A new beam pattern devised by University of Rochester researchers could bring unprecedented sharpness to ultrasound and radar images, burn precise holes in manufactured materials at a nano scale—even etch new properties onto their surfaces.
These are just a few of the items on the “Christmas tree” of possible applications for the beam pattern that Miguel Alonso, professor of optics, and Kevin Parker, the William F. May Professor of Engineering, describe in a recent paper in Optics Express.
The pattern results from what Parker calls “an analytically beautiful mathematical solution” that Alonso devised. It causes a light or sound wave to collapse inward, forming—during a mere nanosecond or less—an incredibly thin, intense beam before the wave expands outward again.
“All the energy fits together in time and space so it comes together—BAM!—like a crescendo,” says Parker, explosively clapping his hands for emphasis. “It can be done with an optical light wave, with ultrasound, radar, sonar – it will work for all of them.”
Most traditional beam patterns maintain a persistent shape as long as the source is operating. However, they are not as intense as the beam created by Parker and Alonso, which the researchers call a “needle pulse beam.” “It is very localized, with no extensions or side lobes that would carry energy away from the main beam,” says Alonso.
Side lobes, radiating off a beam like the halos sometimes seen around a car headlight, are especially problematic in ultrasound. “Side lobes are the enemy,” Alonso says. “You want to direct all of your ultrasound wave to the one thing you want to image, so then, whatever is reflected back will tell you about that one thing. If you’re also getting a diffusion of waves elsewhere, it blurs the image.”
Because it is incredibly narrow, the new beam “makes it possible to resolve things at exquisite resolutions, where you need to separate tiny things that are close together,” Parker says, adding that the beam could have applications not only for ultrasound, but microscopy, radar, and sonar.
According to Alonso, industrial applications might include any form of laser materials processing that involves putting as much light as possible on a given line.
The idea for the needle pulse beam originated with Parker, an expert in ultrasound, who for inspiration often peruses mathematical functions from a century or more ago in the “ancient texts.”
“I could see a general form of the solution; but I couldn’t get past the equation,” he says “So I went to the person (Alonso) who I consider the world’s leading expert on optical theory and mathematics.”
They came up with various expressions that were “mathematically correct,” Alonso says, but corresponded to beams requiring an infinite amount of energy. The solution—“a particular mathematical trick” that could apply to a beam with finite energy—came to him while swimming with his wife in Lake Ontario.
“Many of the ideas I have do not happen at my desk,” Alonso says. “It happens while I’m riding my bicycle, or in the shower, or swimming, or doing something else—away from all the paperwork.”
Parker says this discovery continues an international quest that began at the University of Rochester. In 1986—in the face of worldwide skepticism—a University team including Joseph Eberly, the Andrew Carnegie Professor of Physics and professor of optics, offered evidence of an unexpected new, diffraction-free light form. The so-called Bessel beam is now widely used.
“It had been decades since anyone formulated a new type of beam,” Parker says. “Then, as soon as the Bessel beam was announced, people were thinking there may be other new beams out there. The race was on.
“Finding a new beam pattern is a like finding a new element. It doesn’t happen very often.”
Learn more: New ‘needle pulse’ beam pattern packs a punch
Fast, accurate and inexpensive medical tests in a doctor’s office are only possible for some conditions. To create new in-office diagnostics for additional diseases, researchers report in the journal ACS Nano a new technique that uses ultrasound to concentrate fluorescently labeled disease biomarkers otherwise impossible to detect with current equipment in an office setting.
The markers’ signal could someday be analyzed via a smartphone app.
Ultrasound is a safe, noninvasive, inexpensive and portable technique best known for monitoring pregnancies. But these high-frequency acoustic waves can also be used to gently handle blood components, cells and protein crystals at the microscopic level. With an eye toward point-of-care diagnostic applications, Tony Huang, Zhangming Mao and colleagues wanted to harness these sound waves to help detect even smaller particles and biomarkers for diseases such as cancer that often require special laboratory equipment to detect.
The researchers developed an acoustofluidic chip that, though vibrations, can form a streaming vortex inside a tiny glass capillary tube using a minimal amount of energy. Testing showed that the vortex could force nanoparticles ranging in diameter from 80 to 500 nanometers to swirl into the center of the capillary. The nanoparticles captured biomarkers labeled with a fluorescent tag, concentrating them in the capillary to boost their signal. This increased brightness could make the signal readable with a smartphone camera.
Researchers at The University of Nottingham have developed a break-through technique that uses sound rather than light to see inside live cells, with potential application in stem-cell transplants and cancer diagnosis.
The new nanoscale ultrasound technique uses shorter-than-optical wavelengths of sound and could even rival the optical super-resolution techniques which won the 2014 Nobel Prize for Chemistry.
This new kind of sub-optical phonon (sound) imaging provides invaluable information about the structure, mechanical properties and behaviour of individual living cells at a scale not achieved before.
Researchers from the Optics and Photonics group in the Faculty of Engineering, University of Nottingham, are behind the discovery, which is published in the paper ‘High resolution 3D imaging of living cells with sub-optical wavelength phonons’ in the journal, Scientific Reports.
“People are most familiar with ultrasound as a way of looking inside the body — in the simplest terms we’ve engineered it to the point where it can look inside an individual cell. Nottingham is currently the only place in the world with this capability,” said Professor Matt Clark, who contributed to the study.
In conventional optical microscopy, which uses light (photons), the size of the smallest object you can see (or the resolution) is limited by the wavelength.
For biological specimens, the wavelength cannot go smaller than that of blue light because the energy carried on photons of light in the ultraviolet (and shorter wavelengths) is so high it can destroy the bonds that hold biological molecules together damaging the cells.
Optical super-resolution imaging also has distinct limitations in biological studies. This is because the fluorescent dyes it uses are often toxic and it requires huge amounts of light and time to observe and reconstruct an image which is damaging to cells.
Unlike light, sound does not have a high-energy payload. This has enabled the Nottingham researchers to use smaller wavelengths and see smaller things and get to higher resolutions without damaging the cell biology.
“A great thing is that, like ultrasound on the body, ultrasound in the cells causes no damage and requires no toxic chemicals to work. Because of this we can see inside cells that one day might be put back into the body, for instance as stem-cell transplants,” adds Professor Clark.
New noninvasive technique may lead to low-cost therapy for patients with severe brain injury
A 25-year-old man recovering from a coma has made remarkable progress following a treatment at UCLA to jump-start his brain using ultrasound. The technique uses sonic stimulation to excite the neurons in the thalamus, an egg-shaped structure that serves as the brain’s central hub for processing information.
“It’s almost as if we were jump-starting the neurons back into function,” said Martin Monti, the study’s lead author and a UCLA associate professor of psychology and neurosurgery. “Until now, the only way to achieve this was a risky surgical procedure known as deep brain stimulation, in which electrodes are implanted directly inside the thalamus,” he said. “Our approach directly targets the thalamus but is noninvasive.”
Monti said the researchers expected the positive result, but he cautioned that the procedure requires further study on additional patients before they determine whether it could be used consistently to help other people recovering from comas.
“It is possible that we were just very lucky and happened to have stimulated the patient just as he was spontaneously recovering,” Monti said.
A report on the treatment is published in the journal Brain Stimulation. This is the first time the approach has been used to treat severe brain injury.
The technique, called low-intensity focused ultrasound pulsation, was pioneered by Alexander Bystritsky, a UCLA professor of psychiatry and biobehavioral sciences in the Semel Institute for Neuroscience and Human Behavior and a co-author of the study. Bystritsky is also a founder of Brainsonix, a Sherman Oaks, California-based company that provided the device the researchers used in the study.
That device, about the size of a coffee cup saucer, creates a small sphere of acoustic energy that can be aimed at different regions of the brain to excite brain tissue. For the new study, researchers placed it by the side of the man’s head and activated it 10 times for 30 seconds each, in a 10-minute period.
Monti said the device is safe because it emits only a small amount of energy — less than a conventional Doppler ultrasound.
Before the procedure began, the man showed only minimal signs of being conscious and of understanding speech — for example, he could perform small, limited movements when asked. By the day after the treatment, his responses had improved measurably. Three days later, the patient had regained full consciousness and full language comprehension, and he could reliably communicate by nodding his head “yes” or shaking his head “no.” He even made a fist-bump gesture to say goodbye to one of his doctors.
“The changes were remarkable,” Monti said.
The technique targets the thalamus because, in people whose mental function is deeply impaired after a coma, thalamus performance is typically diminished. And medications that are commonly prescribed to people who are coming out of a coma target the thalamus only indirectly.
Under the direction of Paul Vespa, a UCLA professor of neurology and neurosurgery at the David Geffen School of Medicine at UCLA, the researchers plan to test the procedure on several more people beginning this fall at the Ronald Reagan UCLA Medical Center. Those tests will be conducted in partnership with the UCLA Brain Injury Research Center and funded in part by the Dana Foundation and the Tiny Blue Dot Foundation.
If the technology helps other people recovering from coma, Monti said, it could eventually be used to build a portable device — perhaps incorporated into a helmet — as a low-cost way to help “wake up” patients, perhaps even those who are in a vegetative or minimally conscious state. Currently, there is almost no effective treatment for such patients, he said.
Researchers from the University of Southampton have demonstrated how a pioneering ultrasonic device can significantly improve the cleaning of medical instruments and reduce contamination and risk of infection.
The device supplies a gentle stream of water through a nozzle that generates ultrasound and bubbles, which dramatically improve the cleaning power of water reducing the need for additives and heating.
Using just cold water, StarStream was able to remove biological contamination, including brain tissue from surgical steel.
Principal Investigator Professor Tim Leighton, from the University’s Institute of Sound and Vibration Research, said: “In the absence of sufficient cleaning of medical instruments, contamination and infection can result in serious consequences for the health sector and remains a significant challenge. Our highly-effective cleaning device, achieved with cold water and without the need for chemical additives or the high power consumption associated with conventional strategies, has the potential to meet this challenge and transform the sector.” The research, published in the journal Physical Chemistry Chemical Physics, was funded by the Royal Society Brian Mercer Award for Innovation.