Yusaku Maeda

A novel integrated tactile image sensor for detection of surface friction and hardness using the reference plane structure

In this paper, a tactile sensor with detection abilities of hardness and friction of object surface is proposed and reported. The new detection principles of friction and hardness are realized with the reference plane structure on the device. The device was fabricated with LSI/MEMS integration technology. Completed the devices were evaluated, and the measured normal force sensitivity was 0.07mV/mN/V. On the other hand, the shear force sensitivity was 0.73mV/mN/V. This performance corresponds to the detection ability of frictional coefficient around 0.1. Also, shore A hardness was successfully measured in the range from 22 to 99 HS.

A tactile sensor with the reference plane for detection abilities of frictional force and human body hardness aimed to medical applications

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.

Integrated pressure and temperature sensor with high immunity against external disturbance for flexible endoscope operation

In this study, an integrated pressure and temperature sensor device for a flexible endoscope with long-term stability in in vivo environments was developed and demonstrated. The sensor, which is embedded in the thin wall of the disposable endoscope hood, is intended for use in endoscopic surgery. The device surface is coated with a Cr layer to prevent photoelectronic generation induced by the strong light of the endoscope. The integrated temperature sensor allows compensation for the effect of the temperature drift on a pressure signal. The fabricated device pressure resolution is 0.4 mmHg; the corresponding pressure error is 3.2 mmHg. The packaged device was used in a surgical simulation in an animal experiment. Pressure and temperature monitoring was achieved even in a pH 1 acid solution. The device enables intraluminal pressure and temperature measurements of the stomach, which facilitate the maintenance of internal stomach conditions. The applicability of the sensor was successfully demonstrated in animal experiments.

Intraluminal pressure and temperature sensor aimed at application to flexible endoscope operation

In this study, an intraluminal pressure sensor with high immunity against fluctuation of temperature and illuminance aimed at application of flexible endoscope operation has been developed and demonstrated. The sensor device was specially designed for embedment on the endoscope tip. A 0.1μm thick Cr layer was coated on the device surface to prevent photo-electronic generation caused by strong endoscopes light. On the other hand, compensation of temperature drift on pressure signal was successfully performed with integrated temperature sensor. Measured pressure resolution was 0.4mmHg, and the corresponding pressure error was 3.2mmHg. The packaged device was successfully operated under mimic environment of animal experiment, and monitoring of pressure and temperature was successfully demonstrated even in pH1 acid solution.

A Post-Complementary Metal Oxide Semiconductor Formation Process of High-Adhesiveness SU-8 Structures for Reliable Fabrication of Integrated Microelectromechanical System Sensors

In this study, a post CMOS reliable formation process for high-aspect-ratio SU-8 structures on integrated circuits is newly proposed. Enhancement of SU-8 adhesiveness is realized by forming a thin SU-8 layer (called an adhesive layer) over the surface of the circuit before the SU-8 structures are formed. Improvement of adhesion of thick SU-8 structures is very important to guaranty the reliability of MEMS microsensors. The negative effect of the adhesive SU-8 layer on the mechanical properties of silicon movable structures has been estimated and discussed with simple analytical formulae. Also, the effect of the adhesive layer on the silicon substrate has been demonstrated with test structure patterns. On the basis of the developed technique, a tactile sensor device has been successfully fabricated as an example of the application of this technique.