Robot-assisted acoustic vortex tweezers

Abstract

Acoustic tweezers are a widely used methodology to achieve contactless manipulation. By generating the acoustic potential well to harness the targeted objects, acoustic tweezers have shown significant potential in various biomedical and biochemical research fields. Compared to other mechanisms of contactless manipulation strategies, such as optical, magnetic, electric, acoustic manipulation relies on the compressibility and acoustic impedance of the targeted objects. This feature allows acoustic tweezers to manipulate a wide range of different materials, including droplets, bubbles, cells and solid particles. In recent years, acoustic vortex beams have garnered substantial attention for introducing novel manipulation paradigms to this field. Particularly, acoustic vortex beams generate a ring-shaped acoustic intensity pattern with a Gor'kov potential field, enabling precise trapping and control of objects. Additionally, the angular momentum carried by the acoustic vortex beam can induce rotational motion over the trapped objects, enhancing flexibility for contactless manipulation applications. In this work, acoustic vortex beams were investigated through analytical simulations, and experimental characterizations, and proof-of-concept demonstrations were conducted to show the capabilities of contactless manipulation of the acoustic vortex beam. This work is consisted of two major sections. In section (I), theoretical and experimental analysis methods of acoustic vortex beams were established. In section (II), this work focuses on applying acoustic vortex beams as end effectors in combination with various manipulation platforms to develop novel methodologies. These include: (a) Robot-assisted chirality-tunable acoustic vortex tweezers for contactless, multifunctional, 4-DOF object manipulation; (b) Airborne acoustic vortex end effector-based ii contactless, multi-mode, programmable control of object surfing; (c) Generating multi-pixel thermal images through an acousto-thermal effect; (d) In-petri dish acoustic tweezers; (e) Transformable acoustic clover beams generated by space-division harmonic holography for fourdegree-of-freedom (4-DoF) contactless object manipulation. This work addresses existing knowledge gaps in acoustic manipulation by integrating acoustic vortex beams with robotic arms and linear motion stages to achieve programmable and multifunctional manipulation in biomechanical engineering. Applications include object manipulation through biological barriers, ultrasound imaging-assisted manipulation, multi-pixel acoustic thermal imaging, droplet translation and merging, as well as the congregation of cell spheroids and micro-particles. The developed techniques show the vast potential of acoustic vortex beams in both engineering and biomedical research fields.