Characterizing Material Effects on Direct ToF Signal Response in Optical Tactile Systems

Optical tactile sensing holds transformative potential for robotics, particularly in collaborative environments where touch perception enhances safety, adaptability, and cognitive interaction. However, traditional tactile technologies based on total internal reflection (TIR) and frustrated total internal reflection (FTIR) - such as those used in touchscreen systems - face significant limitations. These include reliance on multiple infrared light sources and cameras, as well as poor adaptability to the complex, curved geometries often found in robotic systems. To address these challenges, we recently introduced OptoSkin [1], an advanced optical tactile sensor based on direct Time-of-Flight (ToF) technology, enabling touch and pressure detection. In this study, we investigate how specific material properties, particularly light scattering, influence the sensitivity of contact point detection under direct ToF sensing. Four materials with distinct scattering coefficients ranging from 0.02 cm^-1 to 1.1 cm^-1 at 940 nm were selected to assess their impact on signal quality across different contact scenarios involving various target surfaces.