Sensitive Detection of Acoustic Vibration at Nanometer Scale.

The detection of vibrations at nanometer scale is crucial for a variety of applications. The spatial resolution of acoustic detection is limited to micrometers due to its long wavelength. Single-molecule probes with a gold nanorod (GNR) have been proposed to detect an acoustic wave at the nanometer scale at room temperature. However, the detection efficiency is extremely low due to the random distribution of probe molecules and GNRs, and the detection can be used only in solid phases. In this work, we chemically linked the GNR and probe molecules using dsDNA, which provided precise distance control. Compared to the previous work, the detection sensitivity was improved by 2 orders of magnitude, approaching the theoretical detection limit, and the detection efficiency was improved from below 1% to over 95%. Furthermore, such a dsDNA connection allows sensitive detection of acoustic wave under water by a single nanodetector for "listening" to musical sounds covering two octaves. These results suggest that our achievement in precise distance control represents a significant step toward the practical application of single molecule detection of acoustic wave.