New fibre fleece aims to stimulate muscles after nerve injuries

Motorcycle accidents, falls, amputations or deep wounds often lead to severe nerve damage in arms and legs. In extreme cases, the spinal cord is affected. Damage to the peripheral nervous system, where spinal nerve fibres are bundled, can also cause lasting problems. Once nerve fibres are severed, sensory deficits appear, and muscles no longer receive the necessary electrical impulses. This results in paralysis and long-term functional decline. 

Minor nerve injuries can sometimes be treated surgically. However, in spinal cord injuries this is not possible. 

“However, repairing the signal pathway does not restore nerve function itself,” emphasizes PD Doha Obed, assistant physician at the Clinic for Plastic, Aesthetic, Hand and Reconstructive Surgery at MHH. “The nerve fibres must regenerate along the entire length from the point of severance to the respective target muscle.” 

During this regeneration process, which can take months, paralyzed muscles often lose their strength. Existing therapies such as functional electrical stimulation (FES), where electrodes are applied to the skin, can help strengthen muscles but do not restore nerve function. Implanted electrodes, on the other hand, are prone to complications such as infections or malfunction. 

To overcome these limitations, the MHH team is collaborating with the Institute for Multiphase Processes at Leibniz University Hannover. Their goal is to develop an ultra-thin, stable fleece made of polyvinylidene fluoride (PVDF), a thermoplastic material resistant to heat and chemicals. 

“The magnetic fibre fleece is piezoelectric, meaning it deforms when an electrical voltage is applied,” explains PD Obed. An external magnetic field generates this voltage, and the resulting deformation produces an electric current that can directly stimulate the muscle beneath the skin. 

The research team is exploring how to activate the implant effectively. 

“We are still working out how best to activate the fibre fleece, for example by using a handy device that works like a kind of mini magnetic resonance imaging tube,” says Dr. Obed. Engineers at LUH are developing miniature measuring probes in the form of implantable microchips to monitor voltage in the muscle without cables. The project, funded with 800,000 euros from the German Research Foundation (DFG), will next be tested in animal models. 

If successful, this technology could be applied not only for rehabilitation after nerve injuries but also for muscle stimulation in stroke patients. 

MEDICA-tradefair.com; Source: Medizinische Hochschule Hannover