Soft-structured sensors and connectors by Inkjet Printing

The properties of conducting polymers deposited onto textiles were studied over 10 years ago by workers at Los Alamos and Milliken who also tested these materials as gas sensors [1-3]. More recently, workers at Wollongong have demonstrated that elastic textiles impregnated with conducting polymers, by in situ chemical polymerization, can act as strain sensors that can be used to track the motion of human joints [4]. A similar approach can be used to make pressure-sensing foams [5]. Others have studied the strain sensing mechanism in more detail and have shown that two effects are important. In one case, cracking of the surface layer on conducting polymer on a fabric leads to a reduction in conductivity as the fabric is stretched [6, 7] . On the other hand, tests on yarns and loops of conducting yarn show that conduction from yarn to yarn decreases as stress is applied to pull their surfaces into contact [8].