field emission characterization has been measured on the carbon nanotubes films-anode setup room temperature and in a vacuum chamber below 10^-4 Pa. The Fowler-Nordheim plot shows a good linear fit, indicating that the emission current only comes from the protruded nanotubes. Threshold field strength of this nanotubes film is about 8 V m/μm for an emission current of 1 μA, and the most field emission current densities of more than 2 mA/cm² are measured for 11 V m/μm. In addition, the bright light spot can be observed, while emitted electron bombardment fluorescent screen.

Structure and morphology of porphyrin aggregates and influence of temperature, microwave and ultraviolet radiation, and acoustic cavitation on aggregation process were investigated using absorption spectroscopy and atomic force microscopy. In ambient conditions TPPS4 forms stick-like J-aggregates with length of 0.05-3 μm, width 22-50 nm and height 4-5 nm. Increased temperature or MW and UV radiation does not influence the aggregates. Acoustic cavitation leads to destruction of stick-shaped aggregates and activates the formation of larger molecular complexes.

A scanning tunneling microscopy (STM) study of [3 x 3] Mn^II supramolecular grids on Au(111) substrates is presented. Two-dimensional ordering via self-assembly is observed at various coverages. Submolecular resolution is attained with solvent deposition of low concentration samples upon freshly exposed substrates. A comparison of submolecular contrast in STM images is conducted and the importance of suitable image processing techniques is demonstrated in resolving the layer structure of obtained high coverage data.

Selective detection of small amounts of toxic gases, such as ammonia and CO is very important to environmental monitoring as well as for medical diagnoses. MoO₃ and WO₃ have been identified as suitable materials for detecting these gases with high sensitivity. Sol-gel processed thin films of MoO₃, WO₃ and their combination have been prepared at SUNY Stony Brook by the hydrolysis of metal alkoxide precursors followed by spin coating and were deposited on alumina heater/electrode containing substrates that were produced by the Brescia group. Sensing tests were carried out in the state-of-the-art gas sensor testing facilities available in Brescia, where the electrical resistance of sensor arrays was recorded as a function of gas concentration, for various combinations of gases (including ammonia, CO, NO₂, Methanol, isoprene, etc) at 10% relative humidity and at temperatures ranging from 400-500°C. The MoO₃-WO₃ composite system showed the best stability at the highest testing temperature. The sensing results obtained are correlated with the structural characteristics of the sensing films. This work has been carried out as a joint collaboration between the Advanced Materials Characterization Laboratory of SUNY Stony Brook (USA) and the Sensor Lab at the University of Brescia (Italy) and was funded by a NSF-AAAS (WISC) grant awarded to Perena Gouma.

A novel technique is presented which integrates the capacity of a laser tweezer to optically trap and manipulate objects in three-dimensions with the resolution-enhanced imaging capabilities of a solid immersion lens (SIL). Up to now, solid immersion lens imaging systems have relied upon cantilever-mounted SILs that are difficult to integrate into microfluidic systems and require an extra alignment step with external optics. As an alternative to the current state-of-art, we introduce a device that consists of a free-floating SIL and a laser optical tweezer. In our design, the optical tweezer, created by focusing a laser beam through high numerical aperture microscope objective, acts in a two-fold manner: both as a trapping beam for the positioning and alignment of the SIL and as an near-field scanning beam to image the sample through the SIL. Combining the alignment, positioning, and imaging functions into a single device allows for the direct integration of a high resolution imaging system into microfluidic and biological environments.

The bubble’s functions in readout process for PdO_x and PtO_x superresolution near-field structure (super-RENS) disk are studied with the PdO_x and PtO_x mask sample and with a repetitive Z-scan method. The results indicate that the optical responses on transmittance and reflectance are related to shape and size of the bubble. The deformation of bubbles before and after repetitive scan is observed by an optical microscope, and the sizes of the bubbles corresponding to different repetitive Z-scan order of times are analysed by an atomic force microscope.

The interaction of actin filaments with myosin is crucial to cell motility, muscular contraction, cell division and other processes. The in vitro motility assay involves the motion of actin filaments on a substrate coated with myosin, and is used extensively to investigate the dynamics of the actomyosin system. Following on from previous work, we propose a new mechanical model of actin motility on myosin, wherein a filament is modeled as a chain of beads connected by harmonic springs. This imposes a limitation on the "stretching’ of the filament. The rotation of one bead with respect to its neighbours is also constrained in similar way. We implemented this model and used Monte Carlo simulations to determine whether it can predict the directionality of filament motion. The principal advantages of this model over our previous one are that we have removed the empirically correct but artificial assumption that the filament moves like a "worm’ i.e. the head determines the direction of movement and the rest of the filament "follows’ the head as well as the inclusion of dependencies on experimental rate constants (and so also on e.g. ATP concentration) via the cross-bridge cycle.

Nanoimprinting is a low cost method to fabricate features from μm down to the nm-range. Different nanofabrication techniques, namely hot embossing, UV-nanoimprinting as well as micro-contact printing will be discussed. Recently achieved results with nanoimprinting methods will be demonstrated.

In recent years, there has been tremendous interest in developing a highly integrated DNA analysis system using microfabrication techniques. With the success of incorporating sample injection, reaction, separation and detection onto a monolithic silicon device, addition of otherwise time-consuming components in macroworld such as sample preparation is gaining more and more attention. In this paper, we designed and fabricated a miniaturized device, capable of separating size-fractioned DNA sample and extracting the band of interest. In order to obtain pure target band, a novel technique utilizing shaping electric field is demonstrated. Both theoretical analysis and experimental data shows significant agreement in designing appropriate electrode structures to achieve the desired electric field distribution. This technique has a very simple fabrication procedure and can be readily added with other existing components to realize a highly integrated "lab-on-a-chip’ system for DNA analysis.

A technique for quantifying velocity profiles of fluids flowing in circular microchannels is presented. The primary purpose of this technique is to provide a robust method for quantifying the effect of surface character on the bulk fluid behaviour. A laser-scanning confocal microscope has been used to obtain fluorescent particle images from a 1 micron thick plane along the centreline of hydrophobic and hydrophilic glass capillaries. The velocities of fluorescent particles being carried in pressure-driven laminar flow of a Newtonian fluid have been evaluated at the centreplane of 57.5 micron capillaries using a variation of particle tracking velocimetry (PTV). This work aims to clarify inconsistencies in previously reported [1-12] slip velocities observed in water over hydrophobically modified surfaces at micron and sub-micron lengthscales. A change in the velocity profile is observed for water flowing in hydrophobic capillaries, although the behaviour appears to be a result of an optical distortion at the fluid-wall interface. This may point to previous suggestions of a thin layer of air adsorbing to the surface. Notwithstanding, the results do not confidently suggest evidence of slip of water on hydrophobic surfaces in microchannels.

A technique is presented for fabricating microchannels for flow investigation with fluorescent particles. The channels were fabricated using plasma etching of a thermoset polymer film, UV15 from Master Bond. The UV15 was spun on a silicon wafer to give a depth of 100μm. A 100nm thick patterned aluminium film was sputtered and patterned on the polymer surface for the etch pattern mask. Sputtering conditions were optimised to prevent damage to the polymer layer. Etch depths to 100μm were obtained. Curing conditions were optimised to prevent wrinkling of the Al/polymer surface during etching. There is a wide variation in the polymer etch rate which can be attributed to many factors. However, one of the most significant is the energy dose (mW/cm²) to cure the polymer. For etch depths greater than 20μm the channels varied from the rectangular cross section shape by undercutting on the walls and deeper etching at the bottom of the channel walls. Conditions for obtaining uniform microchannels for 100μm wide and 50μm deep channels, 5cm long are presented.

Lab-on-a-chip BioMEMS devices have developed in recent years as a way to rapidly perform total biological analysis. With the complexity of fabrication of mechanical parts in microfluidic devices comes the desire to create devices which use alternative methods of pumping, mixing and manipulating fluids and suspended microparticles for reactions - such as electrokinetics. This paper presents novel ways of fabricating electrokinetic devices, which use the phenomenon of dielectrophoresis (DEP) for manipulation of suspended microparticles. Affects of driving waveforms are investigated. Visual results from microparticles are used to show the effect of operation of electrokinetic devices. Improved device designs and device operation are discussed.

A novel technique to bond polymer substrates using PDMS-interface bonding is presented in this paper. This novel bonding technique is promising to achieve precise, well-controlled, low temperature bonding of micro fluidic channels. A thin (10-25μm) Poly(dimethylsiloxane) (PDMS) intermediate layer was used to bond two polymer (PMMA) substrates without distorting them. Micro channel patterns were compressed on a PMMA substrate by hot embossing technique first. Then, PDMS was spin-coated on another PMMA bare substrate and cured in two stages. In the first stage, it was pre-cured at room temperature for 20 hours to evaporate the solvents. Subsequently, it was bonded to the hot embossed PMMA substrate. In the second stage, PDMS was completely cured at 90°C for 3 hours and the bonding was successfully achieved at this relatively low temperature. Tensile bonding tests showed that the bonding strength was about 0.015MPa. Micro fluidic channels with dimensions of 1mmx2cmx1mm were successfully fabricated using this novel bonding method.

Electroosmotic pumping in the microchannels fabricated in polycarbonate (PC), polyethyleneterephthalate (PET) and SU-8 polymer substrates was investigated and species transportation was modeled, in an attempt to show the suitability of low cost polymer materials for the development of disposable microfluidic devices. Microchannels and the fluid reservoirs were fabricated using excimer laser ablation and hot embossing techniques. Typical dimensions of the microchannels were 60μm (width) x 50μm (depth) x 45mm (length). Species transportation in the microchannels under electroosmosis was modeled by finite element method (FEM) with the help of NetFlow module of the CoventorWareTM computational fluid dynamics (CFD) package. In particular, electroosmosis and electrophoresis in a crossed microfluidic channel was modeled to calculate the percentage species mass transportation when the concentration shape of the Gaussian input species plug and the location of the injection point are varied. Change in the concentration shape of the initial species plug while it is electroosmotically transported along the crossed fluidic channel was visualized. Results indicated that Excimer laser ablated PC and PET devices have electroosmotic mobility in the range 2 to 5 x10^-4 cm²/V.s, zeta potential 30 to 70 mV and flow rates of the order of 1 to 3 nL/s under an electric field of 200 V/cm. With the electroosmotic mobility value of PC the simulation results show that a crossed fluidic channel is electroosmotically pumping about 91% of the species mass injected along one of its straight channels.

Medical Test Strips made from plastics provide cheap and reliable analysis of body liquids. The underlying microsystem contains structured microchannels to adjust the filling time as an important parameter for chemical reactions. Columns or pins of some μm dimensons are being placed in the channel to define the fluidic resistance, which is influenced by the distance between these structure elements as well as by their geometry. As no analytic solution exists to describe the microfluidic interaction, the authors have been following approaches based on discrete partial differential equations and behavioural descriptions to obtain a simulation model. Model-based optimization has been performed to get useful sets of parameters to be handed to the industrial partner for manufacturing and therefore verification of the calculated results.

In this work protein patterning has been achieved within a polycarbonate microfluidic device. Channel structures were first coated with plasma polymerized allylamine (ALAPP) followed by the "cloud point" deposition of polyethylene oxide (PEO), a protein repellent molecule. Excimer laser micromachining was used to pattern the PEO to control protein localization. Subsequent removal of a sacrificial layer of polycarbonate resulted in the patterned polymer coating only in the channels of a simple fluidic device. Following a final diffusion bonding fabrication step the devices were filled with a buffer containing Streptavidin conjugated with fluorescein, and visualized under a confocal fluorescent microscope. This confirmed that protein adhesion occurred only in laser patterned areas. The ability to control protein adhesion in microfludic channels leads to the possibility of generating arrays of proteins or cells within polymer microfludics for cheap automated biosensors and synthesis systems.

The smart sensor chip for simultaneous detection of a large number of disease markers is the most recent interest in the field of nanobiotechnology. Potential applications include miniaturized sensors to detect biological agents and diseases, biocompatible and improved systems for drug delivery. They are the simplest biomicroelectromechanical system (BioMEMS) devices that offer a very promising future to the development of novel physical, chemical and biological sensors. They can simultaneously detect a large number of antigens, antibodies, DNA molecules, trace metals, hormones, proteins, gases, microorganisms, toxins, chemical warfare agents, explosives etc. in gaseous, vacuum and liquid medium. Smart sensor chips would be of greater use in intensive care units (ICUs) where multiple disease markers are to be assessed precisely in very less time. These sensors employ highly specific biochemical reactions between complementary biomolecules in the same way that nature has used in our body to detect, diagnose and treat various types of diseases. They have aroused considerable interest because of their high specificity, ultra-high sensitivity, simplicity, low cost, less analyte requirement (in μl), less steps involved, non-hazardous procedure, quick response, low power requirement and a unique capability of detecting a large number of analytes simultaneously in a single step.

Dip Pen Nanolithography (DPN^TM) is a scanning probe technique for nanoscale lithography: A sharp tip is coated with a functional molecule (the “ink”) and then brought into contact with a surface where it deposits ink via a water meniscus. The DPN process is a direct-write pattern transfer technique with nanometer resolution and is inherently general with respect to usable inks and substrates including biomolecules such as proteins and oligonucleotides. We present functional extensions of the basic DPN process by showing actuated multi-probes as well as microfluidic ink delivery. We present the fabrication process and characterization of such active probes that use the bimorph effect to induce deflection of individual cantilevers as well as the integration of these probes. We also developed the capability to write with multiple inks on the probe array permitting the fabrication of multi-component nanodevices in one writing session. For this purpose, we fabricate passive microfluidic devices and present microfluidic behavior and ink loading performance of these components.

We found the simple, effective and low-cost fabrication method of scanning probe tip with carbon nanotube. The assembling apparatus has been discussed and a plausible explanation about attachment mechanism based on dielectrophoretic force has been suggested. In order to find the proper assembling condition, electric field analysis for the round shape tip has been accomplished. Using this condition, the scanning probe tips with carbon nanotube were fabricated at 25% success rate.

Continuous monitoring of the glucose level is a key technology for improved diagnosis and therapy of Diabetes Mellitus patients. Non-invasive optical measurement techniques at the Anterior Chamber of the eye suffer from the lack of intensity of reflected light and the very small magnitudes of the optical effects. Hence using higher magnitude physical and/or chemical effects as primary effects and using non-contact optical readout increases feasibility for in-vivo measurement systems substantially. Hence this article proposes a miniaturized micro structured measurement cell covered by a semi permeable diaphragm to be implanted micro invasively into the anterior chamber of the eye. Osmotic pressure within this cell depends on the intraocular glucose concentration and is translated into deformation of the diaphragm which is measured using white light interferometry. A bio-compatible micro structured interference filter has to be added on parts of the diaphragm to ensure high reflection properties crucial for optical deformation measurement. The article also discusses the special requirements of in-vivo measurements for the optical measurement system.

The purpose of this research is to develop the compact human blood sampling device applied for a health monitoring system(HMS), which is called “Mobile Hospital”. The HMS consists of (1) a micro electrical pumping system for blood extraction, (2) a bio-sensor to detect and evaluate an amount of Glucose, Cholesterol and Urea in extracted blood, by using enzyme such as Glucoseoxidase (GOD), Cholesteroloxidase and Urease. The mechanical design elements of the device are bio-compatible microneedle, indentation unit using a shape memory alloy(SMA) actuator and pumping unit using a piezoelectric microactuator. The design concept is the biomimetic micromachine of female mosquito’s blood sampling mechanism. The performances of the main mechanical elements such as indentation force of the microneedle, actual stroke of the indentation unit using a SMA actuator and liquid sampling ability of the pumping unit using PZT piezoelectric microactuator were measured. The 3 mm stroke of the indentation load generated by SMA actuator was 0.8mN. The amount of imitation blood extracted by using bimorph PZT actuators was about 0.5 microliters for 10 sec. A 60-micrometer outer diameter and 25-micrometer inner diameter Titanium microneedle, which size is same as female mosquito’s labium, was produced by sputter deposition.

In this paper we present a 3D cellular automaton for exploring gene interactions in segmentation of Drosophila larvae. Beginning with the expression levels of maternally expressed genes such as bicoid, our simple model successfully produces the distinctive expression pattern of the even-skipped gene in the developing larvae. This work highlights how complex gene interactions in developing organism can nonetheless be accurately modeled using simple rules.

Consider an array of threshold devices, such as neurons or comparators, where each device receives the same input signal, but is subject to independent additive noise. When the output from each device is summed to give an overall output, the system acts as a noisy Analog to Digital Converter (ADC). Recently, such a system was analyzed in terms of information theory, and it was shown that under certain conditions the transmitted information through the array is maximized for non-zero noise. Such a phenomenon where noise can be of benefit in a nonlinear system is termed Stochastic Resonance (SR). The effect in the array of threshold devices was termed Suprathreshold Stochastic Resonance (SSR) to distinguish it from conventional forms of SR, in which usually a signal needs to be subthreshold for the effect to occur. In this paper we investigate the efficiency of the analog to digital conversion when the system acts like an array of simple neurons, by analyzing the average distortion incurred and comparing this distortion to that of a conventional flash ADC.

Flying insects are capable of performing complex and extremely diffcult navigational tasks at high speeds with amazing ability. The neural computations underlying these complicated maneuvers and the motor activity of the insects have been extensively investigated in the last few decades.^1-5 One the most important discovery was that the motion detectors involved in the control of the optomotor responses are of the correlation type.⁶ In order to improve the velocity estimation by the Reichardt correlators, many scientists have come up with different kinds of elaborations to the basic Reichardt correlator model. In this paper, we have expanded the Dror’s elaborated Reichardt model⁷ and we have included feedback adaptation and saturation in our model and we have conducted a comparative study on the effects of the addition of each elaboration on the performance of the model. The relative error in each case is also studied.

Terahertz time domain spectroscopy (THz-TDS) has a wide range of applications from semiconductor diagnostics to biosensing. Recent attention has focused on bio-applications and several groups have noted the ability of THz-TDS to differentiate basal cell carcinoma tissue from healthy dermal tissue ex vivo. The contrast mechanism is unclear but has been attributed to increased interstitial water in cancerous tissue. In this work we investigate the THz response of human osteosarcoma cells and normal human bone cells grown in culture to isolate the cells' responses from other effects. A classification algorithms based on a frequency selection by genetic algorithm is used to attempt to differentiate between the cell types based on the THz spectra. Encouraging preliminary results have been obtained.

About 10 million people around the world are suffering from blindness, where the path of light is disturbed due to an opaque, irreversible damaged, and inoperable cornea. Although vision is not given to this group of population, the retina is still intact. To date, there is no artificial implant which is able to replace the natural cornea. The work presented here describes an approach to build and implant a micro-optical and microelectronic system to be used as an intraocular vision aid. By overcoming the disturbed light path, it yields to an improved visual acuity of the patient. The main aspect of this bio-mimetic system is to transfer information representing the patient's field of view to the retina. An image of the field of view is captured in real-time outside the eye. After employing data processing, it is wireless transferred to the implanted part of the vision aid. From there, the information emerging from a micro display is imaged to the retina via a micro-optical system. The limited display resolution available inside the eye and the limited dimensions of the eyeball build the constrains of the optical system. A combination of a spatial light modulator together with an imaging lens system realizes intelligent spatial information distribution schemes onto the retina. This ensures a high outcome of visual acuity in the central region of the retina. Various retinal acuities can be realized. The employment of in-vivo adjustment mechanisms of the focal plane is discussed.

The detection of single bacterial cells and novel absorbing labels has been demonstrated through optical resonances in microdroplets. The setup enables high throughput detection of single Escherichia coli (E. Coli) cells without any direct labeling although Rhodamine 6G (R6G) was used as the signal transduction mechanism. A micro droplet acts as an optical cavity that supports Morphology Dependent Resonances (MDRs) at wavelengths where the droplet circumference is an integer multiple of the emission wavelength. The cells inside the droplet have a direct effect on the fluorescence lasing spectrum of R6G fluorescence by means of scattering and local refractive index change. The change in the lasing spectrum can be observed at the concentrations where each droplet has as little as one cell. C60 fluorescence quenching has also been demonstrated in microdroplets. R6G in ethanol (10μM) was used for the fluorescence spectrum measurements. Quenching of the optical resonances was observed when C₆₀ dissolved in ethanol was mixed with the R6G-Ethanol solution. Quenching can be observed at C₆₀ concentrations of 1μM in the final solution. The background signal was also checked by repeating the experiment with only R6G and only C₆₀ in the solvent, assuring that the signal reduction was due to the addition of C₆₀ in to the solution. This quenching mechanism may have many applications in multiplexing in bioassays.

As the population ages, the management of the health is one of the important problems. Development of the harmless medical machine based on MEMS technologies for human body will be the mainly research projects in the future. Before now, we developed the glucose sensor for using at Health Monitoring System (HMS) as one of the medical device based on micromechatronics. HMS is the device that monitors human health conditions continuously. For example, the monitoring target of HMS is the blood. The whole blood contains the manifold health index markers, and it is very important to measure them in the health care. Glucose sensor specifically detects the glucose of the blood, and it monitors the glucose concentration as blood sugar level. This glucose sensor had "separated Au electrode’ which immobilized GOx. By utilizing this style, it becomes possible that the sensor part is easily miniaturized. In our previous work, GOx was immobilized onto Au electrode by using of SAMs (Self-Assembled Monolayor) method, and the sensor using this working electrode detected the glucose concentration of glucose aqueous solution. Furthermore, the miniaturization of Au electrode was realized. In this report, glucose sensor which immobilized GOx using the cross-link method was produced, and the performance comparison with the sensor using SAMs method was carried out. And we carried out operation confirmation of produced glucose sensor using dilution human serum and whole blood. In addition, the cholesterol sensor which immobilized cholesterol oxidase (ChOx), which specifically detects the cholesterol on the blood, onto separated Au electrode by cross-link method was produced. The immobilization of the ChOx was evaluated from the spectra of XPS, and the performance as a sensor was evaluated.

Using MEMs (Micro Electro Mechanical system) fabrication techniques, it is possible make a micro-sized instrument for optical detection of trace amounts of chemical species in aqueous solutions. The red-emitting Eu₂O₃ nanoparticle is suitable for a biolabel for such species because of its long fluorescence lifetime and narrow emission bandwidth. The europium nanoparticles are excited by a laser pulse. Their long-lived emission allows the detected signal to be separated from the laser pulse both spectrally and temporally. The background signal can also be eliminated in this manner. The instrument we present, is assembled with silicon and glass layers with a 200μm deep channel. A Nd:YAG pumped optical parametric oscillator (OPO) is used as the excitation source. The measurement sensitivities using two detectors, a PMT (Photo Multiplier Tube) and an APD (Avalanche Photodiode), are compared. The underlying fundamental principles and the micro-fabrication steps for the instrument and detection are discussed.

A new method of using silicon microneedle array in Bio-Medical applications is introduced in this work. The hollow microneedle array with the facilitation of an insertion guide array have been designed and fabricated. The needles can be pushed down through the second layer of human skin with less-bending. The tip of microneedle will be led by the insertion guide to pierce the skin perpendicularly. The silicon bulk micromachining technique using an inductively coupled plasma (ICP) etcher has been employed to fabricate the microneedle array and the insertion guide array. The array chips are 5x5 mm² for both structures. The needle array chip contains 100 microneedles with 100μm and 30 μm of the outer diameter and the hole diameter respectively. The guide array chip is 100 μm-thick and contains 100 guiding holes with 120 μm diameter. A buckling test of microneedle shows the result that there was no microneedle broken during the test via the guiding holes. Contrary, there were several microneedles broken during the penetration without the facilitation of the guide. The finite-element analysis also supports the test result. After the insertion with guiding has been tested and proved, a wet etching process was added in order to obtain sharper tips.

The scaling-down evolution of semiconductor devices will ultimately attend fundamental limits as transistor reach the nanoscale aria. In this context the MOSFET models must give the process variations and the relevant characteristics like current, conductance, transconductance, capacitances, flicker thermal or high frequency noise and distortion. The new challenge of nanotechnology needs very accurate models for active devices. The design of linear analog circuits lacks models for state-of-the-art MOS transistors to accurately describe distortion effects. This is mainly due to inaccurate modelling of the mobility degradation effect i.e. the dependence of carrier mobility in the inversion layer on the gate normal electric field. For short-channel devices the influence of series resistance becomes important and depends on the gate voltage. The drain current expression incorporating a new mobility relation obtained from quantum mechanical transport analysis and the series resistance influence is in good agreement with experiment.

The use of field effect sensors for biological and chemical sensing is widely employed due to its ability to make detections based on charge and surface potential. Because proteins and DNA almost always carry a charge [1], silicon can be used to micro fabricate such a sensor. The EIS structure (Electrolyte on Insulator on Silicon) provides a novel, label-free and simple to fabricate way to make a field effect DNA detection sensor. The sensor responds to fluctuating capacitance caused by a depletion layer thickness change at the surface of the silicon substrate through DNA adsorption onto the dielectric oxide/PLL (Poly-L-Lysine) surface. As DNA molecules diffuse to the sensor surface, they are bound to their complimentary capture probes deposited on the surface. The negative charge exhibited by the DNA forces negative charge carriers in the substrate to move away from the surface. This causes an n-type depletion layer substrate to thicken and a p-type to thin. The depletion layer thickness can be measured by its capacitance using an LCR meter. This experiment is conducted using the ConVolt (constant voltage) approach. Nucleic acids are amplified by an on chip PCR (Polymerase Chain Reaction) system and then fed into the sensor. The low ionic solution strength will ensure that counter-ions do not affect the sensor measurements. The sensor surface contains capture probes that bind to the pathogen. The types of pathogens we’ll be detecting include salmonella, campylobacter and E.Coli DNA. They are held onto the sensor surface by the positively charged Poly-L-Lysine layer. The electrolyte is biased through a pseudo-reference electrode. Pseudo reference electrodes are usually made from metals such as Platinum or Silver. The problem associated with “floating” biasing electrodes is they cannot provide stable biasing potentials [2]. They drift due to surface charging effects and trapped charges on the surface. To eliminate this, a differential system consisting of 2 sensors that share a common pseudo-reference electrode is used to cancel out this effect. This paper will look at a differential system for multi-arrayed biosensors fabricated on silicon.

In this study, X-ray photoelectron spectroscopy (XPS) is used to study the annealing effects on the structure and chemical states of Si-rich SiOx (x<2) films. The analysis of the XPS Si 2p peaks shows the existence of the five chemical structures corresponding to the Si oxidation states Siⁿ⁺ (n =0, 1, 2, 3, and 4) in the SiOx films. The XPS results clearly show the evolution of various chemical structures and the formation of Si nanocrystals (corresponding to the oxidation state Si⁰) in the SiOx films as a function of annealing temperature and annealing time. The results are explained in terms of the thermal decompositions of the suboxides Si₂O, SiO and Si₂O₃ (corresponding to the oxidation states Si¹⁺, Si²⁺ and Si³⁺, respectively). The thermal decompositions lead to the growth of SiO2 (corresponding to the oxidation state Si⁴⁺) as well as the formation of Si nanocrystals in the SiOx films. On the other hand, the depth profiling experiment was carried out with ion sputtering. The relative concentration of each oxidation state at various depths is determined quantitatively from the XPS analysis. In addition, annealing effects on both the oxidation states and their depth distributions are studied as well.

In this work, we have developed an approach to determination of optical constants of Si nanocrystals embedded in SiO2 matrix synthesized with Si ion implantation. The approach is based on the effective medium approximation, and appropriate models are developed to simulate the secondary ion mass spectroscopy and spectroscopic ellipsometry measurements on the material system. The energy gap expansion of the Si nanocrystals due to the nanocrystal size effect has been obtained by modeling the optical properties with the single-oscillator model. From the energy gap expansion the nanocrystal size can be also obtained with the phenomenological model based on quantum confinement and the bond contraction model. In addition, a novel approach to quantitative determination of depth profiles of optical constants of Si nanocrystals embedded in SiO2 thin films, which is useful to the applications of light emitting and waveguiding of the nanocrystals, is also developed in this work.

Digital medical images used in radiology are quite different to everyday continuous tone images. Radiology images require that all detailed diagnostic information can be extracted, which traditionally constrains digital medical images to be of large size and stored without loss of information. In order to transmit diagnostic images over a narrowband wireless communication link for remote diagnosis, lossy compression schemes must be used. This involves discarding detailed information and compressing the data, making it more susceptible to error. The loss of image detail and incidental degradation occurring during transmission have potential legal accountability issues, especially in the case of the null diagnosis of a tumor. The work proposed here investigates techniques for verifying the voracity of medical images - in particular, detailing the use of embedded watermarking as an objective means to ensure that important parts of the medical image can be verified. We propose a result to show how embedded watermarking can be used to differentiate contextual from detailed information. The type of images that will be used include spiral hairline fractures and small tumors, which contain the essential diagnostic high spatial frequency information.

The non-invasive or minimally invasive real-time spectral analysis of tissue and biological fluids in vivo would be of great assistance for diagnosis and monitoring of a wide range of diseases. We propose here a novel microdevice capable of determining the reflectance spectrum of a sample using a set of micrometer-sized light emitting diodes and a patch of photosensitive material. The purported device would be wireless and remote-powered via RF magnetic fields and due to its dimensions would be suitable as a long-term implant, for example for monitoring glucose levels in diabetics. We present a design for this device, discuss its limitations and suggest some applications, including its use for in vivo biochemical assays.

Materials with exceptionally high content of carbon are used in technologies with various degrees of added value, from quasi-amorphous materials for carbon electrodes used in e.g. lithium batteries to highly-organized materials comprising e.g. nanotubes and fullerenes. The present study aims to test the feasibility of predicting the properties of carbon based materials using (i) molecular modeling and simulation techniques for prediction of compositional stability; and (ii) experimental data regarding materials used for lithium batteries as validation data. It has been found that a higher H/C atomic ratio has a complex influence on lithium uptake. The decrease of the number of the aromatic rings will limit the number of lithium ions allowed in the pore and the increase in pore flexibility will induce a more energetically favorable mechanism for lithium ions uptake (folding/house-of-cards formation against pore expansion).

Evolutionary computation algorithms are increasingly being used to solve optimization problems as they have many advantages over traditional optimization algorithms. In this paper we use evolutionary computation to study the trade-off between pleiotropy and redundancy in a client-server based network. Pleiotropy is a term used to describe components that perform multiple tasks, while redundancy refers to multiple components performing one same task. Pleiotropy reduces cost but lacks robustness, while redundancy increases network reliability but is more costly, as together, pleiotropy and redundancy build flexibility and robustness into systems. Therefore it is desirable to have a network that contains a balance between pleiotropy and redundancy. We explore how factors such as link failure probability, repair rates, and the size of the network influence the design choices that we explore using genetic algorithms.

We explored the potential for use of the contractile proteins, actin and myosin, as biosensors of solutions containing mercury ions. We demonstrate that the reaction of HgCl₂ with myosin rapidly inhibits actin-activated myosin ATPase activity. Mercuric ions inhibit the in vitro analog of contraction, namely the ATP-initiated superprecipitation of the reconstituted actomyosin complex. Hg reduces both the rate and extent of this reaction. Direct observation of the propulsive movement of actin filaments (10 nm in diameter and 1 μm long) in a motility assay driven by a proteolytic fragment of myosin (heavy meromyosin or HMM) is also inhibited by mercuric ions. Thus, we have demonstrated the biochemical, biophysical and nanotechnological basis of what may prove to be a useful nano-device.