Ultra-wide range composite flexible pressure sensor based on air layer structure and carbon nanotube modified dielectric layer

A wide detecting range and high sensitivity are crucial factors to fabricate the flexible pressure sensors with high resolution and precision across various application scenarios. Despite the exploration of numerous microstructures and composite material mediums to enhance the sensitivity of pressure sensors, the detection range has remained narrow, because of the constraint between wide detection range and high sensitivity. In this study, a capacitive flexible pressure sensor with ultra-wide detecting range have been developed, where a multi-walled carbon nanotubes (MWCNTs) reinforced poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE) composite was used as the dielectric layer. At same time, to enhance the sensitivity, an air layer was introduced between dielectric layer and packager layers. Consequently, the detected range as-fabricated sensor could reach to 0.1 – 10 MPa, which was wider than those of the reported flexible sensors. Additionally, it exhibits a high sensitivity (1.673 MPa⁻¹ and 0.302 MPa⁻¹) and excellent linearity in the ranges of 0.1 - 0.5 MPa and 0.5 - 10 MPa, respectively. Furthermore, an online monitoring system for capacitive pressure sensor stress was designed, of which the accuracy reached up to 95.0 %. Based on these results, the designed sensor and detecting system exhibited the potential applications flexible electronic devices and miniature pressure monitoring devices.