Making muscles

One of the differences between engineers and biologists is that engineers are faced with the problem of making something and they’ve got to look for answers whereas biologists are looking at the end product of evolution, so they’re looking at a whole range of answers to problems and they’ve got to try and work out what the question was.

Dr George Jeronimidis explains that he is trying to imitate some of the function of muscle.

"The idea is to use some of the features of muscles in designing engineering components of variable stiffness. Muscle is more or less the architype system for variable stiffness because you can hold a glass of beer and it would be very stiff and you can release it and it would be very soft."

Creative Commons Image UrbanDon via Flickr
Cyborg costume arm made from recycled materials. [Image: Urban Don under CC-BY-NC-SA licence]

Muscle is something which is able to change in volume, and as the change in volume takes place, a contraction is produced. The contraction is transmitted to a tendon and that is how the force is generated the force.

Prof Julian Vincent says that when it comes to producing systems, nature can give us a good idea of what we might be able to do:

"We have the idea and then we think well that’s obviously going to be too expensive to do it the way nature does it because it’s so incredibly complicated and so much fine detail there that maybe if we did it this way we could do it more quickly and more cheaply."

The molecular mechanism for muscle contraction is for the moment way beyond our scientists' reach. However, they have got materials which can do some of the things that muscle does i.e. swell. The team has created a cylindrical structure of fibres. Inside the cylinder is a gel which is capable of expanding.

The whole lot is put in contact with a solvent, for example, immersed in water so that the gel will absorb the water, and will try to swell out. In swelling out, the orientation of the fibres will change and it is possible to make the gel either contract in the long direction and expand laterally or else contract in diameter and become longer. The swelling of the gel can be stimulated by applying an electrical field.

Julian hopes that by having an adapted system like this he can use the elements in all sorts of other ways and one of the ways that he'd like to try is in robotics.

George says that where they want to replicate in a mechanical context some of the actions of arms and legs and muscles, they are obliged to use equivalent systems.

He says: "The ones we use normally are not based on active gels – they are based more on springs, chains and gears and wheels, more traditional engineering ones. We developed our own way of thinking of what biology can offer in an engineering context: how to look at biology as a source of inspiration for engineering technical solutions. We looked at something, tried to understand what features make it work and tried to see if there is a benefit to be had somewhere else."

Julian continues: "Because both the biologist and engineer can bring something different to the party then they can bring something which is outside the normal experience of the other person and the chance of coming up with a novel solution is much greater".