Temperature-compensated gradient-porosity laser-induced graphene pressure sensor overcomes sensitivity-range trade-off for wearable heartbeat monitoring

Flexible pressure sensors enable continuous skin-interfaced monitoring of physiological signals for early disease warning. However, most pressure sensors are constrained by the sensitivity-range trade-off, resulting in insufficient sensitivity for weak physiological signals and a tendency to saturate under higher pressure inputs. Here, we present a laser-induced graphene (LIG)-based temperature-compensated gradient-porosity pressure sensor that resolves sensitivity-range trade-off by concentrically patterning low- and high-porosity regions, broadening the working range without compromising sensitivity, and eliminates the influence of body temperature to pressure sensor by temperature compensation method. The fabricated pressure sensor employes porosity-tunable (65–76%) LIG microstructures generated by modulating the laser power from 35 to 45% of P_max, achieving a pressure sensitivity (S) of 119 kPa⁻¹ for 0 to 200 kPa, demonstrating linearity up to 600 kPa with a S of 47 kPa⁻¹, and stable operation over 10,000 cycles. A temperature sensor is integrated to measure skin temperature and correct temperature-induced drift in the pressure signal. Using 38 °C as the reference, the root mean square error (RMSE) of pressure drift is reduced by 90.65% at 33 °C and 90.35% at 43 °C. In volunteer experiments, heart rate variability (HRV) is used to evaluate the performance of the fabricated sensor for on-body wearable monitoring. The measured HRV values show strong agreement with those from commercial sensor (r > 0.96) while exhibiting a higher signal-to-noise ratio (35.5 dB). Overall, this temperature-compensated gradient-porosity LIG pressure sensor offers a practical route to high-accuracy, wide-range, and high-sensitivity physiological sensing, and advancing wearable sensors development for early disease warning in daily life.