It may sound like a trance to move objects without touching them but, optical trapping technology has been helping scientists move minuscule things around for many years in biology and chemistry. In reality, Arthur Ashkin (1922-2020) received half of the 2018 Nobel Prize for Physics because of this technology’s exceptional achievements.
However, there are certain drawbacks to using laser light, namely the limitations placed on the qualities of the objects that can be moved. Using an array of ultrasound transducers, the acoustic tweezers technique generates non-contact interaction of small objects with sound waves. Researchers were able to create a 3D acoustic field that captured and lifted little polystyrene balls from a reflecting surface using transducers, which are objects that transform energy from one form to another.
Instead of optical rays, they used acoustic trapping. Sound waves can be used to manipulate a larger spectrum of objects, to the point where millimeter-sized particles can be successfully manipulated. Although they haven’t been around as long as their optical counterparts, acoustic levitation, and manipulation have tremendous potential in the lab and beyond. However, there are significant technical obstacles to overcome.
It’s challenging to handle enormous arrays of ultrasonic transducers individually and correctly in real-time and to get the best sound fields to move objects far away from the transducers themselves, especially near the transducers themselves. There are still hurdles in keeping particles trapped and stable. This fascinating new technology offers essential growth from a scientific curiosity to a beneficial tool in the lab and industry.
The approach was shown using 3-mm glass beads trapped in vortex-shaped ultrasonic beams. The beads were steered through complicated 3D routes within a water tank and in the bladders of live pigs by guiding the beams electrically or simply moving the ultrasound transducer. Physicists have been enclosing and manipulating minuscule objects with optical tweezers for decades. When light refracted by a dielectric particle deviate from the axis of a laser beam, it causes a sideways kick, forcing the particle back. This force holds the particle in the beam’s center, where the light intensity is highest. Acoustic tweezers aren’t the same as traditional tweezers.
Reported by: Imaaz Nadeem
Written by: Yashfa Fatima