Yuji Furukawa

Development of a Mechanical Scanning-type Intravascular Ultrasound System Using a Miniature Ultrasound Motor

Intravascular ultrasound (IVUS) plays an important role for the detection of arteriosclerosis, which causes the ischemic heart disease. In mechanical scanning-type IVUS, it is necessary to rotate a transducer or a reflecting mirror. A method that involves rotating the transducer using a torque wire causes image distortion (NURD: non uniform rotation distortion). For a method that involves placing an electromagnetic motor on the tip of an IVUS probe is difficult to miniaturize the probe. Our objectives are to miniaturize the probe (1 mm in diameter, 5 mm in length) and to remove NURD. Therefore, we conducted a study to assess the feasibility of attaining these objectives by constructing a prototype IVUS system, in which an ultrasound motor using a stator in the form of a helical coil (abbreviated as CS–USM: coiled stator–ultrasonic motor) is incorporated, and to clarify problems that need to be solved in constructing the probe.

Biological contractile regulation of micropillar actuator driven by insect dorsal vessel tissue

This paper examines biological regulation of micropillar actuation by insect dorsal vessel tissue. Micromechanical devices using mammalian cardiomyocytes have been reported, but they work only at only at 37degC and at pH of around 7.4. On the other hand, insect cells can survive and proliferate at 20 to 30degC and at pH 6 to 8. We have already proposed utilization of insect heart tissue as a bio-actuator and demonstrated a micropillar actuator. For practical use, a regulation technique should be developed. It was reported that two neuropeptides, proctolin and crustacean cardioactive peptide CCAP could accelerate heart beat. In this study, addition of CCAP at 10-6 M accelerated the frequency of the micropillar actuation 5.6-fold from 0.11 to 0.62 Hz and it returned to nearly the original value in 5 min. Proctolin addition up to 10-5 M had little effect on the actuation. These results showed that CCAP is useful in frequency regulation of a bio-actuator driven by dorsal vessel tissue.

Development of Ultrasonic Micro Motor with a Coil Type Stator

The motor is one of the most important actuators and its miniaturization is strongly desired in the market in order to make electro – mechanical systems as small as possible. Ultrasonic motors are commercially applied to a focussing device of camera and etc. and there exists further demands to miniaturize them so as to adopt to mobile phone, automobile actuators, and micro surgery devices like IVUS. However, the conventional ultrasonic motors are based on a surface propagation and transmission of vibration wave, inevitably, they need many parts and there is a certain limit to miniaturize. Taking these points into account, the present paper proposes a new concept [1,2] in which a coil type stator contacts on a cylindrical rotor directly, hence, the structure becomes very simple and can realize miniaturization. Four different types of ideas and prototypes are proposed, manufactured and tested their fundamental performances.