Control Of Micro Research Articles

Experimental study of a low-g micromachined electrostatically suspended accelerometer for space applications

In this paper a silicon-based micromachined electrostatically suspended accelerometer (Si-MESA), which employs a free parallelepiped proof mass suspended in six degree of freedom, is designed, fabricated and experimentally tested oriented to space applications. The Si-MESA is a glass/silicon/glass sandwich structure fabricated by bulk micromachining, which mainly consists of two anodic bonding steps, a deep reactive ion etching and a wet etching of Al sacrificial layer. The motion of the proof mass with comb teeth on four outer sides is fully servo-controlled with capacitive position sensing and electrostatic suspension. To facilitate ground test of this low-g Si-MESA against the gravity, the input range in the vertical z axis is set to larger than 2 g, while the range in the lateral x and y axes are as low as on the order of several to tens millesimal of the gravity (mg) to achieve higher resolution for potential space applications. The ground test yields specific performances in the lateral x and y axes as follows: the noise floor of 36.8 μg/Hz1/2 and 0.116 mg/Hz1/2, as well as the resolution of 1.454 × 10?5 g and 1.432 × 10?4 g, respectively. The three-axis Si-MESA features extremely low range, high resolution, and long life-span, and has favorable space application prospects such as drag-free control of micro&small satellite and weak gravity measurement.

Self-management evaluation by small-enterprises and micro-enterprises: Exploratory study

Purpose: To know what their habits and customs on planning, developing, information management and control of micro and small enterprises in Catalonia Design/methodology/approach: Four workshops involving 70 people from micro and small companies were carried out. The workshops were organized by institutions related to Catalan companies. The model used in the workshops was the canvas model Findings and Originality/value: The main contribution is the use of canvas as auto diagnostic tool for micro and small businesses, which has allowed us to know which is the reality of this type of business regarding management, highlighting the necessity to have an overview of the company, the necessity to foster the relationship with the external forces, and the lack of relations between key areas. Participants also know the importance of management information Research limitations/implications: The workshops were aimed at people who have contact and participate in the institutions which were performed Practical implications: This research provides a conceptual framework for the companies’ owner to make a diagnosis on your business model and how it is managed. It also allows management practices from the micro and small enterprises, to design a management control system adapted to this type of company Social implications: The results serve as a diagnostic study on the reality of small and micro enterprises, which can be used to design tools and programs that are useful for their development and survival. Originality/value: For the participants Associations aims to promote the development of micro and small enterprises, the diagnosis of the reality of these companies. For the management people, the self-diagnostic tool and for the academic community the exploratory study would allow developing a control system applicable to the reality of the micro and small enterprises.

Manipulation and confinement of single particles using fluid flow.

High precision control of micro- and nanoscale objects in aqueous media is an essential technology for nanoscience and engineering. Existing methods for particle trapping primarily depend on optical, magnetic, electrokinetic, and acoustic fields. In this work, we report a new hydrodynamic flow based approach that allows for fine-scale manipulation and positioning of single micro- and nanoscale particles using automated fluid flow. As a proof-of-concept, we demonstrate trapping and two-dimensional (2D) manipulation of 500 nm and 2.2 μm diameter particles with a positioning precision as small as 180 nm during confinement. By adjusting a single flow parameter, we further show that the shape of the effective trap potential can be efficiently controlled. Finally, we demonstrate two distinct features of the flow-based trapping method, including isolation of a single particle from a crowded particle solution and active control over the surrounding medium of a trapped object. The 2D flow-based trapping method described here further expands the micro/nanomanipulation toolbox for small particles and holds strong promise for applications in biology, chemistry, and materials research.

Controlling colloidal phase transitions with critical Casimir forces

The critical Casimir force provides a thermodynamic analogue of the quantum mechanical Casimir force that arises from the confinement of electromagnetic field fluctuations. In its thermodynamic analogue, two surfaces immersed in a critical solvent mixture attract each other due to confinement of solvent concentration fluctuations. Here, we demonstrate the active assembly control of colloidal equilibrium phases using critical Casimir forces. We guide colloidal particles into analogues of molecular liquid and solid phases via exquisite control over their interactions. By measuring the critical Casimir pair potential directly from density fluctuations in the colloidal gas, we obtain insight into liquefaction at small scales. We apply the van der Waals model of molecular liquefaction and show that the colloidal gas-liquid condensation is accurately described by the van der Waals theory, even on the scale of a few particles. These results open up new possibilities in the active assembly control of micro and nanostructures.

Three-Dimensional Magnetic Manipulation of Micro- and Nanostructures for Applications in Life Sciences

We present a magnetic manipulation system capable of 5 degree-of-freedom (5-DOF) wireless control of micro- and nanostructures (3-DOF position, 2-DOF pointing orientation). The system has a spherical workspace with a diameter of approximately 10 mm, and is completely unrestrained in the rotational degrees-of-freedom. This is accomplished through the superposition of multiple magnetic fields, and capitalizes on a linear representation of the coupled field contributions of multiple soft-magnetic-core electromagnets acting in concert. The system consists of 8 stationary electromagnets with ferromagnetic cores, and is capable of producing arbitrary magnetic fields and field gradients up to 50 mT and 5 T/m at frequencies up to 2 kHz. The capabilities of the system are evaluated through the introduction of the reachable magnetic workspace of the system as well as frequency response and calibration results. Experimental results are presented which demonstrate different magnetic control strategies at sub-mm and sub-μm scale.

Pulse electroanalysis at gold–gold micro-trench electrodes: Chemical signal filtering

Bipotentiostatic control of micro- and nano-trench sensor systems provides new opportunities for enhancing signals (employing feedback currents) and for improved selectivity (by "chemical filtering"). In this study both phenomena are exploited with a gold-gold micro-trench electrode with ca. 70 microm width and ca. 800 microm trench depth. In "generator-collector mode", feedback current enhancement is demonstrated for the hydroquinone/ benzoquinone redox system. Next, a "modulator-sensor mode" experiment is developed in which one electrode potential is stepped into the negative potential region (employing the normal pulse voltammetry method) to induce an oscillating pH change locally in the micro-trench. The resulting shift in the hydroquinone/benzoquinone reversible potential causes a Faradaic sensor signal (employing chronoamperometry). This method provides a "chemical filter" by selecting pH-sensitive redox processes only, and by showing enhanced sensitivity in the region of low buffer capacity. The results for the chemically reversible hydroquinone/benzoquinone system are contrasted to the detection of the chemically irreversible ammonia oxidation.

Second Workshop on Dynamics and Control of Micro- and Nanoscale Systems [Conference Reports

The authors briefly describe the events of the Second Workshop on Dynamics and Control of Micro- and Nanoscale Systems was held at the University of Newcastle, Australia, February 23- 24, 2012. The purpose of this workshop was to bring together some of the leading experts in the field of dynamics and control of micro- and nanoscale systems to discuss emerging research problems and recent advances in the field. The two-day program comprised two keynote speeches and 17 invited presentations.

INTERNAL LOGISTICS, EXTERNAL COMMUNICATION, INFORMATION PROCESSING AND FINANCIAL CONTROL: AN ANALYSIS WITH BRAZILIAN MICRO AND SMALL ENTERPRISES

The aim of this study was to analyze the impact of interaction between external communication, internal information processing and internal logistics in the financial control of Brazilian Micro and Small Enterprises. It was characterized as a survey with a quantitative approach, and the applied statistics consist of confirmatory factor analysis and structural equation models, based on a sample of 183 companies. Considering a significance smaller that 0.05, the main results have presented that internal information processing and internal logistics showed a positive and significant relationship with financial control. Internal logistics and external communication also proved to be positively and significantly correlated.

Theoretical Study of Mechanical Control of Micro- and Nano-Mechanical Systems by Cavity-Induced Radiation Force

We theoretically investigate the possibility of controlling the vibration amplitude of a cantilever used in scanning probe microscopy (SPM) by cavity-induced radiation force (CIRF) exerted on the cavity mirror attached to it. It has been clarified that the amplitude of the cantilever can be decreased by one order of magnitude owing to the nonlinear dynamics induced by CIRF under weak laser irradiation of 30 to 50 µW. This mechanism would be applied to, for example, dynamical control of micro- and nano-mechanical systems, and high-sensitivity SPM based on small amplitude metrology.

Theoretical Study of Mechanical Control of Micro- and Nano-Mechanical Systems by Cavity-Induced Radiation Force

Theoretical Study of Mechanical Control of Micro- and Nano-Mechanical Systems by Cavity-Induced Radiation Force

New Flexure Parallel-Kinematic Micropositioning System With Large Workspace

Flexure-based micropositioning systems with a large workspace are attractive for a variety of precision engineering applications. In this paper, a new idea of multistage compound parallelogram flexure is proposed for the mechanism design of a novel parallel-kinematic XY micropositioning system, which has a motion range larger than 10 mm along with a compact structure. The established quantitative models and the stage performances are validated by conducting finite-element analysis (FEA) and experimental studies. Moreover, an enhanced model-predictive control (EMPC) is presented for positioning control of the system, which has a nonminimum-phase plant. It is shown that the EMPC is capable of producing a low magnitude of output tracking error by imposing an appropriate suppression on the control effort. Simulation and experimental studies reveal that the EMPC scheme outperforms the conventional proportional-integral-derivative (PID) and MPC methods in terms of transient response speed and steady-state accuracy. The idea that is presented in this paper is extendable to design and control of other micro-/nanopositioning systems with either minimum- or nonminimum-phase plants.

Observations of X-Ray Radiation Pressure Force Using High-Speed Diffracted X-Ray Tracking

In single molecular science and technology, it is very important to control dynamical Brownian motions of individual functional protein molecules. Optical trap and tweezer using visible light is the first demonstration of controlling micron-sized particles or molecules. In order to improve both monitoring and controlling internal molecular motions from single molecular units with more super-precisions under in vitro or in vivo physiological conditions, we have proposed new single molecular techniques using shorten wavelength, for example, X-rays, electrons, and neutron. Recently, we observed directed Brownian motions of individual single gold nanocrystals using high-speed Diffracted X-ray Tracking (DXT). We confirmed that this motion is dependent upon X-ray Intensity and the sized of observed gold nanocrystal. The observed force is estimated at atto-Newton level. In my previous research, we utilized the adsorbed protein molecules, and the gold nanocrystals are linked to the adsorbed ones. Because we can not observe free Brownian motions of the individual gold nanocrystals in aqueous solutions using normal speed DXT. In this new experiment of high-speed DXT, a diffraction spot in high-speed DXT was monitored with an X-ray image intensifier (Hamamatsu Photonics, V5445P) and a CMOS CCD camera (FASTCAM SA1.1, Photron) with 128 x 112 pixels. Additionally we utilized high-speed X-ray shutters. The averaged exposure time in single shot was 5μsec.-20μsec. In these experiments, we controlled the size of gold nanocrystals and the energy of quasi-white x-rays. In the future, we will be able to control and measure dynamics of micro- or nano-crystalline materials or labeled single molecular units using x-ray radiation pressure force.

The influence of polymer addition on flexural strength, fracture mode and porosity of traditional ceramics

The usage of an air-swept milling of raw materials is the most efficient method for preventing the negative lime-blowing process of ceramic roofing tiles. However, after air-swept milling the clay minerals lose water which has to be returned back before the shaping procedure. Addition of surface active materials could increase hidrophilicity of the raw material and reduce needed time for re-wetting trough the control of meso, micro and nano porosity of the clay material. In view of that, the object of this research was to study the influence of polyethylene glycol (PEG600) on porosity, mechanical properties and fracture surface characteristics of traditional ceramic materials. It was founded that with the addition of polyethylene glycol (PEG600) to traditional clay materials it is possible to achieve desired porosity, from meso, trough micro and up to nano, without degrading the mechanical properties of the final products.

Autonomous Control of Micro Flying Robot

In the case of a natural disaster such as an earthquake, a micro air vehicle (MAV) would be very effective for surveying the site and environment in dangerous areas or narrow spaces that humans cannot access safely. In addition, it would be helpful for preventing secondary disaster. This paper discusses autonomous hovering control and guidance control of a micro flying robot (μFR). Since a μFR is very small and light, sensors such as a global positioning system (GPS) cannot be carried. So, the three-dimensional position of a μFR is measured by using one charge coupled device (CCD) camera to recognize a marker attached to the μFR. We adopted proportional—integral—derivative (PID) control because its performance can be increased by tuning, even when there is no model. Nevertheless, it is not easy to find the gain of the PID controller for the X and Y directions. Therefore, the first step that we took is modeling based on system identification and then we designed a model-based controller.

Thrust enhancement via gel-type liquid confinement of laser ablation of solid metal propellant

Laser propulsion has been developed as a suitable small thruster technology for the attitude control of micro and nano class satellites. Laser-based thrusters meet the satellite design criteria for being of light weight and cost effective, because they do not require fuel storing and oxidizer for combustion. Also, thrust control by laser propulsion is achieved fairly easy. In this paper, we consider the confinement of plasma expansion by a gel-type liquid material, which results in the enhancement of the thrust for propulsion. We also present our attempts to resolve some known issues regarding laser ablation of solid and liquid targets. The level of thrust is quantified via the momentum coupling coefficient, which was experimentally measured using a ballistic pendulum system. We have discovered that the laser ablation confinement by the gel-type medium results in 2.3 times more enhanced driving force as compared to the water confinement. A proof of performance is demonstrated for using gel-type material for generating propulsion, and material characterization for optimal thrust performance is presented.

Quantitative Analysis of Nucleic Acid Hybridization on Magnetic Particles and Quantum Dot-Based Probes

In the present study we describe sandwich design hybridization probes consisting of magnetic particles (MP) and quantum dots (QD) with target DNA, and their application in the detection of avian influenza virus (H5N1) sequences. Hybridization of 25-, 40-, and 100-mer target DNA with both probes was analyzed and quantified by flow cytometry and fluorescence microscopy on the scale of single particles. The following steps were used in the assay: (i) target selection by MP probes and (ii) target detection by QD probes. Hybridization efficiency between MP conjugated probes and target DNA hybrids was controlled by a fluorescent dye specific for nucleic acids. Fluorescence was detected by flow cytometry to distinguish differences in oligo sequences as short as 25-mer capturing in target DNA and by gel-electrophoresis in the case of QD probes. This report shows that effective manipulation and control of micro- and nanoparticles in hybridization assays is possible.

Novel deposition techniques for metal oxide: Prospects for gas sensing

With the growing need for high performance gas sensors, a variety of preparation methods have been introduced and investigated. In the present contribution, the focus is on novel means for preparing metal oxide gas sensor devices. First, the key gas sensor concepts are reviewed as well as the conventional deposition techniques widely used for thick and thin film deposition of metal oxides such as screen-printing and chemical and physical vapour deposition. This is followed by a review and examination of innovative deposition techniques developed within the past several years, focusing on methods with direct-write features as well as techniques offering precise control of micro- and nano-structural features of the deposited materials.

Guest Editorial Introduction to the Special Issue on Dynamics and Control of Micro- and Nanoscale Systems

The following topics are dealt with: control systems technology; nanoscale system; robotics; iterative control; microscale system.

Control of micro- and nanopatterns of octadecyltrimethoxysilane monolayers using nanoimprint lithography and atmospheric chemical vapor deposition

Octadecyltrimethoxysilane (OTMS) self-assembled monolayers have been grafted on micrometric and nanometric areas of SiO2∕Si substrates using a process combining nanoimprint lithography and atmospheric chemical vapor deposition. The optimization of the process has lead to monolayer square patterns of OTMS with lateral sizes ranging from 2μm down to 50nm. Their coverage uniformity extends on several square millimeters. Their coverage density can be accurately tuned by the deposition time.

Hierarchical Porosity in Self‐Assembled Polymers: Post‐Modification of Block Copolymer–Phenolic Resin Complexes by Pyrolysis Allows the Control of Micro‐ and Mesoporosity

AbstractIt is shown that self‐assembled hierarchical porosity in organic polymers can be obtained in a facile manner based on pyrolyzed block‐copolymer–phenolic resin nanocomposites and that a given starting composition can be post‐modified in a wide range from monomodal mesoporous materials to hierarchical micro‐mesoporous materials with a high density of pores and large surface area per volume unit (up to 500–600 m2 g–1). For that purpose, self‐assembled cured composites are used where phenolic resin is templated by a diblock copolymer poly(4‐vinylpyridine)‐block‐polystyrene (P4VP‐b‐PS). Mild pyrolysis conditions lead only to monomodal mesoscale porosity, as essentially only the PS block is removed (length scale of tens of nanometers), whereas during more severe conditions under prolonged isothermal pyrolysis at 420 °C the P4VP chains within the phenolic matrix are also removed, leading to additional microporosity (sub‐nanometer length scale). The porosity is analyzed using transmission electron microscopy (TEM), small‐angle X‐ray scattering, electron microscopy tomography (3D‐TEM), positron annihilation lifetime spectroscopy (PALS), and surface‐area Brunauer–Emmett–Teller (BET) measurements. Furthermore, the relative amount of micro‐ and mesopores can be tuned in situ by post modification. As controlled pyrolysis leaves phenolic hydroxyl groups at the pore walls and the thermoset resin‐based materials can be easily molded into a desired shape, it is expected that such materials could be useful for sensors, separation materials, filters, and templates for catalysis.