Liquid Metal-Based Flexible Sensing and Wireless Charging System for Smart Tire Strain Monitoring

Real-time monitoring of tire deformation is crucial in achieving vehicle safety, fuel economy, and intervention control before emergencies. It is challenging to integrate sensors for long-term continuous information collection inside high-speed rotating and deforming tires. In this study, we innovatively developed a flexible liquid metal (LM)-based sensing and wireless charging system and applied it for the first time to smart tire strain monitoring. The LM sensors and coils manufactured using microfluidic technology have remarkable stretchability (over 400% tensile strain) and durability, effectively resolving the mismatch between the rigid electronic interface and the complex inner surface of the tire during long-term use. The sensor comprises multiple LM microfluidic sensing layers that provide high linear fit and simultaneously monitor circumferential and axial microstrain in the tire. The system delivers power to the sensors through wireless charging and transmits the sensing signals to the developed mobile application through Bluetooth. We integrated this system into the tires, successfully achieving wireless charging of the lithium battery and real-time monitoring of sensor waveform changes while the vehicle is moving. This work provides valuable insights for the development of next-generation intelligent tires.