Two examples of the use of biological materials in micrometer-size applications are discussed. The first concerns the control of motor protein movement, which is oriented toward actuator application. Two kinds of polymers, PTFE (poly-tetrafluoroethylene) and PMMA (poly-methylmethacrylate), are show to be useful in the control of the trajectories of actin filament movement through adsorption of myosin molecules. The second is a magnetic sensor that uses bacterial magnetic particles. Magnetic particle chains extracted through a magnetic trapping extraction method were immobilized on a cantilever for an atomic force microscope. This magnetic particle probe was sensitive enough to measure a standard magnetic force microscope (MFM) sample when used in an MFM system.

It is well-known that electrically controllable soft actuators can be formed by using the composite composed of ionic-conductive polymer electrolyte membranes and precious metals such as platinum or gold. The response of the polymer electrolyte actuator is quick and soft. This paper describes the preparing method of the composites, the principle of the electric response, the response kinetics of the composite, and the medical application of the polymer actuator.

The immobilization efficiency of the complexes of oligonucleotide/poly(L-lysine) onto Poly(Styrene/Maleic Acid), PSMA, and Poly(Styrene/Maleic Anhydride), PSMAA, has been investigated using X-ray photoelectron spectroscopy and atomic force microscopy (AFM) in conjugation with fluorescence-based measurements of DNA attachment. A mono-molecularly thin layer of either electrostatically or covalently (via amide bond) coupled poly(L-lysine) (PL) allows the “switching” of the chemistry from a COOH-based to NH₂-based one. The COOH-based chemistry has the advantage of a high yield of reaction but the disadvantage of a low surface concentration of DNA molecules (negative-negative electrostatic exclusion) whereas the NH₂-based chemistry provides a higher surface concentration (positive-negative electrostatic attraction) but has a lower yield of covalent binding reaction. The immobilization efficiency of covalently coupled 26-mer oligonucleotides/poly(L-lysine) to polymeric surfaces was estimated as 0.3-0.5 x10¹² molecules/mm² for both polymeric surfaces studied. The electrostatic adsorption of poly(L-lysine)/oligonucleotides onto PSMA and functionalized PSMAA surfaces yielded 0.5 x 10¹¹ and 0.1 x 10¹⁰ molecules/mm², respectively. Although this mode of attachment is not “covalent binding” per se, the evidence is provided that this attachment is strong enough to withstand PCR cycles. The properties of these oligonucleotide/poly(L-lysine) complexes make them promising candidates for DNA-DNA hybridisation assays and PCR.

Silicon, silicon dioxide, glass and other key materials of micro system technology show an inhibiting effect on PCR. This negative influence becomes seriously, if devices are miniaturized, particularly in case of flow-through devices due to their high surface to volume ratio. In contrast, alkyl-substituted surfaces do not inhibit the reaction. Although the silanization improves the compatibility, the suppression of inhibition by wall surface treatment was not stable over longer time intervals. Therefore, the stability of chemical surface modifications was studied in dependence of silanization, material, pH, temperature and buffer composition. The efficiency of surface covering by molecular substitution was characterized by wetting experiments as well as by PCR test runs. The results show that the surface treatment can be optimized by the choice of silanization agents and the concentration of surface active additives.

The development of a nanoparticle based detection methodology for DNA microarray applications is described. Originally reported by Mirkin and co-workers, the technology utilizes gold nanoparticles derivatized with thiol-modified oligonucleotides that are designed to bind complementary DNA targets. A glass surface with arrays of immobilized DNA capture sequences is used to capture DNA targets, which are then detected via hybridization to the gold nanoparticle probes. For maximum signal strength a layer of silver is deposited onto the gold nanoparticles, providing for highly sensitive and specific detection of target sequences using low cost optical detection systems. The relative optical detection limits for silver amplified gold nanoparticle probes and Cy3 based fluorescence have been tested. Furthermore, we report progress towards the direct detection of non-amplified genomic DNA from infectious agents and single nucleotide polymorphisms (SNP) in human genomic DNA based on nanoparticle technology.

We propose the use of a multiple-beam optical tweezer (MOT) system for the formation and active manipulation of an assembly of micro- and nano-scale particles. This method enables the study of arrays of particles for practical applications in all-optical control of an array of pumps, switches and valves for micro-fluidic processes, bio-chemical sensing or lab-on-a-chip devices and guided assembly of colloidal structures to form photonic crystals. A fully dynamic MOT system is constructed using the generalized phase contrast (GPC) method and a phase-only spatial light modulator (SLM). The GPC method enables loss-less light projection and direct transformation of an input phase pattern to an array of high-intensity beams. This straightforward process enables an adjustable number of traps and instantaneous control of the position, size, shape and intensity of each trapping-beam by encoding the appropriate phase pattern on the SLM. We present experimental results showing trapping and dynamic manipulation of multiple micro-spheres in a liquid solution.

The study of enzymatic protein molecules using terahertz time-domain spectroscopy (THz-TDS) has the potential to reveal molecular activity in real time without the use of labelling. Molecular hydration, or bound water, is a critical parameter in enzyme activity and THz-TDS measurements. For the first time we experimentally measure the terahertz-frequency response of nano-sized particles of protein and their level of molecular hydration. These measurements are valuable in understanding the terahertz response of biological systems and in studying the interaction between bound water and proteins.

We present three T-ray (terahertz wave) tomographic imaging modalities: T-ray computed tomography, T-ray diffraction tomography, and tomographic imaging with a Fresnel binary lens. Each of these techniques uses pulses of broadband terahertz radiation to obtain 3-dimensional images of targets with wide potential application. We present images demonstrating the performance of each technique and discuss their relative advantages.

The mm-wave (10-110 GHz) frequency band contains the fundamental rotational resonance frequencies of many molecular gases composed of carbon, nitrogen, oxygen and sulfur. The high specificity of the rotational spectra to organic molecules affords mm-wave spectroscopy having potential use in remotely sensing atmospheric pollutants and the detection of airborne chemicals is gaining importance for arms control treaty verification, intelligence collection and environmental monitoring. This paper considers RF receiver systems for remote chemical detection measurements based on mm-wave spectral line emissions. It discusses the design, performance and operation of specific receiving systems for detecting the presence of ammonia in laboratory based transmit-and-receive experiments.

Diazonaphthoquinone/novolak (DNQ) photoresist have the property of changing physical-chemical properties during exposure to UV light, which reflects in a change of the polymer hydrophobicity. A combinatorial surface having different exposed area was fabricated, in order to study the influence of hydrophobicity over protein adsorption and EDC-mediated covalent attachment. The results indicate two different behaviours, reflecting a substantial different mechanism of interaction. While protein adsorption decreased following the hydrophobicity decrease, covalent attachment increased, thus reflecting the effectiveness of the covalent mediator, which cross-links the protein to the carboxylic groups that form during exposure. Based on the results of the present work, a combinatorial microarray will be fabricated, to be used in the biosensor field.

A novel approach to realize arrays of out of plane micro needles is given. The exterior shape of the micro needles is realized by dry etching using a RIE. The exterior shape is realized in silicon by dry etching using a SF₆ and Argon plasma that achieve the progressive etching of the mask composed by silicon nitride and photoresist. The needles realized present an outer diameter of 900 nm for a height of about 7 microns. The needle is then realized by wet oxidation using a thin film of silicon nitride to perform a LOCOS at the end of the needle. The last step consists in selectively etch the Si₃N₄ and the silicon inside the needle by xenon difluoride.

A lot of researches and developments of medical device based on micromechatronics are performed. We develop the glucose sensor for using at HMS (Health Monitoring System) as one of the devices of those. In the development of a glucose sensor, it is necessary that the efficient hybridization between enzyme (glucose oxidase : GOD) as receptor and semiconductor as transducer. We devised the biosensor which used GOD immobilized gold plate as a gate electrode of the MOSFET. By utilizing this type, it becomes possible that the sensor part is easily miniaturized. When the glucose was detected using this sensor, there was a signal with concentration dependence. Therefore, it was confirmed that the prototype glucose sensor operated as a biosensor. From the above results, MOSFET type biosensor with gate electrode which immobilized GOD produced in this paper seems to be enough available as a glucose sensor. For miniaturization of the system, we examined the relationship between size of the working electrode and detection sensitivity. Consideration of the electrode area was not needed to detect the signal sensitively from the glucose sensor. And when we changed glass reference electrode to Au electrode, the enough sensitivity was obtained, too.

Absence epilepsy is a form of epilepsy common mostly in children. The most common manifestations of Absence epilepsy are staring and transient loss of responsiveness. Also, subtle motor activities may occur. Due to the subtle nature of these symptoms, episodes of absence epilepsy may often go unrecognized for long periods of time or be mistakenly attributed to attention deficit disorder or daydreaming. Spells of absence epilepsy may last about 10 seconds and occur hundreds of times each day. Patients have no recollections of the events that occurred during those seizures and will resume normal activity without any postictal symptoms. The EEG during such episodes of Absence epilepsy shows intermittent activity of 3 Hz generalized spike and wave complexes. As EEG is the only way of detecting such symptoms, it is required to monitor the EEG of the patient for a long time and thus remain only in bed. So, effectively the EEG is being monitored only when the patient is stationary. The wireless monitoring sys tem described in this paper aims at eliminating this constraint and enables the physicial to monitor the EEG when the patient resumes his normal activities. This approach could even help the doctor identify possible triggers of absence epilepsy.

Hypoglycemia - abnormal decrease in blood sugar - is a major obstacle in the management of diabetes and prevention of long-term complications, and it may impose serious effects on the brain, including impairment of memory and other cognitive functions. This paper presents the development of a non-invasive sensor with miniaturized telemetry device in a wrist-watch for monitoring glucose concentration in blood. The sensor concept is based on optical chiralit of glucose level in the interstitial fluid. The wrist watch consists of a laser power source of the wavelength compatible with the glucose. A nanofilm with specific chirality is placed at the bottom of the watch. The light then passes through the film and illuminates a small area on the skin.It has been documented that there is certain concentration of sugar level is taken by the intertitial fluid from the blood stream and deposit a portion of it at the dead skin. The wrist-watch when in contact with the outer skin of the human will thus monitor the glucose concentration. A wireless monitoring system in the watch then downloads the data from the watch to a Palm or laptop computer.

Two-dimensional control over the surface chemistry of substrate materials is of interest to a wide range of applications from microelectronics to biomedical diagnostics. Here, we describe a general principle for creating spatially controlled surface chemistries by subsequent deposition of thin plasma polymer coatings followed by laser ablation. The creation of surfaces with spatially controlled wettability was used as an example. Plasma polymerization of n-heptylamine produced a hydrophilic surface on silicon wafer substrates while subsequent plasma polymerization of perfluoro-1,3-dimethylcyclohexane produced a hydrophobic surface. Excimer laser ablation at an energy density of 125 mJ/cm² was used to remove a defined thickness of the two-layer coating, completely removing the upper layer without exposing the substrate material. Excimer laser ablation resulted in two-dimensional control over the surface chemistry with a resolution of ca. 1 μm. Surface modifications were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Contact angle measurements were used to estimate the wettability of modified surfaces. The method was shown to be suitable for the precise control over the location of droplets containing aqueous solutions. In conclusion, the method described here represents an effective tool for the production of substrates with spatially controlled surface chemistry and wettability.

The immobilization and hybridization of amino-terminated oligonucleotide strands to cyclo-olefin-copolymer (COC) and polycarbonate (PC) surfaces have been investigated for potential application in micro-PCR devices. The oligonucleotides were covalently bound to the plasma-treated COC and PC surfaces via an N-hydroxy-sulfosuccinimide (NHSS) intermediate. Analysis by AFM showed that the oligonucleotides were present on the surfaces as lumps, and that the size, both vertically and laterally, of these lumps on the COC surface was larger compared to the PC surface. The immobilization efficiency of the former was also higher (15.8 x 10¹² molecules / cm²) compared to the latter (3.3 x 10¹² molecules / cm²). The higher efficiency of the COC surface is attributed to the more effective NHSS-functionalization and its higher surface roughness. Subsequent hybridization doubled the height of the lumps, while the lateral dimensions remained essentially unchanged. This is explained in terms of organization of the long probe strands used on the surface as flexible, coil-like polymer chains, which allow the complementary oligonucleotides to bind and increase the height of the lumps. The AFM frictional images showed that the hybridization had the effect of reversing hydrophilicity of the oligonucleotide lumps from being more hydrophilic to more hydrophobic, consistent with the hydrophilic bases of the probe strands being shielded as a result of hybridization.

The need for disposable diagnostic sensors in the health care industry has been a major factor in the development of low-cost microfluidic devices. Polymer materials have been the obvious choice due to their cost effectiveness. However, these materials often do not possess the desired properties for biochip operation, such as their high non-specific binding and poor electroosmotic flow characteristics. Various fabrication techniques have also been developed for polymeric chips over the past few years due to their incompatibility with the traditionally preferred micromachining technologies associated with glass and silicon. This paper presents a method for constructing microfluidic devices in Poly(ethylene terephthalate) (PET) using a direct-write Neodymium Yttrium Aluminium Garnet (Nd:YAG) laser system. Issues involving the operation and fabrication of such disposable devices, with particular emphasis on the development of a bio-chip for DNA diagnostics, are discussed.

The concept of macro scale synthetic jets has been applied to the low Reynolds number channel flows associated with biosensor microfluidics. The current numerical investigation utilizes a hybrid approach of the lattice Boltzmann method for flow field computations and the convection-diffusion equation for passive scalar transport. The study presents results for various synthetic jet geometries, jet inlet conditions, scaling issues and Reynolds numbers. The results indicate limited effects due to synthetic jet cavity-slot geometry and that the synthetic jet imparts momentum to the channel flow thus enhancing fluid mixing.

Lab-on-a-chip microfluidic devices commonly manipulate biological fluids, which contain significant quantities of biomolecules, in particular proteins and DNA. This inevitably leads to the adsorption of these biomolecules to the surfaces of the devices through which the fluid flows. As the dimensions of these devices continue to decrease and approach the sub-micron range, this phenomenon will become more and more important. In this paper, we model the effect of protein adsorption on the flow of fluid through a microchannel, under the assumption that classical hydrodynamics applies. We predict that the adsorption of a thin layer of protein on the walls of a thin microchannel can significantly decrease the effective flow rate and velocity through the channel. Finally, we briefly mention the possibility that the increased wall roughness and modified wall chemistry, attributable to the deposition of the protein, could also lead to the modification of the flow, and in particular, may render the crucial “no-slip” wall condition invalid.

Taylor-Aris dispersion is an unwanted effect in some applications, such as chromatography, because of its rapid dispersion along channel axis direction to cause the difficulties to separation. However, this effect can be used in solving mixing problems. In this presentation, the authors studied mixing of two streams of food dye solution in a microchannel. The two liquids sandwiched in the axis direction, and due to non-slip boundary condition, the slugs of liquids stretched and thus increase their interfacial area. This phenomena was firstly studied by Taylor about the dispersion of solute in a circular capillary, and then improved by Aris. Numerical analysis was applied to design mixing section in microchannels, and simplified experiments were conducted to illustrate the concept.

For effective pulmonary drug delivery of insulin for example, drug particles must be in the range of 1 to 5 microns. A piezoelectrically actuated MEMS atomizer based on Rayleigh instability-driven breakup of filaments has been designed to produce drug particles in this range. Although the formation of droplets from jets have been used extensively in ink-jet printing, the currently presented mode of droplet formation has not yet been demonstrated by any MEMS device. Testing of the vaporiser reveals that the droplets generated lie primarily in the range of 1.0 through 3.0 microns, a range that covers the designed droplet size of 2.5 microns. We thus show that it is possible to implement this mode of droplet generation that will achieve better device efficiency.

Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquotes is presented. The system is used to produce and analyze high numbers of strongly separated cultural volumes. Selected clones may be retrieved from the system. Therefore, the principle of segmented flow is applies. Portions of aqueous culture medium containing one cell or very small cell ensembles are separated from each other by a nonmiscible liquid like dodecane or mineral oil. In addition, the oil separates the cultivation droplets from the innerside of the walls of chip channels and capillaries. This way, compatibility problems between cell wall surfaces and the chemical character of technical walls are excluded. The separated cultivation droplets are guided by micro flow transportation in different channel and chamber topologies. The whole system has the character of a serially working cell processing system. The aliquot generation can be speeded up to frequencies of about 30 Hz in each micro channel. That means, that about 10⁵ individual cultural volumes can be produced per hour or about 2 million per day.

The scanning probe microscope (SPM) system is emerging as an increasingly important tool for non-intrusive interrogation of live cells in vitro. Its particular merit is that it retains complete functionality in a biocompatible fluid environment and can track the dynamics of cellular processes in real time and real space at nm resolution, as an imaging tool, and with pN force-sensing/imposing resolution, as an interaction tool. However, a live cell is a fragile object; meeting the requirements of non-intrusiveness presents a challenging task. The better-known recent contributions of SPM towards explanatory and predictive descriptions of biomolecular interactions at surfaces and interfaces will also be reviewed, and some recent attempts to reconfigure the SPM platform for demonstration of novel bio-device applications will be described.

Biocompatibility and functionality of implanted inorganic medical devices is limited by the local reaction of the organism, with a recently recognized contribution of nearby microvasculature. We explored the possibility to microengineer pre-embedded microvascular networks in the surface of inorganic devices. The implants would thus function as carriers of pre-assembled microvessels, ready to expand, and contribute to local angiogenesis. Based on our own studies on the role played by local microtopography in angiogenesis (the tunneling concept), we have shown the feasibility of endothelial cells cultivation in grooves created on the surface of the materials to be implanted, either polymeric or silicon. In order to develop this new technology, we devised an in situ approach to the study of the cellular behavior on micropatterned surfaces, by use of Laser Scanning Cytometry (LSC). In this report I will present our results regarding the LSC analysis of endothelial cells cultivated in grooves made on the surface of silicon wafers, and the consequences of this treatment on endothelial physiology. When comparing the growth of endothelial cells on line patterned and non-patterned areas, in terms of several morphological parameters of cell nuclei, our data support the conclusion that lateral confinement of endothelial cells induces a quiescent state, possibly by inhibiting their ability to proliferate.

In this paper, we explore the multiphoton excitation capabilities of the scanning total internal reflection fluorescence microscopy (STIRFM) using a focused ring-beam illumination and a high numerical-aperture objective (NA = 1.65). The evanescent field produced by the STIRFM is focused laterally, producing a small excitation volume that can effectively induce non-linear optical process. The theoretical simulation of the focal spot produced in STIRFM geometry shows that the focused evanescent field is split into two peaks due to the strong enhancement of longitudinal polarization component at the focus of a high numerical-aperture objective. Experimental images of two-photon excited CdSe quantum dot nanocrystals show the characteristic split focal spot.

This paper investigates the ability to modify the surface of silicon wafers for selective cell adhesion and the efficacy of solid phase transfections on the modified surface. Silicon surfaces are first modified by plasma polymerization of allylamine (ALAPP) and subsequent grafting of a protein-resistant layer of poly(ethylene oxide) (PEO) on the plasma polymer surface. Spatially controlled excimer ablation was then used to pattern the graft-copolymer surface for selective cell adhesion. X-ray photoelectron spectroscopy and contact angle measurements confirmed the creation of 2D patterns with different surface chemistry. Cell culture experiments with HEK 293 cells showed that cell attachment is limited to the ablated areas. Furthermore, cells could be transformed with plasmid DNA containing the gene for green fluorescent protein. Therefore, the biochip platform described in this paper, has the potential to be developed into a high-density array for analyzing gene products produced from a matrix of living cells.

We propose a new, biologically-inspired model of computation, based on the motion of actin filaments on a myosin substrate, as used in motility assays, noting that this represents a marriage of the fields of natural computing and computing with agents. A highly simplified model of actin motility is presented and used to simulate the simultaneous motion of identical filaments. We show that using some simple formal definitions, we can regard this motion as a continuous computation. We demonstrate using a computer simulation, how actin filaments can be used to solve a traditional maze in a highly parallel fashion, with obvious implications for attacking computationally difficult graph problems. Briefly, we mention the limitations of our model and possibilities for the physical implementation of such a system.

The interest in molecular devices is growing and a number of organic molecules are being studied to achieve commercially viable technology in near future. DNA being the only molecule, which can be, synthesizes in any sequence, orientation and length is a potential candidate for fabrication of Nano devices. It is established fact that life processes are governed by communication through out the length of DNA by charge transfer. Thus, the study of charge transfer in DNA is of great importance in understanding and realisation of DNA based biomolecular electronics. We calculated the ionisation potential of all the four bases of DNA using Harteree Fock Equation with Moller Plesset second harmonic approximation. On the basis of ionisation potential charge transfer in DNA primers has been simulated with respect to sequence and length in light of design of diode, triode and transistors. This paper discusses the calculation of ionisation potentials of individual bases, charge transfer in terms of electron and hole migration. Besides design of electronic components, paper also discusses the application of these calculations in understanding DNA damage chemistry and their experimental validation.

A number of signal processing and statistical methods can be used in analyzing either pieces of text or DNA sequences. These techniques can be used in a number of ways, such as determining authorship of documents, finding genes in DNA, and determining phylogenetic and linguistic trees. Signal processing methods such as spectrograms provide useful new tools in the area of genomic information science. In particular, fractal analysis of DNA "signals" has provided a new way of classifying organisms.

The study of insect vision is believed to provide a key solution to many different aspects of motion detection and velocity estimation. The main reason for this is that motion detection in the fly is extremely fast, with computations requiring only a few milliseconds. So the insect visual system serves as the basis for many models of motion detection. The earliest and the most prominent model is the Reichardt correlator model. But it is found that in the absence of additional system components, the response of a simple Reichardt correlator model is dependent on contrast and spatial frequency. Dror has demonstrated in his work that the addition of spatial and temporal filtering, saturation, integration and adaptation in a correlator based system can make it act as a reliable velocity estimator. In this paper, we try to further investigate and expand his model to improve the correlator performance. Our recent neurobiological experiments suggest that adaptive mechanisms decrease EMD (elementary motion detector) dependence on pattern contrast and improve reliability. So appropriate modelling of an adaptive feedback mechanism is done to normalise contrast of input signals.

Consider an array of parallel comparators (threshold devices) receiving the same input signal, but subject to independent noise, where the output from each device is summed to give an overall output. Such an array is a good model of a number of nonlinear systems including flash analogue to digital converters, sonar arrays and parallel neurons. Recently, this system was analysed by Stocks in terms of information theory, who showed that under certain conditions the transmitted information through the array is maximised for non-zero noise. This phenomenon was termed Suprathreshold Stochastic Resonance (SSR). In this paper we give further results related to the maximisation of the transmitted information in this system.

The bio-activity of polymer surfaces and interfaces depends on surface structure and chemistry, and on the size scale of lateral differentiation. The Atomic Force Microscope (AFM), in its various operational modes, is emerging as an important tool in sub-μm-scale characterization. As-received polyimide surfaces were masked with a TEM grid and irradiated for time periods ranging from 90 to 540 s. Topographical imaging revealed shrinkage of the irradiated regions, presumably arising from loss of species and/or densification. Tip-to-surface adhesion was measured in the Force-vs-distance (F-d) mode. Irradiation was found to cause increased adhesion, arising from increased hydrophilicity and thus greater capillary interaction. Lateral force maps showed that there was an associated increase in friction. This difference is due in part to the additional attractive interaction of the thicker layer of adsorbed moisture, and a contribution from change in surface chemistry. Irradiated surfaces were seeded with live human fibroblasts. One surface was seeded without any additional treatment, whilst another was exposed to poly-L-lysine prior to the seeding. After incubation and growth the surfaces were imaged in PBS (Phosphate Buffered Saline) solution. Growth and strong attachment was evident on both surfaces with no preference to either the irradiated or unirradiated regions.

Biomolecules in a confined solution environment may be subject to electrostatic forces with a range up to 100 nm, while the van der Waals interaction will account for shorter-range forces. The response of two model poly(amino acids) - poly-L-lysine and poly-L-glutamic acid - has been investigated for a number of model surfaces at pH 6 - including silica/Si-oxide. The model amino acids were adsorbed, or covalently coupled, to colloidal probes consisting of a microsphere attached to a force-sensing lever. The methodology was based on sensing of an interaction between the probe and a flat surface through carrying out force versus distance analysis with an atomic force microscope. The results were analysed within the framework of the conventional DLVO theory. The outcomes illustrate both repulsive and attractive long-range interactions that will hinder, or promote, colloidal biospecies in solution from entering the region of short-range force-fields at the physical interface. Accordingly the results have implications for the efficacy of methods and devices that seek to exploit the properties of micro/nano-fluidic systems. Large 'snap-on' distances were observed for some systems and were ascribed to compression of the 'soft' functionalized layers. Those observations and measurements of adhesion provided insights into conformation of the adsorbed species and strength of attachment.

Laterally differentiated chemistry and structure of surfaces are commonly employed in a variety of devices/components (e.g., biosensors, array devices). At present such devices are based on macroscopic technologies. Future applications of differentiated surfaces are expected to place considerable demands on down-sizing technologies, i.e. enable meso/nanoscopic manipulation. The atomic force microscope (AFM) has emerged as an ideal platform for manipulation, visualization and characterisation of surface structures on the nano-scale^1-14. Controlled AFM-based tip-induced lithography on P(tBuMA) thin film polymer surfaces has been obtained, at line widths down to tens of nanometres and depths in the sub-nanometre range. Parameters giving rise to production of nano-structures can in principle be defined for different polymers (lever-induced out-of-plane loading and in-plane shear forces, linear tip speed, tip shape and chemistry, polymer surface chemistry and mechanical properties). However, those sets of parameters, and their relationship to lithographic outcomes, cannot be derived from the currently accepted models for wear between macroscopic objects in sliding contact.

The use of terahertz pulses (T-rays) for imaging has created a wide range of new applications. This paper investigates a number of techniques for optimally classifying terahertz data. Specifically we consider statistical pattern classification methods. A goal of this research is to implement a classifier as for classifying biomaterials. The objective is to train a classifier using THz images of known materials and then to use the classifier to identify the materials present in unknown images. Potential applications in security systems for airports, customs, and post offices are significant, because we can actually identify the material inside the package without opening it, based on a material’s broadband frequency signature.

The application of biotelemetry in the case of a RF controllable microvalve is discussed. Biotelemetry implies the contactless measurement of different electrical and nonelectrical parameters measured on human or animal subjects. A biotelemetry system consists of a transmitter and a receiver with a transmission link in-between. Transmitted information can be a biopotential or a nonelectric value like arterial pressure, respiration, body temperature or pH value. Transducers convert nonelectrical values into electrical signals. Radio frequency (RF) telemetry allows a patient greater mobility. Above all, the application of wireless communication becomes more and more popular in microinvasive surgery. Battery powered implants are most commonly used, but batteries must be changed after a period of time. To avoid this, wireless transcutaneous radio frequency (RF) communication is proposed for the powering and control of medical implants.

During the last half century the electronic components and computers have grown more and more powerful with the shrinking dimensions of transistors which is approaching 100nm with about a billion tiny devices working together on a single processor. The laws of quantum mechanics and limitations of materials and fabrication techniques restrict further reduction below 100nm. The most promising area is Biomolecular Electronics concerning design and fabrication of basic electronic components using biomolecules. Various organic polymers are being studied for visualization of individual molecular electronic wires and diode switches but we see enormous potential in use of DNA for such devices due to its inherent characteristics. This is because DNA can act as insulator semiconductor, conductor or superconductor depending upon the base sequence, length and orientation. The DNA can be coated selectively with metals with molecular level precision giving us capability to design molecular electronic components, such as, diode, triode, transistor, etc. This paper discusses the DNA based language developed by our group for coding and decoding any digital information in terms of DNA sequence. Basic arithmetical operations, such as, addition subtraction, multiplication, division and exponential have been defined in terms of DNA sequence and their validity has been demonstrated. Paper will also discuss our programme on study of DNA electrical behaviour in terms of sequence; length and orientation for development of biomolecular electronic components and for understanding DNA damaged chemistry.

Syndiotactic poly(vinyl alcohol) (PVA)/poly(vinyl pivalate/vinyl acetate) (P(VPi/VAc)) and atactic PVA/PVAc micro- and nanoparticles with skin/core structure have been prepared by heterogeneous saponification of P(VPi/VAc) and PVAc micro- and nanoparticles. Especially, to prepare P(VPi/VAc) and PVAc microparticles having various particle sizes and uniform particle size distribution, vinyl pivalate (VPi)/vinyl acetate (VAc) and VAc were suspension-polymerized using a low-temperature initiator, 2,2’-azobis(2,4-dimethylvaleronitrile). P(VPi/VAc) particles are promising precursor of stereoregular PVA embolic materials which can be introduced through catheters in the management of gastrointestinal bleeders, arteriovenous malformations, hemangiomas, and traumatic rupture of blood vessels. Monodisperse and/or nearly monodisperse P(VPi/VAc) and PVAc microparticles with various particle diameters were obtained by controlling suspension polymerization conditions. Monodisperse P(VPi/VAc) and PVAc microparticles having various particle sizes were partially saponified in the heterogeneous system. PVA/P(VPi/VAc) and PVA/PVAc microparticles having various tacticity and degree of saponification were produced by controlling various polymerization and saponification conditions. The coating of stereoregular PVA micro- and nanoparticles for drug release experiments was conducted with the strepo-avidin-alkaline phosphatase conjugate in variable conditions of pH value, coating buffer, and reaction temperature. Protein-coated syndiotactic PVA micro- and nanoparticles, which does not crosslinking, were more superior to controllability of drug release, durability, and dimensional stability to water and blood than atactic one.

A new bioaffinity sensor based on pulsed terahertz (THz) spectroscopy is able to sensitively detect the presence of ultra-thin bound biomolecular layers. The protein avidin and lipid biotin are noted for their very high binding affinity, and the ease for which they can be attached to residues with importance in many biosensing applications. We demonstrate the sensitivity of the pulsed THz spectrometer to thin avidin layers and to avidin amplified with micron-sized agarose beads. The experimental results can be simply modelled by considering transmission of the THz radiation at the thin film interfaces. We detect less than 10.3 ng/cm² avidin, giving the THz system a detection capability of sub-thin solid films better than ellipsometry and reflectometry techniques.