Multitouch Pressure Sensing with Soft Optical Time-of-Flight Sensors

This paper reports on optical time-of-flight as a detection mode for soft optical deformation sensors. In this work, low-cost miniature light detection and ranging (LiDAR) chips recently developed for consumer mobile device applications perform real-time optical reflectometry at cm scales in soft optical waveguide networks. Our methodscomplement existing work by capturing spatial information that is lost with amplitude-only measurements. We demonstrate its application in a multitouch button system capable of extracting displacement values from soft optical switches with average error in the range of 100-200 microns on 1.5 mm of switch travel. Because making reliable electronic connections to soft materials is a challenging task, we focus on minimizing connector count. Spatial information was extracted from the three-switch optical network using a single LiDAR sensor.