Flexible pressure sensors based on electrospun PAN fiber films incorporated with graphene/polypyrrole composites and engineered PDMS microstructures

Flexible pressure sensors can be conveniently attached to the human body and can be used to effectively track various physiological signals in real time. In this work, flexible pressure sensors were fabricated based on composite fiber materials, exhibiting a microstructured PDMS layer and containing a three-dimensional conductive polyacrylonitrile (PAN) fiber network incorporated with graphene (GR) and polypyrrole (PPy). The working mechanism of the GR/PPy@PAN composite fiber film with microstructured layers in flexible tactile sensors was simulated. The assembled sensor exhibited a wide sensing range (up to 80 kPa), high sensitivity (28.5 k Pa⁻¹), high stability (over 10⁴ cycles), and rapid response/recovery speeds (40 ms/50 ms). These flexible sensors when attached to the human body detected subtle motion signals (e.g., pulse and finger bending) in terms of characteristic current waveforms. In addition, an artificial electronic skin was realized based on an array of 4 × 4 sensors, which gave corresponding responses to tactile stimuli with various magnitudes and coordinates. By analyzing the detected signals from human voice assisted with a machine learning process, speech recognition with high accuracy was realized. Thus, the flexible pressure sensors based on GR/PPy@PAN composite fiber films with microstructured PDMS layers exhibited great potential for multiple applications such as health monitoring, clinical diagnosis, human–machine interaction, and artificial electronic skin.