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Sound waves replace human hands in Petri dish experiments

Sound waves replace human hands in Petri dish experiments

Three experimental proof of concept setups using acoustic tweezers in petri dishes. From left to right, a standing pattern for sorting, a vortex for concentration, and high-frequency ray-like waves for concentration and stimulation. Credit: Tony Huang, Duke University

Mechanical engineers from Duke University demonstrated a series of prototypes for manipulating particles and cells in a petri dish using sound waves. The devices, known in the scientific community as “acoustic tweezers”

;, are the first foray into making this type of instrument, hitherto relegated to laboratories with specific equipment and skills, available for use in a wide range of contexts.

The paper describing the technology appears online September 9 in the magazine Advances in science.

Acoustic tweezers are a powerful and versatile set of tools that use sound waves to manipulate bioparticles ranging from nano-sized extracellular vesicles to millimeter-sized multicellular organisms. Over the past few decades, the capabilities of acoustic tweezers have expanded from simplistic particle trapping to the precise rotation and translation of cells and organisms in three dimensions.

“Recent advances have led to many advanced and versatile tools,” said Tony Jun Huang, the distinguished William Bevan professor of mechanical engineering and materials science, who has been in the field for over a decade. “However, at the end of the day, the success of this field depends on whether end users such as biologists, chemists or doctors are willing to adopt this technology or not. This document demonstrates a step towards a much friendlier workflow to make it easier for end users to adopt this technology. “

In their first application, the acoustic tweezers used sound waves generated from opposite sides of a chip or microfluidic chamber to create nodes where cells or microparticles are trapped. Moving the wave fronts of sound waves to opposite surfaces in the chamber controlled the position of a particle in two dimensions, while adjusting the amplitudes of sound waves could push or pull them into the third.

More advanced configurations have since been demonstrated, in which sound waves reverberate in a fluidic chamber. For example, depending on the application, you can create and modify models to separate and manipulate multiple particles at once, or you can form vortices to concentrate a group of particles.

But as advanced as their capabilities are, acoustic tweezers have therefore been relegated to prototype demonstrations and workshops with specialized equipment; very few biologists have yet adopted this technology.

“Our goal is to bridge the gap between acoustic innovations and the biological / clinical test bed,” said Huang.

In the paper, Huang and his colleagues demonstrate three prototype configurations that use transducers to create sound waves that manipulate particles in the most common cell culture dish found in biomedical laboratories: the Petri dish.

In the first design, a set of four transducers, one on each side of the petri dish, creates sound waves that interact with each other to create a permanent pattern within the liquid dish sample. The setup could be used for multi-pattern cell patterning, cell-cell interaction studies, and 3-D tissue construction.

The second design uses an inclined transducer that sends an angled sound wave from under the petri dish to create a vortex that concentrates the contents of the plate in the center. This ability would allow researchers to concentrate bioparticles for signal enhancement and the construction of large cell spheroids.

In the final configuration, holographic interdigital transducers – two transducers mounted together like a hinge – create high-frequency beam-like waves from underneath the petri dish to control particles in specific locations. Moving from one design to another, the setup can stimulate cells as well as concentrate and trap bioparticles.

Together, the configurations demonstrate easy-to-use acoustic tweezers that can gently manipulate a wide variety of cells and particles without touching or labeling them. Potential applications include cell modeling and printing, cell separation and sorting, control of cell-cell interactions, tissue construction and rotation of multicellular organisms.

“The purpose of this study was to duplicate some of the previous functions of our acoustic tweezers in petri dishes,” said Huang, who also co-founded a company to pursue commercialization of the technology. “Our next goal is to build a single prototype that realizes all the capabilities of these three configurations, if not more.”

Acoustic tweezers move cells in three dimensions, build structures

More information:
“Generation of multifunctional acoustic tweezers in petri dishes for the precise and contactless manipulation of bioparticles” Advances in science (2020). DOI: 10.1126 / sciadv.abb0494

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Duke University

Sound waves replace human hands in petri dish experiments (2020, 9 September)
recovered on 10 September 2020
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