Flexible multifunctional graphite nanosheet/electrospun-polyamide 66 nanocomposite sensor for ECG, strain, temperature and gas measurements

The flexible conductive polymer composites (CPCs) based sensor that can detect strain, temperature or chemical vapor exhibits a huge application prospect in many fields such as soft robotics, electronic skin, thermal protection and electrical nose, etc. However, it is still a challenge to integrate multi functions into one flexible electronic device. In this paper, a flexible, ultralight and highly conductive multifunctional sensor of graphite nanosheet (GN)/polyamide 66 (PA66) nanofibers composite is prepared by electrospinning fibrous mat process and ultrasonic decoration method. The morphology and the structure were characterized by SEM, FTIR, Raman and TGA methods in detail. Attributed to the sensitive three-dimensional conductive network constructed by anchoring the GN into the electrospun PA66 nanofibers with porous structure, this flexible sensor offers the excellent multifunctional response for strain, temperature and gas sensing. In addition, the prepared GN/PA66 nanocomposite was successfully employed as a multifunctional sensor and applied in the detection of human motion and physiological ECG signal. Moreover, benefitted from the high aspect ratio of the GN/PA66 nanocomposite, the flexible sensitive sensor can also monitor the temperature as well and show a typical negative temperature coefficient (NTC) effect of resistance. Besides, the polar chemical vapor of formic acid, DMF and NH3·H2O can be detected accurately whatever the physical states (flat, folding, twisting and knotting) of the flexible sensor. This work provides an effective strategy for integrating the multifunctional flexible electronics with high performance to satisfy the next-generation wearable electronics.