Self‐Powered Piezoelectric Fish Tag for Motion Tracking and Acoustic Transmission

Abstract Acoustic fish tags are the primary method for tracking marine animal behavior. However, existing acoustic fish tags are typically rigid, invasive, and powered by batteries, which raises concerns about biocompatibility and limits the device's longevity. In this study, a self‐powered piezoelectric fish tag (SPFT) is presented based on a hybrid‐mode piezoelectric nanogenerator (HM‐PENG). The HM‐PENG efficiently harvests both flow impact energy and strain energy generated by fish‐tailing, utilizing a cavity structure and an auxetic design. The flexible fish tag can monitor fish behavior and enable self‐powered underwater acoustic transmission. These functions are demonstrated using a robotic fish and a living crucian carp. Through signal modulation and demodulation, detailed parameters of fish locomotion, such as oscillation angle, frequency, and typical movement patterns, are transmitted and decoded. This work advances the development of self‐powered, flexible fish tags, contributing to animal behavioral studies and ocean exploration.