Novel ionic polymer-metal composites equipped with physically loaded particulate electrodes as biomimetic sensors, actuators and artificial muscles

Described is a novel fabrication process of manufacturing ionic polymer-metal composites (IPMCs) equipped with physically loaded electrodes as biomimetic sensors, actuators and artificial muscles. The underlying principle of processing this novel IPMCs is to first physically load a conductive primary powder layer into the polymer (ionomeric) network forming a dispersed particulate layer. This primary layer functions as a major conductive medium in the composite. Subsequently, this primary layer of dispersed particles of a conductive material is further secured within the polymer network with smaller secondary particles via chemical plating, which uses reducing agents to load another phase of conductive particles within the first layer. In turn, both primary and secondary particles can be secured within the polymer network and reduce the potential intrinsic contact resistance between large primary particles. Furthermore, electroplating can be applied to integrate the entire primary and secondary conductive phases and serve as another effective electrode. In this paper, we describe the details of this newly developed technique to efficiently produce an IPMC loaded with spherical silver particles (D-10 < 0.8 mum, D-50 < 1.5 mum, D-90 < 2.5 mum; A(sur) < 6 m(2)/g) and subsequently secured by palladium (D-p similar to 50 nm, via a chemical reducing process). It has been established that such an IPMC is quite comparable in force and displacement performance with the traditional platinum loaded and gold electroplated IPMCs but can be manufactured at about 1/10th of the cost. Yet it produces a low surface resistivity (less than 1 Omega per square), which is highly desirable in creating more uniform deformation. (C) 2002 Elsevier Science B.V All rights reserved.