Wireless sensing in high-speed railway turnouts with battery-free materials and devices.

Sustainable energy technologies enable solutions for future green transportation. Realizing status awareness and effective wireless monitoring of rail transit infrastructure in dark environments, narrow spaces, and unattended conditions has always been a challenge. This study presents a battery-free vibration-powered force sensing system (VFSS) that integrates structural loading, sensing, and energy harvesting. The proposed VFSS can sense a switching force of up to 4 kN in the high-speed railway turnout section, deliver 6.9 mW of average power over a broad frequency band (ca. 500 Hz) under a vibration amplitude of 0.2 mm, and realize wireless data transmission. Through a cross-scale design from the device to the system, we demonstrate an all-in-one smart component that features stress flow, signal flow, and energy flow, which could highlight the implementation of energy structures in the future.