Negative pressure-assisted porous structure with gradient dielectrics design for linearity enhancement of flexible capacitance pressure sensor

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 676; p. 132306
• Main Authors: Zhong, Yan, Wu, Longgang, Gu, Fucheng, Wang, Jiaqi, Dai, Shengping, Zhu, Hao, Cheng, Guanggui, Ding, Jianning
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 05.11.2023
• Subjects: Capacitive sensor; Flexible pressure sensor; Good linearity; High sensitivity; Series-parallel conversion; Series-parallel conversion; Flexible pressure sensor; Good linearity; Capacitive sensor; High sensitivity
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2023.132306

The trade-off between sensitivity and linearity range for flexible capacitive pressure sensors remains unresolved. Herein, a simple and low-cost method is proposed to fabricate porous structure with the aid of negative pressure. The gradient dielectrics are assembled with porous structure doped with different CNT ratios. With the perforated design on the low dielectric layer, the gradient dielectric can realize series-parallel conversion during the pressure-induced deformation process, where the coverage ratio and dielectric properties of low dielectric layer can be appropriately collocated to realize the linear behavior of the capacitance performance over the full-scale pressure. Therefore, the capacitive sensor based on optimized gradient dielectric layer can achieve a high sensitivity of 0.247 kPa−1 and a wide linearity range of 0–175 kPa. With the high sensitivity over a broad pressure range, the capacitive sensor demonstrates its various practical applications in monitoring physiological signals and human motions such as the artery pulse, respiratory, knee bending, elbow bending degree and walking and running status, showing potential in wearable healthcare monitor. [Display omitted] •A capacitive pressure sensor based on gradient dielectric with high sensitivity and wide linearity range is proposed.•Porous dielectrics were fabricated with a simple and low-cost negative pressure-assisted method.•A perforated design on the low dielectric layer can realize series-parallel conversion in the pressure-induced process.•The pressure sensor demonstrates its applications in monitoring physiological signals and human motions.