A novel capacitive sensor featuring surface microstructure and hydrogels for measuring full pressure with high-sensitivity

Abstract

Compared with positive pressure measurement, which is widely used in many fields, negative pressure measurement is often ignored. However, realizing full pressure measurement, that is, positive and negative pressure measurement, with high sensitivity and wide measurement range, is one of the most urgent development directions and key challenges faced by flexible pressure sensors. To overcome this challenging problem, a highly sensitive full-pressure capacitive sensor with surface microstructure and hydrogels is introduced in this paper. The sensing mechanism of the sensor is implemented by detecting the capacitance change caused by the change in the contact area between the hydrogel and the electrode due to the internal and external pressure difference. The PVA/KOH basic gel material is used to resist shear deformation, and the uniform microstructure on the gel surface is achieved by the template method. How to maximize the sensitivity of positive and negative pressure measurements is discussed by carefully evaluating the design parameters of the sensor. The fabricated sensor has a wide measurement range (-100–250 kPa) with high sensitivity (S = 15.6 nF/kPa) in the negative pressure region and (S = 5.2 nF/kPa) in the positive pressure region. In addition, the sensor exhibits fast response, cycle stability, and low measurement limit, which further enhances its performance advantages. In order to validate the application potential of the sensor, the paper conducts experimental verification using the relationship between wind pressure measurement results and the angle of contact with the sensor, as well as the relationship between vehicle speed and wind pressure magnitude. The results show that the designed sensor has potential application prospects in full pressure measurement.