Study on utilization of triboelectric nanogenerator as self-powered touch sensor

Abstract

Triboelectric nanogenerator (TENG) is a new class of energy harvester, which converts external mechanical energy into usable electrical energy, via contact electrification and following electrostatic induction. Apart from utilizing TENG as an energy source, TENG have been utilized as a self-powered active sensor based on the fact that TENG generate electrical signal itself corresponding to external excitations. Especially, TENG based touch sensor have been most intensively studied. However, most studies had focused on validating the potential of TENG based sensor. TENG based touch sensor has various advantages including cost-effectiveness, no restriction in selecting material, design flexibility and self-powered operation. To widen applicable area of TENG based touch sensor, it is important to explore appropriate end application in where the advantages of TENG based touch sensor can be maximized. In this study, three different applications of TENG based touch sensor (fall detection system, fabric keyboard and touchpad) were suggested and the system operation was validated.

Firstly, cost effective fall detection system was demonstrated utilizing TENG based touch sensor array, although unit sensor could be fabricated with very low cost (150 KRW), it was confirmed that the proposed fall detection system accurately classified daily activities and falls (accuracy of 95.75 %). Secondly, based on wide mechanical spectrum and design flexibility of TENG based sensor, a fabric keyboard which can be made only using commercialized fabrics, was demonstrated and the operation was experimentally validated. Due to its cost effectiveness and textile industry compatibility, the proposed keyboard has great potential for an interface device in electronic textile (E-textile). Finally, fabric touchpad was demonstrated by employing crossline array of TENG based sensors. With largely enlarged pixel number, it was shown that more complex operations such as hand writing of a digit could be served.