This paper presents a system integration of micro-piezoelectric energy harvester (MPEH) system based on MPEHs fabricated with an aero-deposited PZT technique, including both the device and the interface circuit design. An in depth look at the deposition method known as aerosol deposition is analyzed. Secondly, various structural designs throughout the years will be introduced and discussed. Thirdly, the non-linear synchronized switching technique interfacing circuit was designed to boost the harvested power in comparison to standard rectifying circuits. The boosting effect in comparison to theoretical expectations will also be presented. The power dissipation effects of self-powered SSHI under low current has also been discussed. Experimental results show that the device based on silicon substrate showed a maximum output power of 21 μW with the output voltage of 2.2 Vrms, excited at 215 Hz under a 1.5 g vibrating source. In comparison, the device based on stainless steel substrate, driven under the same acceleration, had a maximum output power of 34 μW with 1.8 Vrms at the resonant frequency of 202 Hz. The power densities were 4.7 μW mm-2 and 7.6 μW mm-2 for the silicon substrate and the stainless steel substrate based devices, each. The cantilever structured MPEG was later improved to the power output of 200.28 μW. To further improve the output characteristic, the device was tested under vacuumed circumstance, which then gave the output power of 241.60μW, with a 6.02 Vrms under 1.5 g, 104.4Hz. The power boosting circuit gave a power gain of 2.03 times, as the overall system outputs 91.4 μW using the self-powered nonlinear technique under 0.75 g with a similar device. The overall system, using only the standard rectifying circuit was able to light a low consumption red- colored SMD-0805 packaged LED in a duty ratio of approximately 25%.
In this paper, a micro piezoelectric energy harvester based on stainless steel substrate with dual oscillators is presented. The first mirco-dual oscillator design (Figure 6(a)) showed intense stress concentration at the corner of beam, which induced device failure on 0.5g. Therefore, an improved design with better durability by broadening the root of the beam is proposed, fabricated and verified. As we wished to keep the characteristic of low resonance frequencies, the improved device can scavenge energy at a resonance frequency of approximately 40.2Hz. In order to obtain a better output, the device was in d31 mode, and fabricated on stainless-steel substrate. The stainless steel substrate provides superior robustness allowing the micro device to withstand harsher environments. A series of simulation and test is presented, and the performance of the device is demonstrated. The maximum output power of 0.25 g was 2.4μW with the resonance frequency of the device 40.2Hz.