Electrical and Mechanical Properties of Intrinsically Flexible and Stretchable PEDOT Polymers for Thermotherapy

For wearable applications such as electronic skin and biosensors, stretchable conductors are required (∼30% strain to follow the extension). Owing its high conductivity, good flexibility, low cost, ease of processing, poly(3,4-ethylenedioxythiophene) (PEDOT) appears a promising candidate. However, destructive cracks come out above 10% in case PEDOT:PSS, most common form PEDOT. Different strategies have already been investigated solve this problem, including design specific structures or addition plasticizers. This article presents different approach obtain highly conductive PEDOT materials based on doping with small counteranions. We indeed demonstrate intrinsic stretchability (up 30% strain) thin films (35 nm) PEDOT-based counterions. Both thin-PEDOT:OTf (triflate counter-ion) thin-PEDOT:Sulf (sulfate remain structurally resilient up 25–30% strain, their electrical conductivity remains remarkably stable over more than 100 cycles. Under limited (<30%), polarized UV–vis–NIR measurements (parallel perpendicular stretching direction) show that material is improved by chain alignment direction. As proof concept, thermotherapy patch presented. It shows fine temperature control (stability around 40 °C at 9 V bias) uniform heating across surface.