SonoTweezer: An Acoustically Powered End-Effector for Underwater Micromanipulation

Abstract

Recent advances in contactless micromanipulation strategies have revolutionized prospects of robotic manipulators as next-generation tools for minimally invasive surgeries. In particular, acoustically powered phased arrays offer dexterous means of manipulation both in air and water. Inspired by these phased arrays, we present SonoTweezer: a compact, low-power, and lightweight array of immersible ultrasonic transducers capable of trapping and manipulation of sub-mm sized agents underwater. Based on a parametric investigation with numerical pressure field simulations, we design and create a sixtransducer configuration, which is small compared to other reported multi-transducer arrays (16-256 elements). Despite the small size of array, SonoTweezer can reach pressure magnitudes of 300 kPa at a low supply voltage of 25 V to the transducers, which is in the same order of absolute pressure as multi-transducer arrays. Subsequently, we exploit the compactness of our array as an end-effector tool for a robotic manipulator to demonstrate long-range actuation of sub-millimeter agents over a hundred times the agent's body length. Furthermore, a phase-modulation over its individual transducers allows our array to locally maneuver its target agents at sub-mm steps. The ability to manipulate agents underwater makes SonoTweezer suitable for clinical applications considering water's similarity to biological media, e.g., vitreous humor and blood plasma. Finally, we show trapping and manipulation of micro-agents under medical ultrasound (US) imaging modality. This application of our Manuscript

Red blood cell trapping using single-beam acoustic tweezers in the Rayleigh regime

“…According to the linear Euler Equation 10 and its time-averaged term (7), Equation 11 can be further simplified to Equation 12 . 56 …”

Acoustically Actuated Flow in Microrobots Powered by Axisymmetric Resonant Bubbles

“…Given our concerned frequency range of driving acoustic waves (60–100 kHz) and the cross‐sectional diameter of the transducer (60 mm), the natural axial focal distance of the transducer varies between 30 and 60 mm. [ 34 ] Thus, the transducer is positioned at an average axial working distance of ≈45 mm such that the bubble arrays are close to the natural focus of the transducer (Figure S1, Supporting Information).…”

Fabrication, Acoustic Characterization and Phase Reference-Based Calibration Method for a Single-Sided Multi-Channel Ultrasonic Actuator

“…This structure is complex and unsuitable for some application scenarios, particularly when the array can only be used on one side of the targeted trapping region. On the other hand, a traveling wave generates the pressure field without a reflector, making the single-sided array suitable for use in vivo [18][19][20][21][22][23]. A single acoustic beam is produced when multiple traveling waves overlap at the same point.…”