A novel low-pressure MEMS device design with nested circular meanders connected to circular membrane structure
摘要
This research presents a novel microelectromechanical (MEMS) capacitive pressure sensor designed for continuous low-pressure measurement, particularly within the blood pressure range of 0–23 kPa. The main goal of this work is to achieve higher sensitivity and smaller size compared to conventional MEMS diaphragm sensors by introducing a new structural design. The key innovation of this study lies in the integration of a circular polysilicon diaphragm with interdigitated comb electrodes, supported by three sets of circular folded meanders arranged 120° apart. These meanders serve as flexible springs, significantly reducing edge stiffness and improving diaphragm deflection. The total device has a radius of 80 µm, while the diaphragm itself has a radius of 43 µm and a thickness of 3 µm. The diaphragm is separated from the bottom electrode by an air gap of 3 µm. Polysilicon, a common material in MEMS fabrication, is used for all structural layers. Finite element simulations have been performed in COMSOL Multiphysics to analyze diaphragm displacement, stress distribution, and modal behavior. The simulation results have been validated with analytical calculations conducted in MATLAB, showing excellent agreement between both methods. The resonant frequency of the device is 288 kHz, while the maximum diaphragm deflection at 23 kPa reaches 1.17 µm. The sensor demonstrates a mechanical sensitivity of 50.9 nm/kPa and a capacitive sensitivity of 1.38 × 10⁻5 (1/Pa). Compared with conventional fixed-edge diaphragm designs, the proposed nested folded meander structure effectively reduces stiffness, increases sensitivity, and ensures mechanical reliability, making it suitable for compact and accurate low-pressure biomedical sensing applications.