One step densification of printed multilayers by SPS: Towards new piezoelectric energy harvester MEMS

Abstract

Autonomous electronic devices and increasing use of wireless sensors, which are more and more performant, are facing the problem of energy autonomy. This autonomy can be managed either with a preliminary storage and/or energy harvesting. Hence, since 20 years, the energy harvesting research field is intensive focusing on the development of new materials and their integration in micro/nanogenerators. In this research area, Micro-Electromechanical System (MEMS) energy harvesters (EH) using piezoelectric materials is one of the most promising option because of the availability of mechanical vibrations and of the simply electromechanical conversion. Piezoelectric ceramics, commonly used in various applications, are attractive for EH, and among them, Pb(Zr 1x Ti x)O 3 (PZT), despite its lead content, remains mostly studied because of its outstanding properties. For its ceramic process, the main objectives are improved densification, a cost and energy effective processing and integration in microgenerators. In this context, SPS sintering of electroded printed PZT piezoelectric layers supported on stainless steel substrate (SS) is highly challenging. In this chapter, after a section devoted to piezoelectric EH, the device made of screen-printed PZT layers on SS substrate is presented. Then, the authors focus on the strategy to achieve in one step a cantilever transducer where the electroded printed PZT and the SS substrate are co-sintered by SPS. As a first part of this ambitious objective, microstructural, dielectric and piezoelectric properties of the PZT pellet densified by SPS are presented and compared to PZT printed layers conventionally sintered.

Integration of PZT Thick Films on Additively Manufactured Substrates for Vibrational Energy Harvesting Applications

“…The gold paste used for the electrodes is a commercially available paste provided by ElectroScience Laboratory (newly Ferro https://www.ferro.com/). It is named ESL8836 and it contains different oxides such as SiO2, Al2O3, CdO, PbO that will help for the chemical bond on the stainless substrate [4]. In the case of unsatisfactory interfaces, a layer of ESL 4924 dielectric ink is proposed.…”

“…The micro ceramics were composed of a PZT layer between two gold electrodes Au/PZT/Au [3]. Also for energy harvesting application, with a ceramic thick film of PZT integrated on a laser micromachined stainless steel (SS) resonant beam (10x2x0.05mm 3 ), interesting results were already obtained with a power of about 1μW measured at an acceleration of 0.5g and a frequency of 130Hz [2] [4]. For complex passive substrate in energy harvesting, different manufacturing options can be found in the literature such as laser micromachining as in this study, and water jetting [5].…”

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

“…In the second part of this paper, original approaches targeting bulk ceramic and thick-film ceramic MEMS produced using advanced sintering techniques associated with protective layers are introduced. While sacrificial materials have already been shown to act as a pore forming agent or as a thermal or diffusion barrier for bulk ceramics [15,16], carbonate based protective materials have recently appeared to efficiently prevent PZT from chemical reduction during spark plasma sintering (SPS) [17]. Chemistry, microstructure, and stress/strain effects are again issues strongly linked to sintering and whose control has an impact on the performance of the electroactive multilayer.…”