Transparent, Flexible, and Passive Thermal Touch Panel

Abstract

This work presents a touch panel concept, which is enabled by a novel designof thin film thermocouples. The design offers a simple implementation byutilizing a single thin film to function as an array of thermocouples. Theconcept is demonstrated as a flexible, passive, and highly transparent touchpanel. The passive nature of the thermoelectric touch recognition allows theperformance of the presented sensor to be optimal at moderate sheet resistancevalues of the transparent conductive layers. Hence, the concept is highlypotential for low-cost large-area applications and does not rely on costlylow sheet resistance materials such as indium tin oxide. The demonstratorpresented in this work achieves a signal-to-noise ratio of 20 with a rise timeof 90 ms and is able to distinguish individual touches, sweeping with finger,as well as touching by multiple fingers at the same time. In addition, the conceptmay also be used in other thermal distribution mapping applications.