NanoElectroMechanical Systems (NEMS) are class of devices or Microelectromechanical Systems (MEMS) scaled to submicron dimensions. In such nanoscales, it is possible to attain extremely high fundamental frequencies while simultaneously... more
NanoElectroMechanical Systems (NEMS) are class of devices or Microelectromechanical Systems (MEMS) scaled to submicron dimensions. In such nanoscales, it is possible to attain extremely high fundamental frequencies while simultaneously preserving very high mechanical susceptibility. NEMS have critical structural constituent at or below 100nm. NEMS combine smaller mass with higher surface area to volume ratio and are therefore very helpful in applications like high-frequency resonators and ultrasensitive sensors.
In this short article, we summarizes and discusses about recent progress in nano-electro-mechanical system (NEMS) based memory devices research which covers: theories, advantages and challenges.
Future generations of transistors, sensors, and other devices maybe revolutionized through the use of onedimensional nanostructures such as nanowires, nanotubes, and nanorods. The unique properties of these nanostructures will set new... more
Future generations of transistors, sensors, and other devices maybe revolutionized through the use of onedimensional nanostructures such as nanowires, nanotubes, and nanorods. The unique properties of these nanostructures will set new benchmarks for speed, sensitivity, functionality, and integration. These devices may even be self-powered, harvesting energy directly from their surrounding environment. However, as their critical dimensions continue to decrease and performance demands grow, classical mechanics and associated experimental techniques no longer fully characterize the observed behavior. This perspective examines the evolving role of experimental mechanics in driving the development of these new devices. Emphasis is placed on advances in experimental techniques for comprehensive characterization of size effects and their coupling, as well as assessment of device-level response.
Nanorobotics encompasses the design, fabrication, and programming of robots with overall dimensions below a few micrometers, and the programmable assembly of nanoscale objects. Nanorobots are quintessential nanoelectromechanical systems... more
Nanorobotics encompasses the design, fabrication, and programming of robots with overall dimensions below a few micrometers, and the programmable assembly of nanoscale objects. Nanorobots are quintessential nanoelectromechanical systems (NEMS) and raise all the important issues that must be addressed in NEMS design: sensing, actuation, control, communications, power, and interfacing across spatial scales and between the organic/inorganic and biotic/abiotic realms. Nanorobots are expected to have revolutionary applications in such areas as environmental monitoring and health care. This paper begins by discussing nanorobot construction, which is still at an embryonic stage. The emphasis is on nanomachines, an area which has seen a spate of rapid progress over the last few years. Nanoactuators will be essential components of future NEMS.
In this study, influences of intermolecular forces on the dynamic pull-in instability of electrostatically actuated beams are investigated. The effects of midplane stretching, electrostatic actuation, fringing fields, and intermolecular... more
In this study, influences of intermolecular forces on the dynamic pull-in instability of electrostatically actuated beams are investigated. The effects of midplane stretching, electrostatic actuation, fringing fields, and intermolecular forces are considered. The boundary conditions of the beams are clamped-free and clamped-clamped. A finite-element model is developed to discretize the governing equations, and Newmark time discretization is then employed to solve the discretized equations. The static pull-in instability is investigated to validate the model. Finally, dynamic pull-in instability of cantilevers and double-clamped beams are studied considering the Casimir and van der Waals effects. The results indicate that by increasing the Casimir and van der Waals effects, the effect of inertia on pull-in values considerably increases.
The authors report the nanomachining of sub-20-nm wide doubly clamped silicon carbon nitride resonators using low keV electron beam lithography with polymethyl methacrylate resist and cold development. Methodologies are developed for... more
The authors report the nanomachining of sub-20-nm wide doubly clamped silicon carbon nitride resonators using low keV electron beam lithography with polymethyl methacrylate resist and cold development. Methodologies are developed for precisely controlling the resonator widths in the ultranarrow regime of 11–20 nm. Resonators with lengths of 1–20 μm and widths of 16–280 nm are characterized at room temperature in vacuum using piezoelectric actuation and optical interferometry. Clamping and surface losses are identified as the dominant energy loss mechanisms for a range of resonator widths. The resonator clamping points are optimized using an original electron beam lithography simulator. Various alternative clamping point designs are also modeled and fabricated in order to reduce the clamping losses.
A brief description of the stability problem in micro and nano electromechanical devices (MEMS/NEMS) actuated by Casimir forces is given. To enhance the stability, we propose the use of curved surfaces and recalculate the stability... more
A brief description of the stability problem in micro and nano electromechanical devices (MEMS/NEMS) actuated by Casimir forces is given. To enhance the stability, we propose the use of curved surfaces and recalculate the stability conditions by means of the proximity force approximation. The use of curved surfaces changes the bifurcation point, and the radius of curvature becomes a control parameter, allowing a rescaling of the elastic restitution constant and/or of the typical dimensions of the device.
In this paper, we propose the use of multi-pole nanoelectromechanical (NEM) relays for routing multi-bit signals within a coarse-grained reconfigurable array (CGRA). We describe a CMOS-compatible multi-pole relay design that can be... more
In this paper, we propose the use of multi-pole nanoelectromechanical (NEM) relays for routing multi-bit signals within a coarse-grained reconfigurable array (CGRA). We describe a CMOS-compatible multi-pole relay design that can be integrated in 3-D and improves area utilization by 40% over a prior design. Additionally, we demonstrate a method for placing multiple contacts on a relay that can reduce contact resistance variation by 40× over a circular placement strategy. We then show a methodology for integrating these relays into an industrystandard digital design flow. Using our multi-pole relay design, we perform post-layout simulation of a processing element (PE) tile within a hybrid CMOS-NEMS CGRA in 40 nm technology. We achieve up to 19% lower area and 10% lower power at iso-delay, compared to a CMOS-only PE tile. The results show a way to bridge the performance gap between programmable logic devices (such as CGRAs) and application-specific integrated circuits using NEMS technology.
In this work, we report the fabrication of sub-10 nm wide, doubly-clamped silicon carbon nitride (SiCN) resonators of up to 5 μm lengths. An existing resonator fabrication process has undergone a major improvement through the use of a... more
In this work, we report the fabrication of sub-10 nm wide, doubly-clamped silicon carbon nitride (SiCN) resonators of up to 5 μm lengths. An existing resonator fabrication process has undergone a major improvement through the use of a single hydrogen silsesquioxane (HSQ) masking layer for SiCN patterned using electron beam lithography. Novel development strategies, comprising hot development and HF-trimming development, were also used. The crucial role of post-exposure resist processing in improving the resonator resolution and uniformity was demonstrated. Application of the optimized lithographic process has allowed us to claim the narrowest suspended bridge structures of several microns in length achieved to date.
When modeling the hydrodynamics of nanofluidic systems, it is often essential to include molecularlevel information such as molecular fluctuations. To this effect, we present a mesoscopic approach which combines a fluctuating... more
When modeling the hydrodynamics of nanofluidic systems, it is often essential to include molecularlevel information such as molecular fluctuations. To this effect, we present a mesoscopic approach which combines a fluctuating hydrodynamics formulation with an efficient implementation of Electroosmotic flow (EOF) in the small Debye length limit. The resulting approach, whose major ingredient is Dissipative Particle Dynamics, is sufficiently coarse-grained to allow efficient simulation of the hydrodynamics of micro/nanofluidic devices of sizes that are too large to be simulated by ab initio methods such as Molecular Dynamics. Within our formulation, EOF is efficiently generated using the recently proven similitude between velocity and electric field under appropriate conditions. More specifically, EOF is generated using an effective boundary condition, akin to a moving wall, thus avoiding evaluation of the computationally expensive electrostatic forces. Our method is used for simulating EOFs and DNA molecular sieving in simple and complex two-dimensional (2D) and 3D geometries frequently used in nano-fluidic devices. The numerical data obtained from our model are in very good agreement with theoretical results.
In this paper, we report on the main aspects of the design, fabrication, and performance of a microelectromechanical system constituted by a mechanical submicrometer scale resonator (cantilever) and the readout circuitry used for... more
In this paper, we report on the main aspects of the design, fabrication, and performance of a microelectromechanical system constituted by a mechanical submicrometer scale resonator (cantilever) and the readout circuitry used for monitoring its oscillation through the detection of the capacitive current. The CMOS circuitry is monolithically integrated with the mechanical resonator by a technology that allows the combination of standard CMOS processes and novel nanofabrication methods. The integrated system constitutes an example of a submicroelectromechanical system to be used as a cantilever-based mass sensor with both a high sensitivity and a high spatial resolution (on the order of 10 18 g and 300 nm, respectively). Experimental results on the electrical characterization of the resonance curve of the cantilever through the integrated CMOS readout circuit are shown. [1318]
This paper identifies six myths about clean electricity in the southern U.S. These myths are either propagated by the public at-large, shared within the environmental advocacy culture, or spread imperceptibly between policymakers. Using a... more
This paper identifies six myths about clean electricity in the southern U.S. These myths are either propagated by the public at-large, shared within the environmental advocacy culture, or spread imperceptibly between policymakers. Using a widely accepted energy-economic modeling tool, we expose these myths as half-truths and the kind of conventional wisdom that constrains productive debate. In so doing, we identify new starting points for energy policy development. Climate change activists may be surprised to learn that it will take more than a national Renewable Electricity Standard or supportive energy efficiency policies to retire coal plants. Low-cost fossil generation enthusiasts may be surprised to learn that clean generation can save consumers money, even while meeting most demand growth over the next 20 years. This work surfaces the myths concealed in public perceptions and illustrates the positions of various stakeholders in this large U.S. region.
This paper presents the design optimization of high performance three-degree of freedom silicon accelerometer. The purpose of this optimization is to achieve the high sensitivity and high resolution. The optimization has been performed... more
This paper presents the design optimization of high performance three-degree of freedom silicon accelerometer. The purpose of this optimization is to achieve the high sensitivity and high resolution. The optimization has been performed based on considerations of junction depth, the doping concentration of the piezoresistor, the temperature coefficient sensitivity, the noise, and the power consumption. Taking advantage of high piezoresistive effect in nanoscale piezoresistor, the cross-sectional area of the piezoresistor is fabricated to be 15x104 nm2. The result shows that the sensitivity of the optimized accelerometer is improved while the resolution is comparable to previous results. The dimension of sensor is as small as 1 mm2, so it is suitable for many immerging applications.
We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are... more
We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are driven parametrically by the output of a conventional oscillator at a frequency close to the sum of the linear mode frequencies. Above the threshold for parametric instability, the coupled resonators exhibit self-oscillations which arise as a response to the parametric driving, rather than by application of active feedback. We find operating points of the device for which this periodic signal is immune to frequency noise in the driving oscillator, providing a way to clean its phase noise. We present results for the effect of thermal noise to advance a broader understanding of the overall noise sensitivity and the fundamental operating limits.
This paper describes an innovative work for nanorobot design and manufacturing, using a computer simulation and system on chip prototyping approach. The use of CMOS as integrated circuits, with the miniaturization from micro towards... more
This paper describes an innovative work for nanorobot design and manufacturing, using a computer simulation and system on chip prototyping approach. The use of CMOS as integrated circuits, with the miniaturization from micro towards nanoelectronics, and the respective advances of nanowires are considered into the proposed model design and discussed as a practical pathway to enable embedded sensors for manufacturing nanorobots. The proposed nanorobot model is applied to hydrology monitoring. It can be useful for agriculture or environmental monitoring and management.
In this research, a glassy carbon electrode modified with single-wall carbon nanotubes for electrochemical determination of dopamine was studied by cyclicvoltammetry (CV) and differential pulse voltammetry (DPV). The oxidation and... more
In this research, a glassy carbon electrode modified with single-wall carbon nanotubes for electrochemical determination of dopamine was studied by cyclicvoltammetry (CV) and differential pulse voltammetry (DPV). The oxidation and reduction potentials of dopamine using voltammetric technique were measured. The SWCNTs/GC 10 µL was used to test the linearity of anodic oxidation of dopamine by DPV. The peak current increased linearly with concentration of dopamine in the range of 2.5-25 ppm (R 2 =0.9766).For the life time of the SWCNTs/GC, the cut-off criterion of the DPV was detected in the reduction of current by 50 %. The lifetime of the SWCNTsmodified depended on the oxidation of dopamine because of fouling of the electrode surface due to the adsorption of oxidation products. 34 repetition cycles was obtained. The detection limit of the dopamine as obtained from the oxidation current in DPV was 0.021 ppm (S/N=3) with minimum current for the detection of dopamine of 0.033 µA. The reproducibility of electrocatalytical studies was better within 90% (10% RSD). The relative standard deviation (RSD) of 8.42% for 100 ppm dopamine (n=20) showed excellent reproducibility. Drug samples obtained from Radvitee hospital were tested as the mentioned procedure. The percentage recovery of dopamine in drug samples was 120.
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on... more
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on time-resolved extreme ultraviolet detection of the pseudosurface acoustic wave frequency shift upon mass loading the device. The present design opens the path to sensors operating in a frequency range currently unaccessible to electro-acoustical transducers, providing enhanced sensitivity, miniaturization and incorporating time-resolving capability while forgoing the piezoelectric substrate requirement.
This paper reports the successful experimental demonstration of the localized growth of horizontal, dense carbon nanotube (CNT) arrays in situ and at the wafer scale. The selectivity and directionality of the CNT catalytic growth process... more
This paper reports the successful experimental demonstration of the localized growth of horizontal, dense carbon nanotube (CNT) arrays in situ and at the wafer scale. The selectivity and directionality of the CNT catalytic growth process along with the adequate design and fabrication of the catalyst support enables the direct integration of nanotubes arrays into heterogeneous devices. This novel CNT integration method is developed to manufacture conductance based gas sensors for ammonia detection and is demonstrated to produce a yield above 90% at the wafer scale. Owing to its flexibility, the integration process can be useful for a wide range of applications and complies with industrial requirements in terms of manufacturability and yield, requirements for the acceptance of CNTs as alternate materials. A state-of-the-art CNT array resistivity of 1.75 · 10 À5 X m has been found from the CNT characterization. When exposed to low NH 3 concentrations, the CNT sensors show good repeatability, long-term stability, and high design robustness and tackle the reproducibility challenge for CNT devices. Individual device calibration is not needed.
We study the quantum properties of a nanomechanical oscillator via the squeezing of the oscillator amplitude. The static longitudinal compressive force F0 close to a critical value at the Euler buckling instability leads to an anharmonic... more
We study the quantum properties of a nanomechanical oscillator via the squeezing of the oscillator amplitude. The static longitudinal compressive force F0 close to a critical value at the Euler buckling instability leads to an anharmonic term in the Hamiltonian and thus the squeezing properties of the nanomechanical oscillator are to be obtained from the Hamiltonian of the form H = a † a + β(a † + a) 4 /4. This Hamiltonian has no exact solution unlike the other known models of nonlinear interactions of the forms a †2 a 2 , (a † a) 2 and a †4 +a 4 −(a †2 a 2 +a 2 a †2 ) previously employed in quantum optics to study squeezing. Here we solve the Schrödinger equation numerically and show that inphase quadrature gets squeezed for both ground state and coherent states. The squeezing can be controlled by bringing F0 close to or far from the critical value Fc. We further study the effect of the transverse driving force on the squeezing in nanomechanical oscillator.
This paper proposes a new non-volatile semiconductor memory which features a suspended gate integrated with silicon nanocrystals dots as a floating gate and the MOSFET as a readout. Performing three-dimensional finite element simulations... more
This paper proposes a new non-volatile semiconductor memory which features a suspended gate integrated with silicon nanocrystals dots as a floating gate and the MOSFET as a readout. Performing three-dimensional finite element simulations combined with an analytical plate-capacitor model, we clarify the pull-in/pull-out operation of the suspended gate. We also show the dependence of the hysteresis cycle characteristics on material and structural parameters.
Silicon VLSI technology, developed and matured over the past decades, has been fully exploited to build the vast technology area of micro-electromechanical systems (MEMS). The MEMS market is projected to grow with the rate of 30 -40 % per... more
Silicon VLSI technology, developed and matured over the past decades, has been fully exploited to build the vast technology area of micro-electromechanical systems (MEMS). The MEMS market is projected to grow with the rate of 30 -40 % per annum and reach ten billion dollars in 2015. In parallel with such a rapid expansion of the MEMS market, there have also been continuous efforts at making the MEMS smaller in order to boost the operating frequency to GHz and beyond. shows a recent miniaturization trend of semiconductor-based MEMS, superposed on the CMOS downscaling trend (' ').
The effect of the Casimir force in micro-and nanoelectromechanical systems is examined taking fully into account the dielectric properties of the materials, as well as the finite thickness of movable elements in micro-and nanosystems. The... more
The effect of the Casimir force in micro-and nanoelectromechanical systems is examined taking fully into account the dielectric properties of the materials, as well as the finite thickness of movable elements in micro-and nanosystems. The resulting equations are exact, and from the bifurcation diagrams the critical separation before jump-to-contact is determined. It is shown how the critical separation changes, for example, with the dielectric properties of the materials and how these systems can be rescaled based on the information from the bifurcation diagrams.
We report self-assembly and phase transition behavior of lower diamondoid molecules and their primary derivatives using molecular dynamics (MD) simulation and density functional theory (DFT) calculations. Two lower diamondoids (adamantane... more
We report self-assembly and phase transition behavior of lower diamondoid molecules and their primary derivatives using molecular dynamics (MD) simulation and density functional theory (DFT) calculations. Two lower diamondoids (adamantane and
diamantane), three adamantane derivatives (amantadine, memantine and rimantadine) and two artificial molecules (ADMNa and DIMNa) are studied separately in 125-molecule simulation systems. We performed DFT calculations to optimize their molecular geometries and obtained atomic electronic charges for the corresponding MD simulation, by which we predicted self-assembly structures and simulation trajectories for the seven different diamondoids and derivatives. Our radial distribution function and structure factor studies showed clear phase transitions and self-assemblies for the seven diamondoids and derivatives.
For a variety of applications in integrated communication and sensor devices nano-electromechanical systems (NEMS) present a new generation of high frequency components. Up to now conventional excitation mechanisms for NEMS are based... more
For a variety of applications in integrated communication and sensor devices nano-electromechanical systems (NEMS) present a new generation of high frequency components. Up to now conventional excitation mechanisms for NEMS are based either on high magnetic (magnetomotive method) or electric (electromotive method) fields which limits the use of NEMS. We present experiments utilizing a surface acoustic wave (SAW) transducer on GaAs to excite nanomechanical resonators operating at frequencies up to 300 MHz. We show that via SAW full control over the fundamental properties of the resonator sensor is achieved.
A which-way device is one which is designed to detect which of two paths is taken by a quantum particle. One such device is represented by an Aharonov–Bohm ring with a quantum dot on one branch. A charged cantilever or spring is brought... more
A which-way device is one which is designed to detect which of two paths is taken by a quantum particle. One such device is represented by an Aharonov–Bohm ring with a quantum dot on one branch. A charged cantilever or spring is brought close to the dot as a detector of the presence of an electron. In this paper we show that, contrary to popular belief, it is in fact possible to change the state of the oscillator while preserving the quantum interference phenomenon, but that this tells us little about the path traversed by the particle.
Oscillators, which produce continuous periodic signals from direct current power, are central to modern communications systems, with versatile applications such as timing references and frequency modulators 1-7 . However, conventional... more
Oscillators, which produce continuous periodic signals from direct current power, are central to modern communications systems, with versatile applications such as timing references and frequency modulators 1-7 . However, conventional oscillators typically consist of macroscopic mechanical resonators such as quartz crystals, which require excessive off-chip space. Here we report oscillators built on micron-size, atomically-thin graphene nanomechanical resonators, whose frequencies can be electrostatically tuned by as much as 14%.
Magnetic relaxation processes were first discussed for a crystal of paramagnetic transition ions 1 . It was suggested that mechanical vibrations of the crystal lattice (phonons) modulate the crystal electric field of the magnetic ion,... more
Magnetic relaxation processes were first discussed for a crystal of paramagnetic transition ions 1 . It was suggested that mechanical vibrations of the crystal lattice (phonons) modulate the crystal electric field of the magnetic ion, thus inducing a 'direct' relaxation between two different spin states 1-3 . Direct relaxation has also been predicted for single-molecule magnets with a large spin and a high magnetic anisotropy and was first demonstrated in a Mn 12 acetate crystal 8 . The spin-lattice relaxation time for such a direct transition is limited by the phonon density of states at the spin resonance 1 . In a three-dimensional system, such as a single-molecule magnet crystal, the phonon energy spectrum is continuous, but in a one-dimensional system, like a suspended carbon nanotube, the spectrum is discrete and can be engineered to an extremely low density of states 9 . An individual single-molecule magnet, coupled to a suspended carbon nanotube, should therefore exhibit extremely long relaxation times 9 and the system's reduced size should result in a strong spin-phonon coupling 10,11 . Here, we provide the first experimental evidence for a strong spin-phonon coupling between a single molecule spin and a carbon nanotube resonator, ultimately enabling coherent spin manipulation and quantum entanglement 10,11 .
We have demonstrated multi-walled carbon nanotube (MWCNTs) based sensors, which are capable of detecting alcohol vapor with ultra-low power. We fabricated the Si-substrate sensors using an AC electrophoretic technique so as to form... more
We have demonstrated multi-walled carbon nanotube (MWCNTs) based sensors, which are capable of detecting alcohol vapor with ultra-low power. We fabricated the Si-substrate sensors using an AC electrophoretic technique so as to form bundled MWCNTs sensing elements between Au microelectrodes. The I-V measurement illustrates that we can activate the sensors at the Ohmic region of the sensors (at 10µA), which is without any overheat effect. The sensors only need an ultra-low power (~1µW) to detect the alcohol vapor. They exhibit fast, reversible and repeatable response. We have tested the response of the sensors with alcohol concentrations from 10ppth to 400ppth (ppth = parts per thousand). Our result shows that there is a linear relation between the resistance of the sensors and alcohol concentration. Also, we can easily reverse the sensor to the initial reference resistance by annealing them at 100-250µA current within 6 minutes. Moreover, the sensors are selective with respect to flow from air, water vapor, and alcohol vapor. Finally, we have also studied how the temperature of the sensors affects their response towards alcohol vapor. The result shows that the performance of the sensors will deteriorate as the temperature of the sensors increase. Also, the cooling effect of the vapor is not a dominating factor in determining the response of the sensor. Based on our experiments, we prove the feasibility of turning the MWCNTs sensors into a commercialized alcohol sensor with ultra-low power requirements.
The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electromechanical systems. The... more
The importance of thermoelastic damping as a fundamental dissipation mechanism for small-scale mechanical resonators is evaluated in light of recent efforts to design high-Q micrometer- and nanometer-scale electromechanical systems. The equations of linear thermoelasticity are used to give a simple derivation for thermoelastic damping of small flexural vibrations in thin beams. It is shown that Zener’s well-known approximation by a Lorentzian with a single thermal relaxation time slightly deviates from the exact expression.
We investigate the effect of quantisation of vibrational modes on a system in which the transport path is through a quantum dot mounted on a cantilever or spring such that tunnelling to and from the dot is modulated by the oscillation. We... more
We investigate the effect of quantisation of vibrational modes on a system in which the transport path is through a quantum dot mounted on a cantilever or spring such that tunnelling to and from the dot is modulated by the oscillation. We consider here the implications of quantum aspects of the motion. Peaks in the current voltage characteristic are observed which correspond to avoided level crossings in the eigenvalue spectrum. Transport occurs through processes in which phonons are created. This provides a path for dissipation of energy as well as a mechanism for driving the oscillator, thus making it easier for electrons to tunnel onto and off the dot and be ferried across the device.
Electro mechanical switches used for multi-purposs applications with ultra small size in nano meter scale, operating in very small voltage in millivolts, approximately zero leakage current due to air gap separation between electrodes with... more
Electro mechanical switches used for multi-purposs applications with ultra small size in nano meter scale, operating in very small voltage in millivolts, approximately zero leakage current due to air gap separation between electrodes with three terminals that easy to control it. Nano electro mechanical switches are electronic switches similar to those used by conventional semiconductor switches in application as they can be used as relays, logic devices. The basic principle of nano electro mechanical switches is electronic switches operation is fundamentally different from semiconductor switches. They have many advantages over conventional semiconductor switches such as low-power digital logic applications, ability to work with very small voltage signals for low dynamic energy consumption, and durability against hostile environments such as high temperatures and radiation contaminated spaces. In this article, we will design, implement, and test a matrix of nano electro mechanical switches by on line test using the superposition theory. The simulations of these switches were implemented using the MATLAB-Simulink and ORCAD Pspice environments. Also, controlling the flow of current was achieved by means of a nanometer movement to make or break the physical contact between the electrodes.
We describe a prototype micro-laboratory for rapid genetic identification of bacterial pathogens from infected human body fluids. The core module of the detection platform is a microfabricated electrochemical sensor array. Picomolar... more
We describe a prototype micro-laboratory for rapid genetic identification of bacterial pathogens from infected human body fluids. The core module of the detection platform is a microfabricated electrochemical sensor array. Picomolar amperometric detection is achieved through formation of a DNA sandwich between capture and detector probe pairs and bacterial 16S rRNA, coupled with an oxidoreductase cnzymatic transducer. Using the sensor array functionalized with a panel of species-specific DNA oligonucleotide probes, detection of bacterial urinary pathogens have been demonstrated in a pilot clinical validation study demonstrating 98% sensitivity for Gram-negative pathogen detection, using conventional urine culture as the standard. Genotypic species identification is achieved within 45 minutes, compared to 1-2 days needed for standard bacterial culture technique. A biofilter has also been fabricated and validated with clinical urine specimens. Efficient concentration of the pathogens is demonstrated and replaces the need for conventional centrifugation. A microfluidic mixer to facilitate reagent mixing is also under development as part of sample preparation module. Preliminary experimental data indicate good correlation with computational simulation. These are critical milestones towards our development of an integrated point-of-care platform for pathogen detection in body fluids.
The ionization of gases results in a unique fingerprint depending on their nature and concentration. Moreover, according to Paschen's law, the measurement of distinct species is possible by modifying the distance between the electrodes.... more
The ionization of gases results in a unique fingerprint depending on their nature and concentration. Moreover, according to Paschen's law, the measurement of distinct species is possible by modifying the distance between the electrodes. In order to analyze gaseous compounds within a mixture, a novel MEMS tunable sensor incorporating freestanding nanowires is proposed. This device allows controlling the ionization gap by capacitive actuation. Mechanical and electrical characterizations, together with finite elements simulations have been conducted in order to evaluate electric field interactions and minimize interferences. Such system should allow the development of a universal gas sensor with pattern recognition.
A molecular layer deposition approach is reported that produces a new class of hybrid organic-inorganic thin films. These films have very low densities, and display typical atomic layer deposition characteristics: controllable linear... more
A molecular layer deposition approach is reported that produces a new class of hybrid organic-inorganic thin films. These films have very low densities, and display typical atomic layer deposition characteristics: controllable linear growth, conformality, low roughness, and uniform composition. Because of their aluminum content, the alucone films cannot be dry etched with oxygen plasma. In accordance with their molecular structure, the new materials are completely removed in hydrochloric acid solutions. Since they can be etched with accurate control in acidic solutions, these hybrid materials are promising for the fabrication of MEMS/NEMS (Micro/Nano Electro Mechanical Systems) devices. Doubly supported structures with 120 nm air gaps are demonstrated using alucone materials as sacrificial layers.
We simulate the twist of carbon nanotubes using atomic molecular dynamic simulations. The ultimate twist angle per unit length and the deformation energy are calculated for nanotubes of different geometries. It is found that the big tube... more
We simulate the twist of carbon nanotubes using atomic molecular dynamic simulations. The ultimate twist angle per unit length and the deformation energy are calculated for nanotubes of different geometries. It is found that the big tube is harder to be twisted while the small tube exhibits higher ultimate twisting ratio. For multi-walled nanotubes, the zigzag tube is found to be able to stand more deformation than the armchair one. We observed the surface transformation during twisting. Formation of structural defects is observed prior to fracture.
In this research, influences of intermolecular interactions on the behavior of nanobeams are studied. Suddenly applied voltages actuates the clamped-clamped nanobeam. The eff ects of electrostatic actuation, intermolecular forces,... more
In this research, influences of intermolecular interactions on the behavior of nanobeams are studied. Suddenly applied voltages actuates the clamped-clamped nanobeam. The eff ects of electrostatic actuation, intermolecular forces, midplane stretching, the fringing field eff ect and residual stress are considered. Initially, the governing equation is non-dimensionalized, and the partial diff erential equation of motion is converted to a nonlinear ordinary differential equation by means of the Galerkin method. Afterwards, the nonlinear ordinary di fferential equation of motion is solved using the homotopy analysis method. To validate the model, the response of a sample beam was compared with that in the relevant literature. Finally, the eff ects of various parameters on the nonlinear frequency of the response are studied. The results indicate that the nonlinear frequency of oscillations signi significantly decreases by increasing intermolecular e ffects.
THE NETWORK FOR COMPUTATIONAL NAN- otechnology (NCN) is a six-university initiative that was established in 2002 to connect those who develop simulation tools with those who use them. The NCN currently addresses three science themes,... more
THE NETWORK FOR COMPUTATIONAL NAN- otechnology (NCN) is a six-university initiative that was established in 2002 to connect those who develop simulation tools with those who use them. The NCN currently addresses three science themes, nanoelectronics, nano-electrical-mechanical systems (NEMS) and nanofluidics, and nanomedicine, but is expanding its coverage into other areas of nanotechnology. The NCN's strategy to serve and engage the nanotechnology community centers on a unique, science gateway, www.nanoHUB.org, offering online simulation services for research, education, and collaboration and a new way to publish research and instructional materials. The NCN's primary goal is to lower barriers for the use of simulations in emerging fields of study. At the nanoHUB Web site (Figure ), users log on, access state-of-the-art simulation software, run interactive
Advance of technology touches most surely the area of marine engineering. Nanotechnology, as at the top of research interest, has potential to change our lives. Nanocomputers, nanocontrollers or nanomechanical devices will impact every... more
Advance of technology touches most surely the area of marine engineering. Nanotechnology, as at the top of research interest, has potential to change our lives. Nanocomputers, nanocontrollers or nanomechanical devices will impact every aspect of marine technology. One of the nanotechnological products are nano-electromechanical systems (NEMS). NEMS are manufactured and/or assembled by a lot of nanoelements. One of possible elements
A microcantilever based platform for mass detection in the femtogram range has been integrated in the doped top silicon layer of a SOI substrate. The on-plane fundamental resonance mode of the cantilever is excited electrostatically and... more
A microcantilever based platform for mass detection in the femtogram range has been integrated in the doped top silicon layer of a SOI substrate. The on-plane fundamental resonance mode of the cantilever is excited electrostatically and detected capacitively by means of two parallel placed electrodes in a two port configuration. An electromechanical model of the cantilever-electrodes transducer and its implementation in a SPICE environment are presented. The model takes into account non-linearities from variable cantilever-electrode gap, fringing field contributions and real deflection shape of the cantilever for the calculation of the driving electrostatic force. A fitting of the model to the measured S 21 transmitted power frequency response is performed to extract the characteristic sensor parameters as Young modulus, Q factor, electrical parasitics and mass responsivity.
This analysis updates an earlier, preliminary NREL investigation into the proposed Bingaman legislation that did not include changes mandated by the American Recovery and Reinvestment Act of 2009. In particular, it considers an extension... more
This analysis updates an earlier, preliminary NREL investigation into the proposed Bingaman legislation that did not include changes mandated by the American Recovery and Reinvestment Act of 2009. In particular, it considers an extension of production tax credit through December 31, 2012. Available at http://www.nrel.gov/docs/fy09osti/45161.pdf.
Post-processing techniques are applied after the integration and assembly of nanostructures and Microelectromechanical Systems (MEMS) to realize integrated Nanoelectromechanical Systems (NEMS). Experimentation is focused specifically on... more
Post-processing techniques are applied after the integration and assembly of nanostructures and Microelectromechanical Systems (MEMS) to realize integrated Nanoelectromechanical Systems (NEMS). Experimentation is focused specifically on the application of post-processing steps to a locally self-assembled micro-to-nano system comprising of suspended silicon nanowires between two MEMS bridges. Local contact metallization, global metallization for rapid system functionalization and the application of aqueous treatment to the NEMS are among the postprocessing techniques studied. These techniques are evaluated for their effectiveness and compatibility with integrated NEMS and traditional MEMS processes. It is found that local and global contact metallization techniques effectively alleviate inherent problems at the nano-to-micro contact and the aqueous treatment study confirms the effectiveness of the super critical drying process for nanostructures.
This paper presents the novel synthesis design of a three-degree of freedom silicon piezoresistive accelerometer. The purpose of this novel synthesis design is to achieve the high performance device. The design synthesis has been... more
This paper presents the novel synthesis design of a three-degree of freedom silicon piezoresistive accelerometer. The purpose of this novel synthesis design is to achieve the high performance device. The design synthesis has been performed based on considerations of mechanical and electronics sensitivities, noise and thermal effects, respectively. The mechanical sensitivity is optimized due to combination of a FEM software and a MNA one. The electronics sensitivity, noise and thermal effect can be determined by thermal, mechanical and piezoresistive coupled-field simulations. The dimension of sensor is as small as 1.5 mm 2 , so it is suitable for many immerging applications.
One-dimensional nanomechanical resonators based on nanowires and nanotubes have emerged as promising candidates for mass sensors 1-6 . When the resonator is clamped at one end and the atoms or molecules being measured land on the other... more
One-dimensional nanomechanical resonators based on nanowires and nanotubes have emerged as promising candidates for mass sensors 1-6 . When the resonator is clamped at one end and the atoms or molecules being measured land on the other end (which is free to vibrate), the resonance frequency of the device decreases by an amount that is proportional to the mass of the atoms or molecules. However, atoms and molecules can land at any position along the resonator, and many biomolecules have sizes that are comparable to the size of the resonator, so the relationship between the added mass and the frequency shift breaks down 7-10 . Moreover, whereas resonators fabricated by top-down methods tend to vibrate in just one dimension because they are usually shaped like diving boards, perfectly axisymmetric one-dimensional nanoresonators can support flexural vibrations with the same amplitude and frequency in two dimensions 11 . Here, we propose a new approach to mass sensing and stiffness spectroscopy based on the fact that the nanoresonator will enter a superposition state of two orthogonal vibrations with different frequencies when this symmetry is broken. Measuring these frequencies allows the mass, stiffness and azimuthal arrival direction of the adsorbate to be determined.
By using a variational calculation, we study the effect of an external applied electric field on the ground state of electrons confined in a quantum box with a geometry defined by a slice of a cake. This geometry is a first approximation... more
By using a variational calculation, we study the effect of an external applied electric field on the ground state of electrons confined in a quantum box with a geometry defined by a slice of a cake. This geometry is a first approximation for a tip of a cantilever of an Atomic Force Microscope (AFM). By modeling the tip with the slice, we calculate the electronic ground state energy as function of the slice's diameter, its angular aperture, its thickness and the intensity of the external electric field applied along the slice. For the applied field pointing to the wider part of the slice, a confining electronic effect in the opposite side is clearly observed. This effect is sharper as the angular slice's aperture is smaller and there is more radial space to manifest itself. PACS: 73.21.-b; 85.85.+j; 02.90.+p. (J.-A. Reyes-Esqueda) J. A. Reyes-Esqueda, et al. Submission 13/12/04. Microelectronics Journal. 2/10 J. A. Reyes-Esqueda, et al. Submission 13/12/04. Microelectronics Journal.
We present and compare two approaches for the coarse-graining (CG) of models for graphene and carbon nan otubes (CNTs). Such models are required to enable mechanical device simulation on mesoscopic time and length scales hardly reachable... more
We present and compare two approaches for the coarse-graining (CG) of models for graphene and carbon nan otubes (CNTs). Such models are required to enable mechanical device simulation on mesoscopic time and length scales hardly reachable by the molecular dynamics method. The first is a heuristic top-down approach while the second performs a rigorous bottom-up CG based upon an atomistic description.
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on... more
A design for photoacoustic mass sensors operating above 100 GHz is proposed. The design is based on impulsive optical excitation of a pseudosurface acoustic wave in a surface phononic crystal with nanometric periodic grating, and on time-resolved extreme ultraviolet detection of the pseudosurface acoustic wave frequency shift upon mass loading the device. The present design opens the path to sensors operating in a frequency range currently unaccessible to electro-acoustical transducers, providing enhanced sensitivity, miniaturization and incorporating time-resolving capability while forgoing the piezoelectric substrate requirement.
We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are... more
We introduce a new method for reducing phase noise in oscillators, thereby improving their frequency precision. The noise reduction is realized by a passive device consisting of a pair of coupled nonlinear resonating elements that are driven parametrically by the output of a conventional oscillator at a frequency close to the sum of the linear mode frequencies. Above the threshold for parametric instability, the coupled resonators exhibit self-oscillations which arise as a response to the parametric driving, rather than by application of active feedback. We find operating points of the device for which this periodic signal is immune to frequency noise in the driving oscillator, providing a way to clean its phase noise. We present results for the effect of thermal noise to advance a broader understanding of the overall noise sensitivity and the fundamental operating limits.
Resonant glassy nanostrings have been employed for the detection of biomolecules. These devices offer high sensitivity and amenability to large array integration and multiplexed assays. Such a concept has however been impaired by the lack... more
Resonant glassy nanostrings have been employed for the detection of biomolecules. These devices offer high sensitivity and amenability to large array integration and multiplexed assays. Such a concept has however been impaired by the lack of stable and biocompatible linker chemistries. Diazonium salt reduction-induced aryl grafting is an aqueous-based process providing strong chemical adhesion. In this work, diazonium-based linker chemistry was performed for the first time on glassy nanostrings, which enabled the bio-functionalization of such devices. Large arrays of nanostrings with ultra-narrow widths down to 10 nm were fabricated employing electron beam lithography. Diazonium modification was first developed on SiCN surfaces and validated by X-ray photoelectron spectroscopy. Similarly modified nanostrings were then covalently functionalized with anti-rabbit IgG as a molecular probe. Specific enumeration of rabbit IgG was successfully performed through observation of downshifts of resonant frequencies. The specificity of this enumeration was confirmed through proper negative control experiments. Helium ion microscopy further verified the successful functionalization of nanostrings.
