Simulation and investigation of MEMS bilayer solar energy harvester for smart wireless sensor applications

In this paper, design, optimization and simulation of piezoelectric based bilayer MEMS solar energy harvester to power smart wireless sensors is proposed. The electric potential is produced from the solar’s infrared power by using the thermal conduction principle and piezoelectric effect. Bilayer cantilever made of aluminium (Al) and silicon-di-oxide (SiO2) is designed such that it absorbs heat from the sun, causes bending. This induces stress at the fixed end from where the electric potential can be generated by placing the piezoelectric material. With the sinusoidal input heat flux of 1050 W/m2, finite element analysis is carried out in COMSOL software. The bilayer beam with different thickness, thickness aspect ratio and with different heat absorption materials are designed, simulated, compared with numerical calculations and simulation results. Then, different shapes of the beam are taken into account, compared with experimental results in our previous work and judged that triangular could perform with even more displacement comparing with other shapes. The optimized structure is analyzed with aluminium nitride (AlN) piezoelectric material for open circuit voltage generation. AlN is chosen due to its appealing properties such as larger Curie temperature, strong chemical and mechanical properties, low dielectric losses, low leakage current and stability of the piezoelectric coefficient for temperature changes. The designed harvester, on an average, can generate open circuit voltage of 0.81 V which could be further used to charge the rechargeable batteries in remote locations or for powering low power electronics.