Fang says that this is an elegant demonstration, showing that acoustic metamaterials could be used to focus sound beyond the diffraction limit and proving that the devices could work for high-resolution imaging. Earlier this year, he made an acoustic hyperlens that focuses ultrasound waves but not beyond the diffraction limit. "It's the very first proof of concept…but the result is solid and very promising," he says.
Practical use will take time. Bartal says the researchers are trying to make the device compatible with ultrasound frequencies greater than 20 kHz. They are also working on a device for creating three-dimensional ultrasound images. Then they need to adapt their device—make it smaller, for instance, according to Cummer—for use in a practical ultrasound imaging system.
Given that acoustic metamaterials have been around only for the past two years, Cummer believes progress has been quick. "High-quality demonstrations like this suggest to me that we could see applications within a handful of years," he says.
About the Author
Prachi Patel is a contributing editor at IEEE Spectrum. In the October 2009 issue she reported on the progress that engineers have made in constructing wireless neural interfaces. And in the June 2009 issue, she wrote about how experts expect resume fraud to rise during this period of high unemployment.
