A research article published by the Beijing Institute of Technology presented a piezoelectric energy harvester (PEH) weighing only 46 milligrams. By matching the thoracic vibration frequency and optimizing the center of gravity distribution of bees, the device achieved high energy output (5.66 V and 1.27 mW/cm³), with experimental verification showing minimal interference with normal flight behaviors.
The new research paper, published on Feb. 26, 2025 in the journal Cyborg and Bionic Systems, presented innovative approaches including a frequency interval matching methodology and gravity center optimization strategy, offering new design paradigms for micro-scale biological energy harvesting systems.
Recent studies have achieved notable progress in energy harvesting for insect cyborgs through innovative designs and bio-inspired strategies. However, developing lightweight, high-output energy harvesters that minimally disrupt insect flight behavior remains a significant challenge, often relying on iterative trial-and-error approaches during design and testing. "By integrating frequency interval matching with center-of-gravity optimization, we systematically aligned the harvester's resonant frequency with the bee's thorax vibration, enabling efficient energy conversion without compromising flight stability," explained corresponding author Jieliang Zhao, a professor at Beijing Institute of Technology. The proposed piezoelectric energy harvester (PEH) incorporates (a) PVDF films for flexibility and low mass, (b) a double-crystal structure to amplify voltage output, and (c) precise alignment with the bee's natural vibration frequency (210–220 Hz). "This approach eliminates the need for bulky batteries, extending operational lifespan and enhancing the practicality of insect cyborgs in real-world applications," added co-author Jianing Wu from Sun Yat-sen University.
The PEH was fabricated using laser-cut copper substrates and PVDF films bonded with conductive adhesive, followed by 3D-printed molds to finalize its ultralight structure (46 mg). Multiphysics simulations in Comsol validated the design, predicting displacement and voltage outputs that closely matched experimental results. "High-speed CMOS cameras provided critical insights into wing-flapping dynamics, allowing us to optimize the harvester's resonance frequency under varying load conditions," noted Wenzhong Wang, a lead researcher. Testing demonstrated a maximum output of 5.66 V and 1.27 mW/cm³, surpassing existing solutions for beetles and moths.
"The bees exhibited normal flight behavior even with the PEH attached, recovering from flips within 2 seconds and hovering freely—proof of its minimal biomechanical interference," said Zhao. While the harvester excels in energy density and biocompatibility, challenges remain in energy storage and scalability. "Future work will focus on integrating energy management circuits and expanding this methodology to other flying insects, such as dragonflies and butterflies, to establish standardized energy solutions for biohybrid systems," concluded the team. This breakthrough paves the way for self-sustaining insect cyborgs in environmental monitoring and rescue missions, avoiding resource-heavy design iterations through physics-driven optimization.
Authors of the paper include Zhiyun Ma, Jieliang Zhao, Li Yu, Lulu Liang, Zhong Liu, Yongxia Gu, Jianing Wu, Wenzhong Wang, Shaoze Yan.
This work was supported by the National Key R&D Program of China (2021YFB3400200); the Beijing Natural Science Foundation (3212012); the National Natural Science Foundation of China (52075038); the Opening Project of the Key Laboratory of Bionic Engineering (Ministry of Education), Jilin University (KF20200001); and the Opening Project of State Key Laboratory of Tribology, Tsinghua University (SKLTKF20B06).
The paper, "Piezoelectric Energy Harvesting from the Thorax Vibration of Freely Flying Bees" was published in the journal Cyborg and Bionic Systems on Feb 26 2025, at DOI: 10.34133/cbsystems.0210.
