Integrated Design and Fabrication of a Conductive PDMS Sensor and Polypyrrole Actuator Composite

Abstract

Polypyrrole (PPy) has been widely used as an electro active polymer actuator owing to its high energy density, and the applicability in low voltage (i.e. less than 3 V) driven systems. Its scalable fabrication process also enables a PPy actuator to be used in mesoscale (a few millimeter to centimeter) robotic mechanisms. Although many PPy actuator driven mechanisms have been studied previously, its in-situ measurement of the motion of a PPy actuator was rarely investigated. To further expand the potential applications of a PPy actuator in automation and control of mesoscale robots, it is essential to develop a highly integrated sensor-actuator structure. In this work, we proposed a new fabrication process to make one kind by electrochemically synthesize a PPy layer on the opposite side of a carbon doped polydimethylsiloxane (CPDMS) based resistive sensor where a polyvinylidene fluoride (PVDF) membrane was used as a common substrate. A simple way to make a CPDMS sensor was proposed, and its electric and mechanical properties were studied using various material combinations. In addition, the characteristics of a CPDMS-PPy composite was studied using cyclic voltammetry, and the integrated sensor response analysis with and without applied load during the electrochemically induced PPy actuation. The proposed structure was not only able to sense its bending motion, but it could also roughly distinguish the stiffness of an object in contact. To demonstrate a simple application, a compliant linkage structure, which simultaneously actuated and sensed by the proposed composite, was built.