Prototype pacemaker turns heartbeat energy into battery power
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Key takeaways:
- Prototype piezoelectric pacemakers successfully turned heartbeat energy into battery power.
- The device was able to provide approximately 10% of the energy needed to power a leadless pacemaker.
PHILADELPHIA — Researchers at the University of Washington have developed prototype piezoelectric devices to convert energy from a heartbeat into electricity that could recharge the battery of a leadless pacemaker.
The prototypes were able to generate approximately 10% of the electricity needed to power a leadless pacemaker, according to data presented at the American Heart Association Scientific Sessions.
Image: Adobe Stock
Piezoelectric materials produce voltage when bent, stretched or exposed to nearby vibrations. These materials include specific ceramics, polymers, nanomaterials, crystals and composites, according to data published in Small Structures.
Experimental confirmation of the relationship between mechanical stress of piezoelectric materials and electrical potential was done by Jacques Curie and Pierre Curie in 1880.
Today, devices that utilize piezoelectric technology include cellphones, diesel fuel injectors, ultrasonic transducers, acoustic guitar pickups, printers and musical greeting cards.
In a proof-of-principle study, Babak Nazer, MD, associate professor of medicine and director of multidisciplinary ventricular arrhythmia program, and colleagues Abigail Gilstrap, MS, Jedi Biswas-Diener, MS, and Kevin Tang, MS, with the translational electrophysiology laboratory at the University of Washington School of Medicine, evaluated whether piezoelectric materials could be used to extend the battery life of leadless pacemakers by harvesting the energy of a simulated beating heart.
“My laboratory and collaborators and I typically work on CV applications of ultrasound, including ‘therapeutic ultrasound’ in which we typically apply voltage into ultrasound transducers, made of a class of materials called piezoelectrics, in order to get them to emit pressure — sound and ultrasound are ultimately just pressure oscillations,” Nazer told Healio. “So I was inspired to use similar piezoelectric materials to do the opposite: transfer the natural pressure oscillations of the cardiac chamber in which the leadless pacemaker typically lives — right ventricle — into electrical energy to recharge and prolong the battery’s life.”
Using biocompatible piezoelectric materials, Nazer and colleagues constructed three prototypes using polyvinylidene fluoride for the pacemaker housing and a polyetherimide insulator wrapped around an aluminum rod.
After being sealed with epoxy, the dimensions of the piezoelectric-enhanced leadless pacemakers had a radius of 9.5 mm and a length of 26 mm, comparable to the of other contemporary pacemakers (Micra, Medtronic), according to the presentation.
The prototypes were placed within a pulsatile cardiac pressure simulator and subjected to right ventricular systolic and diastolic pressures at 1 Hz, with a pressure transducer and an oscilloscope recording the pressure and prototype’s voltage output, according to the presentation.
The researchers identified 39 megaohm as the optimal resistance for energy harvesting.
Under an assumed pacing output of 1 V at 0.24 millisecond and an impedance of 500 ohm, a pacemaker required a total output 480 nanowatt.
At oscillating right ventricular pressures of 40 mm Hg and 0 mm Hg, Nazer reported the prototype generated 4 V, corresponding to 52.5 nanowatt, or 10.9% of the energy required to power a leadless pacemaker.
Nazer said there is a path to harvest more energy efficiently; however, engineering constraints surrounding the small but significant difference in right ventricular oscillating pressures of 25 mm Hg and 40 mm Hg and diastolic pressures of 0 mm Hg to 10 mm Hg present a challenge.
“Main takeaway is that it is feasible to at least marginally recharge and prolong battery life of a leadless pacemaker using piezoelectrics without changing its size or form factor,” Nazer told Healio. “We need to improve upon our 10% energy harvesting efficiency to be able to prolong battery life more robustly for it to be commercially viable and demonstrate that our device can be safely implanted for a long period of time.
“We have recruited our next group of master’s degree students into our laboratory in partnership with University of Washington’s Master’s in Applied Bioengineering program,” he said. “My collaborator in the University of Washington department of mechanical engineering, Mohammad Malakooti, PhD, MS, and I have applied for several grants to help further this work, which will include improving on materials selection, design and fabrication methods to improve energy harvesting efficiency, and long-term in vivo studies to confirm long-term safety and durability.”
References:
- Breeze P. Marine power generation technologies. Power Generation Technologies (Second Edition) [Internet]: Newnes Publishing; 2014:287-311.
- Chandra Sekhar B, et al. Piezoelectricity and its applications. In: Sahu DR, ed. Multifunctional Ferroelectric Materials [Internet]; IntechOpen Publishing; 2021.
- Experimental pacemaker converts heartbeat energy to recharge battery. https://newsroom.heart.org/news/experimental-pacemaker-converts-heartbeat-energy-to-recharge-battery. Published Nov. 6, 2023. Accessed Nov. 9, 2023.
- Li T, et al. Small Struct. 2021;doi:10.1002/sstr.202100128.
- Lucibella M. March 1880: The Curie brothers discover piezoelectricity. APS News. https://www.aps.org/publications/apsnews/201403/physicshistory.cfm. Published March 2014. Accessed Nov. 9, 2023.
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Gilstrap A, et al. Innovations in pacing, defibrillation and arrhythmia therapies: Abstract 150. Presented at: American Heart Association Scientific Sessions; Nov. 11-13, 2023; Philadelphia.
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