Vertical-graphene-decorated carbon nanofiber mats integrated with laser-induced graphene electrodes for piezoresistive pressure sensors

Abstract

Flexible pressure sensors that combine high sensitivity, a broad operating range, and mechanical durability are needed for wearable electronics, healthcare monitoring, and human–machine interfaces. Here, we report a piezoresistive pressure sensor that integrates a vertical-graphene-decorated carbon nanofiber (VG@CNF) mat with laser-induced graphene (LIG) interdigitated electrodes. The VG@CNF sensing layer was produced by growing spiky vertical graphene (VG) sheets on carbon nanofibers, thereby generating a rough and compressible fibrous network, whereas the LIG electrodes were directly patterned on polyimide by laser scribing to form porous and mechanically robust conductive electrodes. This structural combination promoted pressure-dependent contact formation both within the fibrous mat and at the sensing-layer/electrode interface. Compared with the sensor based on pristine carbon nanofibers without VG, the VG@CNF/LIG device maintained a larger current response over a broader pressure window, exhibiting sensitivities of 0.0142 kPa−1 at 0–60 kPa and 0.0045 kPa−1 at 60–80 kPa, and it remained operable up to 100 kPa. Under 1000 loading–unloading cycles at 100 kPa, the relative current response changed by only 1.7%, indicating good mechanical durability. Proof-of-concept demonstrations, including finger pressing, weight-dependent loading, joint-motion monitoring, and wireless in-shoe detection during running, further confirmed stable and repeatable operation. These results indicate that combining a VG@CNF sensing layer with porous LIG electrodes is an effective structural strategy for improving sensitivity retention at moderate-to-high pressure while preserving a broad working range and mechanical robustness in flexible piezoresistive pressure sensors.