Artificial skin that can sense

Using a mechanism similar to the one used by the organ that allows pit vipers to sense their prey, researchers have developed an artificial skin capable of detecting temperature changes. The material could be grafted onto prosthetic limbs to restore temperature sensing in amputees.

It could also be applied to first-aid bandages to alert health professionals of a temperature increase a sign of infection in wounds. While fabricating synthetic woods in a petri dish, a team led by California Institute of Technology's Chiara Daraio created a material that exhibited an electrical response to temperature changes in the laboratory.

It turned out that the component responsible for the temperature sensitivity was pectin, a long-chain molecule present in plant cell walls. "Pectin is widely used in the food industry as a jellifying agent; it's what you use to make jam. So it's easy to obtain and also very cheap," said Daraio.

Intrigued, the team shifted its attention to pectin and ultimately created a thin, transparent flexible film of pectin and water, which can be as little as 20 micrometres thick (equivalent to the diameter of a human hair). Pectin molecules in the film have a weakly bonded double-strand structure that contains calcium ions.

According to a paper published in the journal Science Robotics, the film senses temperature using a mechanism similar but not identical to the pit organs in vipers, which allow the snakes to sense warm prey in the dark by detecting radiated heat.

In those organs, ion channels in the cell membrane of sensory nerve fibres expand as temperature increases. This dilation allows calcium ions to flow, triggering electrical impulses, the researchers explained.