European team builds robotic fingertip that maps touch through color shifts

Researchers from Queen Mary University of London and Italian partners have built a robotic fingertip whose synthetic skin changes the color of reflected light under mechanical deformation, letting a camera map topology, strain, and contact pressure in real time, IEEE Spectrum reported. The skin uses a Bragg reflector made by exposing light-sensitive film to a red laser so alternating polymer densities reflect specific wavelengths. When the fingertip presses an object, the layers stretch and the reflected color shifts from red toward green and blue as deformation increases. A camera and LED sit inside a transparent silicone finger, with a black outer silicone layer improving contrast. After optimization, the team reported 100-micrometer resolution with no computational latency and demonstrated maps of a human fingertip, a U.S. penny, and a leaf. Giacomo Sasso, a postdoctoral researcher in Federico Carpi's Queen Mary lab, developed the approach after encountering a Nature paper on the mechanochromic material. Shadow Robot director Rich Walker called the method a distinctly different tactile approach. Outside researchers noted soft sensors still face durability questions in real hands; Carpi's group says an outer silicone layer protects the reflector and is talking with companies about uses, including possible surgical instruments.