Design and development of guided four beam cantilever type MEMS based piezoelectric energy harvester

Abstract

MEMS devices have found applicability in remote area of operation such as temperature monitoring in extreme climates, structural health monitoring, and car tire pressure monitors etc. due to compact shape and ability to operate in low power (few microwatts). These devices are generally powered through a small battery but replacement at such remote locations is not feasible which imposes a serious challenge of powering these devices for infinitely long time. Energy harvesting provides an unending power source (few milli-watts) which is adequate to power these MEMS devices having remote area applications. Piezoelectric type energy harvesters are the most promising and efficient vibration energy harvesters that are widely used. Increased depth of cavity due to large displacement, residual stress and lower output potential are demerits of single cantilever type piezoelectric energy harvester. In this paper a new design of guided four beam cantilever type piezoelectric energy harvester is simulated, analyzed and reported. Displacement of 0.095 µm is achieved at an input acceleration of 1 g (9.8 m/s2) which is 32.14 % less than displacement of single beam cantilever which has also been reported and compared with the new proposed design in this paper. Maximum stress calculated at an input acceleration of 5 g is 4.7 × 105 N/m2 on piezoelectric layer and 8 × 105 N/m2 on guided beams which is well below the fracture stress for silicon. Tensile and compressive stress generates potential of opposite polarities that can be harvested using separate set of capacitors. Potential generated ranges from 17.84 to 89.21 mV for input acceleration ranging from 1 to 5 g respectively.