Masayoshi Esashi

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A catheter-tip pH sensor was developed for possible clinical and biomedical application, using an ion-sensitive field-effect transistor (i.s.f.e.t.). Its signal drift in buffer solutions during continuous measurement was less than 3 mV in 24 h (equivalent to about 0·05 pH in 24 h). The electric insulation was perfect when soaked in buffer solutions for more(More)
This paper describes an evaluation scheme that prevents phase ambiguity of surface acoustic wave (SAW) delay-line sensors. Although it is well-known that phase evaluation yields accuracies of 150~1500 times higher than time-delay evaluation, the problem of phase ambiguity has prevented phase evaluation of sensors operating over a range larger than 2 pi.(More)
Component engineering is important for the development of implantable-type rotary blood pumps (RP). The authors are conducting elementary development of an implantable artificial heart. A sensor system detects information in the living body. An automatic control system performs the drive control. Energy is provided by a transcutaneous energy transmission(More)
SUMMARY Active catheters and active guide wires which move like a snake have been developed for catheter-based minimally invasive diagnosis and therapy. Communication and control IC chips in the active catheter reduce the number of lead wires for control. The active catheter can be not only bent but also torsioned and extended. An ultra minature fiber-optic(More)
It is well known that a rotary blood pump (RP) is effective as a small ventricular assist device (VAD). It might be still more effective if pulsation was available. The undulation pump (UP), which is a type of small RP, can also produce pulsation. In Japan, a development project for an implantable type UP ventricular assist device (UPVAD) is now advanced.(More)
Surface effects in ultrathin single-crystal silicon cantilevers of 170 nm thickness, which are optically actuated mainly by the light pressure effect, are investigated under ultrahigh vacuum ~UHV! condition. Annealing the cantilevers at 1000 °C for 30 s in UHV results in an over 1 order of magnitude increase of the quality factor (Q factor!, up to about(More)
Bending motions of the tip of a conventional endoscope are controlled from outside the body by wire traction. A shaft of an endoscope should be relatively hard to avoid buckling by wire traction. Therefore, precise operation of the endoscope is difficult in complex shape areas such as the intestine. Furthermore, patients suffer pain during a procedure with(More)