Designing wearable capacitive pressure sensors with arrangement of porous pyramidal microstructures

Capacitive pressure sensors are essential for advanced applications like wearable medical devices, electronic skins, and biological signal detection systems. Enhancing sensitivity in these sensors is achieved by incorporating porous microstructures into the dielectric layer. The present research focuses on designing a capacitive pressure sensor comprising a porous micro-pyramidal dielectric layer featuring diagonally arranged pyramids. The effects of geometric parameters and material properties such as dielectric constant, porosity, base length, tip width, height, and the distance between the pyramidal microstructures were examined using the three-dimensional finite element simulations. A comparative analysis was conducted to evaluate the accuracy of the numerical solution. The simulation results were compared to experimental measurements, and the findings revealed a high level of agreement. The optimal quantity of data for this analysis was determined using the design of the experiment method, specifically the response surface model. The results show that arranging microstructures diagonally or laterally can impact sensitivity and initial capacitance. Specifically, employing a diagonal arrangement enhanced sensor sensitivity by up to 1.65 times while maintaining the initial capacitance relatively unaffected. Ultimately, this study derived mathematical equations from the collected data to estimate the initial capacitance and sensitivity of the sensor. The model predictions were compared to simulation results, and it was found that the models performed effectively.