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2025

A beam of light propels microdevices to new heights

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Professor Dai Zhaoqing's team at Zhejiang A&F University and Professor He Ximin's team at University of California, Los Angeles collaborated to publish a research paper titled Science in the journal titled " Launching by Cavitation ". This study innovatively proposed and validated an efficient launching mechanism based on cavitation effects, breaking through the limitations of traditional elastic and phase-change driven methods in terms of energy density and release rate, providing a new approach for the beneficial use of cavitation effects. By precisely controlling the violent collapse of bubbles in liquid with lasers, the traditionally destructive cavitation phenomenon is transformed into a controllable and efficient power source, successfully achieving high-speed jumping, swimming, and precise movement of miniature devices, showing significant application potential in robotics, precision operations, and biomedicine.

The first author of the paper is Associate Professor Wang Dalei; co-first authors are Liu Zixiao, Zhao Hongping, Qin Huanqi; corresponding authors are Associate Professors Liu Wei, Wang Dan, Professor Zhou Guoquan, Professor He Ximin, and Professor Dai Zhaoqing.

Extreme Performance: Redefining the Standards of Microscale Motion

With the help of a microsecond-level high-speed imaging system, the team fully captured and analyzed the entire process of cavitation bubbles from nucleation to collapse acting on micro devices, achieving motion visualization. This mechanism brings a comprehensive breakthrough in motion performance: jump height reaches 1.5 meters (1500 times its body length), takeoff speed of 12 m/s, acceleration exceeding 7×10 ⁴ m/s ² , energy efficiency of 0.64%; simultaneously achieving microsecond-level time control, submicron-level spatial positioning, and nano-Newton-level force regulation accuracy, with durability exceeding 500 cycles. All performance indicators improved by 2–3 orders of magnitude compared to existing technologies, resetting the performance limits of microscale motion.

Mechanism Analysis: Precise Control of Multi-Field Coupling of Light-Thermal-Force-Flow

The research team systematically revealed the three-step coupling mechanism of light-controlled cavitation through multi-scale experiments and simulations: first, TiC nanoparticles undergo localized surface plasmon resonance under 808 nm laser irradiation, with a photothermal conversion efficiency of up to 84.47%, raising the interface temperature to 303.1°C within microseconds; second, using the Gilmore model to describe the evolution of "soliton-like" bubbles, it was found that the contraction phase speed can reach 571 m/s, with a collapse time of only 8.4 μs, revealing the microsecond-level energy release mechanism; finally, VOF multiphase flow simulation reproduced the generation process of high-speed jets (10.2 MPa), clarifying the energy transfer path from microscopic bubbles to macroscopic motion.

Theoretical Innovation: Achieving the Leap from Phenomenon to Quantitative Prediction

At the theoretical level, the study achieved three major breakthroughs: establishing a quantitative predictive model for light-controlled cavitation that accurately predicts cavitation thresholds and energy output in different materials and liquid environments; proposing a cavitation energy regulation theory that enables force output from micro-Newtons to milli-Newtons and motion direction control through precise regulation of laser intensity, spot position, and irradiation time; developing a multiphysics coupling numerical method that unifies photothermal effects, phase change processes, fluid dynamics, and solid mechanics within a single framework, completing high-precision simulation of the entire process.

Applications and Summary

This mechanism demonstrates broad applicability: in materials, it is suitable for various photothermal materials such as metals, carbon materials, and polymers; in environments, it is effective in different media including water, glycerol, and PVA solutions; in excitation methods, it is compatible with photothermal, electric spark, and ultrasonic forms; in scale, it covers from micrometer to millimeter levels, following the same physical laws. In biomimetic applications, it can achieve cavitation seeding of vinegar grass seeds (distance >0.7m), chameleon predation processes, and archerfish predation. This high degree of universality provides a solid theoretical foundation for cross-disciplinary applications.

This research not only solves long-standing fundamental scientific problems in the field of cavitation but also establishes a brand-new precise micro-manipulation physical paradigm: realizing the transformation of cavitation behavior from random and destructive to controllable and dynamic; successfully extending cavitation effects to the field of microscale precise manipulation; constructing a multi-field coupling theoretical and experimental framework; completing the leap from qualitative description to quantitative prediction. This breakthrough not only advances the development of cavitation physics but also provides new technical pathways and theoretical support for fields such as micro-nano manufacturing, biomedicine, and precision manipulation.