Ultrasonic tweezer for multifunctional droplet manipulation

Abstract

Spatiotemporally controllable droplet manipulation is essential in diverse applications, ranging from thermal management to microfluidics and water harvesting. Despite considerable advances, droplet manipulation without surface or droplet pretreatment is still challenging in terms of response and functional adaptability. Here, a droplet ultrasonic tweezer (DUT) based on phased array is proposed for versatile droplet manipulation. The DUT can generate a twin trap ultrasonic field at the focal point for trapping and maneuvering the droplet by changing the position of the focal point, which enables a highly flexible and precise programmable control. By leveraging the acoustic radiation force resulting from the twin trap, the droplet can pass through a confined slit 2.5 times smaller than its own size, cross a slope with an inclination up to 80°, and even reciprocate in the vertical direction. These findings provide a satisfactory paradigm for robust contactless droplet manipulation in various practical settings including droplet ballistic ejection, droplet dispensing, and surface cleaning.

Mechano‐Driven Tribo‐Electrophoresis Enabled Human–Droplet Interaction in 3D Space

“…[1][2][3][4][5] The manipulation of droplets in oil has garnered significant attention for its ability to prevent cross-contamination, avoid dispersion, enhance contact angles, and minimize evaporation. [6,7] This has propelled the exploration of electronically controlled droplets, [6][7][8][9][10][11] which offer notable benefits in terms of low power consumption, fast response time, and scalability, distinguishing them from the approaches based on magnetic field, [12] light-driven, [13] acoustic/ultrasonic tweezers, [14,15] thermal evaporation, [16] and bio-wettability. [17] However, obligatory external power supplies make them vulnerable to shortcircuiting.…”

Acoustic Trapping and Manipulation of Hollow Microparticles under Fluid Flow Using a Single-Lens Focused Ultrasound Transducer

“…While tuning the size and modulus of passive microparticles can increase their margination efficiency, the active control of their local concentration within specific confined regions remains elusive. To address these issues, researchers have employed active particle manipulation and trapping systems using optical, , magnetic, , and acoustic forces, , as well as microbubbles , and microrobots , as the stimuli-responsive agents.…”

Acoustofluidics for simultaneous droplet transport and centrifugation facilitating ultrasensitive biomarker detection

“…, using a twin trap ultrasonic field). 30 However, it is unclear if these methods can be integrated with other essential biological sample processing capabilities, such as droplet centrifugation for reagent mixing, concentration, or purification.…”