Scientists Use "Acoustic Holograms" To Form Particles Into Complex 3D Shapes

It's like 3D printing... all in "one shot."

Sound Off

Forget your regular ol' 3D printer. Why not try using sound waves to form a 3D object?

That's exactly what researchers in Germany set out to do, making use of "acoustic holograms" to form distinct 3D shapes out of particles suspended in water — all in "one shot," said study lead author Kai Melde, a researcher from the Max Planck Institute, in a press release.

According to a study on the work, published last week in the journal Science Advances, the researchers were able to create a helix and a figure 8 out of silica gel beads, assembled biological cells into spherical clumps, and even provided a compelling concept for forming the shape of a dove in future experiments.

Acoustic Rock

These acoustic holograms work by cleverly manipulating the pressure exerted by high frequency ultrasonic waves via the inexpensive use of a conventionally 3D-printed plate.

Such a plate is carefully designed so that sound waves from a loudspeaker pass through at varying predetermined lengths, allowing scientists to control the exact amount of pressure exerted across a field in order to move or suspend particles in specific positions.

In effect, the acoustic holograms function as a sort of frame that the suspended particles can adhere to.

Cell Assembly

Melde's previous study in 2016 had already demonstrated this technique could be used to create 2D patterns. It wouldn't be until over six years later, though, that his team were able to add an extra dimension.

"The crucial idea was to use multiple acoustic holograms together and form a combined field that can catch the particles," Melde explained.

However, unlike 3D printers, this technique probably won't be used to manufacture specialized parts or churn out entire houses — at least not in the near future. Instead, the researchers believe that it could have invaluable applications for gently manipulating delicate biological cells, either directly or by placing them in easier to maneuver gel beads, according to the study.

"This can be very useful for bioprinting," said co-author Peer Fischer, a professor of experimental physics at Heidelberg University, in the release. "The cells used there are particularly sensitive to the environment during the process."

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