Piezoelectric cantilever generates power for heart implant: Page 2 of 3

April 25, 2019 //By Bill Schweber
piezoelectric energy harvesting
Researchers have developed a piezoelectric energy harvesting transducer for medical implants, such as pacemakers, using the normal motion of blood vessels.

Fig. 1: Shown is the concept of piezoelectric
thin-film energy harvester for an implantable
cardioverter defibrillator and a flexible porous
PVDF-TrFE dual-cantilever energy harvester
on the AICD lead (A). Image from video analysis
of a chronically implanted pacemaker lead from
a dog (B). A dual-cantilever energy harvester within
a soft tube on the pacemaker AICD lead (C).
(Source: Thayer School of Engineering at
Dartmouth College).

To build the harvester transducer, the researchers used a combination of thin-film energy-conversion materials with a minimally invasive mechanical approach in a modified pacemaker design. They harnessed the kinetic energy of the lead wire that’s attached to a beating heart, and then converted it into electricity to continually charge the batteries – see figure 1. The power-generating material, a specialized polymer piezoelectric film called polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE), is designed with porous structures and then built into either an array of small beams or a flexible cantilever.

The team created a dual-cantilever peizoelectric structure that wraps around the pacemaker’s lead, with the structure’s two free ends available for connection and subsequent energy collection – see figure 2.


Fig. 2: Illustrated are a schematic of the porous
piezoelectric-energy harvester (A); flexible porous
PVDF-TrFE thin film (B); and scanning electron microscope
image of the cross-section of the thin film (C). (Source:
Thayer School of Engineering at Dartmouth College).

The maximum output was 0.5V at 43nA at 1Hz, a little over 20nW. By adding a small proof mass of 31.6 mg on the tip of the dual-cantilever tip, the power output increased by a little over 80% since the added mass enabled a larger bending curvature, resulting in higher electrical output from the harvester.


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