Rachel Brazil looks at how chemists are helping make robots with a more gentle touch

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Source: Massimo Brega, The Lighthouse/Science Photo Library

The original ‘robots’ from Czech playwright Karel Capek’s 1921 play Rossum’s universal robots were not the electromechanical machines we know today; they were flesh and blood. As envisaged, they were far superior to today’s metal robots, which are designed to do the things we find ‘dull, dirty or dangerous’, but incapable of seemingly simple tasks like picking fruit. Now engineers, materials scientists and chemists are looking at how machines made from soft materials might have better control and dexterity, and be better at interacting with living things.

Conventional robots, made from motors and metal bearings, are great for tasks such as spot-welding cars, says Jonathan Rossiter, head of the soft robotics group at Bristol University in the UK. ‘But when it comes to living in our world, having these large movable metal objects in our lives is a little bit challenging.’ Robots are rarely designed to interact with humans, but soft materials could change this, he explains. ‘They can be a little bit more like the kinds of things we interact with, like dogs or cats.’ 

As with many design challenges, nature is providing inspiration. Think about an elephant’s trunk. Made of soft matter in the form of 150,000 muscles, it has the ability to tear down trees but also delicately manipulate objects the size of a peanut. ‘Life has found amazing ways to use the properties of soft matter,’ says Orlin Velev of North Carolina State University in the US, who is designing hydrogel materials that mimic the action of muscle. ‘If you really compare what you can do with a mechanical device and what even the simplest live organisms can do, there is a very big difference. Organisms are flexible, they are adaptable and they can self-repair. It’s really a kind of functionality that is nowhere close to present-day technology,’ says Velev. 

Soft robotic actuators

Adam Stokes from the University of Edinburgh in the UK agrees that soft materials could open up new avenues in robotics and get us closer to the functionality offered by biology. One of the big challenges in soft robotics is finding materials that can act like muscles and provide actuation or movement that is inherently ‘compliant’. A compliant actuator does not follow one rigid path and is responsive. For example, a compliant robot gripper can grasp an egg without crushing it.