Design optimization and simulation of micro-electro-mechanical system based solar energy harvester for low voltage applications

In this paper, the design of a micro-cantilever based solar energy harvester is proposed. Solar energy is converted to electrical voltage using a MEMS solar cell that uses the principle of coefficient of thermal expansion and piezoelectric effect. Initially, the bilayer cantilever made of two different materials (Al and SiO2) is displaced at the free end by absorbing the solar radiation that develops the stress at the fixed end and thus the solar radiation is converted to mechanical energy. Also, the developed mechanical energy (stress) is converted to electric potential by using the piezoelectric material that is positioned at the fixed end of the cantilever. Different shapes of bilayer cantilevers are designed and analyzed for maximum stress distribution. Experimental study on different shapes is also carried out in an INSTRON 8800 compression testing machine with the prototype made of aluminium. The results obtained prove that the triangular beam shows larger displacement and stress when compared with other shapes. Then the optimized structure with maximum stress is evaluated computationally for maximum voltage generation by placing different piezoelectric materials at the fixed end. The size of the designed solar cell is very small (4000 μm2) when compared to the conventional photovoltaic cell which ultimately reduces the cost by the batch fabrication process.