Researchers from Stanford University have developed a new method to transmit magnetic fields below the skin level to power medical implants. The method, midfield wireless powering, uses electromagnetic induction through biological tissues to power devices without exponential decay.
Current wireless systems use a wire coil to generate a magnetic field to power a nearby device, but are limited because the generated field decays exponentially the farther the device is from the wire coil. To solve this issue, the researchers developed a flat plate with a specially designed four-line pattern of conductive material that produces a magnetic field that can transmit through biological tissue without decay. The researchers tested their method using a rice-sized pacemaker implanted in a rabbit and found the system produced enough energy for a low-power medical device while limiting exposure to radiation.