Atomic-to-Nanoscale Silver Design on g-C3N4 for Broad-Range Flexible Pressure Sensors

Flexible pressure sensors play an essential role in wearable electronics, human–machine interfaces, and physiological monitoring systems. Achieving both high sensitivity and a wide dynamic range remains a major challenge. Here we report a piezoresistive flexible pressure sensor based on graphitic carbon nitride (g-C3N4) that addresses this longstanding trade-off through multiscale dimensional engineering of silver (Ag)-based sensing materials. Three Ag-based materials with distinct dimensional characteristics, Ag single atoms, Ag single atom cluster hybrids, and Ag nanoparticles, were synthesized and their piezoresistive behaviors were evaluated across different pressure regimes. The sensor exhibits an ultrafast response and recovery time of 0.5/0.4 s and high reproducibility. Sensing performance shows pronounced size-dependent behavior with nanoparticles providing a robust response at high pressures (>4.5 kPa), single atom cluster hybrids showing optimal sensitivity in the intermediate range (3–4.5 kPa), and single atom sites exhibiting comparable behavior to single atom cluster hybrids at low pressures (<3 kPa). Integration into a robotic hand demonstrates the sensor’s practical applicability, enabling precise tactile control under low pressure (0.85 kPa). This work establishes a generalizable strategy for decoupling sensitivity and dynamic range by engineering Ag from atomic to nanoscopic scales, offering broad applicability in wearable electronic and robotic tactile systems.