Self-powered, tactile pressure sensing skin using crystalline ZnO nanorod arrays for robotic applications

Abstract

Large area arrays of ordered ZnO piezoelectric nanorods are developed on flexible substrates towards self-powered sensing skin for robots. The sensor array is designed to measure tactile pressure in the 10 kPa-200 kPa range with 1 mm spatial resolution. A voltage signal in the range of few mV is observed in response to applied pressure. This work represents the first demonstration of perfectly ordered, vertically aligned, crystalline ZnO nanorod arrays, fabricated in polyimides to ensure conformity to non-planar surfaces such as a robot's. The sensors are self-packaged using a flexible substrate and a superstrate. In addition to the novelty of the sensor structure itself, the work includes an innovative low-temperature hydrothermal ZnO growth process compatible with the temperature restrictions imposed by the polyimide substrate/superstrate. Control of nanorod density and placement is achieved using a thermal nanoimprint lithography based template, another novelty of the presented work.