Flexible 3D Architectured Piezo/Thermoelectric Bimodal Tactile Sensor Array for E-Skin Application

Electronic skin (e-skin) functions as human-machines interaction interfaces, holding great promise in future personal health monitoring and endowing robots with capability of sense of touch. Despite recent exciting progress in e-skin research, accurate discrimination of various tactile inputs remains a great challenge yet. A 3D processing technique is demonstrated here combining laser fabrication and screen printing to construct vertically architectured pressure/temperature bimodal active sensor employing all organic functional materials, i.e., piezoelectric poly(vinylidene fluoride-co-trifluoroethylene) and thermoelectric polyaniline-based composites. The sensor transforms pressure and temperature stimuli into two independent electrical signals without interference, exhibiting high temperature sensing sensitivity (109.4 mu V K-1) with rapid response time (0.37 s) and superior pressure sensing sensitivity over a wide range (100 Pa to 20 kPa). Finite element analyses further explain the thermal harvesting performance of the sensor. Applications of sensor as e-skin in various temperature/stress perception scenarios and its stability are demonstrated. Further, a 4 x 4 pixel bimodal tactile sensor array is integrated for the first time, presenting accurate spatial distribution mapping of pressure/temperature signals simultaneously without interference, and functions without external power supply due to its intrinsic working principle. This study thus moves a step toward multifunctional flexible electronics for e-skin applications.