Mutualistic symbiotic wireless node for next-era smart transportation

Giant sensor networks are increasingly deployed in urban environments to advance smart cities and transportation systems, necessitating numerous integrated power solutions involving batteries and cables. This work presents a green, compact, mutualistic symbiotic power solution for onboard vehicle sensors, integrating dissipated energy harvesting with wireless sensing to achieve long-term, battery-less, and real-time wireless monitoring with high sampling frequency. We present high-performance piezoelectric energy harvesters featuring novel quasi-two-dimensional designs for generating electricity from engine vibrations and functioning in tight and confined spaces. Our solution breaks limitations from wired connections and avoids battery issues while enhancing space and energy utilization. We provide theoretical and experimental insights into the statical and dynamical design theory of the harvester and its performance improvements. Vibration tests show that a 54.3-gram harvester achieves high output power (21.2 mW) and wide bandwidth (8.7 Hz) under weak excitation (0.2g). Its power-generation performance is enhanced to over 242 % of the reported maximum. We also demonstrate the stable performance of the harvester with a self-developed wireless sensor system installed in a driving vehicle. With an improved circuit and a well-adjusted harvester prototype, the system even achieves a wireless sampling frequency exceeding 40 Hz—more than 55 times the reported maximum.