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

Engineers at Queen Mary University of London have developed a new color-changing tactile sensor that allows robots to ‘see’ touch in real-time by converting mechanical forces into visible color patterns.

Invented by Dr. Giacomo Sasso, a postdoctoral researcher in the School of Engineering and Materials Science at Queen Mary University of London, this mechanochromic technology provides instant, high-resolution maps of contact, strain and pressure, with potential applications in precision manufacturing, prosthetics and surgical robotics.

How the color-changing tactile sensor works

The new tactile sensor is based on a soft sensing surface that produces spatially varying structural colors when pressure is applied. As a robot or device interacts with an object, invisible mechanical forces are transformed into dynamic color fields across the material.

These color patterns can be captured immediately using a standard, low-cost USB camera, eliminating the need for complex reconstruction algorithms typically required in vision-based tactile sensing. This direct optical readout enables high-resolution, real-time mapping of how and where contact occurs.

Unlike traditional tactile sensors that rely on dense arrays of embedded electronic elements, the Queen Mary system integrates sensing directly into the material itself. Mechanical interactions are encoded as visible optical signals, simplifying the sensor architecture while increasing spatial resolution.

Advancing robotic touch and precision manufacturing

This color-changing tactile sensor opens new possibilities for robotic manipulation in industrial and research environments. The technology enables the development of robotic grippers capable of assembling micro-scale components with the delicacy required in precision manufacturing, where even subtle variations in force must be monitored and controlled.

By making every small change in pressure visible in real time, the sensor allows robots to handle fragile or intricate parts more safely and accurately. The ability to generate rich pressure maps directly from colour information supports fine-tuned control strategies for advanced automation and soft robotics.

Impact on prosthetics and surgical systems

Beyond manufacturing, the technology has significant potential in healthcare. Integrated into external prosthetics (artificial limbs), the sensor could provide users with a richer sense of touch during delicate daily or clinical tasks, improving feedback and control.

In surgical systems, the mechanochromic material could help distinguish healthy from abnormal tissue by reading fine pressure signatures through its color response. By directly visualizing how force is distributed across tissue, surgical tools and robotic platforms could gain a more nuanced understanding of tissue properties, supporting safer and more precise interventions.

Embedding sensing into the material itself

The new system represents a shift from conventional tactile sensing approaches. Instead of embedding dense, overengineered sensor arrays, the sensing function is moved into the material itself. Mechanical cues are directly transformed into color fields that a simple USB camera can read in real time.

This approach has already delivered the first real-time solution in the field capable of capturing fine details such as finger ridges. The resulting pressure maps are both rich in information and supported by a simplified system architecture, reducing hardware complexity and computational load.

Overcoming trade-offs in vision-based tactile sensing

The idea for the sensor emerged from the need to overcome a persistent trade-off in vision-based tactile sensing. High-resolution systems usually depend on heavy computational pipelines to reconstruct contact geometry, which introduces latency. Faster systems, by contrast, often sacrifice spatial detail.

By encoding mechanical interaction directly into light signals, the Queen Mary team has created a system where touch is not reconstructed but observed directly. The information is already present in the optical response of the mechanochromic material, enabling both high spatial resolution and low latency.

Collaboration in soft robotics and material science

The project is the result of a strong collaboration between Professor Federico Carpi at the University of Florence and Professor James Busfield at Queen Mary University of London, bringing together expertise in soft robotics and material science. Building on years of work on stretchable sensors and polymer characterisation, the team has progressively advanced the ability to interface mechanical compliance with functional sensing.

Within this framework, mechanochromic materials represent a new direction for tactile sensing. Instead of relying on highly engineered microelectronics to interpret deformation, the material itself becomes the sensing medium, directly encoding mechanical interaction into visible optical signals.

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