Researchers at Rice University have developed an implantable neural stimulator that is both wireless and battery-free. The device is powered by an externally applied magnetic field and could be used as part of a system to treat a wide variety of diseases and conditions, including epilepsy, Parkinson’s disease, and chronic pain.
At present, battery powered implants have been clinically approved to provide neural stimulation, which can offer symptomatic relief in diseases such as Parkinson’s and epilepsy. However, batteries have a limited life-span and, once they are depleted, a surgical procedure is required to replace them. Wired implants, on the other hand, are of limited long-term use, as the penetration of wires through the skin poses a serious infection risk.
To address these issues, researchers have been trying to develop wireless and battery-free implants. Now the Rice team has developed an implant that is powered using an externally applied magnetic field. The device avoids the drawbacks of other wireless energy transmission systems, such as radio waves and ultrasound, which can generate harmful amounts of heat or otherwise negatively affect nearby tissue.
The tiny new implant, which is smaller than a grain of rice, is covered with a “magnetoelectric” material that produces an electrical voltage in response to an applied magnetic field. One layer of the material vibrates when a magnetic field is present, and another, a piezoelectric crystal, is stimulated to produce an electric voltage by this vibration. The frequency of the vibrations is too low to affect nearby cells.
So far, the researchers have tested the implants in rodents. When the device was implanted in an area where it would activate a neural reward pathway, the rodents tended to stay in areas of their enclosure where a magnetic field was present that activated the implant.
As no-one had created similar implants before, the researchers had to manufacture most of the components from scratch, and the miniaturization process was also a significant challenge, meaning that the project took over five years.
However, the small size and wireless capabilities of the implants are significant advantages, and mean that they can be implanted nearly anywhere in the body through a minimally invasive procedure.
Via: Rice University