Prof. Paul Herijgers
The field of energy harvesting from the body is hotting up, with pacemakers first in line for recharging. We first reported on body-powered pacemakers last year, when Andreas Haeberlin from the University of Bern explained how his team is powering pacemakers from energy harvested from sunlight, heartbeats and blood flow (1, 2). Since then, the market emergence of leadless pacemakers that sit directly in the heart have added new motivation to the field of energy harvesting, to liberate pacemakers from batteries. We catch up with Dr. Haeberlin to discuss his team’s progress and we introduce the EU funded Manpower consortium, who are harvesting energy from the vibrational movement of the body.
Solar panels implanted under the skin, a clockwork-type mechanism that sits on the heart and is wound up by heartbeats, and mini-turbines in blood vessels harvesting energy from blood flow. It sounds like science fiction but Haeberlin’s team have made sound progress in all projects since we last wrote about his team’s research. The team are busy writing up the results for publication so Haeberlin is coy about discussing results. “The next step is to develop a prototype for implantation in humans,” says Haeberlin.
The advent of leadless pacemakers has given new urgency to the team’s work, according to Haeberlin. “The field of cardiac rhythm devices is undergoing a small revolution with leadless pacemakers,” he says. These pill-sized pacemakers sit directly in the heart, eliminating the need for battery packs that are traditionally implanted at the collarbone, and connected to the heart by leads “We are trying to build a bridge between these two research areas to ultimately build a leadless battery less pacemaker. This is the exciting challenge we’re facing right now.”
Haeberlin’s team is not the only group working on eliminating both leads and batteries from pacemakers. The EU funded MANpower consortium, coordinated by the Tyndall Institute, Ireland, is using specially developed piezoelectric materials that transform mechanical movement energy into electrical energy (1). Prof. Paul Herijgers is a cardiac surgeon and clinical researcher at the University of Leuven in Belgium, and one of nine partners in the consortium. “Humans walk around a lot,” explains Herijgers, “and the movement means acceleration and deceleration, which generate power. If you can harvest this power and transform it into electrical energy you can charge your battery.” Special piezoelectric materials are used to capture energy from movement and the team have optimised their harvester to capture low frequency movements.
HUMANS WALK AROUND A LOT AND THE MOVEMENT MEANS ACCELERATION AND DECELERATION, WHICH GENERATE POWER. IF YOU CAN HARVEST THIS POWER AND TRANSFORM IT INTO ELECTRICAL ENERGY YOU CAN CHARGE YOUR BATTERY
The consortium have managed to pack the piezoelectric harvester and the pacemaker into one small capsule, which will be implanted directly into the heart. Part of the challenge is figuring out which movements generate power, and that’s where Herijgers and his team come into play. “In Leuven we have a large animal experimentation facility with acute and chronic experimental models,“ explain Herijgers, “so we take clinical scenarios and test them in experimental conditions.” These experiments are performed in sheep since they have similarly sized hearts to humans and will shed light on the reliability of energy generation. “For a pacemaker you need reliability, you have to know will this work in each clinical condition,” says Herijgers, “there should be sufficient energy when the patient is sleeping, when the heart is failing, when the heart beat is slow, or if the patient is in a car accident, for example”.
Funding for the MANpower project finishes at the end of 2016, and the team is on track to deliver promising results, says Herijgers. Future plans include a translation into clinical testing of a prototype in humans in three to four years, but “this depends on additional testing”, he says, “Collaboration between the nine project partners has been crucial to the project’s success, but not without its challenges. Engineers sometimes struggle with the variability inherent in clinical and biological research”, says Herijgers, “explaining that the key to effective communication is correctly framing the problem”. The engineers and physicists are very clever people with problem-solving minds. This is very valuable if you can clearly state what the problem is,” he says, “you have to be broadminded and listen to people who are working in completely different fields. Usually you find some connections with a bit of creative thinking, seeing where the needs are, pooling experience.”
Both Haberlin and Herijgers agree that the pacemakers of the future are leadless, and both teams believe that recharging pacemakers using energy harvesting from the body is the best way to avoid cluttering the heart with electronic waste. Is this the beginning of the end for batteries?