A device that harvests energy from heart’s motion could power implantable devices

One of the biggest challenges in the medical field today is how to power implantable devices that are critical to survival for some people with certain conditions. Implantable devices like pacemakers and defibrillators have a finite lifespan, and once implanted that limited lifespan means that the patient is guaranteed another surgery to replace the device in the future. Typically implanted devices last between five and ten years due to their battery life.

There are always risks involved with any surgery, and for the seriously ill people that need these implantable devices, the risks for surgery are often higher than normal. A group of researchers at the Thayer School of Engineering at Dartmouth College in New Hampshire have created a new device that could power implantable electronics like pacemakers and defibrillators in the future. The device is about the size of a dime and combines a thin-film energy conversion material with a minimally invasive mechanical design to create self-charging batteries.

The breakthrough came as the result of a three-year study that was funded by the US National Institutes of Health. The lead researcher on the project was Dartmouth engineering professor John X.J. Zhang; he said that the team was trying to solve the ultimate problem for implantable biomedical devices. That problem is creating a power supply that will allow the implanted device to function for the entire lifespan of the patient without having to perform surgery to replace the battery of the device.

Zhang noted that the device must not impact the function of the body. What the team has devised is a way to modify pacemakers to allow them to harness the kinetic energy of the heart via the lead wire that is attached to the heart. The device can convert the motion of the heart into electricity to continually charge the batteries of the device. Zhang thinks that a self-charging pacemaker is about five years from commercialization.

The device the team created uses a material called PVDF, which is a type of thin polymer piezoelectric film. The material can convert mechanical motion to electricity when designed with a porous structure using either an array of small buckle beams or a flexible cantilever. The device has completed the first round of animal studies with what Zhang calls “great results.” Similar mechanisms could be used to enable data collection for the real-time monitoring of patients.