High‐Performance Wearable Triboelectric Nanogenerators Based on Polyethyleneimine‐Doped Cellulose Acetate for Self‐Powered Dynamic Signature Sensing and Verification

A highly sensitive and efficient triboelectric nanogenerator (TENG) is constructed using tribo‐positive polyethyleneimine (PEI)‐doped cellulose acetate (CA) and tribo‐negative polyvinylidene fluoride layers. An optimal PEI content of 0.7 wt% affords the maximum charge separation efficiency, generating an open‐circuit voltage and short‐circuit current of 334 V and 14.3 μA, respectively. This enhancement originates from the strong hydrogen‐bond interactions between the amine groups in PEI and CA, thereby promoting interfacial polarization and increasing the surface charge density. The developed TENG exhibits excellent mechanical durability after 6000 bending cycles, stable operation at 40 °C and 90% relative humidity, and long‐term reliability (>60 days). Multidimensional output signals are obtained from a 3 × 3 TENG array as a sensing interface that sense pressure, speed, and trajectory, followed by processing using an artificial intelligence‐based machine learning model, achieving high security and authentication performance, which addresses the limitations of conventional security methods related to external power requirements and reliability issues. This study extends the potential of TENG‐based self‐powered dynamic signature authentication systems as a next‐generation information security technology and highlights their broad applicability to wearable and intelligent electronic platforms.