Magnetic Biocompatible Film for Flexible Anti‐Counterfeiting and Self‐Powered Human Motion Health Monitoring

Natural polymers possess the qualities of abundant resources, low cost, as well as excellent biocompatibility and biodegradability, and are ideal materials for next‐generation wearable and portable electronic devices. To further augment the application scope of natural polymer materials, integrating them with functional materials represents a promising approach that is of great value for the sustainable development of triboelectric nanogenerators. Here, we successfully synthesized starch–[CsPbBr ₃ –KBr]–Fe ₃ O ₄ composite films through the combination of natural polymer materials with magnetic and fluorescent components. It is capable of achieving reversible hydrochromic conversion by exposing or removing water. The combination of fluorescent CsPbBr ₃ –KBr, magnetic Fe ₃ O ₄ , and waterproof starch ‐ [CsPbBr ₃ ‐ KBr] ‐ Fe ₃ O ₄ ‐Polydimethylsiloxane leads to the realization of fluorescence and magnetic composite anti‐counterfeiting. This composite anti‐counterfeiting technology presents a novel and highly effective approach for ensuring the authenticity and security of various types of information. In addition, the Composite film based triboelectric nanogenerator has been assembled, which has a stable output with a short circuit current and open‐circuit voltage of 15.1 μA and 170.1 V, respectively. The triboelectric nanogenerator can light 204 red LED lights at the same time, and the electrical output is not reduced even after 4200 mechanical cycles. Furthermore, based on the triboelectric nanogenerator, we have successfully demonstrated a self‐powered sensor that can monitor human movement signals in real time. The sensor has shown broad application prospects in the field of health monitoring and motion analysis.