Researchers in China have developed a rice-sized optical sensor that could enable surgical robots and miniature medical tools to sense touch with remarkable precision. The tiny device measures force, pressure, and twisting movements in every direction using light instead of conventional electronics.
Developed by researchers at Shanghai Jiao Tong University, the sensor measures just 1.7 millimetres and could significantly improve the safety and accuracy of delicate robotic surgeries.
Sensor Helps Robots Detect Unsafe Contact in Real Time
Unlike current robotic surgery systems that rely mainly on imaging, the new sensor provides real-time physical interaction feedback. Existing imaging technologies can clearly display internal structures, but they cannot detect pressure, force, or torque during procedures performed in confined surgical spaces.
Explaining the need for the innovation, Jianlong Yang said, “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.”
He further explained that the technology could help robots identify unsafe contact instantly and adjust their movements during highly sensitive procedures.
“By allowing machines to measure contact force, pressure, shear, and twisting, our technology could enable robots to detect unsafe contact early and respond in real time, especially in small and sensitive environments,” he added.
Researchers Replace Electronics With Light-based Technology
To create the sensor, researchers designed a system around an optical fibre fitted with a soft elastomer tip. When the tip touches an object, it undergoes slight deformation, which changes the way light travels within the device.
Subsequently, a coherent fibre bundle transfers the resulting light pattern to a camera. The system then analyses the captured images using data-driven methods to calculate force and torque from multiple directions.
Importantly, the researchers noted that the optical approach eliminates the wiring complexity commonly associated with conventional miniature force sensors.
“Our sensor works differently from conventional miniature force sensors, such as fibre Bragg grating systems that rely on multiple sensing elements and carefully designed structures to separate different force components,” Yang explained.
“We are not measuring force piece by piece. Instead, we sense the overall contact state in a single step. This shift could make it easier to develop compact tools that can both see and feel,” he added.
Device Successfully Detects Hidden Tumour-like Structures
As reported by Interesting Engineering, the research team tested the sensor under controlled loading conditions using known forces and twisting motions. The device produced highly consistent and repeatable measurements with minimal hysteresis, ensuring reliable readings during both loading and unloading cycles.
Furthermore, the researchers evaluated the sensor using gelatin tissue models embedded with stiff spherical objects designed to mimic hidden tumours. Impressively, the device successfully detected and located the concealed structures beneath the soft material.
Technology Could Improve Safety in Minimally Invasive Surgery
According to the researchers, the technology could greatly enhance tactile guidance during minimally invasive surgical procedures. Surgeons operating robotic systems often work through narrow pathways where accidental contact with delicate tissues can lead to complications.
“Robotic systems used in minimally invasive surgery operate in extremely tight spaces, such as inside the eye or through narrow surgical pathways,” Yang said.
“By making tools and robots safer and more precise, this technology could improve control during delicate medical procedures and reduce the risk of accidental tissue damage,” he added.
Researchers Plan Real-world Testing Before Commercial Use
Moving forward, the research team plans to improve manufacturing consistency and reduce calibration requirements before introducing the technology for commercial applications.
Additionally, they aim to integrate the sensor into medical and industrial robotic systems for long-term testing under real operating conditions. The team also plans to develop compact and user-friendly packaging that clinicians and engineers can easily deploy in practical settings.
The study was published in the journal Optica.