A microchip to help paraplegia patients

LONDON, UK: Offering a new lease of life to the patients suffering from paraplegia, engineers have developed a new type of microchip implant that will enable them to exercise their paralyzed leg muscles.

It is the first time that researchers have developed a device of this kind that is small enough to be implanted into the spinal canal and incorporates the electrodes and muscle stimulator in one unit, said Engineering and Physical Sciences Research Council (EPSRC), which is working on the project. The implant is the size of a child"s fingernail.

Paraplegia is the complete paralysis of the lower half of the body including both legs, usually caused by damage to the spinal cord, and such patients may require assistive technology to move their limbs.

EPSRC, a UK government agency for funding research and training in engineering and the physical sciences, said the project is being led by Professor Andreas Demosthenous from University College London and co-led by Professor Nick Donaldson of University College London. It also includes engineers from Freiburg University and the Tyndall Institute in Cork.

“The work has the potential to stimulate more muscle groups than is currently possible with existing technology because a number of these devices can be implanted into the spinal canal,” said Professor Andreas Demosthenous. “Stimulation of more muscle groups means users can perform enough movement to carry out controlled exercise such as cycling or rowing,” he added.

The devices could also be used for a wide range of restorative functions such as stimulating bladder muscles to help overcome incontinence and stimulating nerves to improve bowel capacity and suppress spasms, said EPSRC.

The new implant will be fitted to the patient's spine. At the moment electrical stimulation of nerve roots in the spinal canal can be carried out using implanted electrodes and an implanted stimulator connected by a cable. This latest research is the first to combine the electrodes and muscle stimulator in one unit so that more nerves can be stimulated and better function achieved.

The researchers said they overcame previous limitations by micro-packaging everything into one tiny unit. Latest laser processing technology has been used to cut tiny electrodes from platinum foil.

These are then folded into a 3D shape (which looks like the pages of a book, earning the device the name of the Active Book). The pages close in around the nerve roots. They are micro-welded to a silicon chip which is hermetically sealed to protect against water penetration, which can lead to corrosion of the electronics.