Detecting single molecules inside a carbon nanotube to control molecular sequences using inertia trapping phenomenon

Abstract

Here we show the detection of single gas molecules inside a carbon nanotube based on the change in resonance frequency and amplitude associated with the inertia trapping phenomenon. As its direct implication, a method for controlling the sequence of small molecule is then proposed to realize the concept of manoeuvring of matter atom by atom in one dimension. The detection as well as the implication is demonstrated numerically with the molecular dynamics method. It is theoretically assessed that it is possible for a physical model to be fabricated in the very near future. V C 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4754617] The manoeuvring of matter atom by atom may be one of the ultimate goals of the science of nanotechnology. 1-3 This goal was partially realized by the scanning tunnelling microscope (STM) with its ability to manipulate atoms on the surface of a metal. There are a number of different approaches to nanoscale mass transport 7-16 based on carbon nanotube (CNT) nanoelectromechanical systems (NEMS) that attempt to exhibit promising properties of the CNT. The experimental approaches include electrophoretic, 7-9 thermophoretic, 10,11 and mechanically actuated 12-16 methods. However, all these approaches failed to achieve manoeuvring matter at the atomic level. On the other hand, in spite of fundamental and applied interest in the interaction of CNTs and nanoparticles due to mechanical vibrations of the CNT, 17-23 little attention has been paid to the manipulation of nanoparticles and nanoscale mass transport based on CNT-enabled NEMS. [4][5][6]12,13 The inertia trapping phenomenon 4-6 which shows that atomic particles in a vibrating CNT have a tendency to move toward the antinodes and stay in the antinodes vicinity, due to inertial forces (or centrifugal forces), is then adopted by this paper to realize the concept of matter manipulation. Although it is not a true full three dimensional (3D) manoeuvring matter at the atomic level, the work could still be valuable in fields like synthetic biology 24 and molecule level data storage 7,25,26 and hopefully a key step to the realization of true 3D nanotechnology. 3 The encoding of a molecular chain can be realized by shooting several kinds of gas molecules into the CNT one by one as shown in Figure 1. One challenge encountered in the present work was, the detection of molecules inside the CNT required by step 2 as shown in Figure 1, which was resolved using a CNT resonator system. The CNT resonator is able to detect the change of its vibration amplitude by detecting the change of electric current in a circuit and thus detect small changes of its eigenfreqency. [17][18][19][20][21] More details about this detection technique are given in supplementary information Sec. A. 30 The detection process can then be split into two categories: (a) increasing the vibrational amplitude due to the insertion of the molecules denoted as "þ," and (b) decreasing the amplitude denoted as "À." For a "þ" detection, the resonator is initially away from res...

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“…In addition to thermal fluctuation, studies confirm that the vibration can also transport particles and droplets in and outside a carbon nanotube (CNT) [ 24 – 27 ]. For example, the nanodroplets are transported along the nanotube with a velocity close to 30 nm/ns when linearly polarized transverse acoustic waves pass linear momentum to the nanodroplet [ 24 , 28 ]. Guo et al demonstrated that water molecules inside a vibrating cantilever are driven by centrifugal forces and can undergo a continuous flow from the fixed to free ends of the CNT by molecular dynamics simulations [ 26 , 29 ].…”