Experimental investigation of fan-folded piezoelectric energy harvesters for powering pacemakers

Abstract

This paper studies the fabrication and testing of a magnet free piezoelectric energy harvester (EH) for powering biomedical devices and sensors inside the body. The design for the EH is a fan-folded structure consisting of bimorph piezoelectric beams folding on top of each other. An actual size experimental prototype is fabricated to verify the developed analytical models. The model is verified by matching the analytical results of the tip acceleration frequency response functions (FRF) and voltage FRF with the experimental results. The generated electricity is measured when the EH is excited by the heartbeat. A closed loop shaker system is utilized to reproduce the heartbeat vibrations. Achieving low fundamental natural frequency is a key factor to generate sufficient energy for pacemakers using heartbeat vibrations. It is shown that the natural frequency of the small-scale device is less than 20 Hz due to its unique fan-folded design. The experimental results show that the small-scale EH generates sufficient power for state of the art pacemakers. The 1 cm3 EH with18.4 gr tip mass generates more than16 μW of power from a normal heartbeat waveform. The robustness of the device to the heart rate is also studied by measuring the relation between the power output and the heart rate.

High-Performance Piezoelectric Energy Harvesters and Their Applications

“…Within such a small space and restricted weight, linear PEHs will have resonant frequencies much higher than that of the heartbeat excitation. To lower the resonant frequency, in 2017 Ansari and Karami 211 proposed a fan-folded structure that consists of bimorph beams folding on top of each other. A 1-cm 3 prototype was constructed with three bimorph beams (PZT-5A layer: 20 3 5 3 0.19 mm 3 ) and a tip mass of 18.4 g. The prototype was excited by a normal heartbeat waveform from a feedback controlled shaker, and generated 16 mW power on average.…”

A Review on Mechanisms for Piezoelectric-Based Energy Harvesters

“…From the relaxation and expansion motion of the heart, the PZT nanogenerator can generate electrical energy and it can be stored inside a specifically designed battery in the pacemaker [226]; 3 mV of voltage could be generated from this mechanism for an adult. Ansari and Karami performed experimentation on PEH for pacemakers; a 1 cm 3 PEH could generate 16 µW of power from a normal human heart beat with a fan-folded structure consisting of a bimorph piezoelectric beam [227]. …”

A miniaturized endocardial electromagnetic energy harvester for leadless cardiac pacemakers

“…These mechanisms were developed to either harvest energy from the heart motion, pressure variations in the heart or blood stream. Piezo-electric mechanisms can be utilized to transform a small portion of the cardiac motion or the blood pressure variations into electrical energy [4][5][6][7][8][9]. They rely on a beam structure with a proof mass, which is bent in the presence of heart motion.…”