A new micro-pressure-sensor with diaphragm size of 100μm has been fabricated by a surface micromachining technique. A circular diaphragm with 1.6μm in thickness, supported at its edge and center, was adopted to decrease the stress concentration at the diaphragm edge. The diaphragm was formed flat-structure by an etch-stop technique of a polysilicon sacrificial layer. The most suitable arrangement of piezoresistors was determined by FEM (Finite Element Method) stress analysis of the diaphragm. A pressure sensitivity of 20 μV/kPa for a pressure range from 60 to 110 kPa absolute, and a temperature coefficient of the sensitivity of -0.26% F. S./°C for a temperature range from -30 to 85°C were obtained.
This paper deals with the development of a sensor which can acquire the information on the surface roughness of various kinds of objects as static friction coefficient for determining grasping force. The sensor has a simple structure, consisting of a circular plate with rubber surface attached to a DC motor axis. The motor gives a turn to the plate which is pressed uniformly to the object surface by a spring. Static friction coefficient is computed by torque when the motor begins to rotate against friction force. Few sensors of this type to obtain the coefficient have been developed in the past. The experimental results show that the static friction coefficient for objects with various surface roughness can be obtained and that the coefficient depends on the pressing force for some of the objects with rough surfaces. It was finally verified that grasping force could be controlled by using the detected coefficient adaptively to hold without any slippage an object whose weight was manually changed.
This paper describes the design, manufacture, and evaluation of a capacitive pressure transducer made of polyimide films which is expected to provide robotic tactile imagers with structural flexibility and high sensitivity: The structure of a pressure transducer cell was first determined, followed by the analyses of the deflection-stress and capacitance-load characteristics of the surface film using finite element methods. In the practical stage of manufacture, a polyimide film was emboss processed and electrodes were deposited on the film to construct a capacitive transducer cell to which a Schmidt-trigger detecting circuit was connected. The operational characteristics of the cell were then examined to show that the actual relation between the deflection and load approximately agreed with the linear analyses and that the capacitance depended with little hysteresis on the gap regardless of the native visco-elasticity of the film, while the operation was stable below 50°C. It was also shown that small stick-slip vibration of a contact rubber surface could be detected by the transducer to verify its high sensitivity.
A new sensor has been developed for examining surface topography, especially in a case that is difficult to examine by optical method. This sensor measures the surface topography by bringing a cantilever beams that is similar to a comb into contact with a sample and measuring the deflection of the cantilever as it is scanned across the surface. And this sensor can measure the surface topography at one time scan across the surface. The cantilever beams were processed from phosphor bronze foil. The piezoresisitive effect of silicon thin film was used to sense the deflection of the cantilever. We fabricated the sensor that had 20 and 160 cantilever beams, 200μm pitch, 7mm length, 30μm thickness, and applied to examine the surface topography of a copper plating surface on printed circuit board. We could observe the surface topography with 10μm resolution of depth direction.
A thin-film gas sensor was fabricated on an SiO2 diaphragm on an Si substrate. This sensor was composed of 2 parts; one was a gas-sensing part which had a semiconducting thin-film of an Fe2O3 based material, and the other was a heating part which had a metal thin-film with 3 layers of Cr/Pt+W/Cr. Both parts were fabricated on the same type of a diaphragm with thin-film and micromachining technologies, and were set face to face at a distance of 50μm. The heater was operated at 600°C by feeding 70mA of DC current. The voltage was 6.6V and the consumed power was 462mW. The gas sensing part was heated up to about 400°C. The conductance of the gas sensing part was about 0.05μS in a fresh air, whereas it was increased when H2 gas or i-C4H10 gas was introduced. The fabrication technologies of the sensor are compatible with those of ICs, and the sensor is apparently a small, light-weighted, and low power-consuming device. Moreover, it would be a promising device as an intelligent or smart sensor.
This paper describes a fiber optic oxygen sensor using phosphorescence and its application to clinical examinations. Since the quenching ratio of phosphorescence is proportional to oxygen partial pressure by the Stern-Volmer's formula, the oxygen concentration is possible to estimate from measured emission intensity. Combining an optical fiber bundle with a luminescent material: Ru(bpy)32+/Nafion membrane, we have fabricated a luminous probe, characteristics of which was experimentally investigated as an oxygen concentration sensor in visible light. The probes were demonstrated to have advantages; they can be operated both in liquid phase and vapour phase. Also they are stable to pH and flow velocities. As a clinical application, the probe reliably measures oxygen concentrations of whole blood in vivo.
A new combustible gas sensor using porous nickel ferrite (NiFe2O4) was fabricated to investigate its gas sensing characteristics. After fine nickel ferrite powder was mixed with camphor powder and then pressed into disks, they were sintered at the range from 1, 200 to 1, 400°C for 2h in air. The optimum sintering temperature and the optimum mixing ratio of nickel ferrite to camphor were found to be 1, 200°C and 1:1, respectively. The gas sensor fabricated under these conditions, with a porosity of 83.7%, had significant sensitivity to hydrogen and saturated hydrocarbon gases. The addition of a small amount of noble metals (Pt, Au, Pd) to the porous nickel ferrite disks also influenced the gas sensitivity. Addition of Pt was effective to increase the sensitivity to hydrogen gas.
The paper aims at discussing an application of A0 mode Lamb wave devices employing ZnO-film/Al-foil composite structure to mass density sensors in liquids. By using the variational technique, theoretical analysis was made on the effect of liquid-loading upon A0 mode Lamb wave propagation in the device, and a simple relation between the A0 mode Lamb wave velocity and physical conditions was derived. The result strongly suggested that the mass density sensor could be realised: by measuring the fractional change in A0 mode Lamb wave velocity, mass density can be determined almost independent of acoustic wave velocities in liquids by making the ZnO-film and Al-foil very thin. It was experimentally shown that the centre frequency (proportional to Lamb wave phase velocity) of the fabricated A0 mode Lamb wave device distinctly shifts due to various liquid-loading: the fractional change in the velocity is almost proportional to mass density of liquids. The error of the measured mass density for seven different liquids was within about 5%.
The humidity-sensitive characteristics in the system PbCrO4 combined with various oxides such as M2O3 (M=AI, Fe), M'O2 (M'=Zr, Sn, Ti, Th) and M"2O5 (M"=Ta) depend on the host composition which is PbCrO4 or Pb2CrO5. In the system PbCrO4-PbO, the effect of composition and microstructure on the humidity-sensitive characteristics of thick film elements were examined to confirm the predominant phase over elements. The sensitivity in low humidity region increased as the host composition of elements changed from hydrophobic PbCrO4 to hydrophilic Pb2CrO5. These results were interpreted by a humidity-sensitive mechanism proposed for hydrophilic Pb2CrO5.
Fiber optic current sensors with temperature-independent sensitivity have been developed. For Faraday rotators of the sensors, highly Bi-substituted rare-earth iron garnets, BixGdYY3-(X+Y) Fe5O12, are prepared by a liquid phase epitaxy (LPE) method. It is found that the temperature dependence of the sensitivity constants is improved by Gd substitution. The crystal with the components of X=1.3 and Y=0.43 is found to show the least temperature variation of the sensitivity constants within ±0.5% between 253 and 353K. The sensor modules using the crystals have good characteristics in practical use. The sensor units for monitoring the condition of power distribution lines have high environmental durability, high insulation, and no electromagnetic induction.
There is no work on taste recognition of optical response patterns from multi-channel optical fiber sensors, although electrode taste sensors using lipid/polymer coatings have been already used. This paper proposes a new taste recognition system using optical response patterns from multi-channel optical fiber sensors having potential sensitive dye coatings. The sensors have been found to give large changes in optical absorption spectra of the dyes when they are immersed in various taste solutions. This results shows that they can be used as a taste sensor. Six dyes, which give large changes in dye absorption, have been selected from twenty dyes and used for six-channel optical fiber taste sensors array. The absorption spectra change data have been processed by multiple discriminant analysis and neural networks using back-propagation algorithm. The analytical results shows that salty(NaCI), bitter(quinidine), sweet(sucrose), sour(HCI), and umami(MSG) substances can be recognized from each other by using the optical taste sensor system.
LWIR 64×64 focal plane arrays (FPAs) were fabricated for detecting 10 μm wavelength radiation, using HgCdTe epilayers. The photodiode arrays were hybridized to Si readout circuits with In bump technique. Noise equivalent temperature differences (NETDs) were estimated for two methods of Si circuits, line address and pixel integration. We also evaluated performance in CCD and MOS circuits as the signal readout circuits. NETDs showed 0.07K with line address method and 0.14K with pixel integration method. NETD values in the signal readout circuits made no significant difference between CCD and MOS circuits.
We have developed heterojunction type gamma-ray detectors and neutron detectors for personal dosimeters. The former are fabricated by forming hydrogenated amorphous silicon film (a-Si:H) on high resistivity silicon substrates by using DC glow discharge in SiH4-H2 mixtures; the latter with hydrogenated amorphous10B-enriched boron film (a-B:H) on silicon substrates by that in 10B enriched B2H6-H2 mixtures. The boron film has a high concentration boron of 1×1023 atoms/cm3. The gamma-ray detector can operate at a low level of noise, 5 keV, at room temperature. We discuss the effect of the distribution of depletion layer on the radiation detection characteristics and its application to the control of the characteristics. For gamma-ray dosimeters, it is important to optimize the surface pattern of depletion layer for the counting efficiency by effectively counting the pulse generated around the depletion region. In neutron detectors, we need to discriminate neutron rays and gamma-rays. The neutron detectors are designed to count the pulses of recoiled protons to increase the counting rate for fast neutrons without increasing the counting rate of gamma-rays. The optimum depth of the depletion layer is estimated to be 13_??_70μm in the energy range of 0.025eV-5MeV.
SiC ceramics is one of the most important material for a thermistor operating at high temperature. In this paper, we deal with a design of the SiC ceramic thermistor using an artificial intelligence. In this system, the input specifications of the thermistor are the thermistor constant, the resistance at the operating temperature, and the cavity size of the package. On the other hand, output data (manufacturing condition) are the firing time, the amount of aluminum content, and the dimension of the thermistor. SiC ceramic thermistor was manufactured based on the output data, and the characteristics as a thermistor were measured. This material design system is considered to be useful system, because the measured characteristics agree with the specifications.
Polyamic acid thin film was electrodeposited on metal foil using the solution containing triethyl-ammonium salt of polyamic acid dissolved in mixed solvent of DMF and methanol. The polyamic acid thin film was continuously imidized to form polyimide dielectric thin film, on which polypyrrole was polymerized as another electrode. Characteristics of this polyimide thin film as a dielectric is similar to that of polyimide film formed by spin coating technique. Applying this method to etched aluminium foil, small size film capacitor which has large capacitance and excellent characteristics was proposed.
Although there are many methods for measuring the glossiness instead of human vision, the psychological glossiness perceived by men can not be expressed enough by the use of conventional methods. When a paper drawing white figures and a paper drawing black ones are registered with half mirror, psychological glossiness may be perceived in spite of having no gloss of each paper itself. In this study, the psychological experiment is made. The paper drawing white circles and the paper drawing black ones are used as the specimen. The psychological glossiness is obtained by NAKAYA's method, which is one kind of the paired comparison method. The results are as follows. The psychological glossiness decreases as the luminance of white circles increases with the luminance of black ones low. When the luminance of black ones is high, the psychological glossiness increases, becomes a maximum, and decreases as the luminance of white ones increases. This may be explained by regarding the psychological glossiness as the sense disturbing the perception of the objects.
Previously, methods of estimating the D layer electron density profile by using the VLF reflection coefficients were studied by solving a Fredholm integral equation of the first kind(1)(2). In this paper, a Fredholm integral equation not belonging to the first to third kinds is obtained for the receiving antenna output voltages for vertical polarizations, assuming known ground wave field strengths. The solution of this equation is iteratively calculated by a full wave technique(1)(2). A simulation of its solution is performed with simulated voltage measurements that include relative phase errors and multi-reflected components from the ionosphere. Voltages inferred from both exponential profiles and in-situ electron density profile measurements are used as input to the simulation. The estimated electron density profile shows fairly good agreement with both the exponential profiles and the insitu measurements.