Fabrication of highly dielectric nano-BaTiO3/epoxy-resin composite plate having trenches by mold casting and its application to capacitive energy harvesting

We propose a fabrication method of dielectric plate having trenches, in which a composite material of nano-BaTiO₃ particles and epoxy-resin is casted into a mold of patterned thick photosensitive dry film. The features are, 1) the relative dielectric constant ε_r is a dozen, which is no less than those of other polymer-based ferroelectric such as poly-vinylidene-difluoride (PVDF), 2) fabrication is compatible to MEMS process, i.e., the size and pattern of trenches are flexibly designed as far as photolithographic resolution admits, 3) trench depth is several tens micron thanks to thick film resist. We applied it to an electret energy harvesting device based on fringe electrical field change inside trenched ferroelectric.The experimental output power of 2.9 nW was achieved for 80 Hz/80 μm forced vibration.