A Novel Defect Detection Sensor Based on Lorentz Force

In this paper, a novel MEMS defect detection sensor based on Lorentz force is designed. The bow beam structure is proposed, 3D model is established by COMSOL Multiphysics 6.0, and a multi-objective optimization of the sensor structural parameters is carried out using the NSGA-II algorithm and MOPSO algorithm. The simulation results show that, the stability of the sensor optimized by the MOPSO algorithm is improved by 56.14 and 87.48%, compared with that optimized by the NSGA-II algorithm and obtained empirically, provided that the minimum capacitance detection requirement is achieved. In addition, the optimized sensor structure has smaller size, better stability and higher sensitivity compared with the reported devices of the same principle, thus is able to detect the Lorentz force variation of 25 nN generated during motion of a 100 μm thick metal sheet with 20 μm micro-defects. These results show that this sensor has potential application in non-destructive testing.