Microcracked strain sensor based on carbon nanotubes/copper composite film with high performance and waterproof property for underwater motion detection

Abstract

As flexible strain sensors have been widely used for monitoring human movement effectively, the exploration of this type of sensor will be of great interest to the sensor research community. This paper presents a flexible strain sensor with outstanding performance and straightforward preparation based on microcrack. A polyurethane film is used as a flexible substrate and carbon nanotube/copper composite films are used as sensitive layers for the strain sensors, which are completely encapsulated in polydimethylsiloxane. Furthermore, the surface morphology of the sensor and the form of crack development are represented in this report, as well as a comprehensive test of the performance. The results show that we designed and manufactured a strain sensor with gauge factors of 60.0 (0 < ε < 14%), 210.6 (14% < ε < 30%) and even up to 348 (30% < ε < 50%) with a sensing range of up to 50%. Under the condition of 60% tensile strain, the sensor can be loaded/unloaded at 2 × 103 cycles without any significant change in the relative rate of change curve of its resistance. The sensor has excellent water resistance and reliability, proving that it can be adapted to most scenarios when used daily. The paper shows that the method produces a sensor with commendable performance and has a significant potential for applications in human motion monitoring systems and electronic skins in water.