Although piezoelectric energy harvesting (PEH) from structural vibrations is well-recognized as a viable paradigm for renewable power generation in the micro- to milliwatt range, most real-life structures, such as bridges, are characterized by low-frequency erratic vibrations, which tend to diminish their practical utility for PEH. This is because the interface circuits involved in rectification and storage tend to lose their efficiency on account of low frequencies and the erratic nature of real-life structural vibrations. This study proposes a fine-tuned D1000 bridge rectifier circuit to circumvent the above problem, culminating in a successful proof-of-concept demonstration of PEH and subsequent storage in Ni–MH rechargeable batteries from real-life bridge vibrations. The unique feature of this experimental study entails successfully utilizing simple-type piezo elements directly bonded to the host structure and operating in the d31 mode. Additionally, piezo elements bonded to a secondary cantilever structure (acting as a parasite to the main structure) are studied for comparison. Here we present a laboratory-based experimental study of a bridge rectifier circuit for charging a battery from the energy harvested using piezoelectric elements. Results show that it is feasible to charge a battery under a low-frequency and low-voltage scenario (Voc = 1 V at 5 Hz) employing the proposed D1000 rectifier circuit. We also present a field evaluation of the fine-tuned circuit on vibrations of a real-life flyover. Storage of energy in the capacitor as well as battery has been successfully realized in a realistic environment, achieving a power of 0.27 mW. This study represents successfully increasing the technology readiness level of PEH from 4 to 7 from structural vibrations.
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