Magnetic microcoils unlock targeted single-neuron therapy for neurodegenerative diseases

Neurostimulation is a medical technology used to treat many conditions affecting the nervous system. It exerts energy on neurons to encourage them to grow and connect with their neighbors. Epilepsy treatment often includes neurostimulation, as do similar treatments for Parkinson’s disease, chronic pain, and some psychiatric conditions.

inside In Journal of Vacuum Science and TechnologyPublished by AIP Publishing, researchers at the University of Minnesota deployed an array of tiny coils (microcoils) to create a magnetic field and stimulate individual neurons.

Existing devices are effective but lack the precision required for some applications, such as cochlear implants or vagus nerve stimulators.

“There are several neurostimulation devices on the market – some already approved by the FDA for patient testing and some awaiting approval,” said author Renata Saha. “But they all come with a caveat – they stimulate large numbers of neurons, including neighboring cells that shouldn’t be stimulated. The medical device industry is looking for a device or technology solution that can stimulate single-cell neurons.”

Instead of using electrodes, Saha and his team used magnetic coils. More than two centuries ago, physicist Michael Faraday described how an electric current flowing through a coil of wire creates a magnetic field. This magnetic field can then induce an electric field in any nearby neuron – the same effect produced by electrodes, but more precisely. However, this technique has a major drawback.

“The amount of current that needs to be driven through these microcoils to reach the required electric field threshold that can stimulate neurons is very high,” Saha said. “This is about three times the current required to drive the electrode to the same threshold.”

To solve this problem, the team made two improvements. First, instead of using a single microcoil, they used an array of eight coils that induce an electric field using much less current per coil. The authors further improved these microcoil arrays by using soft magnetic materials to increase the magnetic field strength of the coils.

“Adding these soft magnetic materials to the core of the microcoil increases the electric field without increasing the current through the microcoil,” Saha said.

The researchers developed a prototype coil array called MagPatch and encapsulated it in a biocompatible coating. They then tested it with human neuroblastoma cells to prove its effectiveness. The cells were affected by the magnetic field without being damaged by the coating, suggesting that the device could potentially be used in clinical settings.

The authors plan to continue development and testing of the MagPatch device to ensure its safety and utility. They hope this will help develop the next generation of cochlear implants.