OPTIMIZATION DESIGN OF ACOUSTIC CODED METASURFACES FOR PARTICLE LEVITATION

Acoustic levitation, a cutting-edge technique with significant potential in fields such as biomedical detection and micro/nano manufacturing, enables contact-free manipulation of particles through the application of acoustic radiation force. However, current acoustic levitation technologies, which predominantly rely on phased arrays or traditional metasurfaces, primarily manipulate particles by repeatedly adjusting the phase of acoustic waves.This approach has notable limitations in terms of manipulation efficiency, levitation height, and the accuracy of levitation forces. To address these challenges, this paper proposes an optimized design method based on acoustic coding metasurfaces to achieve efficient and precise acoustic radiation force and particle manipulation in air. The optimization model is constructed with the phase delay and energy transmission efficiency of coding elements as objectives, enabling the acquisition of the overall optimized coding configuration of the metasurface. By establishing a direct mapping relationship between the acoustic radiation force acting on particles and the topological configuration of the metasurface, based on acoustic field calculations and acoustic radiation force theory, the entire optimization process does not require predefining the morphology of the acoustic field. The results demonstrate that the optimized acoustic coding metasurface can generate an acoustic field distribution that closely matches the target field, with the produced acoustic radiation force values largely consistent with theoretical targets. Instead, it directly targets the required acoustic radiation force for particle manipulation, establishing an inverse correlation between structural parameters and force objectives, thereby effectively enhancing the adaptability and precision of nonlinear acoustic field design.