Transparent, Flexible, and Passive Thermal Touch Panel

This work presents a touch panel concept, which is enabled by a novel design of thin film thermocouples. The design offers a simple implementation by utilizing a single thin film to function as an array of thermocouples. The concept is demonstrated as a flexible, passive, and highly transparent touch panel. The passive nature of the thermoelectric touch recognition allows the performance of the presented sensor to be optimal at moderate sheet resistance values of the transparent conductive layers. Hence, the concept is highly potential for low-cost large-area applications and does not rely on costly low sheet resistance materials such as indium tin oxide. The demonstrator presented in this work achieves a signal-to-noise ratio of 20 with a rise time of 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 concept may also be used in other thermal distribution mapping applications.