Abstract
This paper reports the design, modeling and fabrication of a novel MEMS device for low-frequency, low-g vibration energy harvesting. The new design is based on bi-stable buckled beam structure. To implement the design at MEMS scale, we further proposed to employ residual stress in micro-fabricated thin films. With an electromechanical lumped model, the multi-layer beam could be designed to achieve bi-stability with desired frequency range and excitation amplitude. A macro-scale prototype has been built and tested to verifies the prediction of the performance enhancement of the bi-stable beam at low frequencies. A MEMS scale prototype has been fabricated and tested to verify the frequency range at low excitation amplitude. The MEMS device shows wide operating frequency range from 50Hz to 150Hz at 0.2g without external proof mass. The same device with external proof mass has lower frequency range (< 10Hz) with boosted deflection amplitude.
Highlights
Energy harvesting at MEMS scale will promisingly advance exciting applications such as large wireless sensor networks, Internet of Things etc. due to its high power generation efficiency and small form factor
This paper reports the design, modeling and fabrication of a novel MEMS device for low-frequency, low-g vibration energy harvesting
To implement the design at MEMS scale, we further proposed to employ residual stress in micro-fabricated thin films
Summary
Energy harvesting at MEMS scale will promisingly advance exciting applications such as large wireless sensor networks, Internet of Things etc. due to its high power generation efficiency and small form factor. The mismatches between the operating conditions of current MEMS energy harvesters and the characteristics of the ambient vibrations have long hindered wide applications of this technology. Our previous MEMS device based on nonlinear resonance has achieved high output power of 45μW and wide bandwidth of >20%, while the operation frequency and vibration amplitude are still high (>1000Hz at 4g) [1]. Bi-stable oscillator based energy harvesters have been investigated for widening the bandwidth in recent years’ work. Reported designs have achieved bi-stability utilizing mechanisms such as magnetic force [2, 3], mechanical compression [4, 5], and pre-shape [6]. Basing on the lumped model we have built, the bi-stable oscillator could be designed to achieve buckling and desired frequency and excitation amplitude range
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