A functional electrical stimulation (FES) system generates electrical impulses from skin surface electrodes placed on targeted nerves and muscles. These mild electric shocks make muscles contract and joints move.
One of the most common FES systems helps lift the foot of people who find it difficult or sometimes impossible to move their ankle and toes upward, a common result of a stroke or MS.
These systems use a foot switch to detect when a patient’s foot strikes the ground and lifts off. The signal from this switch is monitored by an embedded microcontroller that activates an electrical stimulator connected to electrodes on the leg muscles.
Dr Jon Cobb from the School of Design Engineering and Computing at Bournemouth University believes these systems could be safer and more comfortable for patients by designing them with fewer wires. With the use of wireless communications he also sees the opportunity for including more sensors and stimulators, making the overall systems more adaptive.
Cobb has begun an up to three-year development programme with Odstock Medical Limited to produce new wireless FES systems capable of adjusting their level of stimulation depending on a patient’s changing situation.
He explained these new systems would be able to detect when a patient suddenly begins walking up an incline or stairs. It could also tell when a patient becomes tired.
Cobb said this will require incorporating sensing technologies for monitoring such changes and providing feedback to the FES controller.
‘The controller itself has to exhibit an intelligent control philosophy to deal with the inherent uncertainty associated with this type of application,’ he added.
According to the National Clinical FES Centre, the concept of FES was first put forward in 1960 when a team led by Russian medical researcher Wladimir Theodore Liberson found that their electrical stimulation device could be used to treat a patient with a dropped foot due to an upper motor neurone lesion. Since then the technique has become a respected way of aiding patients who have incurred damage to their central nervous system as a result of a variety of cases including stroke, MS, spinal cord injury, head injury or cerebral palsy.
Cobb said Bournemouth researchers and Odstock Medical Limited will develop their new and improved FES systems over the next two to three years. This will be followed by a clinical evaluation before commercialisation.