Efficient Piezoelectric Energy Harvesters Utilizing (001) Textured Bimorph PZT Films on Flexible Metal Foils

Abstract

wileyonlinelibrary.comdensity and reduced resonance frequency have been explored, including advanced mechanical design, [ 5 ] maximizing intrinsic piezoelectric materials properties, [ 6,7 ] and using a fl exible passive layer. [ 8,9 ] In the last decade, microelectromechanical (MEMS) energy harvesters based on piezoelectric materials such as AlN and Pb(Zr,Ti)O 3 (PZT) have been studied for use in harvesting energy from small amplitude, mechanical vibration. [10][11][12] Improving the piezoelectric material for a piezoelectric energy harvester (PEH) can be pursued via an energy harvesting fi gure of merit (FoM). The maximum extractable electric power generated at the resonance frequency of a e 31,f mode cantilever structure is [ 13,14 ] where m is mass, ω is angular frequency, Y is Young's modulus, ε 0 is vacuum permittivity, and a is the acceleration. The in-plane piezoelectric coeffi cient ( e 31,f ) and the relative permittivity ( ε r ) control the energy harvesting FoM = ( e 31,f ) 2 / ε r when the mechanical energy is stored in the passive layer. The orientation of the PZT grains strongly infl uences the fi gure of merit. [ 7,15 ] In particular, strongly (001) oriented PZT fi lms, which have a signifi cant fraction of the ferroelectric polarization directed out-of-plane, have large FoM. [ 16 ] From the standpoint of improving the toughness and reliability of the piezoelectric energy harvester, a metal foil is preferable compared to Si, the typical substrate for MEMS. [ 17 ] Moreover, thin metal foils enable low resonance frequencies without etching, and are easily machined. Morimoto et al. [ 8 ] reported a cantilever piezoelectric energy harvester using epitaxial PZT thin fi lms transferred onto stainless steel that shows output power of 5.3 µW at 5.0 m s −2 and 126 Hz without a proof mass. In much the same way, (Na 0.5 K 0.5 )NbO 3 (NKN) piezoelectric thin fi lms coated on Ni-based metal foils were investigated for vibration energy harvesters. [ 18 ] Another benefi t of using metal substrates for PEH is that copper and nickel have larger thermal expansion coeffi cients than many perovskite fi lms. This produces compressive stresses in the tetragonal PZT fi lm on cooling, increasing the volume fraction of the out-of-plane polarization direction. [ 19 ] Thus, high compressive stresses in {001} PZT fi lms give rise to an improved FoM for energy harvesting. [ 7,[19][20][21] Typical PEH designs use a fi xed-free cantilever beam confi guration with or without a proof mass. While fi xed-free Extracting energy from low vibration frequencies (<10 Hz) using piezoelectric energy harvester promises continuous self-powering for sensors and wearables. The piezoelectric compliant mechanism (PCM) design provides a signifi cantly higher effi ciency by fostering a uniform strain for its 1st mode shape, and so is interesting for this application. In this paper, a PCM energy harvester with bimorph Pb(Zr,Ti)O 3 (PZT) fi lms on Ni foil deposited by rf magnetron sputtering is shown to have high effi ciency and large power for low...

Piezoelectric Thick Film Based on Bonding technologies for Energy Harvester

“…(55) We have fabricated a B-PEH based on bulk PZT thick films with a low resonant frequency over a wide range of acceleration, which was realized by utilizing low-temperature bonding and thinning technology on flexible beryllium bronze substrates at a low cost. (56) Figure 6(a) illustrates the threedimensional structure and micromachining process of B-PEH.…”

A Preliminary Study on the IoT-Based Pavement Monitoring Platform Based on the Piezoelectric-Cantilever-Beam Powered Sensor

“…Cho et al (2016) designed a piezoelectric energy acquisition system with magnetic oscillations that harvested inertial energy and vibrational energy [12]. Yeo et al (2016) studied the PCM energy collector of the double crystal Pb (Zr, Ti)O-3 (PZT) film on the Ni foil deposited by rf magnetron sputtering [13]. Hsu et al suggested a locally amplified strain sensor based on the piezoelectric polymer [14].…”

Comprehensive biocompatibility of nontoxic and high-output flexible energy harvester using lead-free piezoceramic thin film

“…[1][2][3][4][5][6][7][8][9][10] Moreover, flexible energy harvesters (nanogenerators) can be easily fabricated using piezoelectric materials, and they are prospective candidates for realizing self-powered flexible electronics. [11][12][13][14] In that pursuit, many researchers have demonstrated high-performance flexible energy harvesters using representative lead-based piezoelectric materials, e.g., Pb(Zr,Ti)O 3 (PZT), 11,12,14,15 even for wearable/bioimplantable applications. [16][17][18][19][20] Although the lead-based materials have excellent piezoelectric properties, they should not be utilized in ecological/biological applications due to their toxicity, a legacy of the acknowledged Pb-related poisoning.…”