A novel flexible substrate-free NH3 sensing membrane based on PANI covered rGO functionalized fiber

To alleviate the lack of sensors on the Internet of Things (IoT), a novel flexible substrate-free sensing membrane has been put forward, of which the fabrication is simple, low-cost and has potential of large-scale production via a vacuum filtration method. After alkaline hydrolysis , paper fibers were covered with reduced graphene oxide (rGO) and further functionalized with a layer of polyaniline (PANI) by in-situ polymerization. The rGO functionalized fiber (GF) played a competent role as the embedded conductive network, efficiently transferring the charge signal from the surface sensing layer. Eventually, the functionalized fibers were re-filmed under a 0.1 MPa negative pressure by vacuum filtration method. The surface area of the film was about 23.76 cm 2 and 1 × 1 cm 2 square was cut for the following test. The sensing membrane based on PANI covered rGO functionalized fiber (PGF) has shown superb sensing performance to NH 3 , with excellent stability, selectivity and sensitivity at room temperature . The linear response range of sensor based on PGF was 25 ppm, the correlation coefficient was 0.9908 and the limit of detection (LOD) was 34 ppb. The response to NH 3 was ∼14% while the responses of other testified interfering gases were all below 0.5%. Most importantly, the sensing membrane has exhibited an excellent capability of resisting bending, and maintained the response to 10 ppm NH 3 (13.55–14.3%) even after 1200 bends, indicating that the sensor has a bright prospect of future wearable applications.