Development of Active Guide-wire for Cardiac Catheterization by Using Ionic Polymer-Metal Composites

Due to the inconvenience in passing bifurcated blood vessels via changing curvature of guide-wires during surgery, active catheter or guide-wire systems are developed recently. For lightweight and large bending deformation, the ionic polymer metal composites (IPMCs) have been employed in many biomedical applications. For controlling an IPMC-based active cardiac guide-wire system, the goal of this research is to develop methods that can actuate an IPMC and detect its deformation without extra sensors. The method is to parallel a reference IPMC with an actuated IPMC. Then a mixed driving signal that consisted of high and low frequencies was applied to drive the IPMCs. The low frequency signal makes the IPMC to deform and change its surface electrical resistance, while the high frequency signal retains the deformation information. By utilizing a lock-in amplifier to demodulate the high frequency signal, the deformation can be measured. When low frequency actuation signal is absent, the sensing signal follows the deformation well. However, when sinusoidal or square wave actuation signals of frequency 0.1 Hz was applied transient error appeared. The error may due to the mismatch of electric resistances and capacitances between the actuation and reference IPMCs. However, when the frequency of actuating signal was reduced to 0.01Hz, the transient error disappeared. For practical applications like catheter guide wire, a low frequency actuation signal induces a large deformation so the method might be feasible for simultaneously sensing and actuating an IPMC.