Nanoelectromechanical systems

Summary form only given. MEMS (micro electro mechanical systems) and NEMS (nano electro mechanical systems ) have been developed based on silicon micromachining for practical applications. Sophisticated MEMS device used as a two-axis rotating gyroscope for navigation control system was developed. A silicon ring rotor is electrostatically levitated and rotated at 12,000rpm. The 4mm diameter ring rotor and 5m radial gap between rotor and electrode were fabricated using deep RIE (reactive ion etching) and the rotor is sandwiched between two glasses which have control electrodes. The levitation is actively controlled by force balancing in all directions using a capacitive displacement sensing and an electrostatic actuation. The rotation is based on the principle of a variable capacitance motor. The function as the high performance gyroscope and accelerometer were successfully demonstrated. Small size relays for high frequency operation are required for LSI tester. MEMS relay which uses a thermal bimetal actuator for making contact to multi-springs was developed. The springs have electrical connections to the backside using electrical feedthrough in a glass, which results in high frequency response up to 20 GHz. Excellent reliability more than 10/sup 7/ cycles was achieved owing to the hermetic scaling performed by wafer level packaging using anodic bonding of glass and silicon. Multiprobe data storage has been developed. High density electrical feedthrough in a glass was used for the interconnection to its control IC. Electrical rewritable recording on a conductive polymer film and a ferroelectric recording were performed. Electron field emitter array for the purpose of multi-column electron beam lithography was developed using carbon nano tube emitter and electrostatic lens for focusing. It was evident that hydrogen covered carbon nano tube reduces the work function for field emission and the emission noise. Highly sensitive sensors using micro-nano structures such as thin cantilevers have been developed. Bow-tie antenna for near field optical microscope and magnetic resonant force microscope will be presented.

Microelectromechanical systems (MEMS) have played key roles in many important areas, for example transportation, communication, automated manufacturing, environmental monitoring, health care, defense systems, and a wide range of consumer products. MEMS are inherently small, thus offering attractive characteristics such as reduced size, weight, and power dissipation and improved speed and precision compared to their macroscopic counterparts. Integrated circuit (IC) fabrication technology has been the primary enabling technology for MEMS besides a few special etching, bonding and assembly techniques. Microfabrication provides a powerful tool for batch processing and miniaturizing electromechanical devices and systems to a dimensional scale that is not accessible by conventional machining techniques. As IC fabrication technology continues to scale toward deep submicrometer and nanometer feature sizes, a variety of nanoelectromechanical systems (NEMS) can be envisioned in the foreseeable future. Nanoscale mechanical devices and systems integrated with nanoelectronics will open a vast number of new exploratory research areas in science and engineering. NEMS will most likely serve as an enabling technology, merging engineering with the life sciences in ways that are not currently feasible with microscale tools and technologies.

In recent years, precise metrology up to nanoscale has attracted substantial attention due to an increasing need for ultra-precision measurement systems for micro electro mechanical systems (MEMS) and nano electro mechanical systems (NEMS) calibration. In this paper, an analytical and numerical investigation for the proposed design of a 6-degree-of-freedom (6-dof) universal measurement system, using a relatively simple and inexpensive but highly sensitive set up, is presented. This system utilizes a convex mirror and two flat mirrors, one angled and one vertical, as targets to reflect laser beams onto photo detectors. These targets, placed on the object of interest for metrology applications, change the direction of the reflected beam when there is any movement in the object, which is detected by the photo detectors. The use of convex and angled mirrors greatly enhances the sensitivity of the system. Geometric relationships are established among all the optical components to predict the final intersection points of the laser beams reflected from the targets with the photo detector planes. These relationships are used to establish a Jacobian partial derivative matrix, which is further used to estimate the target pose when the photo detector outputs are given. Numerical simulation of the measurement process is performed using MATLAB®. Assuming the approximate distance from laser beam origin to target and the target to photo detector as 50 mm, and photo detector resolution as 0.1 µm, translations and rotations less than 50 nm and 2 arc sec, respectively, can be measured accurately. The highest amount of sensitivity in translation is obtained along the Z-axis with minimum a measurement of 3.4 nm; the highest amount of sensitivity in rotation is along the pitch-axis with a minimum measurement of 0.145 arc sec. The corresponding low sensitivity axes are X-axis and yaw-axis, with minimum measurements of 35 nm and 2 arc sec, respectively. The sensitivity and the resolution of the system can be increased many times further by increasing the curvature of the convex mirror or by increasing the distance between the target and the detectors. The analytical and simulation results of this work yield a scientific and engineering guideline for the development of meso, micro, as well as nanoscale metrology systems.

In the last decade, there has been a tremendous development in the field of miniaturization of chemical and biochemical sensor devices. Microelectromechanical systems (MEMS) refer to microscopic devices that have a characteristic length of less than 1 mm but more than 100 nm and combine electrical and mechanical components. Nanoelectromechanical systems (NEMS) refer to nanoscopic devices that have a characteristic length of less than 100 nm and combine electrical and mechanical components. In mesoscale devices, if the functional com‐ ponents are on microor nanoscale, they may be referred to as MEMS or NEMS, respective‐ ly. These are referred to as an intelligent miniaturized system comprising sensing, processing, and/or actuating functions and combine electrical and mechanical components. The acronym MEMS originated in the USA. The term commonly used in Europe is micro system technology (MST) and in Japan, the term is micromachines. Another term generally used is micro/nanodevices.

The century behind and the century ahead.

Reservoir computing (RC) provides a route to use physical systems for computation and machine learning. Owing to their inherent nonlinearity, nanomechanical systems constitute an interesting technology to serve as reservoir. While RC platforms are built using microelectromechanical systems, the energy efficiency, response time, and footprint of these systems can be significantly improved by using nanoscale devices. Herein, the use of nanoelectromechanical systems (NEMS) is investigated, which can be used in RC, utilizing inherent nonlinearities and the fading memory effect from the transient response of NEMS. The smaller size and higher operating frequencies of NEMS enable faster processing rates compared to micromechanical systems, while their compact footprint, low power consumption, and ability to operate under ambient conditions simplify integration into practical applications. In modified national institute of standards and technology (MNIST) handwritten digit–recognition test, this system achieves 90% accuracy with a 3.3 μs processing time per pixel. Also the effect of driving frequency and amplitude on NEMS classification accuracy is investigated using experiments and simulations and it is shown that no significant dependency in any of the parameters is observed. Herein, an estimate for energy consumption of core NEMS RC system on MNIST data is provided. These results highlight the potential for various applications that require efficient and fast information processing in resource‐constrained environments.

Graphene is a wonderful material with outstanding properties which is ideal for micro-electro-mechanical systems (MEMS) and also nano-electro-mechanical systems (NEMS) like sensors and switches including strain gauges, mass and force sensors. Graphene is single atom thick layer of graphite which consists of carbon atoms that are bonded together in a hexagonal honeycomb lattice. A way of fabricating suspended graphene is presented. Graphene grown on copper (Cu) foil using chemical vapour deposition (CVD) method is used for transference on silicon wafer with etched holes on top. Graphene is transferred on the silicon using Poly (methyl methacrylate) (PMMA) method and the analysis is done using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The suspended graphene is quite uniform and the results show that it is a promising approach for suspended graphene, however, considerable effort is needed for the development of the transference and fabrication process.

Due to ongoing experimental advances, nanoelectromechanical systems represent a fascinating field of study which receives increasing attention. Because of their small size, these systems allow for exploring fundamental physics and give rise to a wide range of applications such as high frequency resonators and ultra-sensitive sensors. Because of strong electron-phonon coupling, nanoelectromechanical sys- tems provide a paradigmatic model for bosonic degrees of freedom coupled to an out-of-equilibrium fermionic environment. Many of the applications require a general understanding of the forces which are induced by a quantum environment on a classical system. By considering the na- nosystem as a generic time-dependent scatterer, these reaction forces have recently been expressed via an adiabatic expansion in terms of the scattering matrix and its first adiabatic correction. In this thesis, we present a more efficient and direct derivation of these forces by solely using scattering theory which is natural to the considered problem. Due to the Anderson orthogonality catastrophe small local changes of a scattering potential can drastically affect properties of large quantum systems. In equilibri- um, the orthogonality exponent was related to the friction coefficient of a classical particle moving in a free electron gas. Based on our knowledge on the environment- induced forces, we generalise this idea to out-of-equilibrium situations. To this end, we study the fidelity amplitude and the Loschmidt echo, which are dynamical mea- sures of the Anderson orthogonality catastrophe. A molecular transistor at the ultimate miniaturisation limit has recently been ex- perimentally realised. Atomically precise gating is achieved via repositioning of individual charges by scanning tunnelling microscopy. Remarkably, a pronounced conductance gap instead of the expected charge degeneracy is observed. Motiva- ted by the experimental observations, we explain this behaviour by the presence of two different molecular conformational states, which generalises the conventional picture of single- electron tunnelling through molecular transistors.

Enabling technologies have been developed to synthesize and fabricate organic, inorganic and hybrid nanostructures. The fundamental theory has been further expanded to design, model, simulate and analyze simple nanoelectromechanical systems and devices. There are distinguishing features between nanoscale electromechanical systems, devices, and structures. In general, systems integrate nanodevices and nanostructures. However, using commonly used and accepted notations, we assume that the motion nanodevice is a nanoelectromechanical system (NEMS). A spectrum of fundamental problems primarily associated with devising and discovering novel NEMS remains. These nanodevices can be classified as electronic and motion (rotational and translational transducers - actuators and sensors) nanoscale devices. This paper concentrates on the motion nanodevices. The key focus areas are synthesis, classification and analysis. We emphasize classification and synthesis paradigms with ultimate goal of classifying existing and discovering novel NEMS by performing electromagnetic-geometry synthesis. It is illustrated that NEMS intelligent databases can be developed within evolutionary-based CAD. The synthesis and classification paradigm reported directly leverages fundamental physics laws and high-fidelity modeling, allowing the designer to attain physical and behavioral (steady-state and transient) data-intensive analysis, heterogeneous simulation, optimization, performance assessment, outcome prediction, etc. We focus our attention on rotational and translational nanodevices which can be controlled by driving/sensing controlling/processing nanoelectronics. The examined nanodevices can be considered as NEMS as the electromagnetic-based nanomachines integrate motion and radiating energy nanodevices as well as nanostructures.

Advanced silicon processing techniques developed for the Very Large Scale Integration (VLSI) industry have been exploited in recent years to enable the production of micro-fabricated moving mechanical systems known as Micro Electro Mechanical Systems (MEMS). These devices offer advantages in terms of cost, scalability and robustness over their preceding equivalents. Cambridge University have worked for many years on the investigation of high temperature superconductors (HTS) in flywheel energy storage applications. This experience is now being used to research into superconducting Micro-Bearings for MEMS, whereby circular permanent magnet arrays are levitated and spun above a superconductor to produce bearings suitable for motors and other micron scale devices. The novelty in the device lies in the fact that the rotor is levitated into position by Meissner flux exclusion, whilst stability is provided by flux pinned within the body of the superconductor. This work includes: the investigation of the properties of various magnetic materials, their fabrication processes and their suitability for MEMS; finite element analysis to analyse the interaction between the magnetic materials and YBCO to determine the stiffness and height of levitation. Finally a micro-motor with the above principles is currently being fabricated within the group.

We report upon the excellent magnetocaloric properties of Gd53Al24Co20Zr3 amorphous microwires. In addition to obtaining the large magnetic entropy change (−ΔSM ∼ 10.3 J/kg K at TC ∼ 95 K), an extremely large value of refrigerant capacity (RC ∼ 733.4 J/kg) has been achieved for a field change of 5 T in an array of forty microwires arranged in parallel. This value of RC is about 79% and 103% larger than those of Gd (∼410 J/kg) and Gd5Si2Ge1.9Fe0.1 (∼360 J/kg) regardless of their magnetic ordering temperatures. The design and fabrication of a magnetic bed made of these parallel-arranged microwires would thus be a very promising approach for active magnetic refrigeration for nitrogen liquefaction. Since these microwires can easily be assembled as laminate structures, they have potential applications as a cooling device for micro electro mechanical systems and nano electro mechanical systems.

14 - Silicon-on-insulator (SOI) technology for micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS) sensors

The phenomenon of surface wettability has been a contested issue in phase change heat transfer applications. Its research area has previously broadened in scope from microscale into nanoscale structured surfaces with the aid of high-end techniques such as nanoelectromechanical system (NEMS) and microelectromechanical system (MEMS). However, those techniques are both expensive and time-consuming in creating practical nanoscale-structures. In this study, we propose a streamlined technique to create tunable ultrahydrophobic/philic self-assembled copper oxide nanostructures with multiple tier roughness. Using a bottom-up process, a fast fabrication time can be achieved (relative to NEMS and MEMS) through our simple, cost-effective bulk fabrication technique. As demonstrated through the present experiments, we can control the surface wettability by introducing morphological adaptivity.

Microelectromechanical Systems (MEMS) and Nanoelectromechanical Systems (NEMS) technologies have enabled novel ultracompact sensors. Ranging from various low-power sensors, energy harvesters, to advanced system-in-package (SiP) technology, MEMS and NEMS devices and fabrication technology have proven themselves as indispensable and enabling technologies for realization of the self-sustained wireless sensor nodes. This paper reports the state of the art progress which indicates bright future of self-sustained wireless sensor nodes.

For the WTEC study, the mutually agreed-upon working definition of non-lithography machining included, (1) mechanical (traditional) machining and, (2) non-mechanical (non-traditional) machining. In addition to non-lithography-based micromachines, the study panelists were also interested in establishing the impact of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) on non-lithography-based machining. Examples include the use of MEMS to make a micromold for plastic micromolding, nanoimprint lithography (NIL) and the fabrication of fibers using MEMS spinnerettes.