Future "squishy" robots
MIT researchers and Google-owned Boston Dynamics developed a new wax-and-foam material that can shift between hard and soft states as a basis for future "squishy robots." The research is funded by the US's Defense Advanced Research Projects Agency could potentially lead to robots that might squeeze their way through the body performing surgery or mush through rubble in disaster situations. From MIT News:
To build a material capable of shifting between squishy and rigid states, the researchers coated a foam structure in wax. They chose foam because it can be squeezed into a small fraction of its normal size, but once released will bounce back to its original shape.
The wax coating, meanwhile, can change from a hard outer shell to a soft, pliable surface with moderate heating. This could be done by running a wire along each of the coated foam struts and then applying a current to heat up and melt the surrounding wax. Turning off the current again would allow the material to cool down and return to its rigid state.
In addition to switching the material to its soft state, heating the wax in this way would also repair any damage sustained, Hosoi says. “This material is self-healing,” she says. “So if you push it too far and fracture the coating, you can heat it and then cool it, and the structure returns to its original configuration.”