Microimplants: Medicine heals using electricity

It may sound like science fiction, but it is real medical technology. Tiny implants stimulate specific nerves in the body to treat illnesses. A new generation of these electroceuticals even communicate with smartphones.

Bioelectronic therapy is one of the most exciting future fields of medical research. This goes without saying, since neuronal circuits influence almost all cells. Because of this, much of our body functions via electronic signals. Now, by overwriting these signals with the targeted help of microimplants, alternative methods of treating illness with few side effects become available.

Stimulation currents have long been used in pacemakers, cochlea implants and retina implants. The peripheral nervous system is also treated using electrical impulses in the case of chronic pain, depression and Parkinson’s disease.

The next generation of bioelectronic medicine

But the new microimplants can do much more than that. They are able to normalize pathological organ functions by specifically manipulating signal transmission in the body. To do so, they work wirelessly in nerves, muscles or organs with a very low energy requirement, potentially for a lifetime.

The challenge lies in choosing the right nerve signal from among the hundreds that affect an organ. After that, however, it is possible to influence it over a long distance. For example, the vagus – one of the longest nerves – runs from the brain stem through the abdomen to connect the gut’s nervous system to the brain. As a result, it is involved in the regulation of almost all organs.

By stimulating the vagus nerve, electronic implants from the California biotech company SetPoint Medical, for example, have already been able to stem the production of a second messenger responsible for inflammation, which eased the symptoms of rheumatoid arthritis.

High investment in med-tech

Future topics with higher than average potential are also attracting IT giants such as Google and the like. In 2016, for example, more than EUR 600 million flowed into a joint venture (Galvani Bioelectronics) from the pharmaceutical company GlaxoSmithKline (GSK) and Google’s parent company Alphabet. The goal was to develop microimplants for the peripheral nervous system. Last year, a neurostimulator from Galvani Bioelectronics was able to positively influence the spleen nerve of a patient with rheumatoid arthritis for the first time.

Communicative microimplants from Germany

In Germany, the INTAKT innovation cluster, which is funded by the Federal Ministry of Research, is developing a new generation of networked micro-implants that allow external access via laptop or smartphone.

The focus is on three applications: Treating tinnitus by stimulating the cochlea, alleviating motility disorders of the gut and at least partly restoring the gripping function of the hand following paraplegia.

For the tinnitus application, the implants stimulate the round window of the cochlea in the inner ear, modulating the activities in the acoustic nerve and thereby blurring the phantom noise. In order to remedy gastrointestinal dysmobility, implants distributed in the gastrointestinal tract record its activities in order to initiate a trouble-free digestive process with additional implants.

The partial restoration of gripping function is more complex. To do this, as many as twelve micro-implants stimulate the forearm muscles for a series of hand movements. The patient controls these using an eye tracking system: Predefined eye-, lid- and head movements give instructions to the central control unit, which then orchestrates the network accordingly.

Communicating wirelessly and via Bluetooth

The sensors and actuators are integrated directly into a housing, where they interact wirelessly and via infrared. To this end, Fraunhofer IIS has developed highly miniaturized ASICs that record biosignals from the arm muscles or gut while initiating the appropriate electro-stimulations.

When implants are combined, the energy supply is particularly complex, since the energy consumption varies depending on demand. INTAKT therefore relies on an adaptive, inductive charge that supplies each individual implant with energy around the clock.

Initial preclinical tests showed that the INTAKT applications developed so far work. Now it’s a matter of transferring their development to clinical application and making them usable for patients.