Sensors Could Move Artificial Limbs

Researchers have developed a light-based sensor that could be used to control the movement of artificial limbs.

The St Andrews University team used plastic semiconductors to produce a wearable sensor which senses muscle contraction.

The technology works by shining light into fibrous muscle and observing how the light is scattered.

When muscle is contracted the light is scattered less because the muscle fibres are further apart.

Sensors are then able to detect the changed scattering signals and relay the information, as photocurrents, to a robotic arm which moves.

Scientists said the discovery could start a new era of low-cost disposable wearable optical sensors, relieving patients from risks associated with electrical-based sensors such as electromagnetic interference and immune responses.

The new optical sensors were developed by Professor Ifor Samuel and Dr Ashu Bansal from the university's School of Physics and Astronomy.

Prof Samuel said: "Wearable sensors are important for continuous monitoring of health and our approach offers the advantages of being non-invasive, lightweight, flexible and simple to make.

"By using light we avoid needles that would be needed to make electrical contact.

"A very interesting possible use would be for the control of prosthetic limbs.

"The muscle movements are detected directly by the optical sensor providing a simple interface to control a prosthetic limb.''

The research is published in the Advanced Materials journal.

The team has demonstrated the application of the muscle contraction sensor by showing that it could be used to control a robotic arm which mimicked the movement of a real arm.

Dr Bansal said: "This sensor can distinguish different types of contractions and can add extra functionality to active prosthetics enabling natural movements of the limbs, which is not available with currently available techniques.''

Scientists said the results are important because they suggest how wearable sensors can play a key role in everyday life.

The device consists of a light source and four photodetectors made from semiconducting polymers which are arranged and assembled as a flexible bandage.