Nanoelectromechanical Systems

Nano electromechanical systems are considered as ultra sensitive devices for mass and force detection. Capacitive actuation is widely used in these devices but is known to degrade the quality factor of the resonator due to DC electrostatic damping. We report the enhancement of the quality factor of SiC vibrating nanowires detected nano optomechanically and electrically by applying an AC capacitive driving at a frequency above both the resonance frequency and the electrical cut-off frequency. Self-oscillations are demonstrated for optimal conditions. We developed an analytical model of the phenomenon and showed that it can lead to an improvement of the force sensitivity.

Property characterization of nanomaterials is challenged by the small size of the structure because of the difficulties in manipulation. Here we demonstrate a novel approach that allows a direct measurement of the mechancial and electrical properties of individual nanotube-like structures by in-situ transmission electron microscopy (TEM). The technique is powerful in a way that it can directly correlate the atomic-scale microstructure of the carbon nanotube with its physical properties, providing an one-to-one correspondence in structure-property characterization. Applications of the technique will be demonstrated on mechanical properties, the electron field emission and the ballistic quantum conductance in individual nanotubes. A nanobalance technique is demonstrated that can be applied to measure the mass of a single tiny particle as light as 22 fg (1 f= 10−15).

Over these past years our team has been pioneering an original orientation which is the use of field emission (FE) as a probe of mechanically resonating nanotubes (NTs), nanowires (NWs) and recently graphene. The resonators and electrical environment can be considered to be a nano-electro-mechanical system (NEMS). My goal here is to promote this subject better within the FE community whereas it has mostly been exposed within the NEMs community.

We present in this paper a study on highly resistive SiC nanowires in a singly clamped geometry. We demonstrate that these field emission nanoelectromechanical systems (NEMS) can be synchronized ton an external AC signal and act as an amplifier.

We study the contribution of ohmic dissipation to the mechanical damping of nanoresonators. This damping occurs when DC voltage is applied to a resistive resonator, because the mechanical motion modifies the associated capacitance, thus inducing a dissipative current. Silicon carbide nanowire resonators were studied as a function of applied voltage and their geometrical environment. Nanometric positioners were used to control and continuously modify the position of the resonator with respect to counter electrodes. The experimental results are shown to be in agreement with an electromechanical model developed here, which allows for the establishment of a universal formula for the lower dissipation limit of a nanoresonator in its capacitive environment.

We present here a simple analytical model for self-oscillations in nanoelectromechanical systems. We show that a field emission self-oscillator can be described by a lumped electrical circuit and that this approach is generalizable to other electromechanical oscillator devices. The analytical model is supported by dynamical simulations where the electrostatic parameters are obtained by finite element computations.

In recent years, there has been an increasing interest in nanoelectromechanical devices, currentdriven quantum machines, and the mechanical effects of electric currents on nanoscale conductors. Here, we carry out a thorough study of the current-induced forces and the electronic friction of systems whose electronic effective Hamiltonian can be described by an archetypal model, a single energy level coupled to two reservoirs. Our results can help better understand the general conditions that maximize the performance of different devices modeled as a quantum dot coupled to two electronic reservoirs. Additionally, they can be useful to rationalize the role of current-induced forces in the mechanical deformation of one-dimensional conductors.

We describe a combination of 100-mm wafer scale deep-ultraviolet (DUV) exposure and a microelectromechanical systems (MEMS) process to fabricate silicon nitride membranes with submicrometer apertures to be used as miniature shadow masks or nanostencils. Apertures down to a lateral resolution of 200nm were made in a 500-nm-thick membrane by DUV exposure and dry plasma etching. The membranes were released by a combination of wet silicon etching using potassium hydroxide (KOH) and dry silicon etching using a plasma process. The millimeter-size stencils were used for single-step, local deposition of metal micro- and nano-patterns without the need for photoresist process steps. We have performed stencil deposition on full wafer scale for micro- and nano-patterns in a variety of metals (e.g. Al, Au, Ni, etc.). Dry under-etching of the nanowires resulted in free-standing cantilevered nanoelectromechanical systems (NEMS) structures with resonance frequencies in the megahertz range. The resi...

Μετρήσεις αντίστασης, συνεχούς τάσης και ρεύματος, νόμος του Ohm. Συνεχής τάση: διαιρέτης τάσης, διαιρέτης ρεύματος, ποτενσιόμετρο. Εναλλασσόμενη τάση: εσωτε-ρική αντίσταση πηγής, διαιρέτης τάσης, διαιρέτης ρεύματος. Μετρήσεις με τον παλ-μογράφο: απεικόνιση συνεχών και χρονικά μεταβαλλόμενων σημάτων. Κύκλωμα ο-λοκλήρωσης RC. Φίλτρα RC.

• Many of the potential applications of nanoscale changes with thermal probes such as scanning nanolithography are still applicable in nanoelectronics, especially when extremely high heating and cooling rates can be used in the production of nanowires.

• Nanowires have a structure that has an amazing length-to-width ratio. Nanowires are extremely thin-it is possible to create nanowires with a diameter of just one nanometer, nanowires are used to create the smallest transistors (nanotransistors).

For years, chaotic phenomena have been mainly studied from a theoretical point of view. In the last two decades, considerable developments have occurred in the control, prediction and observation of chaotic behaviour in a wide variety of dynamical systems, and a large number of applications have been discovered and reported (Moon & Holmes, 1999;. Chaotic behaviour can only be observed in particular nonlinear dynamical systems. In recent years, nonlinearity is known as a key characteristic of micro resonant systems. Such devices are used widely in variety of applications, including sensing, signal processing, filtering and timing. In many of these applications some purely electrical components can be replaced by micro mechanical resonators. The benefits of using micro mechanical resonators include smaller size, lower damping, and improved the performance. Two examples of micro mechanical resonators that their complex behaviour is described briefly in this chapter are atomic force microscopy (AFM) and micro electromechanical resonators. AFM has been widely used for surface inspection with nanometer resolution in engineering applications and fundamental research since the time of its invention in 1986 . The mechanism of AFM basically depends on the interaction of a micro cantilever with surface forces. The tip of the micro cantilever interacts with the surface through a surface-tip interaction potential. One of the performance modes of an AFM is the so called "tapping mode". In this mode, the micro-cantilever is driven to oscillate near its resonance frequency, by a small piezoelectric element mounted in the cantilever. In this chapter it will be shown that micro-cantilever in tapping mode may exhibit chaotic behaviour under certain conditions. Such a chaotic behaviour has been studied by many researchers (

Tuning fork experiments at the undergraduate level usually only demonstrate a tuning forks linear resonance. In this paper, we introduce an experiment that can be used to measure the nonlinear tuning curve of a regular tuning fork. Using double-grating Doppler interferometry, we achieve measurement accuracy within ten microns. With this experiment setup, we observe typical nonlinear behaviors of the tuning fork such as the softening tuning curve and jump phenomena. Our experiment is inexpensive and easy to operate. It provides an integrated experiment for intermediate-level students and a basis for senior research projects.

We study the nonlinear behaviors of mass-spring systems damped by dry friction using simulation by a nonlinear LC circuit damped by anti-parallel diodes. We show that the differential equation for the electric oscillator is equivalent to the mechanical one's when a piecewise linear model is used to simplify the diodes I-V curve. We derive series solutions to the differential equation under weak nonlinear approximation which can describe the resonant response as well as amplitudes of superharmonic components. Experimental results are consistent with series solutions. We also present the phenomenon of hysteresis. Theoretical analysis along with numerical simulations are conducted to explore the stick-slip boundary.

Carbon nanotubes 1,2 can be distinctly metallic or semiconducting depending on their diameter and chirality 3 . Here we show that continuously varying the chirality by mechanical torsion 4 can induce conductance oscillations, which can be attributed to metal -semiconductor periodic transitions. The phenomenon is observed in multiwalled carbon nanotubes, where both the torque 5 and the current are shown to be carried predominantly by the outermost wall . The oscillation period with torsion is consistent with the theoretical shifting 8 of the corners of the first Brillouin zone of graphene across different subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Carbon nanotubes could be ideal torsional springs for nanoscopic pendulums 4,9,10 , because electromechanical detection of motion could replace the microscopic detection techniques used at present. Our experiments indicate that carbon nanotubes could be used as electronic sensors of torsional motion in nanoelectro-mechanical systems . Owing to the promise of carbon nanotubes for application in nanoelectromechanical systems (NEMS) , the effects of mechanical deformations on their electronic properties have attracted great interest 14 . Linear electromechanical responses have been observed for axial , radial 17 and flexural 18 strain. Torsional electromechanical effects have been predicted by several groups , but not yet observed. Conductance oscillations have been observed with magnetic fields 6 and gating , but not with strain. To measure the conductance of carbon nanotubes under varying torsional strain, we built torsional nanotube-based NEMS as shown in Fig. , where a suspended multiwalled carbon nanotube is mechanically and electrically connected to a pair of electrodes and a small pedal in the middle. The nanotube is twisted by pressing against the pedal with an atomic force microscope (AFM) tip, and the electrodes allow us to simultaneously measure the twoterminal conductance across the nanotube. The devices were fabricated in an electron-beam lithography lift-off process, followed by wet etching and critical-point drying. Similar devices have been built with multiwalled 5,9,23 and single-wall 10 carbon nanotubes, and used as torsional pendulums 9,10 and nanorotors , but no torsion-dependent electrical measurements were reported.

The energy of a radio wave is reduced through the dispersion, the refraction and the absorption because the medium transferring the vibration of a radio wave is the seawater. In the end the reduced energy of a radio wave causes the reduced transmitting length for communication, the long postponed communication and the frequent error. The subsea communication for the marine environment monitoring which must overcome the weak points of the RF wave and the most practical method for the marine sensor network realization is to use the acoustic wave method, but the energy consumption rate of the acoustic wave communication method is about 100 times greater than the one of the RF wave method. So, the power supply of the sensor node in the marine sensor network system is the most important interest field. In this study, the sample which consists of an acrylic elastomer (VHB4905 film from 3 M), conductible carbon grease(from MG chemical) and electric wire for the basic study of an energy harvesting strategy and technique using EAP actuator was fabricated, and the conductible carbon grease was used for an electrode. The characteristics of the fabricated sample were analyzed through the experiment. We also mixed carbon grease with aluminum powder for conductibility improvement, and the effect of the mixed electrode was confirmed through the conductivity measurement.

No one actually anticipates water damage. It just sort of happens most often at the worst possible time. A pipe bursts when you are not at work. A toilet overflows during the night. A storm sends water into your home when you are not even thinking about it. It's irritating and debilitating, and trying to figure out what to do next can be too much. You glance at the water, you glance at the chaos, and you wonder, "Where do I start? Your first thought may be to grab towels, move furniture around, and blow fans. That's totally understandable. We all need to fix things for ourselves if we can. Water damage is trickery, though. What you see on the surface is not always the whole picture. Water seeps into walls, under floors, and into places you can't easily access. That's where the real problems begin mold, falling floors, destroyed drywall. This is where water damage restoration services enters the picture. These are professionals who have been trained to do just this type of thing. They don't just clean up what you can see, they search deeper. They make sure that nothing is left behind which will harm your home in the future. Let's walk through what they actually do, so you'll know what to expect if this ever happens to you or a member of your family.

Frequency multipliers (FMs) are ubiquitous signal processing circuits in communication systems. Traditionally, this circuit is based on exploiting the nonlinearities found in semiconductor devices, for example, bipolar junction transistors and Schottky diodes. We explore an FM concept based on the coexistence of spring, electrostatic, and Casimir forces, and tunneling. In particular, we provide, for the first time, a theoretical analysis of a nanoelectromechanical quantum tunneling FM. The physics behind the nature of the frequency multiplication mechanism will be elucidated, together with a discussion of circuit modeling, applications and limitations. SPICE simulations are presented.

The separation of two different types of multi-walled carbon nanotubes is studied in a dielectrophoresis-based microchannel system in seven different solvents as the suspending medium.  A simple model was developed to predict the behavior of the multi-walled carbon nanotubes in the above mentioned system. Then, the equations of motion for the multi-walled carbon nanotubes in that system were introduced and the effect of the suspending medium type on the fabrication parameters of dielectrophoretic system, such as applied voltage and inter electrode gap, was surveyed. The calculations indicate that the suspending medium has a direct influence on the design and optimization of dielectrophoretic systems. The geometrical separation of the carbon nanotubes is considered here, and it was found that the model predicts some advantages in separation and sorting multi-walled carbon nanotubes based on their diameter.

Due to its electromechanical applications in the form of nanodevices such as distributors, actuators, and sensors, the electromechanical behavior of piezocomposite structures becomes a new avenue for research. This article presents the derivation of an exact analytical solution of the composite plate based on theory of Kirchhoff’s plate and extended theory of piezoelectricity. The electromechanical behavior of piezocomposite structures accounting the influence of size-dependent properties such as piezoelectric and surface effect is investigated. In addition to this, the parametric analysis is carried out using the different parameters such as aspect ratio and thickness on the electromechanical response of composite structures. The consequences of the present study explore that the influence of size-dependent properties on the electromechanical behavior of composite structures is noteworthy with respect to the size of structures and can be ignored at bulk sizes. The electromechanical...

This paper reports novel characteristic features of thermally-passivated Si nanoelectromechanical (NEM) beams fabricated via SOI-CMOS compatible processes with top-down hybrid EB/DUV lithography. Considerable difference of the resonance frequencies between the measurement results of the NEM beams with various lengths and the finite element simulation results suggests that effects of the undercut of the beam supports are serious for sub-micron beams. The resonance frequency of 332.57 MHz observed for an 800-nm-long beam is, to our knowledge, the highest ever as the fundamental resonance mode of lithographically-defined Si NEM beams. Clear change of the temperature dependence of the resonance frequencies with the varied beam lengths, observed for the first time, can be explained by considering effects of thermally-induced strain on the longer beams at higher temperatures.

As transistors are reaching their fundamental limits in terms of power consumption, miniaturization, and heat generation, there is an imminent need to develop alternate computing technologies. One such an alternative is through micro/nanoelectromechanical systems (M/NEMS) that focuses on ultra-low energy consumption. Computing based on static MEMS switches has been proposed, however these suffer from reliability issues due to contact and stiction. Recently, logic devices based on electro mechanically excited vibrating structures, resonators, have emerged as a potential solution that overcomes these issues. This paper reviews the recent advancements of resonator-based M/NEMS logic devices. First, pioneering works in the field are surveyed. Then, logic devices based on frequency tuning are discussed. Next, cascadability of such logic devices is demonstrated. Finally, a discussion about the challenges of such technology and future prospects is presented. relay technology uses the complementary motion of the switches to perform an inverter . Using a similar technology, a seesaw-relay-based device has been used for logic and memory applications capable of executing the fundamental AND and OR gates . Furthermore, torsional actuators, have been used to perform multiple logic operations using different electrical interconnect schemes . The study in experimentally demonstrates a universal logic device capable of performing all the fundamental logic operation using different electrical interconnects. Furthermore, piezotronic NEMS devices have been also demonstrated to perform high speed and low power logic and memory operations . Despite having some major advantages such as cascadability and zero off-state leakage, M/NEMS switch based devices suffer from contact reliability and stiction issues . This limits the practicality of such devices. One possible solution is capacitive adiabatic logic (CAL), which is a contactless logic operation that promises better reliability than M/NEMS switch-based logic devices . The capacitive adiabatic logic approach relies on a smooth capacitive modulation to achieve quasi zero-power logic dissipation. A detailed analysis and comparison of NEMS and CMOS technologies for low power CAL logic implementation is presented . It is predicted that for a low contact resistance and sub 1 V operation, the energy dissipation by a NEMS based CAL logic operation can potentially be an order of magnitude better than that of the CMOS technology. The study in utilizes four terminal MEMS comb-drive devices for capacitive adiabatic logic. This theoretical investigation shows an energy dissipation of 1 pJ for a mm scale device. Similarly, logic gates AND, OR, XOR, and 1-bit full adder are theoretically demonstrated using a five-terminal comb-drive actuator . Furthermore, cascadability of this technology is also established. Another solution to contact reliability and stiction issues associated with M/NEMS switchbased devices is dynamic resonator-based M/NEMS logic devices. In this approach, an on(off)resonance state of a resonator can be attributed to the 1(0) of the logic outputs. This manuscript will review the different technologies and advancements made in the area of dynamic resonatorbased M/NEMS logic devices. The rest of the paper is organized as follows. Section 2 explains the operating principle of resonator-based logic devices. Section 3 presents an overview of various techniques developed to realize various computing operations. Finally, Section 4 presents the conclusions.

Attempts are underway to fabricate an electrostatically actuated device which uses the overlaying nanotube of a MWNT junction as the dynamic member. The underlying MWNT behaves as a stationary rail on which the top nanotube rests and, during actuation, will ...

We present the first results about microelectromechanical (MEMS) resonators fabricated on epitaxial nitride semiconductors with thin buffers engineered for MEMS and NEMS applications. These results assess the use of thin buffers for GaN MEMS fabrication. On a 700 nm thick AlGaN/GaN epilayer, a high tensile stress is observed to increase the resonant frequency. The electromechanical coupling efficiencies of integrated transducers are assessed and compared with previously obtained results on commercially available 2-µm thick epilayers used for power transistor applications. A 28 nm/V actuation efficiency is measured on the 700-nm thick structure which is slightly better than the one measured on the 2-µm buffer. The electrical response of a gate-less detector designed as a piezoresistance was carried out and a gauge factor of 60 was estimated. These results show that material issues can be unlocked to exploit the potentialities of III-nitrides for NEMS applications.

Mechanical characterisation of thin film is crucial for development of MEMS/NEMS devices. A simple mechanical characterisation method is developed using a surface profilometer. Surface profilometer is used to scan along the micromachined cantilevers and produce the bending profile, from which the Young's modulus can be extracted. The following MEMS materials: SiN, Ni, Ni/SiN bimorph, Nanocrystal Diamond (ND), SiC have been characterised. The results are compared and in agreement with those obtained from nanoindentation and resonance frequency method. The advantages and disadvantages of these three methods are discussed.

Micro beams have been widely used in the last decades, as components of MEMS (Micro Electro Mechanical Systems) and NEMS (Nano Electro Mechanical Systems). In the present work, a finite element formulation is developed for Timoshenko micro beams, taking into account the size-dependent effects. For this purpose the modified couple stress theory is used [1]. The modified couple stress theory takes advantage in simplicity, since it reduces the additional elasticity constants to only one [2], it is the length scale parameter. A dynamic study is carried out, considering the material length scale effects. The results are compared with those obtained by the classical elasticity theory. The first natural frequencies and the corresponding modal shapes of beams with different boundary conditions are obtained and compared with available results in the technical literature.

Carbon nanotubes (CNTs) were originally discovered by S. Iijima in 1991 as a byproduct of fullerene research . CNTs are unique nanostructures with remarkable electronic and mechanical properties and have attracted tremendous interest worldwide. Interest from the research community first focused on their exotic electronic properties, since nanotubes can be considered as prototypes for a onedimensional quantum wire applicable in nanometer-sized electronics. As other useful properties have been discovered, particularly strength, interest has grown in potential applications that exploit both the electronic and mechanical properties, e.g., nanomechanical and nanoelectromechanical systems (NEMS) such as nanotweezers, memory, sensors, actuators, and switches. These results have demonstrated that CNTs hold great promise for NEMS applications. Meanwhile, researchers have made remarkable progress in synthesizing CNTs since their initial discovery . Today CNTs can mainly be produced using electric arc-discharge, laser ablation, and catalytic chemical carbon vapor deposition (CVD). In all these techniques, carbon vapor condenses into tubular structures. By adding appropriate metal catalysts, which are commonly transition metals, CNTs with one single wall (single-walled carbon nanotubes, SWCNTs) or with multiple walls (multi-walled carbon nanotubes, MWCNTs) can be preferentially grown depending on the applied growth conditions. SWCNTs preferentially bundle (Fig. ) mostly in the form of closely packed hexagonal arrays, where individual nanotubes are held together via van der Waals interaction with a typical intertube distance of 0.33 nm. SWCNTs can also be considered as the fundamental cylindrical structure which forms the building blocks

Nanowire resonators with near single-molecule detection sensitivity are highly susceptible to environmental factors due to their small size. Typically, these sensors require ultralow temperature conditions to function effectively, which are unfavorable for monitoring biochemical reactions. To address the technical bottleneck of insufficient stability and sensitivity of nanowire resonators at room temperature, this study utilizes ZnO nanowire (NW) resonators with larger dimensions that can operate at room temperature. By employing feedback control technology, the equivalent mass of the ZnO NW resonator is significantly reduced, thereby improving its sensitivity to-2921.42 Hz/zg. This breakthrough achieves the single-molecule detection limit at room temperature, elevating the mass detection capability to the level of an ethanol molecule (approximately 0.076 zg). Furthermore, through precise deposition of a sensitive layer on the nanowire, the ZnO NW resonator enables accurate real-time monitoring of ethanol gas molecule adsorption and desorption within a vacuum chamber. The measurement error for the mass of an individual ethanol molecule is as low as 3.9%. These findings represent a substantial advancement in single-molecule detection technology.

Maintaining the exterior of your home or business is vital to preserving its value, appearance, and structural integrity. One of the most effective ways to keep your property looking fresh and protected is through professional pressure washing services. While it might seem like a straightforward task, professional pressure washing offers numerous benefits that go beyond simple cleaning. In this article, we'll explore key benefits of hiring expert pressure washing service for both residential and commercial properties.

Maintaining the exterior of your home or business is vital to preserving its value, appearance, and structural integrity. One of the most effective ways to keep your property looking fresh and protected is through professional pressure washing services. While it might seem like a straightforward task, professional pressure washing offers numerous benefits that go beyond simple cleaning. In this article, we'll explore key benefits of hiring expert pressure washing service for both residential and commercial properties.

Growth of monolayer, bi-layer, and tri-layer single-crystalline graphene (SCG) using chemical vapor deposition method is reported. SCG's mechanical properties and single-crystalline nature were characterized and verified by atomic force microscope and Raman spectroscopy. Electro-mechanical switches based on mono- and bi-layer SCG were fabricated, and the superb properties of SCG enable the switches to operate at pull-in voltage as low as 1 V, and high switching speed about 100 ns. These devices exhibit lifetime without a breakdown of over 5000 cycles, far more durable than any other graphene nanoelectromechanical system switches reported.

Carbon nanotube transistor arrays (CNTFETs) were used as biosensors to detect DNA hybridization and to recognize two anabolic steroids, stanozolol (Stz) and methylboldenone (MB). Single strand DNA and antibodies specific for STz and MB were immobilized on the carbon nanotubes (CNTs) in situ in the device using two different approaches: direct noncovalent bonding of antibodies to the devices and covalently trough a polymer previously attached to the CNTFETs. A new approach to ensure specific adsorption of the biomolecules to the nanotubes was developed. The polymer poly (methylmethacrylate 0.8 -co-poly (ethyleneglycol) methacrylate 0.8 -co-N-succinimidyl methacrylate 0.1 ) was synthesized and bonded noncovalently to the nanotube. Aminated single-strand DNA or antibodies specific for Stz and MB were then attached covalently to the polymer. Statistically significant changes were observed in key transistor parameters for both DNA hybridization and steroids recognition. Regarding the detection mechanism, in addition to charge transfer, Schottky barrier, SB, modification, and scattering potential reported by other authors, an electron/hole trapping mechanism leading to hysteresis modification has been determined. The presence of polymer seems to hinder the modulation of the electrode-CNT contact. Matrices de transistores de efecto de campo basados en nanotubos de carbono (CNTFETs) fueron usados como biosensores para la detección de la hibridación de ADN y para el reconocimiento de dos esteroides anabolizantes, estazonolol (Stz) y metil-boldenona (MB). Secuencias simples de ADN y anticuerpos específicos para Stz y MB fueron inmovilizados sobre los nanotubos de carbono, (CNTs), in situ en los dispositivos usando dos estrategias diferentes; enlace directo no-covalente y enlace covalente a un polímero previamente fijado a los CNTFETs. Se ha desarrollado una nueva estrategia para asegurar la adsorción especifica de las biomoléculas a los CNTs. Se sintetizó el polímero poli (metilmetacrilato 0.8 -co-(polietilenglicol) metacrilato 0.8 -co-N-succinimidil metacrilato 0.1 ) que fue enlazado no-covalentemente a los CNTs en el dispositivo. Posteriormente una secuencia simple de ADN o en su caso el correspondiente anticuerpo específico para Stz o MB fueron enlazados covalentemente al polímero. Se observaron cambios estadísticamente signiticativos en parámetros clave del transistor tanto para la hibridación de ADN como para el reconocimiento de los esteroides anabolizantes. Respecto al mecanismo de detección, además de transferencia de carga, modificación de la barrera de Schottky, SB, y dispersión de potencial publicados en la bibliografía, se ha detectado un mecanismo de atrapamiento de electrones y huecos que lleva a una modificación de la histéresis. La presencia del polímero parece impedir la modulación ejercida por los contactos electrodo-CNT.

In this paper we present a different approach using a focused ion beam (FIB) as lithographic tool to define nanometric width gaps, which are then transferred to a silicon substrate by reactive ion etching (RIE). This process has been developed to fit the technological requirements for micro-and nano-electromechanicals systems (M-NEMS) applications.

This paper presents a fully-integrated NEMS resonator, operable at frequencies in the MHz range, together with a compact built-in CMOS interfacing circuitry. The proposed lowpower CCII circuit allows detailed read-out of the nanocantilever structure for either extraction of equivalent circuit models or comparative studies at different pressure and DC biasing conditions. In this sense, extensive experimental results are presented for a real mixed electro-mechanical system integrated through a combination of in-house standard CMOS technology and nanodevice post-processing by nanostencil lithography. The proposed read-out scheme can be easily adapted to operate the nanocantilever in closed loop operation as a stand alone NEMS oscillator.

The use of nano technology in the applications of nano sensors has facilitated bio control andprecise regulation of nano environmental functions . Nano structures are widely used in the fi eld ofnano biosensors due to their small size in nanometers and multiple functions in specifi cplaces . Develop diff erent types of multifunctional MEMS / NEMS devices with micro andnanoelectronic features for biomedical applications (BioMEMS / BioNEMS ) through diff erentmanufacturing techniques and biocompatible nanomaterials. However, the integration of deviceswith the physiological environment of nano-biosensors is considered a fundamental problem. Mostof them lose their function due to the limitations of nano particles in nano bio sensors andcauseUndesirable eff ects. In laboratory conditions and in the applications of bio-environmentalnano-sensors, the performance of bio-MEMS implants such as bio -sensors, smart stents , etc. And the architecture of nano biosensors is essential.

MEMS technology and (nanoelectronics) in medical sciences and histology, such as (polymeric chainreaction microsystems (PCR) for DNA amplifi cation and identifi cation and pinhole microscopes forreviewing micromachines (STMs), (creating chips inspired by biological principles) Science enablesthe detection of dangerous biological and chemical agents and micro-systems for selecting anddisplaying drugs with very high operational capacity.

Our current efforts reveal the preparation of SiO 2 @TiO 2 nanocomposites having different thicknesses of silica shell and the relationship to photocatalytic activity (PCA) for the photo-oxidation of naphthalene and anthracene. The presence of SiO 2 coating over TiO 2 surface was demonstrated by FT-IR analysis, with peaks corresponding to Si O Si (1081 cm -1 ) and Si O Ti (950 cm -1 ) bonds observed. High-resolution transmission electron microscopy analysis confirmed the presence of SiO 2 in the asprepared nanocomposites and the amount of Si, Ti, and O was determined by energy dispersive X-ray spectroscopy analysis. Increasing the SiO 2 shell thickness increases the surface area of the nanocomposites (69-235 m 2 /g), which enhances naphthalene/anthracene adsorption. However, the observed PCA trend presents an inverse correlation to the adsorption studies, where the as-prepared samples possessing the highest surface areas exhibited the least PCA, while catalysts having lower surface areas (among silica coated samples) displayed the highest PCA in the degradation of naphthalene and anthracene to CO 2 . Despite complete degradation of naphthalene and anthracene, incomplete mineralization occurred, ascribed to the formation of various intermediates, identified by GC-MS analysis.

Many biomolecules have a great ability to diff erentiate between a certain type ofDNA from diff erent nanotubes. The diameter-dependent selective dispersion ofSWCNTs is obtained by using chitosan polymer and polyethylene glycol (PEG)oligomeric polymer through twist absorption.

Nanostructures refer to materials or structures that have at least one dimension between 1 and 100nanometersThe importance of nanoscale is in changing the properties and characteristics ofmaterials in these dimensions. Properties such as electrical conductivity, electromagneticproperties, etc. Starting to change the properties of the material by shrinking it depends above all onthe type of material and the desired property. For example, by reducing the dimensions of amaterial, generally some of the electromagnetic properties of nano-molecular materials such as theconductivity of nano particles in materials are improved. This increase in strength does not happenonly in the range of a few nanometers, and the strength of materials of several tens or even hundredsof nanometers may be much higher than the mass material of a large scale. On the other hand, thechange of some properties such as conductivity in nano-transistors and electromagnetic propertiesin nano-wires may occur in dimensions of only a few nanometers.Self-assembly (nanoparticles) innanostructures is a spontaneous process by which nanomolecules/nanophases are transformed intoorganized functions.

Note: In electronic nanotechnology, the change in the distance between the atoms of theparticles and the geometry of the particles also aff ects the electronic properties of thematerial. When the size of the particles decreases, the electrical bonds in metals become fi ner.

Note: Many methods have been developed to produce nanoparticles or nanostructured particles, which include vapor, liquid and solid state processes. In general, chemical reactions to produce nanoparticles can take place in any of the solid, liquid, and gas states. The common method is to produce materials in a solid state, by crushing the particles, their contact surface is increased, and further, to increase the penetration of atoms and ions, this mixture is increased at high temperatures. In chemistry, the substances with which chemical reactions begin are called reactants, and the substances that are transformed into them during the reaction (reactants) are called products. Reactants can be solid, liquid or gas. In addition, reactants or They are an independent element or they can be multi-component compounds. Multicomponent