Improving MEMS Inertial Switch Design Process Through Simultaneous Analysis of Design Parameters

The design of micro-electromechanical systems (MEMSs) inertial switches is a challenging issue that is studied from different points of view, such as threshold acceleration, directional sensitivity, and shock resistance. For a reliable design, this article presents a systematic approach for designing the switch derived from the outcomes of the theoretical modeling. First, the switch’s dynamic model based on a mass-spring system is created. Then, the spring stiffness coefficient equations in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${x}$ </tex-math></inline-formula>-, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${y}$ </tex-math></inline-formula>-, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${z}$ </tex-math></inline-formula>-direction are extracted. Next, the interrelation between design parameters and the impact of variable modifications on these parameters are examined. The study highlights the crucial role of the natural frequency in the design of the inertial switch structure. To achieve an optimal design, this parameter must be carefully selected in conjunction with considerations of pulsewidth, electrode spacing, and response time. By formulating equations for the spring stiffness coefficients in the three orthogonal directions, it becomes possible to determine the geometric parameters of the spring that minimize off-axis sensitivity. The analysis and comparison of the variables’ influence in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}_{x}$ </tex-math></inline-formula>, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}_{y}$ </tex-math></inline-formula>, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}_{z}$ </tex-math></inline-formula> demonstrate that increasing the thickness of the structure is the most efficacious factor in facilitating the development of an optimal design.