Nanomechanical Device Research Articles

M1-10 FIB-CVDを用いたナノ機械デバイス作製における動特性解析法(M1 製作技術,材料)

M1-10 FIB-CVDを用いたナノ機械デバイス作製における動特性解析法(M1 製作技術,材料)

A DNA-based nanomechanical device with three robust states

DNA has been used to build a variety of devices, ranging from those that are controlled by DNA structural transitions to those that are controlled by the addition of specific DNA strands. These sequence-dependent devices fulfill the promise of DNA in nanotechnology because a variety of devices in the same physical environment can be controlled individually. Many such devices have been reported, but most of them contain one or two structurally robust end states, in addition to a floppy intermediate or even a floppy end state. We describe a system in which three different structurally robust end states can be obtained, all resulting from the addition of different set strands to a single floppy intermediate. This system is an extension of the PX-JX(2) DNA device. The three states are related to each other by three different motions, a twofold rotation, a translation of approximately 2.1-2.5 nm, and a twofold screw rotation, which combines these two motions. We demonstrate the transitions by gel electrophoresis, by fluorescence resonance energy transfer, and by atomic force microscopy. The control of this system by DNA strands opens the door to trinary logic and to systems containing N devices that are able to attain 3(N) structural states.

Harnessing optical forces in integrated photonic circuits

The force exerted by photons is of fundamental importance in light-matter interactions. For example, in free space, optical tweezers have been widely used to manipulate atoms and microscale dielectric particles. This optical force is expected to be greatly enhanced in integrated photonic circuits in which light is highly concentrated at the nanoscale. Harnessing the optical force on a semiconductor chip will allow solid state devices, such as electromechanical systems, to operate under new physical principles. Indeed, recent experiments have elucidated the radiation forces of light in high-finesse optical microcavities, but the large footprint of these devices ultimately prevents scaling down to nanoscale dimensions. Recent theoretical work has predicted that a transverse optical force can be generated and used directly for electromechanical actuation without the need for a high-finesse cavity. However, on-chip exploitation of this force has been a significant challenge, primarily owing to the lack of efficient nanoscale mechanical transducers in the photonics domain. Here we report the direct detection and exploitation of transverse optical forces in an integrated silicon photonic circuit through an embedded nanomechanical resonator. The nanomechanical device, a free-standing waveguide, is driven by the optical force and read out through evanescent coupling of the guided light to the dielectric substrate. This new optical force enables all-optical operation of nanomechanical systems on a CMOS (complementary metal-oxide-semiconductor)-compatible platform, with substantial bandwidth and design flexibility compared to conventional electrical-based schemes.

Electrostatically actuated silicon-based nanomechanical switch at room temperature

We demonstrate a silicon-based high-frequency nanomechanical device capable of switching controllably between two states at room temperature. The device uses a nanomechanical resonator with two distinct states in the hysteretic nonlinear regime. In contrast to prior work, we demonstrate room-temperature electrostatic actuation and sensing of the switching device with 100% fidelity by phase modulating the drive signal. This phase-modulated device can be used as a low-power, high-speed mechanical switch integrated on-chip with silicon circuitry.

A frustrated nanomechanical device powered by the lateral Casimir force

The coupling between corrugated surfaces due to the lateral Casimir force is employed to propose a nanoscale mechanical device composed of two racks and a pinion. The noncontact nature of the interaction allows for the system to be made frustrated by choosing the two racks to move in the same direction and forcing the pinion to choose between two opposite directions. This leads to a rich and sensitive phase behavior, which makes the device potentially useful as a mechanical sensor or amplifier. The device could also be used to make a mechanical clock signal of tunable frequency.

Determination of tensile strength distribution of nanotubes from testing of nanotube bundles

Single-walled carbon nanotube (SWNT) bundles are subject to tensile testing using a self-developed nano-mechanical testing device. The tensile strength of SWNT bundles, as well as reported data of multi-walled carbon nanotubes (MWNTs) and SWNT ropes, are studied by statistical approach. It is shown that the tensile strength distributions of carbon nanotubes (CNTs) or SWNT ropes can be adequately described by a two-parameter Weibull model. Considering the nonlinear elastic behavior of CNTs, a relation between individual CNT and CNT bundle strengths is studied, and a method for determining the tensile strength distribution of individual CNTs or CNT sub-bundles from experimental measurements on CNT bundles is proposed. Therefore the process for determining the strength distributions of individual CNTs can be greatly simplified by testing CNT bundles instead.

A Nonlinear Mechanical Model for Tension of Bundles of Single-Walled Carbon Nanotubes

Tensile strength distributions of multi-walled carbon nanotubes (MWNTs), single-walled carbon nanotube (SWNT) ropes and sub-bundles are studied by statistical approach based on the experimental data sets. It shows that the distributions can be adequately described by a two-parameter Weibull model. Considering further their nonlinear stress-strain behavior, the force-strain relation and tensile strength of SWNT bundles are studied. The Weibull modulus of the sub-bundles in a SWNT bundle can be estimated in terms of the maximum sustained force and the failure strain of the bundle. A SWNT bundle was subjected to tensile testing using a nano-mechanical testing device. The result suggests that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT bundles, mainly at large strain.

Operation of a DNA Robot Arm Inserted into a 2D DNA Crystalline Substrate

The success of nanorobotics requires the precise placement and subsequent operation of specific nanomechanical devices at particular locations. The structural programmability of DNA makes it a particularly attractive system for nanorobotics. We have developed a cassette that enables the placement of a robust, sequence-dependent DNA robot arm within a two-dimensional (2D) crystalline DNA array. The cassette contains the device, an attachment site, and a reporter of state. We used atomic force microscopy to demonstrate that the rotary device is fully functional after insertion. Thus, a nanomechanical device can operate within a fixed frame of reference.

Electronic Aharonov-Bohm Effect Induced by Quantum Vibrations

Mechanical displacements of a nanoelectromechanical system shift the electron trajectories and hence perturb phase coherent charge transport through the device. We show theoretically that in the presence of a magnetic field such quantum-coherent displacements may give rise to an Aharonov-Bohm-type of effect. In particular, we demonstrate that quantum vibrations of a suspended carbon nanotube result in a positive nanotube magnetoresistance, which decreases slowly with the increase of temperature. This effect may enable one to detect quantum displacement fluctuations of a nanomechanical device.

Force-strain relation of bundles of carbon nanotubes

The force-strain relation and tensile strength of carbon nanotube bundles are studied based on the assumption that the tensile strength of individual carbon nanotubes (CNTs) obeys the Weibull distribution, with nonlinear stress-strain behavior. The Weibull modulus of the CNT that characterizes the dispersion of tensile strength can be estimated in terms of the maximum sustained force and the failure strain of the bundle. Bundles of single-walled carbon nanotubes (SWNTs) were subjected to tensile testing using a nanomechanical testing device. Results show that the nonlinear behavior of SWNTs does affect the force-strain relation of SWNT bundles, more apparent at large strain.

A nanomechanical device based on light-driven proton pumps

In this paper, a hybrid device based on a microcantilever interfaced with bacteriorhodopsin(bR) is constructed. The microcantilever, on which the highly oriented bR film isself-assembled, undergoes controllable and reversible bending when the light-driven protonpump protein, bR, on the microcantilever surface is activated by visible light. Severalcontrol experiments are carried out to preclude the influence of heat and photothermaleffects. It is shown that the nanomechanical motion is induced by the resulting gradient ofprotons, which are transported from the KCl solution on the cytoplasmic side of the bRfilm towards the extracellular side of the bR film. Along with a simple physicalinterpretation, the microfabricated cantilever interfaced with the organized molecular filmof bR can simulate the natural machinery in converting solar energy to mechanical energy.

Propulsion with a Rotating Elastic Nanorod

The dynamics of a rotating elastic filament is investigated using Stokesian simulations. The filament, straight and tilted with respect to its rotation axis for small driving torques, undergoes at a critical torque a strongly discontinuous shape bifurcation to a helical state. It induces a substantial forward propulsion whatever the sense of rotation: a nanomechanical force-rectification device is established.

Single molecule nanometronome.

We constructed a DNA-based nanomechanical device called the nanometronome. Our device is made by introducing complementary single-stranded overhangs at the two arms of the DNA four-way junction. The ticking rates of this stochastic metronome depend on ion concentrations and can be changed by a set of DNA-based switches to deactivate/reactivate the sticky end. Since the device displays clearly distinguishable responses even with a single base pair difference, it may lead to a single molecule sensor of minute sequence differences of a target DNA.

Energy exchanges in carbon nanotube oscillators

Energy exchanges between orderly intertube axial motion and vibrational modes arestudied for isolated systems of two coaxial carbon nanotubes at temperatures rangingfrom 300 to 500 K. It is found that the excess intertube van der Waals energy,depleted from the intertube axial motion, is primarily stored in low-frequencymechanical modes of the oscillator for an extended period of time. This constitutesthe first computer simulation of a nanomechanical device that exhibits negativefriction.

Ion‐Triggered Multistate Molecular Switching Device Based on Regioselective Coordination‐Controlled Ion Binding

Molecular devices capable of accessing different controlled conformational states, while optically signaling the occupied state, are attractive tools for nanotechnology since they relate to both areas of molecular mechanical devices and logic gates. We report here a simple molecular system that allows access to four distinct conformational and optical states. It is based on the regioselective complexation of metal ions to a heterocyclic ligand triad, which is dictated by the accessible coordination geometry and electrostatic properties of two distinct binding subunits. Thus, local conformational switching is brought about by tetrahedral coordination (of Cu(I)) or octahedral coordination (of M(2+) ions) to bidentate and tridentate binding subunits, respectively. The shape modifications undergone represent an ion-controlled nanomechanical device. They give controlled access to four different states that display different physico-chemical (e.g. optical) properties and provide a basis for logic gate operations.

Strain-Induced Coupling of Spin Current to Nanomechanical Oscillations

We propose a setup which allows us to couple the electron spin degree of freedom to the mechanical motions of a nanomechanical system not involving any of the ferromagnetic components. The proposed method employs the strain-induced spin-orbit interaction of electrons in narrow gap semiconductors. We have shown how this method can be used for detection and manipulation of the spin flow through a suspended rod in a nanomechanical device.

Translation of DNA Signals into Polymer Assembly Instructions

We developed a DNA nanomechanical device that enables the positional synthesis of products whose sequences are determined by the state of the device. This machine emulates the translational capabilities of the ribosome. The device has been prototyped to make specific DNA sequences. The state of the device is established by the addition of DNA set strands. There is no transcriptional relationship between the set strands and the product strands. The device has potential applications that include designer polymer synthesis, encryption of information, and use as a variable-input device for DNA-based computation.

A nanomechanical device based on linear molecular motors

An array of microcantilever beams, coated with a self-assembled monolayer of bistable, redox-controllable [3]rotaxane molecules, undergoes controllable and reversible bending when it is exposed to chemical oxidants and reductants. Conversely, beams that are coated with a redox-active but mechanically inert control compound do not display the same bending. A series of control experiments and rational assessments preclude the influence of heat, photothermal effects, and pH variation as potential mechanisms of beam bending. Along with a simple calculation from a force balance diagram, these observations support the hypothesis that the cumulative nanoscale movements within surface-bound “molecular muscles” can be harnessed to perform larger-scale mechanical work.

Characteristics of Nano-Electrostatic Actuator Fabricated by Focused Ion Beam Chemical Vapor Deposition

The three-dimensional (3D) nanostructure fabrication technology using focused ion beam chemical vapor deposition (FIB-CVD) is very effective for highly efficient 3D nanomechanical device fabrication. We can fabricate 3D nanostructure easily and freely with this fabrication technology using FIB-CVD. Here, we demonstrate the fabrication of various 3-D nano-electrostatic actuators and manipulators on a glass capillary by 30 keV Ga+ focused-ion-beam-assisted deposition with phenanthrene vapor as a precursor, and the operation of these actuators and manipulators by applying voltage onto a Au-coated glass capillary under an optical microscope is shown. Furthermore, the structural characteristics and functionalities of them are described in this paper.

A protein-driven DNA device that measures the excess binding energy of proteins that distort DNA.

A DNA nanomechanical device was constructed by linking two triple-helical DNA motifs with a shaft of conventional DNA bearing the binding site for the integration host factor (IHF, shown as green ellipse in the picture). Binding of IHF to this site causes marked shaft bending, which can be monitored by fluorescence resonance energy transfer between donor (D) and acceptor (A) dyes.