Silly putty just got smart, in the form of a viscous black gel that can stretch, self-repair and detect facial expressions.
A team led by Yizhou Zhang at the King Abdullah University of Science and Technology in Saudi Arabia and his colleagues added a type of graphene-like material called an MXene to another material called a hydrogel, which is a mix of water and a polymer.
The resulting putty was able to stretch to 35 times its original length. The material can also be easily reshaped, and if separated can be reattached simply by pressing the two pieces together.
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MXenes are a type of two-dimensional nanomaterial made up of atoms-thick sheets of metal stacked like an accordion 鈥� Zhang鈥檚 team used a form of titanium carbide. They also conduct of electricity, which gives the gel another useful property.
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By measuring changes in the electrical resistance of the gel, Zhang鈥檚 team were able to use it as a biosensor capable of reading signals from the human body, without needing any additional components.
They attached a thin sheet of the hydrogel to a test-subject鈥檚 throat and were able to convert their speech into electronic signals. Attached to the forehead, the gel could reliably detect different facial expressions.
Both of these applications hold promise for helping people with paralysis to communicate or control devices, says Zhang. Such a biosensor would also be cheap and easy to produce as the titanium carbide is made from titanium aluminium carbide, a commonly used ceramic material that is also non-toxic.
Science Advances
