A post-CMOS process for chip-level monolithic integration has been developed. A metal probe array for recording neural signals is utilized as a test vehicle to realize the integration process. This probe array is fabricated on a 2 mm x 2 mm chip containing eight ultra-low power CMOS operational amplifiers. A LIGA-like process is employed utilizing UV lithography on SU-8 photoresist and pulse electroplating technique. Pulse plating significantly reduces stress in the deposited material. The post-CMOS fabrication process is utilized to fabricate 70 μm high probes having different aspect-ratios that are monolithically integrated on the CMOS chip.

The charge pump CMOS circuit designs are presented for bio-medical applications wherein the clock voltage is boosted internally. Four and six-stage charge pumps are implemented in 1.5 μm n-well CMOS process. The charge pump circuits can be operated in 1.2 V - 3 V power supply voltage range. Outputs of 12.5 V and 17.8 V are measured from four and six-stage charge pumps, respectively with a 3 V power supply. The charge pump circuits can also be used to generate clock voltage higher than the input clock voltage. In the present design, the clock voltages, 8 V and 11 V have been generated from four-stage and six-stage charge pumps, respectively which are nearly 2.5 and 4 times the input clock voltage of 3 V. The technique of boosting the clock internally has been applied in implementation of a bio-implantable battery powered electrical stimulation chip.

In this work, a remote power delivery system to charge rechargeable batteries that power a Bio-implanted Electrical Stimulation System (BESS) is first described. A loosely coupled inductive transmitter and receiver system has been used to power a bio-implanted gastric pacer. The receiver coil, rechargeable batteries, battery charging chip and the chip containing stimulation circuitry form a hybrid integrated microsystem. A design methodology for this Remote Power Delivery System (RPDS) is proposed. The BESS chip is also designed for electrical stimulation. It is a special IC chip which takes power from the rechargeable batteries and provides output pulses of 9.9 V amplitude at a frequency of 103 Hz and a duty cycle of 5%. The BESS chip contains a battery switching circuit and a pulse conditioning circuit which first provides pulses of 3 V amplitude. It also has an internal charge pump and a pulse booster circuit to boost the pulse amplitude to 9.9 V. Hybrid packaging is considered for integrating the implantable electrical stimulation circuitry and the remote power delivery system. Screen printed interconnects are used to integrate the BESS chip, the battery charging chip, discrete components and the receiver circuit of the RPDS.

Microwave-driven smart material actuators were first envisioned and developed as the best option to simplify the complexity and weight of hard wired networked power and control for smart actuator arrays. A power allocation and distribution scheme (PAD) was originally devised to simplify the wiring of thousands of control cables. The original design was limited to 20 volts, the maximum drain-source voltage of a dual-gate MOSFET used in the circuit. The present research sought to extend the usable voltage range to 200 volts.

The design and development of wireless mocrosensor network systems for the treatment of many degenerative as well as traumatic neurological disorders is presented in this paper. Due to the advances in micro and nano sensors and wireless systems, the biomedical sensors have the potential to revolutionize many areas in healthcare systems. The integration of nanodevices with neurons that are in communication with smart microsensor systems has great potential in the treatment of many neurodegenerative brain disorders. It is well established that patients suffering from either Parkinson’s disease (PD) or Epilepsy have benefited from the advantages of implantable devices in the neural pathways of the brain to alter the undesired signals thus restoring proper function. In addition, implantable devices have successfully blocked pain signals and controlled various pelvic muscles in patients with urinary and fecal incontinence. Even though the existing technology has made a tremendous impact on controlling the deleterious effects of disease, it is still in its infancy. This paper presents solutions of many problems of today's implantable and neural-electronic interface devices by combining nanowires and microelectronics with BioMEMS and applying them at cellular level for the development of a total wireless feedback control system. The only device that will actually be implanted in this research is the electrodes. All necessary controllers will be housed in accessories that are outside the body that communicate with the implanted electrodes through tiny inductively-coupled antennas. A Parkinson disease patient can just wear a hat-system close to the implantable neural probe so that the patient is free to move around, while the sensors continually monitor, record, transmit all vital information to health care specialist. In the event of a problem, the system provides an early warning to the patient while they are still mobile thus providing them the opportunity to react and trigger the feed back system or contact a point-of-care office that can remotely control the implantable system. The remote monitoring technology can be adaptable to EEG monitoring of children with epilepsy, implantable cardioverters/defibrillators, pacemakers, chronic pain management systems, treatment for sleep disorders, patients with implantable devices for diabetes. In addition, the development of a wireless neural electronics interface to detect, transmit and analyze neural signals could help patients with spinal injuries to regain some semblance of mobile activity.

The previous experimental results showed that 230 volts of output was obtained from a 6 x 6 array at a far-field exposure (1.8 meters away) with an x-band input power of 20 watts. This result showed a feasibility of using a microwave to power feed and control smart actuators. Based on the previous research reported, we have achieved 500 V output level for practical applications. However, the rectenna has rigid structures that may give a limitation of flexibility of the smart actuators’ system. In order to apply this concept into real applications, the rectennas have to be flexible, so that it could be patched on smart actuators. In this paper, a design concept of various flexible rectennas and their performances in terms of design parameters such as geometry of rectenna will be discussed as well as integration for a system. The performance of flexible designed rectennas as a preliminary experiment will be presented in terms of the input power, output power of the rectennas, various shapes of rectennas in an array for difference applications, and their efficiencies.

The design, fabrication and experimental evaluation of a Ku-Band 3 dB Wilkinson power divider on high resistivity silicon (HRS) are presented in this paper. The measured insertion for the powder divider is 3.5 dB and isolation between port 2 and 3 is 12 dB respectively. CPW lines were fabricated on two different silicon substrates (HRS, and CMOS grade silicon) and it is shown that the loss characteristics for a 50Ω CPW patterned on the surface-stabilized HRS is only 0.16 dB at 15GHz. In contrast, the insertion loss for CPW line on CMOS grade silicon is 8.3 dB at 15 GHz. Thus, the low insertion loss could be achieved by stabilizing the surface of HRS with a thin polysilicon layer.

This paper presents the design and development of 3-bit polymer MEMS phase shifters for wireless communication applications. Polymer membrane and ferroelectric (barium strontium titanate) thin film on silicon substrates are employed for device fabrication. BI-CPW design and fabrication processes of ferroelectric and polymer materials compatible with current silicon technology are investigated. Mechanical operation with low DC bias voltage and scattering parameters of a polymer MEMS switch and phase delay lines are measured. The small size and low pull down voltage demonstrated in this research are promising characteristics for commercial applications of 3-bit polymer MEMS phase shifters with low cost.

In this paper, we presents a 4×4 stacked phased array antenna system operating at 15GHz, which can be used for commercial as well as military applications including low earth orbiting (LEO) satellites communications and airborne defense system. The phased array antenna consists of 4 subarrays having 4 tapered slot antennas, phase shifters, power dividers, and high voltage controllers. Each component is constructed on low temperature co-fired ceramics (LTCC) that is a multilayer electronic packaging technology and has a unique ability to integrate passive components such as resistors, capacitors and inductors in to a monolithic package. The phase shifter we have developed herein using barium strontium titanate (BST) thin films shows continuous phase shifts of 0°~90° at 15GHz when DC bias voltages are applied up to 300 V between the ground and signal line. By controlling the voltages independently applied to each phase shifters, the beam shape and direction radiated from the array antenna can be changed and steered.

Organic thin film transistors using pentacene as the active material elaborated on flexible substrates are presented in this paper. Organosilane octadecyltrichlorosilane (OTS) is used to treat the gate oxide surface prior to pentacene deposition. This OTS treatment is expected to improve the device performance in terms of field-effect mobility, subthreshold slope, on/off current ratio, and threshold voltage. To pattern the organic active layer, polymer polyvinyl alcohol (PVA) that is a water-soluble polymer is used as photoresist. By using the PVA, the pentacene film can avoid exposure to harmful organic solvents or developers during patterning. The simulated results of a typical thin film resistors with gate length and width of 20μm and 200 μm, respectively, shows a field-effect mobility of 0.98cm²/Vs in the saturation region for V_DS=30V, and an on/off current ratio larger than 10⁶.

Nanostructured Origami 3D Fabrication and Assembly Process is a method of manufacturing 3D nanostructured devices using exclusively 2D micro- and nanofabrication techniques. The origami approach consists of first patterning a large 2D membrane and then folding the membrane along predefined regions to obtain the final 3D configuration. We report on the materials, actuation, and modeling aspects of building an origami structure. Experimental results from fabricated devices as well as future applications of the technique are also presented.

A hierarchical MEMS synthesis and optimization architecture has been developed for MEMS design automation. The architecture integrates an object-oriented component library with a MEMS simulation tool and two levels of optimization: global genetic algorithms and local gradient-based refinement. An object-oriented data structure is used to represent hierarchical levels of elements in the design library and their connectivity. Additionally, all elements encapsulate instructions and restrictions for the genetic operations of mutation and crossover. The parameterized component library includes distinct low-level primitive elements and high-level clusters of primitive elements. Surface micro-machined suspended resonators are used as an example to introduce the hierarchical MEMS synthesis and optimization process.

Injection molding technology is one of the most promising candidates for the economically viable manufacturing of nanoscale parts, but the composition and surface properties of tooling materials become more critical as the size of the molded features decreases. In the study, the effect of novel tooling with micro and nanoscale features was investigated by employing this tooling as inserts for micro injection molding of polycarbonate. Parts molded from etched silicon wafers with pattern depths of 300 nm and widths of 200 to 980 nm showed a significant decrease in replication quality with the size the features, probably because polymer adhered to the tooling surface. Silicon tooling from a different source and titanium-coated gallium arsenide tooling produced higher quality replication. The replication quality from the silicon tooling, however, was constant over 3000 molding cycles and coated gallium arsenide inserts survived the molding pressures; (the uncoated gallium arsenide fractured). These findings suggest that modifications to the insert surfaces will allow for viable tooling for injection molding of plastic parts with nanoscale features.

Noble metal nanoparticles interact strongly with visible light due to resonant excitation of conduction electron oscillations, an interaction referred to as a local surface plasmon resonance (LSPR) interaction. This LSPR interaction results in an enhancement of the electromagnetic field surrounding the nanoparticle, with a concomitant enhancement of optical signals. Recent interest in SER spectroscopy (SERS) has been rekindled by the observation of single molecule SERS. Nanofabrication provides a method for producing metal substrates for SERS with well-defined size and shape characteristics. Gold nanopillar structures are fabricated for this work by electron beam lithography. Rabbit skeletal-myosin-II HMM and actin can be produced in gram quantities and provide the basis for a highly reproducible in-vitro motility assay system. Using this well established assay linked with SERS we can look at how the heads of myosin interact with filaments of actin to produce steps in greater detail. This technique will provide information of subtle mechanistic interactions between components of a molecular motor, with the future possibility of providing a model system for measuring the “proximity effect” in ligand binding (e.g. protein-protein and DNA-DNA interactions) and LSPR-analyte interactions.

In this paper, microstereolithography (MSL) is introduced to fabricate a sophisticated 3D objects in micro size such as hollow pyramidal and helical structures, which are used for electromagnetic absorber applications. The hollow helix can be constructed by staking a hundred layers of 2D annuluses, taking a slight angular increment for the each layer. It is expected that the helices that has ferromagnetic nanoparticle incursions show improve the performance of the electromagnetic absorbers consisting of helix arrays. The paper also presents a new approach to combine the MSL with conventional silicon micromachining process by demonstrating MEMS bridge structures.

It is already established that functional electrical stimulation is an effective way to restore many functions of the brain in disabled individuals. The electrical stimulation can be done by using an array of electrodes. Neural probes stimulate or sense the biopotentials mainly through the exposed metal sites. These sites should be smaller relative to the spatial potential distribution so that any potential averaging in the sensing area can be avoided. At the same time, the decrease in size of these sensing sites is limited due to the increase in impedance levels and the thermal noise while decreasing its size. It is known that current density in a planar electrode is not uniform and a higher current density can be observer around the perimeter of the electrodes. Electrical measurements conducted on many nanotubes and nanowires have already proved that it could be possible to use for current density applications and the drawbacks of the present design in neural probes can be overcome by incorporating many nanotechnology solutions. In this paper we present the design and development of nanowire arrays for the neural probe for the multisite contact which has the ability to collect and analyze isolated single unit activity. An array of vertically grown nanowires is used as contact site and many of such arrays can be used for stimulating as well as recording sites. The nanolevel interaction and wireless communication solution can extend to applications involving the treatment of many neurological disorders including Parkinson’s disease, Alzheimer’s disease, spinal injuries and the treatment of blindness and paralyzed patients with minimal or no invasive surgical procedures.

Aligned polyaniline nanotubules were prepared by electropolymerization/template method. Scanning electron microscopy micrographs reveal their alignment, uniform dimension as well as open-ended properties. Nickel was successfully encapsulated inside the polyaniline nanotubules by chemical treatment followed by electroplating process. Energy dispersive spectroscopy confirms the presence of nickel inside the polyaniline nanotubules.

Different versions of ab initio quantum chemical models (cluster and periodic boundary conditions approximations) have been used to analyze the effect of finite length and the partial filling of the highest occupied orbital on the band-gaps of carbon nanotubes. In agreement with the previous calculations in the tight-binding approximation and pi-electron open shell model, it has been shown that the ground state of the nanotube with the zigzag structure is triplet. It has been confirmed that these tubes exhibit metallic or semiconductor properties with a very narrow half-filled conduction band. The band-gap is of order few tens of eV, and it is estimated that approximately 0.1-0.2% of pi-electrons belong to the conduction band of finite zigzag nanotubes. The triplet state is predicted to be the ground state of finite-length carbon nanotubes.

Carbon nanotubes exhibit excellent properties which make them a good candidate as the electrode material for bioapplications. In this paper, various carbon nanotube based electrodes were prepared by thick film technique. After enzyme immobilization, they can be used as biosensors for glucose detection. We present our fabrication steps, electrochemical measurement of functional nanotube based biosensors. Also, influences of Ph value and interferences were tested. Preliminary results show purified carbon nanotubes electrodes exhibit better electrochemical performance for glucose detection, compared with other nanotube based electrodes.

The performance of new biosensor design -- Micro-ElectroMechanical Diaphragm (MEMD) -- made from PVDF piezoelectric polymer is reported. The resonant frequencies changing with featured size of MEMD are characterized. The resonant behavior in liquid media shows that the damping effect of MEMD is lower than that of MC. Yeast cell detection demonstrated the feasibility of using this platform as biosensor in real time detection. Finally, the preliminary study on microelectronic fabrication of MEMD is presented.

A novel approach is proposed in this work to fabricate metallic nano-cantilevers using a one-mask process and deep reactive ion etch (DRIE) technique. Proof-of-concept experiments were conducted, and 40-nm-thick Al and 70-nm-thick Au cantilevers of lengths from 5μm and widths in the range of 200-300nm were fabricated on a silicon substrate. It is found that the silicon underneath the suspended beams had been completely etched. The fabricated metallic nanocantilevers have potential applications in detecting molecules with high sensitivity. Initial stress induced deflection studies have shown these metallic nanocantilevers to be very sensitive to surface modifications.

This paper discusses the development of new multifunctional smart materials based on Carbon Nanofibers (CNF) and Multi-Wall Carbon Nanotubes (MWCNT). The material properties of CNF/MWCNT are a little lower than the properties of Single Wall Carbon Nanotubes (SWCNT). However, the CNF/MWCNT have the potential for more practical applications since their cost is lower. This paper discusses the development of four CNF/MWCNT-based sensors and actuators. These are: (i) an Electrochemical Wet Actuator for use in a liquid electrolyte, (ii) an Electrochemical Dry Actuator for use in a dry environment, (iii) a Bioelectronic sensor; and (iv) a MWCNT neuron for structural health monitoring. These materials are exciting because of their unique properties and many applications.

We investigate Tungsten (W) nanorod electrodes as gas ionizers. These W nanorods having square-base pyramidal apexes are grown using a glancing angle sputter deposition technique with substrate rotation. We show that few tens of volts of anode voltage applied to the W nanorods are sufficient to ionize a range of different gas species including Ar, CO₂, N₂ and O₂. A distinct ionization onset voltage is observed for each individual gas specie, which suggests that these nanostructured ionization devices may be useful for gas sensing applications. In addition, the low anode voltage and high ion currents observed in this study indicates that the gas ionization devices could be operated using commercially available off-the-shelf batteries.

The spectral dependence of photoconductivity of structure nanodimensional Ge/c-Si was measured on infrared spectrophotometer DCS-12 which contains Ge quantum holes on a surface of single-crystal substrate. The photoconductivity spectrum of nanodimensional Ge/c-Si structure was received at room temperature. The investigated samples are made by molecular-beam epitaxy method, rectangular frame type (5x5 micron) contact was generated on a surface of Ge layer. The thickness of a contact strip was equaled to 0,5 micron. The second contact was soldered to the back side of the singlecrystal surface. A shifting voltage of U = 1,5 V was switched in the opposite direction (negative potential to Ge slice) At measurements of photoconductivity of structure. It is necessary to note that photoconductive signal was 3 orders less, than at inverse displacement. It specifies presence heterotransitions between Ge and c-Si layer. The photosensitivity of a standard silicon photodiode was investigated for comparison of such assumption. For example the spectral dependence of photosensitivity of standard silicon photodiode ΦB-142K is represented. The spectral position of a photoconductivity curve was the same to standard silicon photodiode at room temperature. The value of photosensitivity of a researched sample was compared with the standard photodiode. Is established, that both these values are of the same order. It is possible to explain it by presence of a potential barrier between Ge and Si. It is known that longwave border of photoconductivity is defined by width of the forbidden zone of the semiconductor. The increase of photoconductivity is caused by increase of absorption at rising of quantums energy of the exited radiation (at reduction of wavelength). The form of a photoconductivity spectrum of the photodiode ΦB-142K and absence of a hole in the spectrum in short-wave area (1,5-2,1 micron) specifies that the speed of a surface recombination is equal to zero. For the structure nanodimensional Ge/c-Si, otherwise, significant hole in this area was observed at the room temperature. So, samples had the large speed of surface recombination. To observe the contribution of nonequilibrium charge carriers to the photoconductivity of structure nanodimensional Ge/c-Si it is necessary to cool down to T < 100 Κ. The intersubband transitions can occur in nanodimensional Ge at such temperatures. So, it is necessary to expect observation of a photosensitivity in the infrared, which corresponds energy of these transitions. It is possible to explain photosensitivity of nanostructures by existence of interzoned transitions in nanodimension Ge. The spectral dependence of photosensitivity of structure nanodimensional Ge/c-Si in IR- of area is received.

Power consumption is a critical concern of many sensors used in diversified applications, especially where the replacement of batteries is impossible or inconvenient. Strain energy harvesting technique is an attractive approach to solve this problem using piezoelectric materials. The feasibility of a self-powered piezoelectric microaccelerometer system using lead zirconate titanate (PZT) thin film is studied in this paper. Since the electromechanical coefficient d₃₃ of PZT is larger than d₃₁, and the transverse (33 mode) mode is also easier to fabricate, our design and analysis are focused on the transverse mode in constructing the PZT-based self-powered microsystem. The PZT-based cantilever structure with interdigitated electrodes and silicon seismic mass at the free end are designed to have specific resonance frequencies ranging from tens to thousands of hertz. The capability of energy storage and acceleration sensitivity in the proposed microaccelerometer are concurrently evaluated. A trade-off exists between these two major functions and the desirable operating frequency of the proposed system, i.e., the compromise depends on the demands of particular applications.

Based on mass-loading effect on a microcantilever, there are two approaches for sensing the presence of molecules: dynamic and static methods. In this note, we demonstrate that the two methods actually use the same form of relationships for their sensing purposes, and that if the designed adhesion region of a cantilever is only partially occupied by molecules then neither method can be applied to accurately determine the number of molecules adsorbed.

Fe_73-xAl_xSi₁₄B_8.5Cu₁Nb_3.5 (x = 0, 2) nanocomposite materials consisting of a nanocrystalline phase in an amorphous matrix were obtained by annealing their precursor amorphous ribbons, which were prepared by the melt-spinning technique, at different temperatures ranging between 350°C and 650°C for 45 min in vacuum. Investigation on their magnetic and magnetoimpedance properties indicates that the Al-containing sample (x = 2) possesses superior magnetic softness and giant magnetoimpedance (GMI) effect over the Al-free counterpart. This can be likely ascribed to the increased magnetic permeability, decreased coercive force and decreased resistivity. The increased magnetic permeability is resulted from a reduction in magnetocrystalline anisotropy and saturation magnetostriction. The correlations between magnetic softness, electrical properties and GMI behaviour is discussed in the light of the skin effect model. These results indicate that the Al-containing Fe-based nanocomposite material can be used for GMI sensor applications.

The objective of this work was to demonstrate smart wireless sensing nodes capable of operation at extremely low power levels. These systems were designed to be compatible with energy harvesting systems using piezoelectric materials and/or solar cells. The wireless sensing nodes included a microprocessor, on-board memory, sensing means (1000 ohm foil strain gauge), sensor signal conditioning, 2.4 GHz IEEE 802.15.4 radio transceiver, and rechargeable battery. Extremely low power consumption sleep currents combined with periodic, timed wake-up was used to minimize the average power consumption. Furthermore, we deployed pulsed sensor excitation and microprocessor power control of the signal conditioning elements to minimize the sensors’ average contribution to power draw. By sleeping in between samples, we were able to demonstrate extremely low average power consumption. At 10 Hz, current consumption was 300 microamps at 3 VDC (900 microwatts); at 5 Hz: 400 microwatts, at 1 Hz: 90 microwatts. When the RF stage was not used, but data were logged to memory, consumption was further reduced. Piezoelectric strain energy harvesting systems delivered ~2000 microwatts under low level vibration conditions. Output power levels were also measured from two miniature solar cells; which provided a wide range of output power (~100 to 1400 microwatts), depending on the light type & distance from the source. In summary, system power consumption may be reduced by: 1) removing the load from the energy harvesting & storage elements while charging, 2) by using sleep modes in between samples, 3) pulsing excitation to the sensing and signal conditioning elements in between samples, and 4) by recording and/or averaging, rather than frequently transmitting, sensor data.

In this paper, we propose a closed loop Micro-Opto-Electro-Mechanical (MOEM) accelerometer employing a nonuniform cantilever beam and an Anti Resonant Reflecting Optical Waveguide (ARROW) on silicon. The MOEM acelerometer consists of a Mach Zehnder Intereferometer (MZI) and an electro-elasto-optic phase modulator to nullify the acceleration induced phase change so as to make the device work in closed loop form. It is shown that MOEM accelerometers with noise equivalent acceleration of 0.255 μg/√Hz, a dynamic range of 160g, scale factor stability of 1.57 ppm/°C and shock survivability of more than 1000 g is feasible.

For the translation stage of nanometer scale, fiber optic EFPI sensor is suggested for the feedback control system on account of its high sensitivity, small size, simple system and relatively low cost. The novel signal processing algorithm for the real-time demodulation of EFPI output signal was developed and verified. The local linearity in the adjacent fringe values was shown, and used for the sinusoidal approximation of the nonlinear output signal. The real-time signal processing program was designed and the intensity signal of the EFPI sensor was demodulated to the phase shift with this program. The theoretical resolution of 0.36~8.6 nm in the displacement range of 0~200 μm was obtained. The sensor system was applied to the 1-D nano-positioner with a Piezo-electric actuator. The positioner successfully reached to the desired destination within 1 nm accuracy.

We have developed SH (shear horizontal) surface acoustic wave (SAW) sensors for detection of the immobilization and hybrdization of DNA (deoxyribonucleic acid) on the gold coated delay line of transverse SAW devices. The experiments of DNA immobilization and hybridization were performed with 15-mer oligonucleotides (probe and complementary target DNA). The sensor consists of twin SAW delay line oscillators (sensing channel and reference channel) operating at 100 MHz fabricated on 36° rotated Y-cut X-propagation LiTaO₃ piezoelectric single crystals. The relative change in the frequency of the two oscillators was monitored to detect the immobilization of probe DNA with thiol group on the Au coated delay line and the hybridization between target DNA and immobilized probe DNA in a pH 7.4 PBS (phosphate buffered saline) solution. The measurement results showed a good response of the sensor to the mass loading effects of the DNA immobilization and hybridization with the sensitivity up to 1.5 ng/ml/Hz.

In this paper, we report an innovative all-polymeric drug-supply device. The micro outlet of the device was ablated through a polymethyl methacrylate (PMMA) layer using a microheater. The size of the ablated micropore was mainly related to the heater temperature profile, and the molten PMMA took the gold heater lines away from the pore area, avoiding possible block of the gold lines to the flow out of the pore. Simulation was conducted to find the temperature profile on the surface of the microheater, and experimental results have a good match with simulation results.

There is an urgent need for biosensors that are able to detect and quantify the presence of a small amount of biological threat agents in a real-time manner. The magnetostrictive microcantilever (MSMC) as the biosensor platform is reported in this paper. The resonance behavior and the sensitivity of MSMC as sensor platform were characterized and compared to the theoretical calculation. The stability and the performance of the MSMC in liquid are studied. The feasibility of MSMC as a high performance biosensor platform is demonstrated by detecting yeast cells in real-time manner used MSMC based-biosensor. Compare to current microcantilevers, the MSMCs have following advantages: 1) remote/wireless driving and sensing; 2) easy to fabricate. More importantly, the MSMC exhibits very high quality merit factor (Q value).

This paper describes a novel method for the fabrication of nanodot arrays with 30nm period which will be used as a platform for the highly sensitive and specific Surface enhanced Raman spectroscopy (SERS) detection of the polymerase chain reaction (PCR). The usual detection methods for PCR involve time consuming methods of DNA labelling, using labels that are capable of altering original DNA properties. We present a detection method which has the advantages of being label free, requiring small analyte volumes and achieving high sensitivity due to SERS enhancement. The required reproducible SERS environment is achieved by the nanofabrication of gold pillars on glass with the use of an electron-beam writer.

This paper presents the design and development of passive wireless sensors for bio-hazard vapors in wireless sensing network, based on reflected-wave phase monitoring. Composite thin film with functionalized carbon nanotubes (f-CNT) and polymethylmethacrylate (PMMA) is employed as a sensing material on a coplanar waveguide. Resistance increase with absorption of dichloromethane gas into composite thin film is observed by resistance measurement. Phase measurement of reflected wave from resistive loads demonstrates high sensitivity using a network analyzer. Based on the radio frequency characteristics, wireless gas sensing network integrated with a circulator and two antennae is tested. Measurement results of sensors and reference loads using the wireless sensing network shows large differential phase shifts which is sufficient to monitor bio-hazards material in real-time with high sensitivity.

Microcantilever sensor with embedded piezoresistor has been proposed to measure the surface stress change from biochemical reaction. However, the sensor performance is adversely influenced by the piezoresistive thermal stress and biaxial surface stress loading. A mechanics model of piezoresistive microcantilever subject to surface stress loading is developed in this paper. A double-microcantilever design composed of the top immobilized microcantilever and the bottom sensing microcantilever is also proposed such that the surface stress loading can be converted to a concentrated force loading. The effect of biaxial surface stress can thus be limited to the immobilized microcantilever with the uniaxial strain in the sensing microcantilever. Analyses show that the surface stress sensitivity can be increased by high length ratio and lower thickness ratio of the two cantilevers. More than two orders of magnitude in measurement sensitivity can be achieved and the induced thermal noise can be minimized.

It is known that rapid mixing in microchannels overcomes the inherent diffusion-limited mixing of laminar flow. Consequently, many techniques that enhance microfluidic mixing are under development: slanted wells, shallow grooves, electrokinetic instability mixing and surface layers, etc. The long-term goal of this work is the optimization of surface-property distributions to control mixing and provide surface-directed flows. In this work, binary fluid mixing is explored using the lattice Boltzmann Method (LBM) to simulate flows in two-dimensional, microfluidic channels having surface temperature variations. Previous work has shown the advantages of controlled wall temperature distributions (i.e., flow-through PCR devices). Over 100 mixing scenarios were simulated by varying the Reynolds number, wall temperature distributions, binary fluid density ratios and interaction strengths, and the coupling strength between momentum and temperature. If one adds channel geometry variations, we are optimizing a mixing function over a multidimensional parameter space of large dimension. This vector-valued mixing function contains two scalar-valued objective functions. Each objective function measures the mixing obtained for fluid 1 and fluid 2. The optimization problem is to find designs that simultaneously attain an optimal mix of both fluids. Consequently, we have a massive, computationally-intensive, multiobjective optimization problem. In multiobjective optimization problems, many acceptable designs can be obtained by trading one objective function against the other. For example, one might accept a slightly worse mixing of fluid 1 for a much better mix of fluid 2. We demonstrate optimal mixing as a function of these designs, that is the variation of the wall temperatures and the heater lengths.

Structural Health Monitoring ideally would check the health of the structure in real time all the time. Simplifying the sensor system and the data acquisition equipment plays a very important role in achieving this goal. This paper discusses a practical technique that uses long continuous sensors and biomimetic signal processing to simplify health monitoring. The testing of a structural neural system with an updated analog processor module is discussed in this paper. A neuron is formed by connecting sensor elements to an analog processor. The structural neural system is formed by connecting multiple neurons to mimic the signal processing architecture of the neural system of the human body. This approach reduces the required number of data acquisition channels and still predicts the location of damage within a grid of miniature neurons. Different types of sensors can also be used. A piezoelectric ribbon sensor can sense damage due to impacts or crack growth because these damages generate Lamb waves that are detected by the neural system. The neuron can also receive diagnostic waves generated to check the structure on demand and when it is not in operation. In addition, new continuous multi-wall carbon nanotube sensors are being used as strain and crack detection neurons that operate during both static and dynamic loading. In general, the Structural Neural System may provide an advantage for the continuous monitoring of most large sensor systems in which anomalous events must be detected, and where it is impractical to have a separate channel of data acquisition for each sensor. Moreover, the data reduction technique and damage detection algorithm are easy to understand, simple to implement, reliable, and many sensor types can be used.

In this work, an analytical relationship is derived for a doubly-clamped microbeam when it buckles after release from the substrate. In terms of the relationship, compressive residual stress in the doubly-clamped microbeam can be determined according to its buckled shape, allowing one to find the compressive residual stress directly without much experimental effort. This relationship has been used to determine compressive residual stresses in four types of doubly-clamped SiO₂ microbeams. In addition, four methods have been applied to find the elongations of these SiO₂ microbeams, and the corresponding results are compared. Finally, the residual stresses in doubly-clamped SiO₂ microbeams predicted according to the derived relationship are compared with those found in SiO₂ microcantilevers, and the results have a good match.

In this work, a new method was developed to increase the stiffness of PDMS (Polydimethylsiloxane) masters using Si plates, aimed at reducing residual deformations of the PDMS masters induced in the molding process. Using this method, both global and local residual deformations in the reinforced PDMS master have been reduced.

RF MEMS switches provide a low-cost, high performance solution to many RF/microwave applications and these switches will be important building blocks for designing phase shifters, switched filters and reflector array antennas for military and commercial markets. In this paper, progress in characterizing of THALES capacitive MEMS devices under high RF power is presented. The design, fabrication and testing of capacitive RF MEMS switches for microwave/mm- wave applications on high-resistivity silicon substrate is presented. The switches tested demonstrated power handling capabilities of 1W (30 dbm) for continuous RF power. The reliability of these switches was tested at various power levels indicating that under continuous RF power. In addition a description of the power failures and their associated operating conditions is presented. The PC-based test stations to cycle switches and measure lifetime under DC and RF loads have been developed. Best-case lifetimes of 10¹⁰ cycles have been achieved in several switches from different lots under 30 dbm RF power.

In this paper, microstrip stepped-impedance hairpin resonator (SIR) low-pass filter (LPF) and slow-wave band-pass filter (BPF) using dielectric supported air-gapped microstrip line (DAML) of surface micromachining on GaAs substrate are proposed. The DAML structure, which is a new low-loss micromachining transmission line, is useful for the integration of MEMS and/or MMIC components. Design parameters for the proposed SIR low-pass and slow-wave band-pass filters are derived based on stepped-impedance theory. The proposed slow-wave BPF is designed to produce a passband of 10% at the fundamental frequency of 60 GHz. and a new SIR LPF with aperture and IDC (inter-digital capacitor) is designed for 3-dB cutoff frequency of 33 GHz. The measurement results of the BPF filter and LPF filter agree well with simulation results. These filters are useful for many millimeter-wave system applications.

Recent technological advances have enabled the fabrication of mechanical resonators down to micrometer and even nanometer scales, with super high frequencies. One particularly interesting aspect of the physical behavior of microelectromechanical systems (MEMS) is their nonlinear mechanical response at relatively small deviations from equilibrium which is caused by nonlinear electromagnetic forces, nonlinear stiffness, heat transfer porperties. It is important to understand the nonlinear behavior of MEMS in order to improve their future designs. Hybrid numerical - experimental optical techniques are applied for holographic imaging and characterization of non-linearity in micro-mechanical relays, in particular their cantilevers. The apparent simplicity of the problem is misguiding due to non-linear interaction between the cantilever and the bottom electrode. Therefore the results of optical measurements of the cantilever dynamics are inaccurate due to the shift of the fringes in time average laser holographic interferograms. Numerical modeling helps to solve non-uniqueness of the inverse problem and to validate the interpretation of the pattern of fringes.

Development of a taste sensor with high sensitivity, stability and selectivity is highly desirable for the food and beverage industries. The main goal of a taste sensor is to reproduce five kinds of senses of humans, which is quite difficult. The importance of knowing quality of beverages and drinking water has been recognized as a result of increase in concern in environmental pollution issues. However, no accurate measuring system appropriate for quality evaluation of beverages is available. A highly sensitive microsensor using horizontally polarized Surface Acoustic Waves (SH-SAW) for the detection and identification of soft drinks is presented in this paper. Different soft drinks were tested using this sensor and the results which could distinguish between two popular soft drinks like Pepsi and Coca cola is presented in this paper. The SH-SAW microsensors are fabricated on 36°-rotated Y cut X propagating LiTaO₃ (36YX.LT) substrate. This design consists of a dual delay line configuration in which one line is free and other one is metallized and shielded. Due to high electromechanical coupling of 36YX.LT, it could detect difference in electrical properties and hence to distinguish different soft drinks. Measured electrical characteristics of these soft drinks at X-band frequency using free space system show distinguishable results. It is clear from these results that the microsensor based on 36YX.LT is an effective liquid identification system for quantifying human sensory expressions.

This paper presents the research on stability analysis of carbon nanotubes (CNTs) via elastic continuum beam and shell models. The estimation of the flexural stiffness of a single-walled nanotube (SWNT) via elastic beam model is proposed based on the postulate analyzed and provided in the paper. The validation of the stiffness is conducted with the ab initio calculations of the vibration of a SWNT. Based on the stiffness proposed, the stability analysis of CNTs is further conducted and validated with the well-cited research results by Yakobson and his collaborators. In addition, more predictions of various buckling phenomena of carbon nanotubes by beam and shell models are provided and studied. In the end, the kink phenomenon in a SWNT under pure bending is discussed via the continuum model. Last but not least, the results on the kink of a SWNT under an initial bend is presented. It is hoped that this paper will pave the way toward a better understanding of continuum models’ application in the stability analysis of carbon nanotubes.

A cantilever-type electrostatically actuated microelectromechanical (MEMS) switch and its fabrication technology have been developed for the first time in Lithuania, in Kaunas University of Technology. The microdevices were fabricated using nickel surface micromachining technology on substrates made of semiconductor (silicon) and insulator materials (quarts and ceramics). The microswitch consists of cantilevered nickel structure suspended over actuation and contact electrodes. The width of the cantilever contacting element is 30 μm, thickness is about 2.0 μm and length ranges from 67 to 150 μm. Implementation of microswitches as a substitute for present switching devices poses many problems. In particular lower switching speed and reduced lifetime are considered to be among the most significant ones. These characteristics are determined both by design and dynamic phenomena that are taking place during its operation. Specifically, when the microswitch closes, it bounces several times before making permanent contact. These impact interactions greatly influence microswitch durability and switching speed. With the aim of improving these parameters a comprehensive finite element model is being developed that takes into account not only electrostatic actuation and squeeze-film damping effects but also describes important dynamic phenomena - impact interactions that take place during switching. Experimental research of electrical and dynamic characteristics is also carried out with the purpose of device model validation and correction. The paper presents design and fabrication process of the developed microswitch as well as initial simulation and measurement results.

Quantum logic gates (QLGs) or other logic systems are based on quantum-dots (QD) with a stringent requirement of size uniformity. The QD are widely known building units for QLGs. The size control of QD is a critical issue in quantum-dot fabrication. The work presented here offers a new method to develop quantum-dots using a bio-template, called ferritin, that ensures QD production in uniform size of nano-scale proportion. This technology is essential for NASA, DoD, and industrial nanotechnology applications such as: ultra-high density data storage, quantum electronic devices, biomedical nanorobots, molecular tagging, terahertz radiation sources, nanoelectromechanical systems (NEMS), etc. The bio-template for uniform yield of QD is based on a ferritin protein that allows reconstitution of core material through the reduction and chelation processes. By either the magnetic or electrical property of reconstituted core materials, the QD can be used for logic gates which are fundamental building blocks for quantum computing. However, QLGs are in an incubation stage and still have many potential obstacles that need to be addressed, such as an error collection, a decoherence, and a hardware architecture. One of the biggest challenges for developing QLG is the requirement of ordered and uniform size of QD for arrays on a substrate with nanometer precision. The other methods known so far, such as self-assembled QD grown in the Stranski-Krastanov mode, are usually randomly organized. The QD development by bio-template includes the electrochemical/chemical reconstitution of ferritins with different core materials, such as iron, cobalt, manganese, platinum, and nickel. The other bio-template method used in our laboratory is dendrimers, precisely defined chemical structures. With ferritin-templated QD, we fabricated the heptagon-shaped patterned array via direct nano manipulation of the ferritin molecules with a tip of atomic force microscope (AFM). We also designed various nanofabrication methods of QD arrays using a wide range manipulation techniques. The precise control of the ferritin-templated QD for a patterned arrangement are offered by various methods, such as a site-specific immobilization of thiolated ferritins through local oxidation using the AFM tip, ferritin, arrays induced by gold nanoparticle manipulation, thiolated ferritin positioning by shaving method, etc. In the signal measurements, the current-voltage curve is obtained by measuring the current through the ferritin, between the tip and the substrate for potential sweeping or at constant potential. The measured resistance near zero bias was 1.8 teraohm for single holoferritin and 5.7 teraohm for single apoferritin, respectively.