Leveraging a temperature-tunable, scale-like microstructure to produce multimodal, supersensitive sensors.

Abstract

The microstructure of a flexible film plays an important role in its sensing capability. Here, we fabricate a temperature-dependent wrinkled single-walled carbon nanotube (SWCNT)/polydimethyl-siloxane (PDMS) film (WSPF) and a wrinkle-dependent scale-like SWCNT/PDMS film (SSPF) successfully, and address the formation and evolution mechanisms of each film. The low elastic modulus and high coefficient of thermal expansion of the PDMS layer combined with the excellent piezoresistive behavior of the SWCNT film motivated us to investigate how the scale-like microstructure of the SSPF could be used to design multimodal-sensing devices with outstanding capabilities. The results show that SSPFs present supersensitive performance in mechanical loading (an effective sensitivity of up to 740.7 kPa-1) and in temperature (a tunable thermal index of up to 29.9 × 103 K). These exceptional properties were demonstrated in practical applications in a programmable flexile pressure sensor, thermal/light monitor or switch, etc., and were further explained through the macroscopic and microscopic piezoresistive behaviors of scale-like SWCNT coatings.