Theoretical and experimental study on magnetically-actuated micromirrors for electromagnetic NDE

Abstract

Magnetically-actuated Micromirrors as Micro-electromechanical devices have exhibited their superiority over other magnetic sensing techniques in terms of high sensitivity and high spatial resolution, which is favoured not only by quantitative measurement but also imaging of magnetic field distribution. In our research into magnetic field sensing and imaging, a 2D magnetic field sensing system with magnetically-actuated micromirrors has been proposed. Before the system is constructed, extensive investigation of magnetically-actuated micromirrors with different structures and materials has been conducted via theoretical and experimental study. FEMLAB and IntelliSuite have been employed for theoretical analysis of the sensitivity of micromirrors with different structures in correlation with the variation of external magnetic fields in order to optimise micromirror dimensions and beam cantilever design. Following the innovative fabrication of practical micromirrors, an optical measurement system has been set up to specifically characterise micromirrors of various dimensions and configurations in terms of sensitivity to the variation of external magnetic field. Detection sensitivity of 1 deflection degree of micromirror per Gauss of magnetic field has been achieved, which benefits not only the further improvement of micromirror sensitivity via optimal design and fabrication, but also the establishment of a micromirror-based 2D magnetic field sensing and imaging system for ENDE with high sensitivity and high spatial resolution