Scientists Develop ‘Acoustic Tweezers’ Able to Manipulate Living Cells Without Touching Them

A team of scientists from Duke University in the USA has developed a set of “acoustic tweezers” that allow them to manipulate living cells using sounds waves, rather than physical contact. The instrument is precise enough to allow scientists to manoeuvre nano-sized particles of living matter.

Acoustic tweezers are not a new technology per se and have existed in some form for decades. However, until now they have been both extremely specialised and expensive pieces of equipment as well as not working well in combination with other laboratory apparatus. That’s meant previous examples of the technology have not been widely used by biologists.

The new technology developed by the Duke team is, says Professor Tony Jun Huang of the department of mechanical engineering and materials science, much easier to use and can manipulate organic matter in a standard lab Petri dish. Its seen as being used to “handle” entities such as nanometre-sized structures found within individual cells such as vesicles and millimetre-long fish larvae.

“Recent advances have led to many advanced tools”, says Professor Huang.

 “However, the success of this field depends on whether end users such as biologists, chemists or clinicians are willing to adopt this technology. This paper demonstrates a step toward a much friendlier workflow to make it easier for end users to adopt this technology.”

The Duke team’s acoustic tweezers create soundwaves by using transducers. A tilted transducer sending out an angled sound wave from beneath a Petri dish creates a whirlpool effect that draws the contents of the dish into the centre. Another technique is to use two transducers to emit high-frequency beam-like sound waves. Again, coming from below a Petri dish, these can “prod” nano-sized particles.

Published in the journal Science Advances, the research is part of a wave of study into methods of manipulating miniscule organisms and matter. In 2018 another group of scientists published their research on “optical tweezers”, that were able to manipulate individual atoms using lights. The scientists behind the project said it demonstrated the possibility of “designer molecules” being built atom at a time. The process was described by one of the team involved as “more akin to putting together Lego than mixing together chemicals.”

Another potential use of acoustic tweezers could be to manoeuvre tiny amounts of drugs to precise locations deep within the human body. That could, for example, allow precision administration of toxic cancer treatments directly to tumour sites. Doing so would reduce the patient’s overall exposure to the drugs dramatically, eliminating a large portion of side effects and collateral damage to the body.

Gene therapies which involve infiltrating a small target group of cells with genetic material is another potential application of the tweezers. Unlike optical tweezers developed in the 1980s and still used today to trap nano-sized material such as viruses, bacteria and single cells in a beam of light, the new acoustic tweezers rely on both simpler, less expensive technology and do not damage organic material. Trials have shown no damage to both red blood cells and zebrafish embryos held by the acoustic tweezers for up to 30 minutes.