Phase-Changing Material Could Allow Low-Cost Deformable Surgical Robots

In the movie 'Terminator 2,' the shape-shifting T-1000 robot morphs into a liquid state to squeeze through tight spaces or to repair itself when harmed. Now a phase-changing material built from wax and foam, and capable of switching between hard and soft states, could allow even low-cost robots to perform the same feat. The material, developed at MIT, could be used to build deformable surgical robots. The robots could move through the body to reach a particular point without damaging any of the organs or vessels along the way. Robots built from the material could also be used in search-and-rescue operations to squeeze through rubble looking for survivors.

Transcript

00:00:06 Traditionally when we think about robots we think about rigid pieces that are linked together. Things like C3PO. Things like WALL-E. What we're trying to do is build robots that emulate biological systems. So they have soft components, they are very deformable, they can squeeze through small spaces and they can interact safely with people. And so what we're trying to do is to go away from metal a little bit. We wanted to develop tunable stiffness structures and materials. The idea is that the robot should be soft in situations where we want to conform to the environment or squeeze through tight spaces, but we also would need it to be rigid when we need to apply loads on the

00:00:46 environment so that we can adequately push against objects and that sort of thing. So what we were looking for was a material that could shift between soft and hard states. So what you're looking at here is a soft scaffold of foam that has been coated in wax. When the wax is heated you get the soft structure and when the wax re-solidifies it regains its rigidity. So imagine if your components were more compliant then perhaps we could increase the robots capabilities. For example if you wanted to use this composite foam-wax that has tunable stiffness properties to make some autonomous robot or to control the shape of a robot you can have

00:01:27 different segments of the foam coated in wax and selectively change the stiffness of them. So lets say you have three segments and you wanted to just bend the middle one, you keep the outer two segments rigid in the cold state, and you heat up the middle one so that it softens and you can bend it; for example by pulling a string or a cable that goes down the length just to bend that one. And then of course if you want that shape or that segment to freeze in its new shape, you let it cool in whatever bent position, at room temperature. I think that the structures you are seeing here are just the beginning of a whole new class of robotics. Again, imagine robots that have the

00:02:08 same capabilities of biological systems. Mice, we all know we can't keep mice out of anything because they can squeeze through tiny, tiny cracks. This is something that could be useful for robots in search-and-rescue applications, where you have to go through rubble. It could be useful in medical applications where you have to squeeze through small parts of the body. It could be useful in areas where robots have to interact safely with humans; there's a whole host of applications out there.