Researchers have developed a sensor about the size of a grain of rice that can measure forces and twisting motions in all directions using light instead of traditional electronics. The new sensor could help robotic tools and medical devices “feel” what they are touching, especially at very small scales.

“Although modern imaging systems can show structures clearly, they do not provide information about physical interaction, such as force or torque, and existing force sensors are often too bulky or complex to fit into miniature tools,” said research team leader Jianlong Yang from Shanghai Jiao Tong University in China. “By allowing machines to measure contact force, pressure, shear and twisting, our technology could make it possible for robots to detect unsafe contact early and adjust their actions in real time, especially in small and sensitive environments.”

In Optica journal, the researchers describe their new sensor, which measures just 1.7 millimeters and uses a single optical signal to measure forces and torques in all directions at once. Proof-of-concept tests showed that the sensor can detect stiffness variations and locate hidden structures in models that mimic a tumor embedded in tissue.