Integrated surface microstructure and enhanced dielectric constant for constructing simple, low-cost, and high-performance flexible capacitive pressure sensor

Designing microstructure surface or enhancing the dielectric constant of functional layer is a common useful strategy to improve the pressure sensing performances of flexible capacitive pressure sensors, but it usually involves complex preparation processes (such as artificial microstructure and preparation of composite materials). Considering the limitations of a single strategy in improving the pressure sensing performance of capacitive pressure sensor, herein, we propose a simple strategy that integrates surface microstructure and enhanced dielectric constant of functional layer for constructing a high-performance flexible capacitive pressure sensor. Specifically, the polyester fiber conductive tape and filter paper with intrinsic rough surfaces are selected as microstructure electrodes and dielectric layer, respectively. Meanwhile, by introducing the daily carbon ink into filter paper, the moderate conductivity of the carbon ink is utilized to enhance the dielectric constant of the filter paper dielectric layer. The results show that the proposed the pressure sensor has wide pressure detection range of 0.1−100 kPa, high sensitivity (1.47 kPa−1, 0.1−10 kPa) and good durability (4000 cycles at 20 kPa). Taking the pressure range of 10−100 kPa as an example, the sensitivity of carbon ink paper-based sensor is 60 times higher than that of sensor without carbon ink. The enhanced working mechanism of the sensor is clarified by combining testing and characterization. In addition, the proposed pressure sensor has potential applications in wrist pulse, respiratory rate, walking record, morse code transmission,and stoma bag detection. This work provides a useful reference for constructing simple, low-cost and high-performance flexible capacitive pressure sensor.