Made from a gelatine-based material and consisting salt, it enables robots to repair themselves at room temperature
Self-healing robots often require heat to be healed, which consumes lots of energy. At the same time, such self-healing robots aren’t considered to be durable enough to take varying loads.
Now researchers at the University of Cambridge have developed self-healing, biodegradable, 3D-printed materials that could be used for the development of artificial hands and other soft robotics applications. The 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. Applications include robotics, tactile interfaces, wearable devices and more.
“Incorporating soft sensors into robotics allows us to get a lot more information from them, like how strain on our muscles allows our brains to get information about the state of our bodies,” said David Hardman, researcher at the Department of Engineering, University of Cambridge.
The self-healing 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 work began when researchers found that printing sensors containing sodium chloride (salt) instead of carbon ink resulted in a material with desirable properties. Because salt is soluble in the water-filled hydrogel, it provides a uniform channel for the movement of ions that lead to conduction.
“We started with a stretchy, gelatine-based material which is cheap, biodegradable and biocompatible and carried out different tests on how to incorporate sensors into the material by adding in lots of conductive components,” said David Hardman.
Upon measuring the electrical resistance of the printed materials, it was discovered that changes in strain resulted in a highly linear response, which could be used for calculations material deformations. Addition of salt enabled sensing of highly-stretchable lenghts (more than 3x the sensor’s original length). This enabled incorporation of the material into flexible and stretchable robotic devices.
Inexpensive and easy to make using 3D printing or casting, the self-healing materials exhibit long-term strength and stability. Even though made entirely from food-safe materials, the sensor never dries out.
“It’s a really good sensor considering how cheap and easy it is to make,” said Dr Thomas George-Thuruthel, also from the Department of Engineering. “We could make a whole robot out of gelatine and print the sensors wherever we need them.”
Although the material is a proof-of-concept, if developed further, it could be incorporated into artificial skins and custom-made wearable and biodegradable sensors.
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