How chemistry can make robots move and feel

Organic chemist Michael Lerch is fascinated by ‘engineering solutions’ that can be found in nature. He is working on smart materials, such as heat-absorbing coatings to keep your house cool or coatings that absorb unpleasant odours. And he wants to make robots that move more smoothly by using smart materials that can act as a chemistry-based operating system.

FSE Science Newsroom | René Fransen

‘Smart materials are often designed by engineers, who mostly rely on available components. As a synthetic chemist, I can design and make the components I need.’ Lerch originally trained as a classic synthetic organic chemist in Ben Feringa’s lab, building molecular motors and switches. During his time as a postdoctoral researcher at Harvard University (US), he became fascinated by the way nature creates functional materials. ‘A car is made from some thirty thousand individual parts. By contrast, biological materials are made from large assemblies of cooperating cells.’

Arms that think for themselves

It may seem a bit odd for a chemist, but Lerch is fascinated by robotics. He finds the current robots big and clumsy. ‘The average robot has lots of sensors to scan the environment and actuators to move or respond, all controlled by a central computer. However, they can only execute what is pre-programmed in that central computer,’ says Lerch.

In nature, an octopus has a central brain, but its arms can ‘think’ for themselves. Humans also have decentralized systems. ‘When you stumble, a local reflex system will prevent you from falling.’ The brain may determine where we go, but those local systems keep us going. Such systems may also help robots to quickly adapt to their environment.

Moving microrobots

So how does such a decentralized system work? Lerch uses chemical reactions instead of computer chips. ‘We have, for example, molecules called mechanophores, which respond to stretching or pressure.’ These molecules will then activate a series of other reactions – a bit like a Rube Goldberg machine – to induce a specific movement. It is possible to design the reactions to store information, make calculations, or even execute a specific series of movements.

Lerch is currently able to use this chemical equivalence of a computer program to produce movement on the scale of just tenths of a millimetre. At this scale, controlling movement is quite a challenge since normal control mechanisms do not work at such a small scale. This would be useful in microrobots which are too small to accommodate computer chips. And the chemistry-based operating system could also be capable of creating a local response. For instance, when a robot hand has a sensor that detects a soft object, a locally generated chemical signal could adapt the grip strength.

Socially engaged

And chemistry can do much more. Lerch also works on smart coatings, which might one day keep your house cool or absorb unpleasant odours. And perhaps smart paint could one day detect damage in a wall. But Lerch is also aware that chemistry – and science in general – has its dark side. ‘Research can use a lot of energy, and it produces some 2 per cent of global plastic waste.’

When he started his tenure track position in Groningen, he was asked to supervise several PhD students carrying out projects aimed at making research more sustainable. ‘I have always been socially engaged, so I was eager to contribute. The project gained momentum and now, the University of Groningen has become a beacon in the Green Labs movement.’