Researchers at Rice University in Texas, USA have designed a new material that can convert magnetic energy into electricity to stimulate nerves in a precise manner. The development could lead to groundbreaking treatment for individuals suffering from neurological conditions or injuries in which nerves are completely severed.
The researchers tested the magnetoelectric material, which converts magnetic fields to electricity, in rats with completely severed nerves. They said that the stimulation was done remotely, and, in their testing, it was able to stimulate injured peripheral nerves in the rodents.
“Magnetoelectric materials were ideal candidates for use in neurostimulation. They respond to magnetic fields, which easily penetrate the body, and convert them into electric fields ⎯ a language our nervous system already uses to relay information,” said Joshua Chen, lead author of the study.
While magnetoelectric materials have for long been seen as having potential to treat various neurological conditions, researchers have struggled to get neurons to respond to the frequency of electric signals generated by them. The new material developed resolves this issue with faster electric signal generation.
“The material’s qualities and performance could have a profound impact on neurostimulation treatments, making way for significantly less invasive procedures,” said Dr Jacob Robinson, professor of Department of Electrical and Computer engineering and Bioengineering, Rice University, Texas, USA in a statement.
The researchers added that they envision a future in which an injection of the small amount of this magnetoelectric material in the target site will be sufficient to stimulate the nervous tissue.
Development of the material
The magnetoelectric material used in this study is composed of piezoelectric layer of lead zirconium titanate, present between two layers of metallic glass alloy (Metglas). This alloy can be magnetized and demagnetized very rapidly.
This metallic glass alloy vibrates upon application of magnetic field, explains Dr Gauri Bhave, a researcher at Rice University’s Department of Electrical and Computer Engineering.
“This vibration means it is basically changing its shape. The piezoelectric material is something that, when it changes its shape, creates electricity. So, when those two are combined, you get the conversion in which the magnetic field applied from outside of the body turns into an electric field,” Dr Bhave said in a statement.
One of the issue the research team faced was that electric signals produced by magnetoelectric material are too fast and uniform to be detected by the neurons. To solve this, they modified their material to generate a non-uniform signal which neurons respond to.
Proof of concept
To test the application of this material in the real world, they used it to stimulate the peripheral nerves in the rats. “In completely severed peripheral nerve, we created an electrical bridge where we could sense a nerve signal on one end and use that signal to actuate our magnetoelectric material present on other end of nerve gap. This material now stimulates the other end of the severed nerve.,” said Chen.
He added that the material bridges the nerve gap with a delay of only a few milliseconds thereby restoring its function. This could have potential in neural rehabilitation and for making prosthetics that wearers can control much better than existing systems on the market.
While the proof of concept was successful, the researchers said they are looking to do more animal studies to understand recovery and long-term implantation.
“We made a material with properties non-existent in nature that let us control neurons with magnets! We’d love to see what other kinds of magnetoelectric metamaterials we can make and how it might enable miniature, remote-controlled bioelectronics,” says Dr Chen.