245 mm length IPMC catheter with an ellipse-like cross-section

摘要

Abstract The development of robot catheter systems is desired to treat aneurysms that are difficult to treat using conventional catheter surgery. Many researchers developed a robotic catheter actuated by an ion polymer metal composite (IPMC) actuator. However, a limitation of previously developed IPMC catheters was that they could not realize sufficient displacement. To overcome this problem, we proposed the use of an ellipse-like catheter, which has a lower second-moment-of-area compared to that of the previous one. Additionally, it has a larger displacement than the conventional catheter but cannot achieve the proposed values of 1.0 mm for applied voltages of 1.2 V, and a 20 mm length point from the root. Moreover, the previous catheter had a length of only approximately 50 mm, and it is much shorter than a 1 m catheter. In the present study, we developed a novel IPMC catheter having a length of 245 mm and a second-moment-of-area of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>4.0</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width=".25em"/> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">mm</mml:mi> </mml:mrow> <mml:mn>4</mml:mn> </mml:msup> <mml:mo>,</mml:mo> </mml:math> which is 11 times lower than that of the previous one. Experiments showed that for an applied voltage of 1.25 V from the 20 mm length point from the tip, the tip moved by 1.0 mm. Thus, the target value was achieved. However, to move the tip 1.0 mm by applying a voltage from the root, a voltage of 2.0 V is required, which is higher than the voltage required to start water electrolysis. This is because the voltage decreases due to the resistances of the electrodes of the IPMC catheter, which are 30 and 25 Ω.