An experimental study on a piezoelectric vibration energy harvester for self-powered cardiac pacemakers

Abstract

Background: Over the past half-century, cardiac pacing technology has been reported. In this study, we designed, prepared, and tested the performance of a self-energized cardiac pacemaker driven by piezoelectric vibration energy collection technology, which converts the kinetic energy of the heart into electrical energy. A record in vivo output current of 54 nA was obtained in an adult rat by the implanted piezoelectric transducer.

Methods: First, the kinetic energy of the heart was collected by an implanted piezoelectric energy collector and supplied to the cardiac pacemaker. Then, the heart was pierced from the outside, and the cardiac tissue was stimulated by the pacing electrode, and self-powered pacing.

Results: The average voltage and average current of the piezoelectric vibration energy harvester in vitro were 3.5 mV and 60 nA, respectively. After implantation of the device into rats, the average voltage and current were measured immediately and reached 3.2 mV and 54 nA, respectively. The average voltage and average current reached 3.0 mV and 48 nA after 1 week, and 2.1 mV and 31 nA after 12 weeks. The electrical performance of the self-powered pacemaker in this study is based on piezoelectric energy collection technology. The implanted piezoelectric vibration energy collector drives the pacemaker to generate electrical pulses, which directly stimulates the myocardial tissue through the epicardium to achieve the pacing effect.

Conclusions: These results evidence the feasibility of the in-situ epicardial pacing strategy. This research will promote the design and development of self-powered cardiac pacemakers.

Keywords: Self-powered; cardiac pacemaker; electrical properties; piezoelectric vibration energy harvesters.

Figure 1

Design and dimensional annotation of the flexible piezoelectric energy harvester.

Figure 2

Finite element analysis of the piezoelectric energy harvester unit with and without a metal layer. (A) Results of finite element analysis for stress distribution and the corresponding output voltage of the piezoelectric energy harvester unit without a beryllium-copper layer. (B) Results of finite element analysis for stress distribution and the corresponding output voltage of the piezoelectric energy harvester unit with a beryllium-copper layer under the same vertex deformation of 1.54 mm.

Figure 3

Fabrication process of the piezoelectric energy harvester. (A) Fabrication process of the piezoelectric component. The (B) assembly and (C) encapsulation of the piezoelectric energy harvester.

Figure 4

Analysis of the in vitro output performance of the piezoelectric energy harvester. The electrical properties of the piezoelectric energy harvester were measured with the thumb pressed against the side of the index finger: (A) current (nA): 60, and (B) voltage (mV): 3.5.

Figure 5

The process of implanting the piezoelectric vibrator near the cardiac apex. (A) The piezoelectric vibrator for rats; (B) the piezoelectric vibrator prototype compared with an index finger; (C) the piezoelectric vibrator with wire; (D) chest incisions; (E) size comparison between exposed rat hearts and a coin; (F) after implantation of the piezoelectric vibrator.

Figure 6

Time series data of the output current plotted for different voltage sweep frequencies after implantation of the piezoelectric vibrator.

Figure 7

Heart rate of the rats before and after implantation of the piezoelectric vibrator. (A) Heart rate of the rats before device implantation: 190 beats/min; (B) heart rate of the after device implantation: 188 beats/min.

Figure 8

Schematic illustration of the circuits of the piezoelectric vibrator.