Widening frequency bandwidth with parametric coupling in a wings-inspired low frequency MEMS energy harvester

Efficient energy harvesting with miniaturized harvesters for both low and random frequency vibrations remains a large challenge. This paper presents a wings-inspired design to implement a parametric coupling mechanism for widening the frequency bandwidth of a Micro-Electro-Mechanical System (MEMS) energy harvester (abbreviated as PCEH). The proposed PCEH is composed of two harvesting units, micro-fabricated by SU-8 with a serpentine geometry for decreasing working frequency, which like two wings, are placed at the bilateral of a flexible silicon middle support. When PCEH is excited, the flexible support can oscillate around its equilibrium position due to the lateral vibration of two wings. The parametric coupling is realized by alternately modulating the stiffness of each wing and verified by theoretical analysis, numerical simulation, and experimental measurements. Compared to those of non-parametric coupling energy harvesters (abbreviated as NPCEH), bandwidths and harvesting capacity of two wings in PCEH are increased by 55.4% and 73.7%, and by 3.3 and 2.5 times, respectively. The proposed PCEH opens a new way for widening the frequency bandwidth of energy harvesters at micro scale and lays a foundation for self-powered systems.