Resonance frequency analysis of MEMS based on piezoelectric microcantilever beam for vibration energy harvesting applications – ABSTRACT

Project Tag: 2209OS

Microfabricated microcantilevers are widely used as a nanomechanical tool for diagnostics, molecular detections and many sensor devices. Its easiness, sensitivity and cost of manufacture make it a key element for many applications. Piezoelectric material covered unimorph microcantilevers would provide energy generation from ambient sources as a result of its freely vibrating body. To generate the maximum amount of energy, the microcantilever structure’s resonance frequency (natural frequency) should have be specifically adjusted for energy sources. However, the resonance frequency is limited by cantilever’s dimensions and materials. In this study, we have represented the effect of microcantilever dimensions on resonance frequency using by finite element method and numerical calculations.

  1. This project is being supported by The Scientific And Technological Research Council of Turkey (TUBITAK) within 2209/A -2013/2 Research Founding Program for undergraduate students.
  2. This project is being accepted by 10th Nanoscience and Nanotechnology Conference as a poster presentation.

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Nowadays energy storage problems have become an important issue in parallel with developing new electronic devices. Besides, growing energy needs are forced to find new alternative energy sources. Thus investigating renewable power harvesting technologies has become incremental. Microcantilevers are one of the basic micromechanical structures. They are fixed at one ends and the other ends can move freely like a diving board. Microcantilevers are widely used for environmental monitoring, medical diagnostics and chemical detection. Its basic shape and minimal manufacturing needs make it one of the important instrument for nano/microdevices. From this aspect piezoelectric material covered multilayered unimorph microcantilever structures also would be able to harvest surround energy using its sensitive vibrating body.
Piezoelectric materials are crystal structures and they can efficiently convert mechanical strain to electrical charge. Also, they can be easily applied for microdevices using microfabrication techniques. Thus microcantilevers would be able to harvest energy from ambient sources.
Energy harvesting is used for capturing minute energy from ambient sources, accumulating them and storing them. With recent technological advancements in wireless technology, energy harvesting is highlighted as an alternative for conventional battery.
As designed as microcantilever-based on energy harvesting devices would have been able to convert a large amount of energy from ambient sources. Therefore cantilever’s natural frequency should be adjusted for an ambient source.
Resonance (natural) frequency could be simply described as maximum magnitude of the vibration frequency of the structure. Moreover, the resonance frequency is basically related to cantilever’s material and dimension parameters. Consciously designed cantilevers will be able to harvest the maximum amount of energy from ambient sources. Hence resonance frequency of double layered unimorph cantilever should have been investigated.
In this study, we have represented and demonstrated the finite element method (FEM) to understand the effect of thickness and length parameters on resonance frequencies of silicon-based on microcantilever beam. A thin layer of Lead Zirconate Titanate (PZT-5H) was integrated on rectangular silicon proof mask cantilever as a piezoelectric material. COMSOL Multiphysics which is a commercial FEM Software was used for analysis. Mode shapes and mode frequencies are obtained. The results are compared with Euler-Bernoulli based on analytical calculation results which are done by MATLAB.

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