Self-healing, biodegradable, 3D printed materials could be used in the development of realistic artificial hands and other soft robotics applications. (Credit: University of Cambridge)

Low-cost jelly-like materials can sense strain, temperature, and humidity. And unlike earlier self-healing robots, they can also partially repair themselves at room temperature. The soft sensing technologies could transform robotics, tactile interfaces, and wearable devices.

The 3D printed materials can detect when they are damaged, take the necessary steps to temporarily heal themselves and then resume work — all without the need for human interaction. The researchers started with a stretchy, gelatin-based material that is cheap, biodegradable, and biocompatible. They carried out different tests on how to incorporate sensors into the material by adding in lots of conductive components.

The researchers found that printing sensors containing sodium chloride — salt — instead of carbon ink resulted in a material with the properties they were looking for. Since salt is soluble in the water-filled hydrogel, it provides a uniform channel for ionic conduction — the movement of ions.