Heartbeat Energy Harvesting Using the Fan-Folded Piezoelectric Beam Geometry

Abstract

A three dimensional piezoelectric vibration energy harvester is designed to generate electricity from heartbeat vibrations. The device consists of several bimorph piezoelectric beams stacked on top of each other. These horizontal bimorph beams are connected to each other by rigid vertical beams making a fan-folded geometry. One end of the design is clamped and the other end is free. One major problem in micro-scale piezoelectric energy harvesters is their high natural frequency. The same challenge is faced in development of a compact vibration energy harvester for the low frequency heartbeat vibrations. One way to decrease the natural frequency is to increase the length of the bimorph beam. This approach is not usually practical due to size limitations. By utilizing the fan-folded geometry, the natural frequency is decreased while the size constraints are observed. The required size limit of the energy harvester is 1 cm by 1 cm by 1 cm. In this paper, the natural frequencies and mode shapes of fan-folded energy harvesters are analytically derived. The electro-mechanical coupling has been included in the model for the piezoelectric beam. The design criteria for the device are discussed.

Investigating the influence of the viscoelastic material as a heart muscle simulator on the powering leadless pacemaker from heartbeats by using a piezoelectric beam

“…The formulation for the multi-mode power frequency response function with any input was done by Ansari and Karami. 31 By using this formulation and considering viscoelastic parameters, power generation for our configuration with any kind of base excitation in the frequency domain can be obtained as equation (43). Where, a ( ω ) is the base acceleration signal in the frequency domain.…”

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

“…The expression for the multi-mode power frequency response function is [31]: $$\frac{p(\omega )}{{a_b}^2(\omega )}=\frac{1}{2R}{\left(\frac{{\sum }_{j=1}^{\infty }\frac{j\omega {\chi }_j{\gamma }_j}{{\omega }_{nj}^2+2\zeta {\omega }_{nj}j\omega -{\omega }^2}}{\frac{1}{R}+j\omega C_{\mathrm{normalp}}+{\sum }_{j=1}^{\infty }\frac{j\omega {{\chi }_j}^2}{{\omega }_{nj}^2+2\zeta {\omega }_{nj}j\omega -{\omega }^2}}\right)}^2,$$ where p is the output power, a b is the base acceleration, R is the load resistor, C p is the overall internal capacitance for the piezoelectric layers, ω nj is the natural frequency of the j th mode, ζ is the damping, χ j and γ j are the coupling coefficient and the base acceleration coefficient. Please refer to the [18] to read more about the details on the governing equations, finding the mode shapes, and why the fan-folded design is chosen as the configuration of the energy harvester.…”

“…The modeling of a fan-folded configuration was studied in [18]. The expression for the multi-mode power frequency response function is [31]:…”

Power Optimization Configuration for Piezoelectric Cantilever Arrays

“…The research stretches from the properties of piezoelectric materials, manufacturing, up to measurement techniques and practical applications; while in application wise, it is extended from sensor, actuator, transducer and now micro-power generator [1][2][3]. Recent researches had shown increasing interest in looking into methods to improve the performance of piezoelectric micro-power generator.…”