MEMS interdigitated electrode pattern optimization for a unimorph piezoelectric beam

Abstract

This paper presents optimization of interdigitated (d 33 ) piezoelectric MEMS unimorph cantilever beams for harvesting vibration energy or for tuning resonators. The analysis of the poling behavior of the piezoelectric material is the key feature. While it is common that simplified models of interdigitated piezoelectric devices assume some uniform and well-defined poling pattern, the finite element modeling used in this work shows that not to be the case. A percent poling factor is developed to investigate the real losses associated with non-uniform poling. A parametric study in terms of electrode patterns, piezoelectric layer dimensions, and electrode dimensions is carried out to examine their effect on the percent poling factor. Design guidelines are provided to help ensure that such piezoelectric MEMS devices are developed to obtain optimum energy harvesting or tuning performance.

Electrospun Piezoelectric Polymer Nanofiber Layers for Enabling in Situ Measurement in High-Performance Composite Laminates

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Piezoelectric Energy Harvesting Solutions

“…Several research papers were published, attempting to analyze and unravel the problem of inefficient polarization [ 58 – 60 ]. In particular, Knight and colleagues [ 60 ] came up with finite element analysis resulting in a 0.8 optimal ratio between the width of each electrode fingers and the thickness of piezoelectric material, while the ratio between width of the cantilever beam and the finger spacing should be as large as possible. d 33 and d 31 unimorph configurations were also compared in terms of charge generated, by introducing a parameter that accounts for the percentage of the 3-direction polarized material (% d 33 ).…”

Constitutive Equations of Piezoelectric Layered Beams With Interdigitated Electrodes

“…In Section III, the analysis of the second derivative (25) and the capacitance (33) assumes that the electric field has uniform distribution. However, in reality, the field is distributed inhomogeneously [31] as shown in Fig.5. Hence, the parallelplate capacitance model is poorly justified.…”