Nested Carbon Nanotubes Research Articles

Actuation mechanism of a nanoscale drilling rig based on nested carbon nanotubes.

With the increasing emphasis on health and the continuous improvement of medical standards, more and more micro/nano devices are being used in the medical field. However, the existing micro/nano devices cannot effectively solve various problems encountered in medical processes and achieve specific therapeutic effects. Based on this, this article designs a new type of nanoscale drilling rig. The nanoscale drilling rig is composed of double-layer nested carbon nanotubes with multiple electrodes, and is powered by an external power source, making it easy to perform long-term surgery in the human body. Through coding strategies, we can adjust the surface charge density and distribution of the nanoscale drilling rig, thereby controlling its periodical rotation and achieving precise medical treatment. In addition, in order to control the length of the nanoscale drill bit, meet the treatment needs of different parts of the human body, and reduce damage to the human body, we have designed a structure of ion electric double layers so that the drill bit can be fixed in different positions, reducing the risk of treatment to a certain extent. This drilling rig enriches the functions of micro/nano devices, which is beneficial for the development of the medical industry.

A controllable nanoscale telescopic arm designed by encoding the nested multi-walled carbon nanotubes.

Micro/nano manipulation technologies have shown enormous potential in the field of accurate surgery, which is expected to promote the development of precision medicine. Therefore, scientists have been devoted to designing and manipulating nanoscale devices and tools which can conduct surgical functions, such as penetration, drilling and cleaving targeting either single cells or biological tissues. To enrich the functionality of the family of nanomachines, a theoretical nanoscale telescopic arm manipulated by charge-tunable multi-walled carbon nanotubes is designed in this work. By using predesigned encoding strategies that could periodically alternate the external electric fields and surface charge densities of the nanorings embedded in the carbon nanotubes, well controlled manipulations of the telescopic arm are realized in MD simulations to mimic nanoscale surgeries. The telescopic arm can stretch out by the external electric force and draw back by vdW attraction between the nested nanotubes. Meanwhile, the electric double layer formed around the nanoring area in the nanotube is used as a brake during the retraction process to make the nanotube halt stably at the target position. The working distance could also be tuned by changing the number of the nested nanotubes, which presents a promising avenue for varieties of biomedical applications.

Telescopic oscillations of double-walled carbon nanotubes in the presence of an inner semi-infinite tube

Telescopic oscillation of nested carbon nanotubes is capable of generating GHz frequency. A main challenge against their practical applications is how to control and tune such oscillations. In this paper, we demonstrate that by displacing the tip of a semi-infinite tube inside a conventional double-walled oscillatory system, we can change the vdW force distribution acting on the oscillating tube. By changing this distribution, the dynamics of the system is altered; hence, the oscillations are retuned. The positioning of the tip can be controlled externally by moving its other end. The proposed mechanism provides a solution to control and tune this type of oscillatory systems during the course of oscillations. Concerning the different system parameters (i.e. geometrical parameters and initial conditions), we perform a thorough study to reveal how the oscillatory frequency will change by moving the tip of the semi-infinite tube.

Tuning the oscillation of nested carbon nanotubes by insertion of an additional inner tube

Different mechanisms of nano-oscillators with telescopic oscillations have attracted lots of attention due to the possible generation of GHz frequencies. In particular, nested carbon nanotubes are of special interest for which different mechanisms have been examined. In this paper, we will show that insertion of an additional inner tube into a conventional double walled carbon nanotube (DWCNT) oscillator not only can increase the oscillatory frequency considerably but also provides a wide range of system parameters for tuning the oscillatory behavior as well as its frequency. The insertion of an additional tube results in a number of different vdW force profiles (which only depend on the length ratios of the three tubes). Being subject to these different vdW force profiles and trigged with different initial velocity, an oscillating tube can exhibit various types of motions. We use a phase division diagram to discriminate the system parameters according to the different types of motions. Accordingly, a comprehensive study of the oscillatory frequency is also carried out. To perceive an insight into the effectiveness of insertion, a comparison is also made with the counterpart DWCNT oscillator. It is observed that this new mechanism offers a number of new possibilities in designing and characterizing a carbon nanotube based oscillator.

Dimensionless Analysis of Carbon Nanotube Oscillators: Design Aspects

AbstractIn the past decade, gigahertz nano-oscillators have attracted much attention. Of particular interest are nested carbon nanotubes with telescopic movements. Recent work on this type of oscillator has led to new results and new insights into such oscillatory systems. That work has also led to the introduction of a special initial velocity at which the oscillatory frequency is unique and independent of the core length. This finding stimulates the idea of developing a nondimensional formulism for the oscillatory frequency of such systems, which is the prime objective of the work undertaken herein. The results generated are in nondimensional form and cover a wide range of system parameters. Utilizing the new formulas derived, different aspects of the oscillatory frequency are studied and discussed. The generality of the formulation presented in this paper provides a better perception of such systems and helps in designing the system parameters.

On New Aspects of Nested Carbon Nanotubes as Gigahertz Oscillators

Nested carbon nanotubes exhibit telescopic oscillatory motion with frequencies in the gigahertz range. In this paper, our previously proposed semi-analytical expression for the interaction force between two concentric carbon nanotubes is used to solve the equation of motion. That expression also enables a new semi-analytical expression for the precise evaluation of oscillation frequency to be introduced. Alternatively, an algebraic frequency formula derived based on the simplifying assumption of constant van der Waals force is also given. Based on the given formulas, a thorough study on different aspects of operating frequencies under various system parameters is conducted, which permits fresh insight into the problem. Some notable improvements over the previously drawn conclusions are made. The strong dependence of oscillatory frequency on system parameters including the extrusion distance and initial velocity of the core as initial conditions for the motion is shown. Interestingly, our results indicate that there is a special initial velocity at which oscillatory frequency is unique for any arbitrary length of the core. A particular relationship between the escape velocity (the minimum initial velocity beyond which the core will leave the outer nanotube) and this specific initial velocity is also revealed.

Improved Adherence Strength between Diamond Grains and Electrolytic Nickel Bonds by Carbon Nanotube Coatings

New coating methods were proposed to improve the adherence strength between diamond grains and electrolytic nickel bonds on electroplating diamond tools. Diamond grains covered by nested carbon nanotubes (CNTs) were constructed using self-assembly techniques. The grains were first amino-functionalized by silane coupling or photochemical UV treatment. Acid-treated CNTs adsorbed automatically onto amino-terminated grains in N,N-dimethylformamide (DMF) solution by amino-CNT interactions. Subsequent drying and readsorption deposited CNT coatings onto the grains by CNT-CNT interactions due to van der Waals forces. Scanning electron microscope observations indicated that the thickness of CNT coatings on photochemical UV-treated grains was more uniform than that of coatings on grains treated by silane coupling. The adherence strength between the grain and electrolytic nickel bonds was evaluated by shear tests. The adherence strength of the CNT-coated grains was 200-250% of that of the uncoated grains. The photochemical UV treatment was more effective than silane coupling for improving adherence strength. It was surmised that this was due to the uniform thickness of the CNT coatings and the absence of high molecular weight layers contained in the silane coupling agents between CNTs and diamond grains.

Development of CNT-Coated Diamond Grains Using Self-Assembly Techniques for Improving Electroplated Diamond Tools

Single crystalline diamond grains covered by nested carbon nanotubes (CNTs) were constructed using self-assembly techniques. The acid-treated CNTs (MWCNTs-COOH) are first adsorbed onto amine-terminated diamond grains, which were chemically functionalized by silane coupling treatments, in N, N-dimethylformamide solution. Then, the drying and readsorption cycle deposited CNT coatings on the diamond grains due to CNT-CNT interactions caused by van der Waals forces. When the diamond grains were bonded to steel substrates by electroplating using nickel sulfamate plating bath, the bonding strength of the CNT-coated diamond grains to the Ni matrix was almost twice as large as that of the normal diamond grains. Hence, the CNT-coated diamond grains are very useful for improving the tool life of electroplated diamond tools.

Cobalt-doped carbon nanotubes: Preparation, texture, and magnetic properties

The nested carbon nanotubes discovered by Ijima and co-workers as a by-product of fullerene production extended the dimension and geometries of fullerenes into the domain of nanoparticles. These nanotubes are fiberlike structures consisting of concentric graphite sheets nested along the axis extending as long as several micrometers, and diameters of these nanotubes are limited to less than 100 nm. In this paper we report preparation, structural and magnetic properties of cobalt-doped carbon nanotubes. We observed a tubular structure made of coaxial graphite sheets. The inside, of these carbon nanotubes, was filled with cobalt particles. The magnetic properties of the Co-doped nanotubes were measured using a SQUID magnetometer. The undoped (pure) carbon nanotubes exhibit diamagnetic behavior. The Co-doped nanotubes exhibit superparamagnetic behavior with saturation of magnetization at about 0.5 T and coercive field of 750 G.