Nano piano’s lullaby could mean storage breakthrough

Nano piano concept: Arrays of gold, pillar-supported bowtie nanoantennas (bottom left) can be used to record distinct musical notes, as shown in the experimentally obtained dark-field microscopy images (bottom right). These particular notes were used to compose “Twinkle, Twinkle, Little Star”.

Researchers from the Univ. of Illinois at Urbana-Champaign have demonstrated the first-ever recording of optically encoded audio onto a non-magnetic plasmonic nanostructure, opening the door to multiple uses in informational processing and archival storage.

“The chip’s dimensions are roughly equivalent to the thickness of human hair,” explained Kimani Toussaint, an associate professor of mechanical science and engineering, who led the research.

Specifically, the photographic film property exhibited by an array of novel gold, pillar-supported bowtie nanoantennas (pBNAs)—previously discovered by Toussaint’s group—was exploited to store sound and audio files. Compared with the conventional magnetic film for analog data storage, the storage capacity of pBNAs is around 5,600 times larger, indicating a vast array of potential storage uses.

To demonstrate its abilities to store sound and audio files, the researchers created a musical keyboard or “nano piano,” using the available notes to play the short song, “Twinkle, Twinkle, Little Star.”

“Data storage is one interesting area to think about,” Toussaint said. “For example, one can consider applying this type of nanotechnology to enhancing the niche, but still important, analog technology used in the area of archival storage such as using microfiche. In addition, our work holds potential for on-chip, plasmonic-based information processing.”

The researchers demonstrated that the pBNAs could be used to store sound information either as a temporally varying intensity waveform or a frequency varying intensity waveform. Eight basic musical notes, including middle C, D and E, were stored on a pBNA chip and then retrieved and played back in a desired order to make a tune.

“A characteristic property of plasmonics is the spectrum,” said Hao Chen, a former postdoctoral researcher in Toussaint’s PROBE laboratory and the first author of the paper appearing in Scientific Reports. “Originating from a plasmon-induced thermal effect, well-controlled nanoscale morphological changes allow as much as a 100-nm spectral shift from the nanoantennas. By employing this spectral degree-of-freedom as an amplitude coordinate, the storage capacity can be improved. Moreover, although our audio recording focused on analog data storage, in principle it is still possible to transform to digital data storage by having each bowtie serve as a unit bit 1 or 0. By modifying the size of the bowtie, it’s feasible to further improve the storage capacity.”

Read more: Nano piano’s lullaby could mean storage breakthrough