A new approach to develop ionic polymer–metal composites (IPMC) actuator: Fabrication and control for active catheter systems

Abstract

The ionic polymer–metal composite (IPMC) is one type of electro-active materials with the characteristics of low electric driving potential, large deformation and aquatic manipulation. It is highly attractive to biomedical applications as an actuator or a sensor. The main purpose of this study was to develop an IPMC actuator for active catheter systems. The first step was to develop a low cost and high reliability fabrication procedure to yield an IPMC actuator. In the second step, the dynamic behavior of the actuator was tested in an aqueous environment. An empirical model was then constructed, which consisted of a fourth-order linear system, a nonlinear gain and a time delay. To linearize the dynamic behavior of this actuator for better actuating performance, a nonlinearity compensation method by a second-order polynomial was proposed. In the final step, the bending behavior of the constructed IPMC actuator with an open-loop and a closed-loop controller design was investigated. The results indicated that a low cost but reliable IPMC actuator was fabricated successfully. Its production time was less than half of current manufacturing time (more than 48 h). The bending motion at low operation frequencies was well controlled by a conventional PID controller without adding complicated control algorithm. Our proposed algorithm decreased the maximum overshot from 30 to 4.2%, and the steady-state error from 15 to 4%. Though the rise time was increased from 0.084 to 0.325 s, it was within the limit for many biomedical applications.