Robots can now 'see' touch thanks to a new color-changing tactile sensor

Engineers at Queen Mary University of London have developed a tactile sensor that lets robots interpret touch through changing colors. The system uses a soft mechanochromic sensing surface: when pressure or strain is applied, it generates spatially varying structural colors. A standard camera can capture these color patterns immediately, producing high-resolution maps of contact, pressure and deformation without complex reconstruction algorithms.

The researchers say this approach addresses a long-standing trade-off in vision-based tactile sensing. Systems with fine spatial resolution often need computationally demanding processing to reconstruct contact geometry, which can create delay. Faster approaches can lose detail. In the new design, mechanical information is encoded directly into visible optical signals, so sensing is embedded in the material rather than relying on dense arrays of conventional electronic sensing elements.

The work was led by postdoctoral researcher Giacomo Sasso at Queen Mary's School of Engineering and Materials Science, with collaborators from the University of Florence, the University of Trieste and the University of Trento. The team reported that the sensor captured finger ridges and described it as a real-time solution that combines high sensor density with a relatively simple architecture. The study was published in Science Advances.

Potential applications include robotic grippers handling microscale components in precision manufacturing, where subtle force changes matter. The technology could also give external prosthetic limbs a richer sense of touch during daily or clinical tasks. In surgical systems, the color response could help distinguish healthy from abnormal tissue by detecting fine pressure signatures. The research builds on work in soft robotics, stretchable sensors and polymer characterization, presenting mechanochromic materials as a route for materials themselves to function as tactile sensing media.