Energy-harvesting electronic surgical implants answer one of the most important questions in medical technology development: how will the device get power? Possibilities for product design and placement in the body expand significantly if you don’t have to allow for battery replacement or wired power connections. We’ve written about energy-harvesting nanotube yarns, body heat as an energy source, and even using bacteria to power biosensors.

Neuroengineers at Rice University recently published a paper in the journal Neuron that describes their research and development work to create a neurostimulator approximately the size of a grain of rice. The device harvests power from magnetic energy. The Rice researchers first demonstrated the capability of harnessing magnetoelectric energy for clinical-grade implants in rodents. The next step was the biggest challenge: to make the same technology work in a small enough form to be implanted in the skull of small animals. Surgeons can implant a rice-grain-size implant “almost anywhere in the body with a minimally invasive procedure,” according got a Rice news release.

The engineers combined two material layers in the tiny magnetoelectric power plant. The first layer is a magnetostrictive foil made of iron, boron, silicon, and carbon. When the foil is within a magnetic field, the molecules vibrate. The second device layer is a piezoelectric crystal that converts the mechanical energy of the vibrating molecules into electrical voltage.

Surgeons currently implant conventional battery-powered neural stimulators to treat epilepsy, Parkinson’s disease, and chronic pain. According to Rice engineers, smaller neural stimulation implants also could be used in treating depression, obsessive-compulsive disorder, chronic pain, and opioid addiction. Patients could receive neurostim treatments by moving into the range of an appropriate magnetic field. The project developers state that the magnetoelectric foil generates electrical power at frequencies that stimulate brain cells without harming them.

As a person who uses two types of neurostimulation to treat chronic pain that require recharging batteries — a TENS machine and a PEMF band – the convenience of tiny implants that could accomplish the same results is highly appealing.