High-sensitivity gas sensors based on arranged polyaniline/PMMA composite fibers

•Aligned poly(methyl methacrylate) fibers were fabricated by electrospinning and then nanostructured polyaniline (PANI) was grown on the surface of the parallel PMMA fibers via in situ solution polymerization.•The gas sensing properties of the composite fibers were investigated under ultra-low ammonia concentrations at room temperature.•The arranged fibers had high sensitivity upon exposure to ammonia vapor of 1–30ppm.