TacLight: A Six-Axis Soft Optical Tactile Sensor for Physical and Virtual Interaction

Tactile sensing is a fundamental enabler of robust interaction in environments characterized by dense and uncertain contacts. Yet, existing tactile sensors remain far from human inspiration: they are often mechanically rigid or restricted in the richness of the signals they provide. This paper aims to make a step towards solving this challenge by introducing TacLight: a compact, camera-free optical tactile sensor capable of detecting all six independent force/torque components—normal, shear, torsional, and twisting forces. The sensor is also capable of localizing the contact point. The sensing principle relies on infrared LEDs that emit light through a transparent porous elastomer, while a thin white reflective layer on top enhances light reflection, with distributed photoresistors registering transmitted intensities. Deformations of the porous medium perturb internal light paths, producing direct variations in the electrical output that encode contact mechanics without computationally heavy reconstruction. TacLight achieves high sensitivity (100 mV/N in the 0–3 N range), maintains excellent linearity (R2 > 0.95) with a 10 mm elastomer layer, and preserves a compact, low-cost, and scalable architecture. Two demonstrations highlight TacLight’s versatility. In human–machine interaction, a joystick-like device enables intuitive drone control in a simulation environment. In robotic manipulation, tactile feedback improves the success rate of an imitation-learning-based peeling task compared with a baseline without tactile sensing.