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An enhanced glucose biosensor based on a charge transfer technique glucose sensor (CTTGS) is described and demonstrated experimentally. In the proposed CTTGS, which is accumulation method (d-gluconate+H(+)) ion perception system, the quality of output signal with "signal integration cycles" is high. With the proposed CTTGS it is possible to amplify the sensing signals without an external amplifier by using an accumulation cycle. It can be supposed that measurements of small (d-gluconate+H(+)) ion fluctuation are difficult by ion-sensitive field effect transistor (ISFET) because the theoretical maximum sensitivity is only 59 mV/pH and the small output signals are buried in the 1/f noise component of the metal-insulator-semi-conductor field-effect transistor (MISFET). Therefore, the CTTGS has many advantages, such as high sensitivity, high accuracy, high signal-to-noise ratio (SNR), and has been successfully demonstrated using a charge transfer technique. The CTTGS exhibited excellent performance for glucose with a large span (1445 mV) and good reproducibility. Moreover, the CTTGS has good sensitivity in this range of 7.22mV/mM, a lower detection limit of about 0.01 mM/L and an upper detection limit of about 200 mM/L compared with amperometric glucose analysis which has been studied recently. Under optimum conditions, the proposed CTTGS exceeds the performance of the widely used ISFET glucose sensor. The sensitivity of the CTTGS (7.22 mV/mM) was seven times higher than that of the ISFET (1 mV/mM). Furthermore, the sensitivity obtained for human glucose levels was 29.06 mV/mM with a non-linear error of +/-0.27%; the linearity is y=0.0294x+1.8612 and R(2)=0.9999, which is acceptable for clinical application. Real sample analysis is investigated in blood glucose level by our developed CTTGS ISFET system.

This paper presents a glucose biosensor, which was developed using a Au/Ni/copper electrode. Until now, research regarding the low electrical resistance and uniformity of this biosensor electrode has not been conducted. Glucose oxidase (GOD) immobilized on the electrode effectively plays the role of an electron shuttle, and allows glucose to be detected at 0.055 V with a dramatically reduced resistance to easily oxidizable constituents. The Au/Ni/copper electrode has a low electrical resistance, which is less than 0.01 Omega, and it may be possible to mass produce the biosensor electrode with a uniform electrical resistance. The low electrical resistance has the advantage in that the redox peak occurs at a low applied potential. Using a low operating potential (0.055 V), the GOD/Au/Ni/copper structure creates a good sensitivity to detect glucose, and efficiently excludes interferences from common coexisting substances. The GOD/Au/Ni/copper sensor exhibits a relatively short response time (about 3s), and a sensitivity of 0.85 microA mM(-1) with a linear range of buffer to 33 mM of glucose. The sensor has excellent reproducibility with a correlation coefficient of 0.9989 (n=100 times) and a total non-linearity error of 3.17%.

In this paper, a novel radio frequency (RF) induced power supply system for micro sensor nodes is presented. The system receives RF-electromagnetic wave of a mobile phone and rectifies it to generate a DC voltage by a rectenna (a rectifying circuit with an antenna). A charge pump (CP) circuit boosts up an output voltage of the rectenna, and the boosted voltage is stored to a large capacitor. When the boosted voltage of CP circuit reaches to an arbitrary voltage, a switch circuit between the output of CP circuit and an input of a voltage regulator turns on and supplies a regulated DC voltage to a load through the voltage regulator. The power supply system mounts one Schottky barrier diode (SBD) and three large value capacitors of surface mount devices (SMD) on deep holes fabricated by deep reactive ion etching (DRIE) process around CMOS circuits. The system was fabricated with 0.6 μm-CMOS technology, and can supply well-regulated 4.0 V/1 mA DC power to the load for 10 ms periodically.

A wide dynamic range photogate-type active pixel image sensor based on a self-regulation principle is reported. A 5 ×5 element prototype sensor was fabricated using a 5 µm single-poly, single-metal negative channel metal oxide semiconductor (NMOS) silicon integrated circuit technology. The key techniques are based on the feedback of a floating diffusion (FD) potential to the photogate applied voltage and on the control of the sub-threshold characteristic of the photogate using an ion implantation process. The proposed sensor makes it possible to automatically adjust the sensitivity of each pixel using only three transistors. The conversion of the irradiated light to the output voltage is linear under low-light conditions, while it is nonlinear under bright light. The photo-electric conversion characteristics are similar to those of a linear-logarithmic image sensor. The dynamic range can be expanded without the need for an additional capacitor, an analog-to-digital (A/D) converter or any complex circuitry. Compared with a conventional photogate-type image sensor that was fabricated on the same chip, the dynamic range was expanded by 28 dB.

In this paper, CMOS-based low-noise amplifiers with JFET-CMOS technology for high-resolution sensor interface circuits are presented. A differential difference amplifier (DDA) configuration is employed to realize differential signal amplification with very high input impedance, which is required for the front-end circuit in many sensor applications. Low-noise JFET devices are used as input pair of the input differential stages or source-grounded output load devices, which are dominant in the total noise floor of DDA circuits. A fully differential amplifier circuit with pure CMOS DDA and three types of JFET-CMOS DDAs were fabricated and their noise performances were compared. The results show that the total noise floor of the JFET-CMOS amplifier was much lower compared to that of the pure CMOS configuration. The noise-reduction effect of JFET replacement depends on the circuit configuration. The noise reduction effect by JFET device was maximum of about − 18 dB at 2.5 Hz. JFET-CMOS technology is very effective in improving the signal-to-noise ratio (SNR) of a sensor interface circuit with CMOS-based sensing systems. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

In this paper, we present a thermally measurable contact and noncontact-type thermoelectric sensor using a silicon-on-insulator (SOI) structure, because single-crystal silicon has a higher Seebeck coefficient than any other thermoelectric material. The sensor was designed to have 17 pairs of n- and p-type single-crystal silicon strips and a selective absorption area (SAA) that consists of aluminum and silicon dioxide. The thermoelectric sensor based on the SOI structure was fabricated and measured using a complementary metal–oxide–semiconductor (CMOS) process. The measured sensitivity of the sensor was 0.19 mV/°C, when human skin directly touched the sensor surface. In the noncontact measurement of the sensor while varying the distance between the lamp (EFD10EL/8, NEC) and the sensor, the maximum electromotive force (EMF) of the sensor was -1.55 mV at a 2 mm (6.09 mW) distance.

The effect of mechanical stress on the MOSFET performance under various biasing conditions is presented here. Study on the stress sensitivity suggests an increased sensitivity at higher drain voltages. Higher stress sensitivity obtained at higher drain voltage is due to impact ionization. Stress sensitivity shows a good linearity with the applied stress at higher operating voltages. Optimum gate voltage and drain voltage exists for maximum sensitivity. The results are promising for their application in high sensitivity smart stress sensors for varieties of applications.

This paper reports about a novel wafer-level integration technique of discrete surface mount devices (SMDs). It enables wafer-level mounting of plural kinds of SMDs on a silicon (Si)-wafer using vibration and gravity force. Deep holes with 400-m depth are formed on the surface of a Si-wafer by deep reactive ion etching process after general integrated circuit process for positioning of SMDs. A non-conductive adhesive (CYTOP) are coated on the deep holes and it is used to fix the aligned SMDs. SMDs are distributed on a Si-wafer mounted on vibration generator, and then a vibration is applied. The SMDs migrate due to the reduced friction between the wafer surface, and they drop into the holes on the silicon wafer. The size of the holes has an appropriate clearance to the size of SMD. In order to align two or more kinds of SMDs, sizes of the deep holes on a Si-wafer are adjusted to the size of each SMD. SMDs with the largest size are dropped into the holes first, and then the secondary large SMDs are dropped into the holes with the corresponding size. SMDs are finally connected electrically by wire bonding at the final step. In the experiment, two different sizes of SMD were successfully mounted into all the holes on a Si-wafer automatically. This technology will be a wafer-level process technology which is very promising to integrate two or more kinds of discrete elements.

This paper presents the integration of an inductor by complementary metal-oxide-semiconductor (CMOS) compatible processes for integrated smart microsensor systems that have been developed to monitor the motion and vital signs of humans in various environments. Integration of radio frequency transmitter (RF) technology with complementary metal-oxide-semiconductor/micro electro mechanical systems (CMOS/MEMS) microsensors is required to realize the wireless smart microsensors system. The essential RF components such as a voltage controlled RF-CMOS oscillator (VCO), spiral inductors for an LC resonator and an integrated antenna have been fabricated and evaluated experimentally. The fabricated RF transmitter and integrated antenna were packaged with subminiature series A (SMA) connectors, respectively. For the impedance (50 Ω) matching, a bonding wire type inductor was developed. In this paper, the design and fabrication of the bonding wire inductor for impedance matching is described. Integrated techniques for the RF transmitter by CMOS compatible processes have been successfully developed. After matching by inserting the bonding wire inductor between the on-chip integrated antenna and the VCO output, the measured emission power at distance of 5 m from RF transmitter was -37 dBm (0.2 μW).

A smart microfluidic DNA sensor with an integrated signal-processing circuit for electrochemical analysis has been successfully fabricated. The sensor comprises an integrated electrochemical sensing electrode, a microfluidic channel-type reactor, and operational amplifiers for electrochemical measurement. The microfluidic reactor employs a laminar flow principle. Generally, a relatively large and expensive system is necessary for electrochemical measurement. In the fabricated smart chip, signal-processing circuits for measuring cyclic-voltammogram characteristics are integrated, permitting cyclic-voltammograms to be successively measured, using only two simple sources of electrical power.

We have fabricated a 32 × 32 silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS) active pixel image sensor with a pinned photodiode on a handle wafer. The structure of one pixel is a four-transistor type active pixel sensor (APS) which consists of a reset and a source follower transistor on a seed wafer, and is comprised of a photodiode, a transfer gate, and a floating diffusion on the handle wafer. The photodiode could be optimized for better quantum efficiency and low dark currents because its process on the handle wafer is independent of that of transistors on a seed wafer. Most of the wavelengths are absorbed within the visible range, because the optimized photodiode is located on the handle wafer. The image has been captured by the fabricated 32 × 32 SOI CMOS image sensor with array pixels, vertical scanner, horizontal scanner, and delta-difference sampling circuit.

In this paper, we fabricated piezoresistive pressure sensor with dry etching technology which used ICP-RIE (inductively coupled plasma reactive ion etching) and etching delay technology which used SOI (silicon-on-insulator). Structure of the fabricated pressure sensor shows a square diaphragm connected to a frame which was vertically fabricated by dry etching process and a single-element four-terminal gauge arranged at diaphragm edge. Sensitivity of the fabricated sensor was about 3.5 mV/V kPa at 1 kPa full-scale. Measurable resolution of the sensor was not exceeding 20 Pa. The nonlinearity of the fabricated pressure sensor was less than 0.5 %F.S.O. at 1 kPa full-scale.

In this paper, technical development results of "sensitive endoscope hood" for an endoscopic surgery operative procedure, NOTES (Natural Orifice Translumenal Endoscopic Surgery) with a flexible endoscope is reported. A microsensor integrating an absolute pressure sensor and a temperature sensor is embedded inside of the thin wall of a disposable endoscope hood. Intraluminal pressure and temperature of stomach can be measured under the NOTES operation using the sensor hood, and it is very helpful to keep the inside condition of stomach for the operating doctor. Especially, monitoring of stomach pressure have two important purposes. The first importance is quantitative measurement of tumor sizes under a constant intraluminal pressure of stomach for treatment selection. The second importance is prevention of putting the patient in danger caused by over transmission of air. Monitoring with embedded sensor in flexible endoscopic surgery have not been tried and reported in NOTES field with single flexible endoscopy. This is the exploratory work in the area of flexible microscopic surgery, and is a new technology field and challenge of well-established MEMS sensors. The developed endoscopy hood was tested in an animal experimentation with Beagle dog, and its performance and robustness have been successfully demonstrated.

In this study, stable detection principle of MEMS hardness sensor using "reference plane" structure is theoretically analyzed and demonstrated with experimental results. Hardness measurement independent to contact force instability is realized by optimum design of the reference plane. Fabricated devices were evaluated, and “shore A” hardness scale was obtained as reference in the range from A1 to A54 under a stable contact force. Contact force dependence was effectively reduced by 96.6% using our reference plane design (i.e. very stable to the contact force change). Below 1N contact force, maximal signal error of hardness is suppressed to A4. This result corresponds to the detection ability of fat's hardness, even if the contact force is instable. Thorough the experiments, stable detection of human body hardness has been demonstrated without any control of the contact force.

In this paper, a novel optical self-alignment technology for realization of compact optical multi-gas sensor system is newly proposed. This technology realizes high precision alignment of discrete optical components on a single silicon chip or combined multi silicon chips. Designing the optical path in parallel to the surface of silicon chip, discrete optical lenses and fibers are interconnected with a MEMS optical spectrometer and mirrors to form a compact optical gas detector system in a small size. Also, "height" of optical components can be adjusted to the optical axis by stacking the precisely aligned silicon chips. Micro optical system was fabricated using the developed alignment technology, and the position alignment error in in-plane direction (X- and Y-axis) was with in ±1μm in maximum. On the other hand, the maximum position error in out-of-plane direction (Z-axis) was below ±20μm. These values are high enough to fabricate our on-chip micro optical sensor system.

In this paper, a novel rotational MEMS diffraction grating for realization of micro-sized spectroscope system with SiOB (Silicon Optical Bench) technology is newly developed, and its evaluation results are reported for the first time. Since this device has “out-of-plane” optical surface on the rotational actuator, concept of micro optical bench is applicable to realize precision alignment in the micro spectrometer. A diffraction grating was fabricated by silicon, and it is mounted on the stage of an electrostatic rotational actuator. Driving the stage by ±3.5° at DC80V, wavelength of white light was successfully modulated in the range from 515nm to 763nm at an 11% diffraction efficiency.

In this paper, a new extraction method of information for quantification of the fingertip sense which is never extracted by previous tactile sensors is reported for the first time. The MEMS two-axis tactile sensor used for the purpose can get the correlation between the surface shape and the local frictional force at the same time and at the same point. Obtained correlative relationships using the device were carefully analyzed with statistical analysis and FFT, and various objective facts have been made clear. For example, the rougher the feel texture of a paper surface, the lower the mutual relation between the time-domain waveform of surface micro roughness and the corresponding instantaneous frictional force. This is an example of never known knowledge about surface feel of touch, and a lot of information to quantify the sense of touch has been extracted using the novel MEMS tactile sensor in this study.

In this paper, a novel device to create patternable atmospheric-pressure plasma-jet array at a fine-pitch (320µm) is newly developed, and the evaluation results of the fabricated devices are reported for the first time. Micro plasma jet array are created by multi-channel gas discharges individually in microfluidic channels on a silicon chip, and high density of sub-mm pitch plasma jet array is realized in this study. Also, different kinds of plasma-jet can be created at a very close distance. Two different kinds of plasma-jet have been generated at a 320µm distance. Combining reactive gases for plasma creation, micro-scale reaction for material deposition, etching, and surface treatment can be realized. As a demonstration of plasma irradiation, photoresist sample was exposed to two plasma jets, and 1.0µm/min etching rate was obtained at a 30mW power.

In this study, advantages of optical path extension in absorption photometry microchip for highly sensitive hemoglobin measurement have been demonstrated. Stability in repetitive measurement is evaluated with real blood samples. Long optical path (5 mm) is realized on the microchip for highly sensitive absorption photometry. Two 45° mirrors are fabricated in ‘Multi-layered smart-MEMS structure’ to form a long optical path. Different type of microchip with different optical path length (0.5 mm) without 45° mirrors was also fabricated for characteristic comparison. Both types of the microchip were evaluated with food color solution, and each characteristic were compared. As a result, effects of optical path extension are clearly shown as detectable lower limit improvement. Furthermore, no adverse effects due to utilization of 45° mirrors were observed. It has been demonstrated that optical path extension with 45° mirrors is very effective to realize highly sensitive measurement in the microchip. Stability in repetitive measurement of the microchip was evaluated with real blood sample for the first time. In repetitive blood sample measurement, slight degradation of photocurrent of photodiode, which corresponds to hemoglobin concentration in the microchip, was observed. It is considered that the degradation is caused by protein adhesion to the surface of the mirrors and the photodiode. However, influence of the degradation can be removed by measurement method of introducing reference solution and sample solution alternately into each channel. Furthermore, normal range of human hemoglobin has been covered with linear range of the microchip. A small coefficient of variation of 0.61% or less was obtained in the measured results. From these results, blood hemoglobin measurement with high sensitivity has been realized with stabilized characteristics in repetitive measurement.

We have fabricated 32 × 32 SOI CMOS active pixel image sensor with pinned photodiode on handle wafer in order to reduce dark current, transfer charge completely, and improve spectral response. The four transistor type active pixel image sensor is comprised of reset and source follower transistors on SOI seed wafer, while the pinned photodiode, transfer gate, and floating diffusion are fabricated on SOI handle wafer. The pinned photodiode could be optimized because the process of the photodiode on SOI handle wafer is independent of the transistor process on SOI seed wafer. The optimized pinned photodiode is simulated in order to understand complete charge transfer at 3.3 V and 2.5 V of transfer gate voltage, respectively. We also investigated the optical response of fabricated active pixel image sensor under different illumination density conditions from He - Ne laser source at 3.3 V and 2.5 V of transfer gate voltage.

In this paper, a pH image sensor, which is capable of measuring two-dimensional (2-D) distributions and dynamic images of various chemical reactions in real time, is presented. The novel pH imaging sensor developed in this work use a charge transfer technique and with them it is possible to form images of variations in chemical reactions. A prototype pH image sensor was successfully fabricated using complimentary metal-oxide semiconductor (CMOS) circuit process technology and was used to measure two-dimensional distributions of various chemical reactions in moving images at 30 frames/s. It is expected that this sensor can be used for novel applications such as in the medical and biochemistry fields.

We have fabricated a 32 × 32 silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS) active pixel image sensor with a pinned photodiode on a handle wafer. The structure of one pixel is a four-transistor type active pixel sensor (APS) which consists of a reset and a source follower transistor on a seed wafer, and is comprised of a photodiode, a transfer gate, and a floating diffusion on the handle wafer. The photodiode could be optimized for better quantum efficiency and low dark currents because its process on the handle wafer is independent of that of transistors on a seed wafer. Most of the wavelengths are absorbed within the visible range, because the optimized photodiode is located on the handle wafer. The image has been captured by the fabricated 32 × 32 SOI CMOS image sensor with array pixels, vertical scanner, horizontal scanner, and delta-difference sampling circuit.

In this paper, a novel concept of silicon-microelectromechanical system tactile image sensor aimed at fingertip tactile applications and evaluation results of a prototype device are presented. Array of strain-sensitive sensor pixels is integrated on a pneumatically swollen silicon diaphragm with signal processing circuits in monolithic configuration. Elastic surface of the tactile image sensor is realized using repulsive force of the air pressure applied to diaphragm backside. Contact force distribution of an object is detected from the stress distribution change on the diaphragm using piezoresistor array. Force range and force sensitivity can be controlled by the pressure even after device packaging step. In this principle, fine pitch of pixels and a large-scale sensing array can be easily realized using the abilities of silicon CMOS technology. In addition, the movable stroke of sensor surface can be made much longer than the individually formed micromechanical pixels. A prototype device, of the new concept, with 3040 /spl times/ 3040 /spl mu/m/sup 2/ sensing diaphragm was fabricated with integrated 6 /spl times/ 6 array of 420-/spl mu/m pitch pixels. Increased movable stroke of the swollen diaphragm from the original surface is around 30 /spl mu/m at 23-kPa pressure at the top. Realized spatial resolution of the prototype device is approximately 400 /spl mu/m, which is determined by the relationship between the pixel pitch and mechanical crosstalk among the pixels. Positions of touch and their contact force amplitudes were detected as a two-dimensional distribution of the output voltage from the pixel array in a multipoint contact test. The maximum input-force range can be controlled from 21 to 176 mN by changing the backside pressure from 5 to 64 kPa. Through the evaluation of the fabricated device, major advantages of this tactile image sensor have been demonstrated successfully.

A novel sensor array, which is filter-less fluorescence detection sensor, was successfully fabricated using CMOS 5 μm silicon integrated circuit technology. Previously filter-less fluorescence detection sensors were proposed and fabricated, and they were able to sense fluorescence intensity. CMOS image sensor technique was applied for the filter-less fluorescence detection sensor, and it was able to operate a charge accumulation mode. Consequently, it was confirmed that general CMOS image sensor technique can be applied to the novel filter-less fluorescence detection sensor.

A new method is presented of on-chip optical spectroscopy, functioning without the need for a bandpass filter or grating. The principle of optical spectroscopy is based on the difference of optical absorption coefficients with wavelength. The optical intensity is calculated from the different penetration depths in Si. The key to the new spectrometer is the use of a photogate active pixel providing the selective control of photo-generated charge using the gate voltage. To demonstrate this spectrometer, a novel filterless fluorescence detection sensor has been fabricated in our laboratory, using standard 5-/spl mu/m CMOS silicon integrated circuit technology. The SYBR-Green label fluoresces at 520 nm when exited by 470-nm radiation. In a simulation experiment using two LEDs, the fluorescent intensity detected was 1/300 of the excitation light intensity (intensity of fluorescence was 1 /spl mu/W/cm/sup 2/, while the excitation illumination was 300 /spl mu/W/cm/sup 2/). In an experiment using actual DNA solution containing SYBR-Green, it was confirmed that the fluorescence detection sensor successfully detected the fluorescent label without the need for a filter.

A novel sensor device, comprising of fused photo-sensors and ion-sensors, is proposed. We describe how a prototype device was successfully fabricated using a CMOS process. In the proposed device, a photo-sensor and an ion-sensor are fused in the same pixel, enabling the photo-signal and the ion concentration density to be detected simultaneously in the same sensing area. Therefore, the relationship between light distribution and ion distribution can be clarified by using this novel sensor array. The dependence of the photo-sensing region on the power of the input-light was measured. It was found that the output signal is proportional to the input-light power, and is not influenced by the pH value of the solution. The dependence of the output signal on the pH was also investigated, and it was found that it was not influenced by the light intensity.

In this paper, a thermo-pneumatic in-channel microvalve applicable to integrated blood test system is presented. Thermo-pneumatic actuator separated in drive chamber part and thermal expansion chamber part (two-chamber configuration) is newly proposed for the purpose to reduce direct heat transfer from microheater to flow channel. Polydimethylsiloxane (PDMS) is employed as the diaphragm material for a long stroke actuation in microvalve operation and high sealing performance of liquid. It is also used as adhesive layer between glass and silicon in the structure. The microvalve with the proposed structure was fabricated. Both static and dynamic flow control characteristics were evaluated with a liquid sample (DI water) and a gas sample (N 2 ), respectively. A high ON/OFF ratio of liquid sample was obtained thanks to the soft PDMS diaphragm. Liquid sealing performance in the closed state was high enough for our application (

In this study, the characteristic improvement of Si (111) metal–oxide–semiconductor field-effect transistor (MOSFET) by decreasing the interface states has been investigated. As a process step for this characteristic improvement, long-time annealing in hydrogen ambient was performed after complementary MOS (CMOS) fabrication. It is found from the evaluated results that the interface state density of the Si (111) MOS structure decreases markedly upon increasing the annealing time. Furthermore, the S-factor and mobility of (111) MOSFETs were improved markedly. In particular, the field effect mobility of a (111) p-MOSFET was higher than that of a (100) p-MOSFET in spite of its possessing large interface states. It has been experimentally confirmed for the first time that long-time hydrogen annealing is an essential and effective process for the fabrication of (111) MOSFETs with a standard Si–SiO2 system.

An infrared light sensor based on principle of a field emission from Pb(Zr, Ti)O3 (PZT) thin plate has been studied. The sensitivity is able to be improved to perform a surface polish, and the emission efficiency of polished emission plane increased to twice than that of the unpolished emission plane. On a low infrared light irradiation condition, a noise level of emission current was very large. To use a micro-channel-plate (MCP) device, the amplification of the emission electrons was carried out. The emission electrons could be multiplied 40 times, the emission electron was clearly observed under low irradiation conditions. The electron emission-type infrared light sensor is also useful to detect an infrared light on low irradiation condition.

In this paper, an SOI-CMOS precision front-end amplifier using autozeroing technique for wide range and high temperature operation of smart microsensors is presented. SOI-CMOS amplifiers can operate over 150 °C, while, temperature drift of offset voltage is a serious problem to be solved for precise signal detection. A new autozeroed circuit configuration with voltage-decay cancellation technique is applied to SOI-CMOS pre-amplifier for stabilization of offset voltage at high temperature environments. Voltage-decay due to leakage current from capacitor voltage memories is almost cancelled out in the SOI-CMOS amplifiers. Offset drift in the fabricated amplifier is well suppressed by the cancellation technique without any device trimming after circuit fabrication. Robustness and stability of the front-end amplifier for wide range and high temperature operation has been experimentally demonstrated up to 200 °C in this study.

Accumulation method ion sensor (AMIS), an expected high sensitive ion sensor, is proposed and prototype one is fabricated using a charge coupled device (CCD) process. The principle of the accumulation method ion sensor is based on the charge transfer techniques. The AMIS is operated in a signal integration mode. Charges corresponded to an ion concentration is transferred from a sensing part to the floating diffusion region on several times, and the signal charges are accumulated in the floating diffusion region. It is expected that the signal-to-noise ratio (SNR) of the chemical potential information increases n0.5 times, as the signal is integrated n times. The output signal was measured by using the equivalent signal. It was found that the output signal from AMPS, which was integrated five times, was lineally changed to the input signal and the total sensitivity was 450 mV/pH. This sensitivity is about nine times higher than that of ion sensitive field-effect transistor (ISFET).

A new electron-emission-type infrared light sensor, which uses the principle of electron emission from a Pb(Zr,Ti)O3 (PZT) thin plate, has been proposed. However, the electron supply route to the emission plane is not yet well understood. As pulsed infrared light was irradiated onto the sensor, the emission current increased rapidly and decreased slowly. The emission current peak value did not change during the continuous detection operation. When the infrared light is shielded, electron emission stops, the temperature of the PZT thin plate returns to the initial state, and an electric field appears due to spontaneous polarization. It is assumed that electrons are supplied through the PZT thin plate from the back-surface electrode to the emission plane via this electric field. In the pulsed infrared light irradiation experiment, we could recognize that the emission current peak value does not depend on the light shielding time. An electron supply model from the back-surface electrode through the PZT thin plate during a detection operation is proposed. In a quasi steady or thermal equilibrium state, the electron supply to the emission plane of the PZT thin plate is sufficient for a detection operation under ordinary irradiation conditions. Therefore, the proposed sensor is viable for use as an infrared sensor or imager under ordinary infrared light irradiation.

A large number of Si wires on Si(111) can be fabricated selectively by the vapor–liquid–solid growth method with a high aspect ratio greater than 100. The diameter of the wire can be controlled from less than a micron to a few hundred microns. We propose a novel smart field electron emission device using silicon nano-wires fabricated by this vapor–liquid–solid growth method, and demonstrate field electron emission with a quite low operation voltage from a gated silicon nano-wire. The threshold voltage is about 13 V, and the value is similar to those for gated carbon-nanotube field emitters. The emission current reaches 10 nA at 15 V gate voltage.

In this paper, a new concept and potential demonstration of functional microfluidic integrated circuits using MEMS technology are presented. The fluidic integrated circuits were constructed utilizing analogous relationship between MOSFET and pneumatic microvalve with a diaphragm structure. The signal transmitted through the circuit is the fluidic signal, that is, the pressure or the flow-rate of the fluid. The pneumatic microvalve in this study is expressed by small-signal equivalent model similar to that of a MOSFET. Small signal behavior of microfluidic integrated circuits can be expected using the model, if the parameters in the model are extracted properly from fabricated microvalves. As an example of a fluidic circuit, pressure inverting amplifiers including integrated two microvalves were fabricated and evaluated. As a result, they showed sharp pressure transfer curves similar to MOS inverter circuits. A maximum pressure gain of 32.0 dB was obtained, and it can be used for pressure amplification in analog applications. In addition, they can be used as pressure inverter logic circuits for digital applications. Although the theory and design environment of the new microvalve circuit technology have not been established yet, multifunctional fluidic analog and digital circuits can be realized for special application fields different from electronic integrated circuits.

Multichannel 5 ×5-site Si microprobe electrode array has been developed for neural activity recording. Si microprobes were fabricated successfully at predetermined sites on a chip using Au dots and Si2H6 gas source molecular beam epitaxy (GS-MBE), a method based on vapor-liquid-solid (VLS) growth. Selective VLS Si growth allowed the design of three-dimensional (3D) microprobes with 40 µm spacing in a 5 ×5 array. The diameter and the length of the Si probe can be widely changed by changing the Au dot size and the Si growth time, respectively. In addition, the circular-cone-shaped Si probe has a shape suitable for penetration into neural tissues, and can be realized by increasing growth pressure. The mechanical strength of the Si probe was evaluated with observation of its bending and penetration into a gelatin membrane, which indicated that the Si probes are strong enough to withstand the application. Signal recording with the same amplitude as neural activity was also performed using the fabricated Si probe array chip. These results confirm that high-density neural signals from neural tissues can be obtained with the multichannel 3D VLS Si microprobe array chip.

In this paper, a three-axis accelerometer for high temperatures using constant temperature control of silicon on insulator (SOI) piezoresistors is proposed for reduction of temperature drift. The accelerometer has surrounding mass structure, and piezoresistors for four wheatstone bridges to detect three-axis acceleration. A temperature sensor using the whole resistance of four wheatstone bridges and micro-heaters are integrated on the beam structures. The structure of accelerometer was optimized with finite element method (FEM) simulation program, ANSYS. The accelerometer was fabricated with SOI wafers by bulk-micromachining. Temperature dependence of the fabricated three-axis accelerometer on variation of atmospheric temperature (from room temperature to 300 °C) is much reduced by keeping the temperature of piezoresistors at 300 °C. Temperature coefficient of sensitivity (TCS) is much reduced to 72% of the original TCS.

In this paper, a suppression method of generated distortion on the beam structures due to thermal stress is investigated for reduction of remainder thermal drift in three-axis accelerometer for high temperatures. An arrangement of piezoresistors for acceleration detection is presented to further reduction of thermal drift. Thermal drift analysis and design of advanced three-axis accelerometer for high temperatures without temperature dependence has been carried out with the finite element method (FEM) program, ANSYS. Experimental results agreed well with these theoretical results. Design considerations that enable the three-axis accelerometer to have stable sensitivity and offset are described with the simulated results.

In this paper, the result of developing a fully wireless pressure sensor based on endoscopy images for an endoscopic surgery is reported for the first time. The sensor device has structural color with a nm-scale narrow gap, and the gap is changed by air pressure. The structural color of the sensor is acquired from camera images. Pressure detection can be realized with existing endoscope configurations only. The inner air pressure of the human body should be measured under flexible-endoscope operation using the sensor. Air pressure monitoring, has two important purposes. The first is to quantitatively measure tumor size under a constant air pressure for treatment selection. The second purpose is to prevent the endangerment of a patient due to over transmission of air. The developed sensor was evaluated, and the detection principle based on only endoscopy images has been successfully demonstrated.

In this paper, a novel configuration of (horizontal type) MEMS tactile sensor that can interact with micro surface roughness at a high resolution are proposed and reported for quantification of the fingertip sense. Two-axis movements of the contactor-tip are independently detected by the two independent suspensions. The contactor is sticking out of the side surface of the silicon chip, and its over-range motion is protected by the embedded stopper structure during the sweeping motion for tactile sensing on the object. In the evaluation experiment, Correlation between the surface shape and the local frictional force were successfully obtained at the same time and at the same point for many samples (paper, plastic, rubber etc.) for the first time.

In this study, a novel tactile sensor with detection abilities of human body hardness and frictional force is reported. A new device configuration of back-side contact is proposed to realize a higher sensitivity of hardness, and low sensitivity to normal force. Miniaturization and sensitivity improvement of tactile sensor are important to apply the sensor to palpation inside of the body. Surface frictional force was successfully measured with rubber block in real time using our tactile image sensor. A completed device was evaluated, and shore A hardness was measured in the range from 1 HS to 54 HS. This performance corresponds to the hardness detection ability of adiposus in human body.

A pneumatically actuated silicon microvalve applicable to integrated microfluidic systems is presented. All the ports of this microvalve are in-channel, and connectable to any surface fluid channels in microfluidic systems. This microvalve controls fluid flow by means of the controlled gap between glass and silicon diaphragm actuated by a control pressure. In addition, the diaphragm is also deformed by the outlet pressure of the microvalve. Due to the feature, this microvalve shows saturation of flow rate like MOSFETs operated at saturation region. The fabricated microvalve device was evaluated focusing on analogous relationship between MOSFET and the microvalve. Fluids such as air and DI-water were well controlled by the control pressure. Fluid starts to flow in the microvalve when the control pressure exceeds its "threshold pressure." Hysteresis due to sticking of diaphragm was not observed in the characteristics. Air flow rate of the microvalve was gradually saturated with the increasing of the outlet pressure as expected. Through the evaluation, analogous relationship between this microvalve and MOSFET has been experimentally demonstrated.

The a-Si:H photodiode film is suitable for photoconversion in stacked-type image sensors. If a photocurrent in an a-Si:H p-i-n photodiode film is multiplied by the avalanche phenomenon, a highly sensitive image sensor can be realized. A photocurrent multiplication phenomenon was observed in a p-type hydrogenated amorphous silicon carbide (a-SiC:H)/i-type hydrogenated amorphous silicon (a-Si:H)/n-type crystalline silicon (c-Si) heterojunction p-i-n photodiode film. In this photodiode film, a maximum multiplication gain of photocurrent of 40 times was confirmed. To clarify the multiplication mechanism, the shot noise of the photocurrent in the a-Si:H p-i-n photodiode film was investigated. The measured shot noise in the multiplication region was larger than an ideal shot noise which was assumed to be free of excess noise. This indicates that the photocurrent was multiplied by avalanche process. The excess noise factor of our p-i-n photodiode film was also estimated.