MEMS Technologies for Energy Harvesting

The objective of this chapter is to introduce the technology of Microelectromechanical Systems, MEMS, and their application to emerging energy harvesting devices. The chapter begins with a general introduction to the most common MEMS fabrication processes. This is followed with a survey of design mechanisms implemented in MEMS energy harvesters to provide nonlinear mechanical actuations. Mechanisms to produce bistable potential will be studied, such as introducing fixed magnets, buckling of beams or using slightly slanted clamped-clamped beams. Other nonlinear mechanisms are studied such as impact energy transfer, or the design of nonlinear springs. Finally, due to their importance in the field of MEMS and their application to energy harvesters, an introduction to actuation using piezoelectric materials is given. Examples of energy harvesters found in the literature using this actuation principle are also presented

Dielectric, ferroelectric and piezoelectric properties of13; (1 x2013; x)[Pb0.91La0.09(Zr0.60Ti0.40)O3]x2013;x[Pb(Mg1/3Nb2/3)O3],13; 0 xA3; x xA3; 1

The dielectric, ferroelectric, and piezoelectric13; properties of ceramic materials of compositions13; (1 x2013; x)[Pb0.91La0.09(Zr0.60Ti0.40)O3]x2013;x[Pb(Mg1/3Nb2/3)O3],13; x = (0, 0.2, 0.4, 0.6, 0.8, and 1.0) were studied. The above13; compositions were prepared by mixing the individual13; Pb0.91La0.09(Zr0.60Ti0.40)O3 (PLZT) and Pb(Mg1/3Nb2/3)13; O3 (PMN) powders in order to design materials with13; different combination of piezo and dielectric properties.13; The powders were calcined at 850 C for 4 h. The presence13; of various phases in the calcined powders was13; characterized by X-ray diffraction (XRD) technique.13; The compacts were prepared by uniaxial pressing and13; were sintered at 1250 C for 2 h. The sintered compacts13; were electroded, poled at 2 kV/mm dc voltage and their13; dielectric, ferroelectric, and piezoelectric properties13; were measured. In general, it was observed that the13; dielectric constant, loss factor and the slimness of the13; ferroelectric curves increase with the PMN content13; while the remnant polarization, saturation polarization,13; and the coercive fields were decreased. It is now possible13; to design materials with a wide combination of d33, K,13; and loss factor by varying PLZT and PMN ratio

Ferroelectric, dielectric and piezoelectric properties13; of Pb1x2013;xCex(Zr0.60Ti0.40)O3, 0 xA3; x xA3; 0.08

The ferroelectric, dielectric and piezoelectric13; properties of compositions Pb1x2013;xCex (Zr0.60Ti0.40)O3,13; (x = 0.0, 0.01, 0.02, 0.04, 0.06 and 0.08) are studied. The13; above compositions are prepared from their constituent13; oxides, calcined at 900 C for 4 h and various phases13; present are characterized by X-ray diffraction (XRD)13; technique. The above powders are uniaxially pressed into13; circular compacts, sintered at 1,250 C for 2 h, electroded,13; poled at 2 kV/mm D.C. voltage and their electrical properties13; are measured. The XRD analysis shows the presence13; of rhombohedral phase up to 2 mol% ceria while tetragonal13; phase found at higher concentrations. It is observed that13; the ferroelectric, dielectric and piezoelectric properties13; increase with the addition of ceria with a maximum at13; 2 mol% and then decreases. The higher piezo properties13; associated with low ceria concentration are attributed to13; rhombohedral phase