Half-Encapsulated Rigid Microsphere Arrays for Enhancing the Sensitivity of In-Plane Integrated Pressure Sensor

Abstract

As the key block of the application in the field of wearable electronic devices and next-generation robots, flexible piezoresistive sensors have attracted more and more attention. However, it is still a challenge to fabricate a piezoresistive sensor with high sensitivity, high stability, and a large detection range due to the traditional structure limitations. This paper proposed a flexible lateral-circuited piezoresistive sensor with a mechanotransduction structure. The lateral electrode design was achieved by using an AgNWs woven 3D network deposited on an elastic substrate. The zirconia microspheres were assembled in the cavities forming the mechanotransduction structure. It was found from theory and experiments that the microsphere arrays can weaken the load dissipation effect in the elastic substrate and magnify the effect of the mechanical stimulation. The as-obtained result of the deformation of the pressure sensor with zirconia microspheres arrays showed a differential expansion, which is contrary to the compression of the blank sample. Moreover, the sensor shows high linear sensitivity (1.7 kPa <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) in the detection range of 0 kPa - 120 kPa, fast response/recovery time of 23 ms / 22 ms, and relatively high stability (2400 cycles). On the other hand, the sensor also showed relatively high temperature and high humidity stabilities. This result verifies that the zirconia microsphere arrays have highly efficient mechanotransduction. This work provides a new perspective for designing and preparing high-sensitivity and wide-range pressure sensors.