A breakthrough at the U.S. Department of Energy‘s Lawrence Berkeley National Laboratory in Berkeley, California, could lead to high-frequency ultrasound imaging with up to 1,000 times higher resolution than today’s medical ultrasounds.
Xiang Zhang, PhD, summed up the research this way:
We have demonstrated optical coherent manipulation and detection of the acoustic phonons in nanostructures that offer new possibilities in the development of coherent phonon sources and nano-phononic devices for chemical sensing, thermal energy management, and communications.
Dr. Zhang is the Ernest S. Kuh Endowed Chair and professor of mechanical engineering at the University of California, Berkeley, and a faculty scientist with Berkeley Lab’s Materials Sciences Division. He was quoted in a lab news release. And, no, we don’t really know what he’s talking about either.
However, an article published online last week in Nature Communications has all the details. Dr. Zhang is senior author.
The researchers used laser pulses of less than a picosecond and gold nanoparticles shaped like the cross on the Swiss flag (or a plus sign). The laser pulses generated acoustic phonons, which are quasi-particles of vibrational energy that move through an atomic lattice as sound waves, at a frequency of 10 gigahertz. Medical ultrasounds typical reach frequencies of only about 20 megahertz.
The higher frequency should allow the creation of much sharper images than today’s ultrasound can provide.
The researchers work in materials sciences, so they’re dreaming primarily of industrial uses. For example, the ultrasound vibrations could be used as nanoscale “hammers” to impose physical strains on materials along different axes at ultrahigh frequencies. That could reveal otherwise undetectable flaws.
However, it seems a good bet that the technique will have uses in medical imaging as well. Stay tuned.
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