Screen-Printed Ceramic Based MEMS Piezoelectric Cantilever for Harvesting Energy

Abstract

Screen-printing technology provides a convenient method in fabricating thick-film conductive circuits and devices in the past few decades. Conventionally, piezoelectric thick-film is printed on alumina substrate with high mechanical Q-factor and resonates at higher frequency outside the range of ambient vibration. As the piezoelectric charge generation is proportional to the mechanical stress on the material, therefore the substrate can be removed in order to lower the natural frequency of the structure. In this paper, a series of piezoelectric ceramic cantilevers were fabricated in the form of free-standing cantilever. An additional layer of ceramic was also introduced to the upper and lower electrode to prevent delamination. The issue of zero resultant stress for the sandwiched piezoelectric cantilever was solved by repeating the electrode-PZT-electrode layer to form a multilayer structure. It was found from the experiment that an electrical output power of 32 μW was generated when it operates at its resonant frequency at 403 Hz.

The Role of Sacrificial and/or Protective Layers to Improve the Sintering of Electroactive Ceramics: Application to Piezoelectric PZT-Printed Thick Films for MEMS

“…This gain in performance was associated with a better quality of interface between the AgPd electrode and PZT, because of the presence of the MgTiO3 additive in the electrode helping to adjust the CTE of the electrode [24]. Photographs and SEM images of PZT free-standing thick films components developed by Kok et al, Santawitee et al, and Grall et al [24,36,49] are shown in Figure 6. These images reveal curvatures and porosity-related oissues that have to be overcome during the shaping and conventional sintering (T < 900 °C) of piezoelectric screen-printed multilayers.…”

“…In the carbon approach, the sacrificial layers are burnt during the sintering under air. Kok et al [9,49] reported a piezoelectric energy harvester based on free-standing PZT cantilevers (9 mm wide, 4.5 to 18 mm long, ≈90 µ m thick) for which a graphite sacrificial layer is used, as in LTCC ceramic MEMS [19l]. Here, because of the important thermal expansion coefficient's mismatch between the AgPd electrodes and the sandwiched PZT, additional thin uniform layers of non-active PZT (unpoled) (≈10 µ m) were hence printed on both sides of the cantilever to prevent delamination and warpage (Figure 6a,b).…”

“…Comparison of the properties of PZT films used in thick-film ceramic MEMS[9,24,25,30,31,40,42,46,[49][50][51].…”