Implants Powered By Heart

Battery lifetime is one of the challenges for designing implantable biomedical devices. But by letting the body act as its own power supply, John A. Rogers of the University of Illinois, Urbana-Champaign, and coworkers have addressed that challenge: They have created flexible devices that continuously convert the mechanical motions of the heart, lungs, and diaphragm into electrical energy (Proc. Natl. Acad. Sci. USA 2014, DOI: 10.1073/pnas.1317233111). When the devices bend, the mechanical displacement is converted into electrical energy via the piezoelectric effect. Each of the team’s energy-harvesting modules consists of 12 groups of 10 lead zirconate titanate ribbons sandwiched between electrodes. To test the devices, the researchers integrate one of the modules into a circuit with a rechargeable battery, affix the device to an animal heart, and measure the voltage output. Michael C. McAlpine, whose group at Princeton University has previously developed methods for printing piezoelectric devices in flexible materials, says Rogers and coworkers “take those concepts to the next level by fully integrating this approach into large device arrays that can be implemented on a variety of organs for harvesting biomechanical motion to power an implantable device such as a pacemaker.”