In recent years, new actuators with multiple degrees of rotational freedoms (DoRFs) drive were produced and those applications have attracted attention. On the other hand, rotary encoder that enables to detect multi-DoRF has not been developed enough. Therefore the development of a new rotary encoder is necessary. In this paper, we aim at developing a new non-contact rotary encoder that enables to detect multi-DoRF. We propose a new method to detect multi DoRFs without touching and exam the effectiveness of this method. As a result of developing a prototype rotary encoder, we showed the efficacy of proposed method and confirmed that (1) the detection performance of this method was affected by the magnetic repeatability coefficient, and that (2) the performance required to be less than 0.2 magnetic repeatability coefficient to keep 100 percentage of correct answer.

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In order to realize a vibration sensor which can operate without power supply, an optimization of the sensor configuration was studied using commercial piezoelectric bimorphs. The dependences of the energy conversion efficiency on weight of metal mass attached to the tip of the piezoelectric bimorph and peripheral circuit components were investigated. Vibration sensors using several piezoelectric bimorphs with different weights were designed, fabricated and tested.

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We propose that thin and light-weighted silicon Fresnel lenses is suit for thermal imaging. We adopted a one-mask process with photolithography and inductive coupled plasma reactive ion etching (ICP-RIE) to fabricate silicon three-dimensional structure. Thermal image was taken with a Fresnel lens, which we designed with ray-trace method and fabricated with the three-dimensional (3D) fabrication process. Thermal cameras have been expensive because germanium lenses are difficult to be machined. Since the 3D fabrication process suits mass production compared with other method like multi-level lithography, competitive-price FIR optical systems can be realized.

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Thermoelectric (TE) devices have emerged as one of the most promising new technologies for use as sensor module energy harvesters and as waste-heat recovery systems. Low-cost and large-area printed TE devices are suitable because heat sources are widely distributed through-out the environment. In addition, high reliability is also required of the TE materials because the devices are operated in high-temperature environments over long periods of time. In this study, we developed glass matrix TE composite materials that have a higher softening temperature than organic materials. Using low melting point vanadate glasses as the matrix materials, we fabricated n-type Bi₂Te₃— vanadate glass and p-type Bi_0.3Sb_1.7Te₃—vanadate glass composites. The figure of merit (ZT) of both materials was approximately 0.2 at temperatures between 25 and 300°C. We also fabricated a pair of thermocouple devices using these vanadate glass composites with simple printing process, and an output voltage of 5 mV was obtained when the thermocouple pair was placed on a hot plate heated to 90°C.

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We developed all polymer piezoelectric film which consists of polyethylene terephthalate (PET) film substrate, conductive polymer poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) electrodes, and polyvinylidene difluoride (PVDF) piezoelectric film in order to achieve the low resonance frequency of energy harvesting device. Existing piezoelectric films have been deposited on rigid silicon or inorganic materials which lead to high resonance frequency and low efficiency of energy generating under low frequency of human or animal motions. Therefore, we developed all polymeric piezoelectric films on very soft PET films. To deposit PVDF film on PEDOT:PSS coated PET, low temperature coating process using low boiling temperature solvent (methyl ethyl ketone) and annealing method (under 150°C) was developed. Developed film achieved low frequency of 81 Hz.

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We have developed the two-dimensional chemical sensor using a photoconductive polymer film. This paper presents the refined fabrication process and the characteristics of the devices. We investigated poly(N-vinylcarbazole) (PVK) and poly(2-vinylcarbazole) (2-PVK) as the photoconductive materials. Copper(II)2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (Bu-CuPc) was used as dopant for dye sensitization. We fabricated the devices by spin-coat method. From the results of our study, the device fabricated by using 2-PVK with Bu-CuPc showed high photoconductivity, high S/N and concentration dependence. The detection limit of K₃Fe(CN)₆/K₄Fe(CN)₆ was approximately 1nM. Moreover, it was found that the photoconductivity depended on the quantity of dopant and the thickness of the film. It was also found that the S/N depended on the flatness of the film. In future study, we will intend to perform two-dimensional measurement.

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This paper describes the fabrication and assembly of a tubular micro-torsion-actuator of TiNiCu shape memory alloy (SMA) with a co-axial bias mechanism of TiNi super elasticity alloy (SEA). The tubular bias mechanism with spring beams (O.D: 880 µm) was inserted and assembled in the SMA tubular actuator, which consisted of deformable beams and joint rings (O.D: 970 µm, wall thickness: 35 µm). The SMA actuator was pre-twisted before the assembly process, resulting in counter-rotation when the SMA recovered its initial shape. The tubular actuator and the bias mechanism were fabricated from an SMA tube and SEA tube, respectively, using cylindrical photolithography, electrochemical etching, and chemical polishing processes. The bias mechanism was easily inserted and co-axially assembled to the SMA tubular actuator by a technique of extending and shrinking the SMA joint rings. The assembled micro-torsion-actuator could be actuated to a rotation angle of 13° per 4 mm length by direct electric heating of 340 mW.

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It is difficult to prepare homogeneous dielectric film on the large wafer. Chemical solution deposition method is useful for wafer level film preparation because large area film can be easily obtained. However, this method has many process parameters and their optimization is very hard. We therefore introduce a statistical method to reduce the optimization process. Crystallization temperature was clarified to be the most important factor among our selected parameters for high quality dielectric films in our previous study. We investigated more precisely the process parameters that familiar with the temperature based on the usage of larger orthogonal array. The results showed that the precursor formation temperature is the most important factor for high permittivity films. We next prepared the dielectric film on the 4-inch wafer under the optimum conditions for both high orientation and high electrical properties. We successfully formed the film with good properties and (100) preferred orientation as a result. These results will be useful for fabricating MEMS devices and integration technology of electrical devices such as capacitors in wafer level fabrication.

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We developed a new structural ion sensor for measuring sodium ions without using a reference electrode. The ion sensor, which is all solid state, has a structure of double electrodes, which are integrated on the base plate, inside the sodium ion sensitive membrane. The ion sensitivity of the sensor was 41.4 mV/decade in the range of 10^-1 to 10^-4M. To investigate the response mechanism of the potential between two electrodes, the impedance characteristic was measured using the electrochemical impedance method. The impedance of the ion sensitive membrane changed by changing the sodium ion concentration in solution. These results suggest a correlation between the membrane potential and the membrane impedance. In conclusion, the potential difference between the electrodes is caused by the difference in ion concentration of the electrodes.

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A Sagnac interferometer based on the fiber-optic gyroscope requires two couplers to constitute a reciprocal optic system. In order to simplify the conventional minimum configuration, we have investigated a single-coupler interferometer with reciprocity using the self-coupling effect of light source. The proposed interferometer was applied to a vibration sensor for physical security technology. At many important facilities, fences with vibration sensors are installed along the boundary of the premises to prevent any intrusion. The optical fiber type is suitable for situations in which the vibration sensors need to be easily fixed to the fences, particularly around intricately shaped premises for monitoring a wide range of areas. The sensor's basic characteristics were compared with conventional and non-reciprocal types and its performance as a vibration sensor was verified. Since it enables the simplification of optical systems and assembly processes, the self-coupled optical pickup is effective in reducing the cost of optical fiber sensors.

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