Flexible LIG Pressure Sensor Incorporating a PVA-Based Conical Microstructured Layer Fabricated via Flash Foam Stamp Technique

To reconcile the inherent trade-off between high sensitivity and wide sensing range, a flexible resistive pressure sensor fabricated via a flash-foam stamp-assisted process is presented. The device is composed of a PVA-based conductive hydrogel layer with conical microstructures and screen-printed laser-induced graphene (LIG) electrodes produced by direct laser writing on polyimide (PI). Precise microstructure replication is enabled by this low-cost, scalable method without the need for cleanroom lithography. A sensitivity of 0.2413 kPa⁻¹ over 0–3 kPa is achieved by the sensor, along with a wide detection range of 0–66 kPa, rapid response/recovery times of 0.1s, low hysteresis of 1.16%, and stable operation over more than 2000 cycles. Physiological signals such as pulse, subtle motions, and large joint movements (knee, elbow) are reliably captured. Multipoint recognition is demonstrated through a 3×3 pressure-sensing array. These results highlight the potential of LIG pressure sensors incorporating flash-foam-fabricated PVA-based conical microstructures for applications in wearable health monitoring, human–machine interfaces, and soft robotics.