A Curved Frog-Arm MEMS capacitive pressure sensor for ICP monitoring

This study presents the design and finite element simulation of a microelectromechanical systems (MEMS) capacitive pressure sensor developed for intracranial pressure (ICP) monitoring over a range of 0–5 kPa (0–37.5 mmHg), covering both physiological and elevated pathological conditions. To enhance sensitivity while maintaining mechanical robustness and linearity, a modified suspension configuration termed the Curved Frog-Arm is introduced. Unlike conventional cantilever and standard Frog-Arm supports, the proposed curved geometry provides superior mechanical compliance and significantly reduces the total area subjected to high stress by confining peak stress to localized boundary zones, thereby preventing premature mechanical failure and extending the stable linear operating range up to 5 kPa while promoting quasi-piston diaphragm deformation. Finite element simulations conducted in COMSOL Multiphysics demonstrate a mechanical sensitivity of 0.26 μm/kPa and a capacitive sensitivity of 34.46 fF/kPa. Compared with the conventional Cantilever Arm, the proposed structure achieves approximately 451.6% and 1449.5% improvements in mechanical and capacitive sensitivities, respectively. Furthermore, it achieves a 50.7% reduction in geometric nonlinearity compared to the standard Frog-Arm design. Comprehensive eigenfrequency and thermo-elasto-mechanical analyses confirm the dynamic integrity and thermal robustness of the proposed device. Additionally, noise and resolution evaluations demonstrate an ultra-low thermomechanical noise-equivalent pressure density of 1.44×10 –5 Pa/√Hz and an exceptional theoretical pressure resolution of 0.29 Pa (0.0022 mmHg), fulfilling the stringent precision criteria for ICP diagnosis. Owing to these combined advantages, the sensor achieves a superior figure of merit (FOM) compared with previously reported MEMS capacitive pressure sensors, providing an optimal trade-off among high sensitivity, wide operating range, structural miniaturization, and mechanical reliability for continuous biomedical ICP monitoring.