Key features in the development of unimorph stainless steel cantilever with screen‐printed PZT dedicated to energy harvesting applications

Abstract

The design and processing of vibrational energy harvester based on screen-printed piezoelectric lead zirconate titanate (Pb(ZrxTi1-x)O3 (PZT)) are described here. Two different structures, a simple cantilever and a complex zigzag geometry made of PZT layer sandwiched between gold electrodes and supported on a metallic stainless steel substrate have been successfully fabricated by screen printing thick film technique. Compared to bulk PZT ceramics, the main limiting features at different scales are porosity, interfaces, and bending issues. The microstructural analysis of the interfaces in the cantilever has highlighted the formation of an interface between the substrate and the bottom electrode which ensures cohesion of the structure but can limit its dynamic. Bending has shown to be dependent on the thickness of the active piezoelectric layer. Dielectric and electromechanical characterizations performed on multilayers, bulk ceramics, and free-standing screen-printed disks are compared and discussed on the basis of interface issues.

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

“…The addition of only 3% in weight of LBCu was shown to be efficient for PZT sintering, both the melting of the binary system Bi2O3-Li2CO3 and the presence of CuO play a significant role in lowering the sintering temperature [47,48]. For bounded layers, a diffusion/adhesion layer is formed between the substrate and the Au layer, as already observed in [40,42]. In the case of the free-standing PZT layer, only a slight diffusion of Sr into the Au layer is observed, showing the efficiency of the Au electrode as a barrier to limit PZT/SrCO3 crossdiffusion (Figure 5c).…”

“…In this section, since some studies have already reported PZT screen-printing on silicon [37,38] followed by its release, only thick films printed on ceramic substrates and partially or completely dissociated from the substrate are considered. Bounded screen-printed PZT layers can be found in the literature [39][40][41][42], and more recently lead-free piezoelectric layers [43]; however, to the best of our knowledge, only screen-printed PZT thick films have been released from the substrate. When processing screen-printed PZT thick films using a conventional process, the PZT layers contain a residual porosity.…”

“…The good results obtained sintering thick films using a protective layer on one hand and bulk ceramics by SPS (Section 3.2) on the other lead to the ultimate stage of obtaining a complete thick-film-based MEMS by SPS in a single step. To do so, as in [42], the stack of layers (Au/PZT/Au) is first screen-printed on a stainless steel substrate, and the assembly is then sintered by SPS in one step.…”

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

Analysis of Energy Harvesting Enhancement in Piezoelectric Unimorph Cantilevers

“…In most cases, the structure of an energy scavenger is a cantilever beam with a piezoelectric layer [16,17]. Because of their relatively low resonance frequency and relatively high strain average per specific loading, cantilever beams are considered important [18].…”