| Research Abstract |
In order to put the active catheter which can bend the tip portion freely to practical use, the microactuator of 15mm of length which consists of thin-membrane electrode of gold connected to ion-exchange polymer and this was connected at the tip of a microcatheter with 1mm of outer diameters and a length of 150 cm. Four electric insulation slots were formed in gold electrode by excimer laser ablation, and four lead lines have been arranged among the tip part from the hand. The operation control part at hand enabled it to regulate the direction and the angle, which an actuator transforms through a joystick. If current flows in ion-exchange polymer, by movement of counter-ion, swelling happens in the negative side of the actuator, contraction happens in the positive side. This active catheter was made as an experiment, and examined whether mechanical and physical conditions-that pliability, flexibility, and water resistance etc. -would be fulfilled for clinical use with the blood vessel model made from glass. It showed that the active catheter could bend easily in this glass model, although the problems, that a limit is in the bending power that resists blood pressure, and a response are slow, were remained. Further improvement can be performed and a catheter tip can be more bent now in a glass model for a short time. Then, the animal experiment using adult dogs was performed. By anastomozing the venous porch extracted from the external juglar vein to canine common carotid artery, creating the aneurysm model and this active catheter was induced via transfemoral route. Although required for the motional response to electrical stimuli for about 1 minute, it was able to navigate to this aneurysm model turned to in the direction of 90 degrees at the sidewall of the parent vessel, without a guide wire. Furthermore, it has checked that it could navigate without a guide wire also to the tortuous peripheral arteries.
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