Tunable multiwalled nanotube resonator
Inventors
Jensen, Kenneth J. • Girit, Caglar O. • Mickelson, William E. • Zettl, Alexander K. • Grossman, Jeffrey C.
Assignees
Publication Number
US-8573031-B2
Publication Date
2013-11-05
Expiration Date
2026-08-25
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Abstract
A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.
Core Innovation
The invention is a tunable nanoscale resonator utilizing a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile piezoelectrically controlled contact. This device harnesses the telescoping ability of MWNTs, allowing controllable sliding of an inner nanotube core from its outer casing, effectively changing the length and tuning the resonant frequency. Resonant energy transfer with the nanoresonator can detect molecules at specific oscillation frequencies without chemical labels, enabling label-free chemical species detection.
The problem addressed is the limited frequency range of existing nanoscale resonators, which typically operate at a single or narrow frequency range, restricting their application. Current resonators often made from silicon have complicated physical models, and known nanotube resonators lack wide tuning capability. This invention proposes a fundamentally different resonator that exploits the unique telescoping property of MWNTs to provide a tunable frequency range.
The invention provides various embodiments including apparatus comprising an extendable MWNT attached at both ends to an extension means that displaces the ends, thereby changing length and resonance frequency. Excitation means such as currents within electromagnetic fields cause vibration. Methods include displacing mounts to extend the nanotube, exciting it to vibrate, detecting amplitudes, controlling displacement to maximize vibration at resonant frequency, measuring vibration frequency, and calculating changes in length or applied forces from frequency shifts. Label-free chemical detection methods use tunable nanoresonators to detect target molecules by resonant energy transfer without chemical labeling.
Claims Coverage
The patent contains two independent claims; one related to a method for tuning and detecting vibrations of a multiwalled nanotube resonator, and another related to a method for label-free detection of target molecules using a tunable nanoresonator.
Method for tuning and detecting multiwalled nanotube vibrations
A method comprising providing a mount attaching both ends of a multiwalled nanotube; exciting it to vibrate; detecting vibration amplitude; controlling displacement to maximize amplitude at a resonant frequency; and changing nanotube length to change the resonant frequency. Excitation may include passing current through the nanotube within an electromagnetic field. Application of force to the mount can change the nanotube's length, and the force magnitude can be determined from frequency changes. The frequency of vibration is measured.
Label-free detection of target molecules using tunable nanoresonator
A method comprising providing a tunable nanoresonator without a chemical label; tuning the nanoresonator to a specific target oscillation frequency; and detecting a target molecule by resonant energy transfer with the nanoresonator. The nanoresonator can be a carbon multiwalled nanotube. Detection is based on either onset of oscillations or reduction in amplitude of oscillations at the target frequency.
The claims cover inventive features for tuning the resonant frequency of a multiwalled nanotube resonator by varying its length via displacement mounts and excitation methods, and for label-free detection of target molecules by resonant energy transfer with the tunable resonator without requiring chemical labels.
Stated Advantages
Wider frequency range compared to competing tunable nanoresonators.
Unique sliding ability allows position sensing applications unlike immobile resonators.
Nearly perfect atomic structure and precisely controlled geometry make it ideal for studying dissipation physics.
Extreme sensitivity of resonance frequency to nanotube length enables applications in precision distance sensing, strain gauges, mass, force, position, and frequency sensors.
Label-free detection capability permits detection of multiple molecules without chemical functionalization or labeling, allowing continuous measurements without sensor degradation.
Documented Applications
Precise mass, force, position, and frequency measurement using tunable nanotube resonators.
Nanoscale positioning device and extremely sensitive strain gauge applications based on sensitivity of resonance frequency to length.
Label-free detection of chemical species and target molecules by resonant energy transfer at specific oscillation frequencies without chemical labels.
Study of the physics of dissipation in nanoscale resonators.
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