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We present a design of a nanoscale inertial measurement unit or a data archive using a graphene-nanoflake (GNF) sandwiched between crossed graphene-nanoribbon (GNR) junctions. When an external force applied is below the retracting force, the inertial force exerted on the movable GNF can telescope it. Then, the self-restoring force increases as the attractive van der Waals force between the GNF and the GNRs, which enables the GNF to automatically and fully retract back into the sandwich position immediately after the externally applied force is released. When the external force exceeds the retracting force, the GNF escapes from the crossed GNR junctions, which enables the device to be used as non-volatile memory. The heterostructure of GNR/h-BN/GNR can be considered as an advanced structure in the proposed scheme.

Superlubric motions of graphene nanoflakes (GNFs) on graphene have opened up more applications of graphene for micromachines and nanomachines. Here, we investigate the dynamic behavior of a GNF shuttle on a graphene nanoribbon (GNR) with carbon nanotube (CNT) blocks via molecular dynamics simulations. The GNF moves on a GNR superlubrically, and the CNTs as building blocks induce bistable potential wells so that the GNF is stabilized. MD simulation results indicate that when a GNF shuttle approaches the CNTs, a potential well is created by an increase in the attractive van der Waals energy between the GNF and CNTs, and bistability at the local energy minima positions can be achieved near the CNTs. In order for the GNF shuttle to escape the local energy minima positions, a high external force must be applied to overcome the potential energy barrier. However, after the GNF shuttle escapes from one of the bistable positions, only a low external force is required to stabilize the GNF shuttle. This work explicitly demonstrates that a GNF-GNR/CNT system could be applied to alternative nonvolatile memory and high-speed mass storage by using GNR-CNT arrays.

We have investigated the motion of a C60 molecule absorbed on sinusoidal graphene nanoflake (GNF) via molecular dynamics simulations. Since C60 deposited on sinusoidal GNF is favorable on energetic grounds, the C60 molecule moved toward one of the valleys of sinusoidal GNF without energy barrier. So no sooner the C60 molecule was deposited on the sinusoidal GNF, then the C60 molecule immediately began to move toward the valley of the sinusoidal GNF Since the position of the C60 molecule can be changed by externally applied force fields and has a binding energy of 0.754 eV in the valley of sinusoidal GNF, the sinusoidal C60/GNF can be applied to a switchable nonvolatile memory device. This work provides the probability of alternative 'bucky shuttle' memory based on the sinusoidal C60/GNF hybrid nanostructure.

A tunable graphene-resonator was investigated using classical molecular dynamics modeling and simulations. The fundamental resonance frequency variation of the graphene resonator was found to be very closely related to the average tension acting on both its edges. The initial stain-induced tension could be adjusted by using the mismatch between the negative thermal expansion coefficient of the graphene and the positive thermal expansion coefficient of the substrate, and the deflection-induced tension could be controlled by an electrostatic capacitive force due to the gate voltage. For very small initial axial-strains, the tunable range reached above several hundred gigahertz. As the initial axial-strain on the graphene-resonator increased, both the tunability and the tunable range decreased. The fundamental resonance frequency as a function of the calculated gate voltage was in good agreement with previous experiments. Considering the variables that affect the tension variation, this graphene-resonator is suitable for use as an ultra-sensitive accelerometer, thermo-sensor or weight scale, as well as many other types of sensor.

We presented simple schematics of a nanoscale inertial measurement unit based on the self-retraction motion of the graphene flakes. When an external force is applied to the nanoscale graphite flake, the inertial force exerted on the movable layer can telescope it, then the self-restoring force also arises as the van der Waals force between the interlayers of the flake, which each suspended flake can automatically and fully retract back onto the top of the graphite platform immediately after the externally applied force is released. Since the van der Waals force linearly increases with the increasing size of the flake, the sensing limitation can be controlled. When the external force does not exceed the retracting force, this addressed nanoscale inertial measurement unit can be semi-permanently used. Therefore, the size and the thickness of the graphene flake should be carefully selected with a tradeoff. These graphite flakes can be utilized as a basic structure in various nanoelectromechanical devices, such as switch and memory, linear and angular accelerometers, and pressure sensors.

A tunable graphene-nanoribbon (GNR)-resonator was investigated via classical molecular dynamics simulations. Resonance frequencies increased with increasing externally applied gate-force and axial-strain, and could be tuned above several hundred GHz. Tunable resonance frequencies achieved from the gate force were higher than those achieved from the axial-strain. The operating frequencies of GNR-resonators without axial-strain or with small axial-strains were most widely tuned by the gate, and almost linearly increased with increasing mean deflection. As the axial strain increased, the tunable ranges of the GNR-resonators were exponentially decreased, although the operating frequencies increased. GNR-resonators without axial-strain could be applied to wide-range-tuners, whereas GNR-resonators with high axial-strain could be applied to high-frequency-fine-tuners.

Molecular dynamics methods are used to model the vibrational behavior of a suspended graphene-resonator that absorbs a finite mass at constant temperature. The effective molecular dynamics simulations easily estimate the fundamental frequency shifts of the suspended graphene with attached mass. The resonance frequency of the graphene-resonator can be functionalized by both the attached mass and the applied force. The results obtained from the molecular dynamics simulations were in good agreement with those of previous related experimental and theoretical works. For this graphene-based scaled nanobalance, the possible frequency-shift ranges increased with increasing applied force and with decreasing attached mass, they then reached 75–80% of the fundamental resonance frequency of a bare graphene-resonator. The mass sensitivity of the graphene-resonator reached ∼10 −24 g and a logarithmically linear relationship was found in the frequency-vs-mass curves for attached masses of 10 −21 –10 −19 g.

We propose schematics for an ultra-sensitive pressure sensor based on graphene-nanoribbon (GNR) and investigate its electromechanical properties using classical molecular dynamics simulations and piezo-electricity theory. Since the top plate applied to the actual pressure is large whereas the contact area on the GNR is very small, both the sensitivity and the sensing range can be adjusted by controlling the aspect ratio between the top plate and the contact point areas. Our calculation shows that the electrical conductivity of GNRs can be tuned by the applied pressure and the electric conductance of the deflected GNR linearly increases with increasing applied pressure for the linear elastic region in low pressure below the cut-off point. In the curves for both the deflection and potential energy, the linear elastic regime in low pressure was explicitly separated with the non-linear elastic regime in high pressure. The proposed GNR-based nanoelectromechanical devices have great potential for application as electromechanical memory, relay or switching devices.

Superlubricity in nanoscale graphene structures has been of interest for developing graphene-based nanoelectromechanical systems, as well as for the study of basic mechanical properties. Here, we investigated the translational and rotational motions of a square graphene nanoflake with retracting motions by performing classical molecular dynamics simulations. Our results show that the kinetic energy of the translational motion was exchanged into the kinetic energy of the rotational motion. Thus, square graphene nanoflake oscillators have very low quality factors in translational motions. We discuss that square graphene nanoflakes have great potential to be a core component in nanoelectromechanical systems by detecting their motions with ultrahigh sensitivity to facilitate the development of sensor, memory, and quantum computing.

We investigated the tension and strain energy variations as a function of the axial strain in static conditions in graphene nanoribbon resonators and the resonance frequency change with tensile loading in dynamic conditions via classical molecular dynamics simulations. This theoretical study presents the application of graphene nanoribbon resonators tuned by tensile loading as ultrahigh frequency devices. The non-linear mechanical properties of the resonators were found, and for small axial strains, the mechanical properties of the graphene nanoribbon, such as strain-energy vs . axial-strain and frequency vs . strain or tension, were estimated by the classical continuum theory. The resonance frequencies increased with increasing axial strain, and such a relation could be regressed by a linearly increasing line on a log – log scale. The increasing resonance frequency due to increasing tension could be regressed by a square root function.

We investigated an ultrahigh sensitive accelerometer based on graphene nanoribbon resonators. Sensing acceleration can be made by their resonance frequency shift and/or their capacitance change. Schematics and the static properties were introduced and the dynamic properties were investigated via classical molecular dynamics simulation. As the acceleration increased, the oscillations of the deflections were going dramatically faster and the mean deflections increased, then the capacitance continually varied with large amplitudes and the resonance frequencies linearly increased in a log – log scale by power regression. The energy loss decreased with increasing time, and the average quality factors were dramatically reduced with increasing acceleration.

We investigated the dynamics properties of the carbon-nanotube (CNT) oscillators with intertube gaps via classical molecular dynamics simulations. The maximum frequencies of the CNT-oscillators were achieved when the lengths of the outertube including the gap were the same as the length of the coretube, and so their maximum frequencies, with the same coretube length, were the same as each other regardless of the gap's value. Their resonance frequencies were complexly correlated with the geometric parameters and initial conditions such as initial velocity and displacement. Increasing the outertube's length by increasing the gap was the most important parameter in estimating the resonance frequency of the CNT-oscillator with an intertube gap between outertubes. Finally, we note that CNT-oscillators with intertube gaps can be applied as frequency-controlled oscillators by manipulating this gap.

In this paper, we investigated cantilevered carbon-nanotube-resonators encapsulating finite nanoclusters with different linear-densities via classical molecular dynamics simulations, which included the use of the approximation model. Through this we can simply obtain the fundamental frequency shifts of the cantilevered carbon-nanotube-resonators encapsulating finite nanoclusters. As the linear mass density of the encapsulated finite nanocluster increased, the frequency-shift-range also increased. Previous works focused on the resonance-frequency-shift due to the attached mass but our molecular dynamics simulation looked into the dependence on the linear density of the encapsulated nanocluster as an important parameter to analyze the vibration features of carbon-nanotube-resonators. The molecular dynamics simulation results were in good agreement with those of previously related experimental and theoretical works.

We investigate the nano mass transfer in an ultrahigh frequency carbon-nanotube-resonator encapsulating a nanocluster via classical molecular dynamics simulations. When the carbon-nanotube-resonator vibrated, the encapsulated copper nanocluster more rapidly approached the end of the cantilevered carbon-nanotube-resonator. Such phenomena were due to the migration of the encapsulated copper nanocluster due to the centrifugal force induced by the vibrating nanotube resonator. So the resonance frequency change could be time-dependently found. For the movable copper nanocluster in carbon nanotube resonator, the vibrational spectra when the copper nanocluster inside the carbon nanotube resonator rapidly settled at the capped edge were different from those obtained when the copper nanocluster continuously oscillated inside the carbon nanotube resonator. Such results showed that the frequency of the carbon-nanotube-resonator encapsulating the movable copper nanocluster could be adjusted by controlling the mean position of the oscillating copper nanocluster. The movable nanocluster inside a carbon-nanotube can be applied to a nanotube-based data storage media by sensing the position of the nanocluster.

We investigated the cantilevered carbon-nanotube-resonator including electromigratively movable nanoparticle via classical molecular dynamics simulations and continuum model. The change of the effective mass value, which was closely correlated with the position change of the encapsulated nanoparticle, could be regressed by a power function, the resonance frequency of the carbon-nanotube-resonator could be tuned by controlling the nanoparticle’s position, and the possible frequency-shift-ranges then reached 18–85%. The suggested device could be served as a data-storage-media for electromechanical nonvolatile-memory as well as a frequency-tuner.

We investigated an ultrahigh frequency carbon nanotube resonator encapsulating a nanocluster, as another tunable resonator, via classical molecular dynamics simulations and continuum models. The fundamental frequency of cantilevered carbon nanotube resonator encapsulating a copper nanocluster could be adjusted by controlling the position of the encapsulated copper nanocluster. Data obtained from the molecular dynamics simulations were analyzed with continuum theory, and we found that statistically the change in the effective mass factor was greatly correlated with the position change of the encapsulated nanocluster.

We investigated a linear nanomotor based on the telescoping carbon nanotube motion induced by electromigration of an encapsulated nanoparticle. The nanoparticle motion induced by the electric current makes the inner nanotube linearly telescope or retreat. Theoretical results using a kinetic Monte Carlo method were in good agreement with previous experiments. The telescoping speed of the linear nanomotor exponentially decreased with increasing mass of the inner nanotube.

We have successfully synthesized morpholinium ionic-liquid-stabilized palladium nanoparticles by electrochemical reduction. The palladium nanoparticles (NPs) were characterized by using transmission electron microscopy and X-ray diffraction. The sizes of the particles produced could be controlled by adjusting the current density and the duration of the electrolysis. The particle sizes increased with decreasing current density and increasing electrolysis duration. X-ray diffraction of the resulting NPs indicated that the particles had a crystalline structure.

Model of frequency-controlled carbon-nanotube oscillators are proposed and their dynamic properties are investigated via classical molecular dynamic simulations. Their operation frequencies can be changed by engineering the intertube gap, which dominantly affects their operating frequencies in the improved bandwidths rather than those achieved by initial velocity engineering.

We propose an angular-velocimeter with a carbon nanotube resonator for sensing the angular velocity of a rotating body. When centrifugal force exerted by the rotation of the system causes an elongation of the carbon nanotube resonator due to the centrifugal force, the frequency spectra of centrifugal force is dependent on the angular velocity of the rotating plate, and feedback sensing is then achieved via operating frequency shift. Such a nanoelectromechanical device is investigated via molecular dynamics simulations and the classical continuum theory. The model of the classical continuum theory is in good agreement with the results obtained from the classical molecular dynamics simulations.

We have successfully synthesized morpholinium ionic liquid-stabilized palladium (Pd) nanoparticles by electrochemical reduction. For characterization of Pd nanoparticles, FT-IR, UV-visible spectroscopy, and Transmission electron microscopy (TEM) were employed. The FT-IR spectrum of Pd nanoparticles indicated the surface binding of the IL to the nanoparticles. The UV-visible spectrum showed that nano-sized Pd particles were produced. The particle size was controlled by the adjustment of the current density, temperature, and electrolysis duration. The TEM images showed an average size of 2.0, 2.2, 2.4, 2.9, 3.5, 3.9, and 4.5 nm. Nearly a 0.5 nm-sized control of the nanoparticle was achieved. The particle size increased with a decrease in the current density and an increase in temperature and electrolysis duration. The electron diffraction patterns of resulting nanoparticles indicated that the particles had a crystalline structure.

The 2,2,2-trifluoroethanol (TFE)+quinoline mixture was chosen as a potential working fluid used in an absorption chiller. Heat capacity was measured and correlated by a polynomial equation as a function of temperature and concentration, and the parameters of the regression equation were determined by a least-squares method. The cycle simulation for a double effect absorption cycle was carried out at various operation conditions. The appropriate operation condition and COP values were calculated for the absorption cycle by using the proposed working fluid. TFE+quinoline solution could be a promising working fluid as an alternative to the LiBr+H 2O and H2O+NH3 systems based on the operation range and simulation results.

In this paper, we investigated the resonant frequencies of multi-walled carbon nanotube (MWCNT) resonators with short outertubes according to the classical molecular dynamics approach. The resonant frequencies of the MWCNT resonators with short outertubes were influenced in both the wall number and the length of the short outertubes. The resonance frequencies of MWCNTs with short outertubes could be modeled by Gaussian distribution functions. Both the bandwidth and the sensitivity increased with increasing the wall number of the outertubes. The maximum frequency increased with increasing the diameter and with increasing the wall number of the outertubes for MWCNTs. So the effects of increasing the wall number of the outertubes were very important factors for understanding the vibrational frequency changes of MWCNTs with short outertubes as well as the effect of increasing the lengths of the outertubes.

We conceptually investigated a carbon-nanotube-based tuner operated by the telescoping nanotube motion in a multi-walled carbon-nanotube induced by electromigration of an encapsulated nanoparticle. The telescoping lengths in the proposed carbon-nanotube-based tuner could be achieved from the electromigration phenomena of the nanoparticle embedded in the carbon nanotube. So the core part is the nanoparticle shuttle and a multi-walled carbon-nanotube with ultra-low interlayer friction. The tuning of this telescoping carbon-nanotube-based tuner is achieved from the electric current flow. The properties of operation were investigated via classical molecular dynamics simulations and then the parameters of the continuum model were then calibrated to fit the results of the molecular dynamics simulations. Since the effective boundary considered as the movable clamp affected the vibration of the telescoping nanotube, the calibrated Young's modulus of this work were lower than the those of the previous works. Presented tuners are controllable in a few nanometers, and their operations are robust and reliable.

The vibrational properties of various double-walled carbon nanotube resonators were investigated via a classical molecular dynamics approach. The fundamental frequencies of double-walled carbon nanotube resonators with short outer tubes were closely related to the intertube spacing and the chirality of the outer tubes. Even though the length of the outer tube was 1 nm, the vibration of the outer tube affected that of the inner tube. For nanotubes with similar intertube spacing, both maximum frequencies were similar. For their corresponding maximum frequencies, the lengths of the outer tubes of the zigzag nanotubes were slightly less than those of the armchair ones.

We investigated the characteristics of a capacitive nano-accelerometer based on a telescoping carbon nanotube by means of classical molecular dynamics simulations. The position of the telescoping nanotube was controlled by an externally applied force, and feedback sensing was based on the capacitance change. The capacitance variations, which were almost linearly proportional to the applied acceleration, were monitored within an error tolerance.