Paper-Based Bimodal Sensor for Electronic Skin Applications

Abstract

We present the development of a flexible bimodal sensor using a paper platform and inkjet printing method, which are suited for low-cost fabrication processes and realization of flexible devices. In this study, we employed a vertically stacked bimodal device architecture in which a temperature sensor is stacked on top of a pressure sensor and operated on different principles, allowing the minimization of interference effects. For the temperature sensor placed in the top layer, we used the thermoelectric effect and formed a closed loop thermocouple composed of two different printable inks (conductive PEDOT:PSS and silver nanoparticles on a flexible paper platform) and obtained temperature-sensing capability over a wide range (150 degrees C). For the pressure sensor positioned in the bottom layer, we used microdimensional pyramid structured poly(dimethylsiloxane) coated with multiwall carbon nanotube conducting ink. Our pressure sensor exhibits a high-pressure sensitivity over a wide range (100 Pa to 5 kPa) and high -endurance characteristics of 10(5). Our 5 x 5 bimodal sensor array demonstrates negligible interference, high-speed responsivity, and robust sensing characteristics. We believe that the material, process, two-terminal device, and integration scheme developed in this study have a great value that can be widely applied to electronic skin.