Scientists at the University of Helsinki, in collaboration with the Public University of Navarre and the University of Michigan, have demonstrated a prototype ultrasonic tube that can confine and guide liquids, gases, powders and even electrical discharges through the air using nothing but sound waves. The device, described as the closest thing to magic by the project leader, could eventually enable contactless handling of corrosive or sticky materials that damage conventional pipes.
The prototype consists of 256 miniature ultrasonic transducers arranged around a cylindrical structure. The transducers emit sound waves at about 40 kilohertz, controlled in such a way that they interact to produce an acoustic field that exerts forces on passing materials, keeping them confined to a specific path. By adjusting the timing of the waves, the researchers can bend or redirect that path without any moving parts.
The tube measures just eight centimetres long and draws about 50 watts of electricity. In experiments, the team successfully guided flowing water, directed powders into different containers, steered mist and gas streams, and controlled the path of electrical discharges.
Previous acoustic manipulation systems have largely focused on suspending and moving individual particles or droplets, but the new system can handle continuous streams. The concept was inspired by an earlier project in which the researchers used ultrasound to clean substances stuck to the inner surfaces of pipes. They then wondered if they could eliminate the problem entirely by removing the pipe's physical walls.
"Of all the experimental setups I have seen, I would say this is the closest thing to magic," said Ari Salmi, Professor of Electronics at the University of Helsinki and project leader.
Potential applications include contactless transportation of corrosive or sticky materials, handling sensitive substances that are easily contaminated, and precise delivery of materials. The researchers believe they could connect similar modules in series to create much longer tubes.
One limitation is the amount of hardware required: 256 speakers for an eight-centimetre tube. Another is the intensity of the ultrasound. The researchers note that at the centre of the tube the sound intensity is comparable to the continuous roar of gunfire right next to the ear, and even outside the device it is comparable to standing beside a jet engine. However, at 40 kHz, the sound is above the normal range of human hearing. The research was published in the journal PNAS.
Analysis
Why This Matters
- The technology could revolutionise handling of hazardous, corrosive or sticky materials by eliminating physical contact and contamination risks.
- It enables continuous streams rather than individual particles, opening new possibilities for chemical processing, pharmaceuticals and manufacturing.
- If scaled up, ultrasonic pipes could replace conventional pipelines in specialised settings, reducing maintenance and waste.
Background
Acoustic manipulation has been used for decades to levitate small objects and droplets. However, previous systems could only handle individual particles or small batches. This prototype is the first to demonstrate continuous guidance of multiple states of matter (liquid, gas, powder, plasma) through the air using sound alone. The work builds on earlier research where ultrasound was used to clean pipe interiors, leading the team to ask whether the pipe itself could be removed.
What to Watch
- Whether the researchers can scale the tube length by connecting modules in series, as they suggest.
- Development of more efficient speaker configurations to reduce hardware requirements.
- Exploration of real-world applications in industrial settings where physical pipes are impractical or dangerous.
Checked
12 claims in this story checked against 1 source: 11 supported.
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- SupportedResearchers demonstrated an ultrasonic tube that guides liquids and gases through the air.New Atlas: Technology-Innovation-Outdoor News: “Scientists at the University of Helsinki, in collaboration with researchers from the Public University of Navarre and the University of Michigan, have now demonstrated a semblance of the technology behind that concept, with an ultrasonic tube that can physically confine and guide matter through the air.”
- SupportedThe prototype uses 256 speakers to confine and steer matter with sound.New Atlas: Technology-Innovation-Outdoor News: “The invisible, massless tube, made of nothing but ultrasonic sound waves from 256 miniature speakers, can guide liquids, gases, powders, and even plasma”
- Partly supportedThe technology could enable contactless transport of hazardous substances.New Atlas: Technology-Innovation-Outdoor News: “As far as potential applications go, the team envisions contactless transportation of substances, particularly corrosive or sticky materials that can damage conventional pipes or build up on their inner surfaces.”
- SupportedThe research involved the University of Helsinki, the Public University of Navarre and the University of Michigan.New Atlas: Technology-Innovation-Outdoor News: “Scientists at the University of Helsinki, in collaboration with researchers from the Public University of Navarre and the University of Michigan”
- SupportedThe tube can guide liquids, gases, powders and electrical discharges through the air using sound waves.New Atlas: Technology-Innovation-Outdoor News: “In their experiments, the researchers successfully guided flowing water, directed powders into different containers, steered mist and gas streams, and even controlled the path of electrical discharges.”
- SupportedAri Salmi called the setup “the closest thing to magic.”New Atlas: Technology-Innovation-Outdoor News: ““Of all the experimental setups I have seen, I would say this is the closest thing to magic,” says Ari Salmi, Professor of Electronics at the University of Helsinki and project leader.”
- SupportedThe transducers’ sound waves interact to create a field that keeps materials on a particular path, which can be redirected by adjusting the waves.New Atlas: Technology-Innovation-Outdoor News: “By carefully controlling the timing of these waves, the researchers can make them interact to produce an acoustic field that exerts forces on passing materials, keeping them confined to a particular path. Adjusting the field allows the team to bend or redirect that path”
- SupportedThe prototype tube is eight centimetres long.New Atlas: Technology-Innovation-Outdoor News: “The prototype tube measures just 8 cm (3.1 inches) long”
- SupportedThe prototype draws about 50 watts of electricity.New Atlas: Technology-Innovation-Outdoor News: “and draws about 50 watts of electricity”
- SupportedExperiments guided flowing water, powders, mist and gas streams, and electrical discharges.New Atlas: Technology-Innovation-Outdoor News: “In their experiments, the researchers successfully guided flowing water, directed powders into different containers, steered mist and gas streams, and even controlled the path of electrical discharges.”
- SupportedUnlike earlier acoustic manipulation systems focused largely on individual particles or droplets, the new system can handle continuous streams.New Atlas: Technology-Innovation-Outdoor News: “Previous acoustic manipulation systems have largely focused on suspending and moving individual particles or droplets, but the new system can handle continuous streams.”
- SupportedThe researchers say the ultrasound is comparable in intensity to gunfire beside the ear at the tube’s centre and to a jet engine outside it.New Atlas: Technology-Innovation-Outdoor News: “According to the researchers, the ultrasound at the center of the tube has an intensity comparable to the continuous roar of gunfire right next to your ear. Even outside the device, the acoustic intensity is comparable to standing beside a jet engine.”
