There was a moment, after much trial and error, when a team of engineering researchers at Concordia University realized they had achieved something remarkable.
It might not have looked like much from the outside: a few clicks on a computer screen, the hum of a 3D printer, and a few bubbles solidifying in a plastic dish filled with liquid.
But this – at precisely 19:27 on April 27, 2018 – was the first time in the world that someone successfully printed a 3D object using sound waves.
“We were jumping, frankly, because we couldn’t believe it,” said Muthukumaran Pakirisamy, professor of engineering and director of the Optical Bio-Microsystems Laboratory at Concordia.
“It was a great moment for us … we had a lot of fun and parties afterwards!”
Now the team is celebrating again their research, published last April in the journal Nature Communicationswas honored as one of the 10 best scientific discoveries of the year by Quebec Science Journal.
It’s a technology that Packirisamy’s team believes could be used in the future for everything from repairing spacecraft and nuclear reactors to printing medical devices directly into the patient’s body.
Small bubbles
Direct sonic printing works through a process called cavitation, explained Mohsen Habibi, a research associate at the lab.
Ultrasonic waves are used to trigger a series of tiny chemical reactions lasting only a matter of nanoseconds. The reactions produce a tremendous amount of pressure and heat, causing bubbles to form in the print material, which then harden.
“These bubbles basically create polymerization, so they harden the liquid resin into a solid,” Habibi said.
As these bubbles form and solidify, the 3D object takes shape, layer by layer, into whatever design the team wants.
The development team believes this technology could be used for everything from repairing spacecraft and nuclear reactors to printing medical devices directly into the patient’s body. (Ainslie MacLellan/CBC)
So far, they’ve printed everything from delicate honeycomb patterns to gears and propellers and even the outlines of human ears and noses.
High Intensity Focused Ultrasound (HIFU) has already used in medical procedures for tissue destruction, such as for tumor ablations.
“This is the first time we’ve used this sound chemistry of ultrasound waves to create things,” Pakirisamy said.
He said sonic printing can produce objects 100 microns thick – about the width of a human hair – and can work with different materials such as plastic, metal, ceramic or biomaterials.
Sound potential
While 3D printing itself isn’t new, Packirisamy said direct sonic printing offers some advantages over existing technologies, many of which use lasers to manipulate the building material so the object can take shape.
“Sound can penetrate barriers where light cannot,” Pakirisamy said.
This opens up the potential to 3D print an object directly into a hard-to-reach location, such as an airplane engine or under the skin of a surgical patient.
If a polymer or synthetic tissue is injected into the patient’s body, the sonic printer can be used outside the body to shape the material into the desired shape, he said.
Everything from stents to — eventually — synthetic organs can be printed, according to Pakirisamy.
“We can also repair internal bio-organs. This is a future opportunity,” he said.
The team tested this theory by sending ultrasound waves through a 15mm layer of pig tissue. They were able to print a small 3D maple leaf on the other side.
While this all sounds a bit sci-fi, PhD student Sherwin Forughi said it could theoretically allow patients to avoid open surgery.
“This allows surgeons to perform minimally invasive operations and … will reduce recovery time for patients,” he said.
Top 10 discoveries
Partly because of these potential impacts on society, the study was named one of the top 10 scientific discoveries of the year by the journal Québec Science.
“It’s amazing, it’s something that can have a lot of applications in a lot of industries. Obviously in hospitals, but also in the aerospace industry and many industries,” said Melissa Guimet, editor-in-chief of the journal Québec Science, on CBC’s All in a Weekend.
While 3D printing itself is nothing new, researchers say that direct sonic printing offers some advantages over existing technologies. (Ainslie MacLellan/CBC)
“It’s something that has had a big impact in the scientific community,” she said. “A lot of people were amazed by this work.”
For Pakirisamy, the magazine’s accolades were unexpected but welcome, adding that the team now feels a renewed sense of purpose to continue their work.
“This is a really defining moment for us,” he said.
“It gives us new momentum and new impetus to take the technology and apply it to society in a much more meaningful way.”
LISTEN | Learn more about Concordia University’s Optical-Bio Microsystems Lab:
Sunrise Montreal 10:19 Concordia researchers honored for work on printing 3D objects using sound waves
Daybreak’s Ainslie MacLellan takes us inside Concordia University’s Optical Bio-Microsystems Lab, where researchers have developed direct sound printing, a technology they hope could lead to less invasive surgeries in the future.
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