Thermochromic and Piezocapacitive Flexible Sensor Array by Combining Composite Elastomer Dielectrics and Transparent Ionic Hydrogel Electrodes

Electronic skin (e-skin) is an important building block to achieve human-machine interfaces, functional prostheses, and health monitoring devices. While high pressure and temperature sensitivity with visible indication are important for e-skins, such multifunctionality often requires complex fabrication and integration processes, which hinders practical applications. Here, a simple solution is shown to fabricate a bimodal e-skin sensor array that is capable of changing color as a response to a range of temperatures (26-40 degrees C) with an ability to sense finger tap (approximate to 20 kPa pressure) as a pressure sensor. The bimodal functionality of thermochromic response and tactile sensing is achieved by judicial material selection of our custom-developed elastomer composite containing thermochromic dye, which is sandwiched by tough and transparent stretchable electrodes of ion-containing polyampholyte hydrogels. The e-skin array is potentially promising for applications in internet-of-things and soft robotics.