Researchers at the University of California at Berkeley (UCB) have developed a tunable, nanotube resonator that could lead to exquisitely sensitive and versatile sensors.

Nanoresonators are tiny vibrating beams, bridges or other structures. Because their resonant frequencies are highly dependent on various factors, such as their mass, length and the stresses they are experiencing, nanoresonators make extremely sensitive measurement devices. (Recently, a nanoresonator-based scale managed to detect mass small enough to register the presence of a single bacterium.) Most nanoresonators operate at a single frequency or a very narrow band of frequencies. If a different frequency is required, you have to build a different resonator.

The UCB nanoresonators, however, are tunable because they are made of telescoping nanotubes that can extend like a trombone slide. By securing the telescoping nanotubes between two surfaces that can be moved relative to each other, the researchers were able to vary the nanoresonator frequencies over ranges of 50–75 MHz. Each nanometre change in length leads to roughly a 1 MHz shift in frequency, making the nanoresonators highly sensitive position and force sensors as well as tunable mass and frequency measurement devices.

doi: 10.1103/PhysRevLett.96.215503

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