Flexible, multi-functional sensor based on all-carbon sensing medium with low coupling for ultrahigh-performance strain, temperature and humidity sensing

An ultrahigh-performance multi-functional sensor integrating strain, temperature and humidity sensing has been investigated. The sensing medium is only composed of carbon nanocoils (CNCs) and carbon nanotubes (CNTs). For strain sensing, due to the high elasticity provided by CNC skeleton and the recoverable conductive cracks with a width of hundreds of microns generated by the dense CNT film, the sensor delivers excellent sensing properties, including the advantages of ultrahigh gauge factor (up to 352085), wide strain range (up to 100%), high strain resolution (0.01%), fast response time (16 ms) and robust cycle stability (10000 cycles). In addition, this all–carbon sensing medium can also be used for temperature and humidity sensing in an ultrawide temperature range of 7 to 400 K and humidity sensing over a relative humidity range of 10% to 80% with a high signal-to-noise ratios. It is worth noting that the integrated multi-functional sensor can simultaneously detect the stimuli of strain, temperature and humidity with low coupling. Multiple applications can be detected accurately, such as human motions, breathing behavior, pulse wave, different vibration modes and so on. Therefore, the all-carbon-based sensor provides a promising strategy in developing multi-functional integration for smart wearable devices, electronic skins, and other multi-functional sensing devices.