Engineers from Dartmouth College have created a dime-sized device that could allow implanted biomedical devices to be charged indefinitely using the natural kinetic (motion) energy of the heart. In a study conducted over the last three years and published in the journal Advanced Materials Technologies in January this year, an implant with piezoelectric materials was combined with a pacemaker to convert heartbeats into electricity. Considering the 5-10 year replacement requirement for the average battery-powered implantable biomedical device, this invention could soon mean a significant reduction in invasive and risky surgeries.
Piezoelectricity is mechanical stress converted into electricity. Pressure, sound waves, and other vibrations coming into contact with piezoelectric materials cause the materials’ atoms to shift, creating positive and negative charges. In the Dartmouth invention, moving heart tissue squeezes a flexible container with piezoelectric material inside, creating charges which are sent through the pacemaker’s lead wire back to its battery. This continuous charging cycle, in theory, would enable any biomedical implant where motion was a component of the device’s location to last for the lifetime of a patient.
The project’s engineers have two more years of National Institutes of Health (NIH) funding to complete a pre-clinical and regulatory approval process, and a commercially available version is expected to be about five years away. The potential for the device has already been recognized by significant players in the biotech industry. Andrew Closson, one of the study’s authors, explained in a news article about the device, “There is already a lot of expressed interest from the major medical technology companies…[and we are]…moving forward with the entrepreneurial phase of this effort.”
The idea of harvesting heart energy is not a new one. A team of researchers from the University of Illinois demonstrated a proof-of-concept in 2014 using a flexible, piezoelectric patch on anesthetized sheep. After stitching multiple patches in an optimal orientation on the sheep’s heart, the voltage produced was found to be sufficient to power a standard pacemaker. Other devices that could be powered by this type of technology include cochlear implants and implantable defibrillators.
Implantable electronic medical devices are frequently seeing improvements in the field of biotechnology and thus directly relevant to the Dartmouth engineers’ invention. In November of last year, a study was published demonstrating the effectiveness of a spinal implant used to amplify brain signals. After epidural electrical stimulation was delivered to the spinal cords of three paralyzed participants, all were able to regain motion in their lower limbs. Piezoelectric functionality in a device like this one would be a natural inclusion.