A highly-sensitive wearable capacitance pressure sensor based on calcium copper titanate/polydimethysiloxane/graphene oxide and polydimethysiloxane/silver nanowires sanwich strustures combination for human body monitoring

Abstract

In recent years, flexible pressure sensors, with their high sensitivity, low detection limit, wide working pressure range and fast response speed, have been playing an important role in the development of wearable artificial devices, human-computer interaction and healthcare systems, and have attracted wide attention. However, the pressure sensors face challenges related to the weak tightness of bipolar materials, low charge density, and limitation in dielectric layers. In this paper, we present a novel configuration of flexible capacitive pressure sensors, utilizing a polydimethysiloxane (PDMS) thin film covered by silver nanowires (PDMS/SN, PSN) as the electrode materials and a porous material composed of calcium copper titanate (@CCTO), PDMS and graphene oxide (GO)(@CCTO/PDMS/GO, @CPG) as the positive electrode material. The sacrificial material, sugar, is employed to create dense internal pores within the substrate material, @CPG, leading to the formation of a profoundly porous substrate. The integration of the flexible capacitive pressure sensor using @CPG/PSN results in enhanced output performance. The modified sensors achieves a sensitivity of 0.22 kPa−1, which is 7 times higher than that of a pure PDMS dielectric layer sensor. Moreover, the sensors has a response time of 87 ms, a low detection pressure of 5 Pa with an extensive detection range from 0 to 150 kPa, and are capable of enduring 7200 cycles without sustaining damage. To validate the practical performance of the @CPG/PSN sensor, various human body activities are detected, including swallowing, coughing, neck bending, wrist bending, elbow bending, finger flexing, and holding objects like cups using a digitally designed glove capable of accommodating different materials. The pressure sensor based on @CPG/PSN demonstrates significant promise in detecting both low and high pressures, thus expanding the potential applications of capacitive pressure sensors.