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Micromachines, Volume 2, Issue 2 (June 2011), Pages 82-318

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Research

Jump to: Review

Open AccessArticle FISHprep: A Novel Integrated Device for Metaphase FISH Sample Preparation
Micromachines 2011, 2(2), 116-128; doi:10.3390/mi2020116
Received: 10 February 2011 / Revised: 25 March 2011 / Accepted: 27 March 2011 / Published: 4 April 2011
Cited by 5 | PDF Full-text (904 KB) | HTML Full-text | XML Full-text
Abstract
We present a novel integrated device for preparing metaphase chromosomes spread slides (FISHprep). The quality of cytogenetic analysis from patient samples greatly relies on the efficiency of sample pre-treatment and/or slide preparation. In cytogenetic slide preparation, cell cultures are routinely used to [...] Read more.
We present a novel integrated device for preparing metaphase chromosomes spread slides (FISHprep). The quality of cytogenetic analysis from patient samples greatly relies on the efficiency of sample pre-treatment and/or slide preparation. In cytogenetic slide preparation, cell cultures are routinely used to process samples (for culture, arrest and fixation of cells) and/or to expand limited amount of samples (in case of prenatal diagnostics). Arguably, this expansion and other sample pretreatments form the longest part of the entire diagnostic protocols spanning over 3–4 days. We present here a novel device with an integrated expansion chamber to culture, arrest and fix metaphase cells followed by a subsequent splashing protocol leading to ample metaphase chromosome spreads on a glass slide for metaphase FISH analysis. The device provides an easy, disposable, low cost, integrated solution with minimal handling for metaphase FISH slide preparation. Full article
(This article belongs to the collection Lab-on-a-Chip)
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Open AccessArticle Mori-Tanaka Based Estimates of Effective Thermal Conductivity of Various Engineering Materials
Micromachines 2011, 2(2), 129-149; doi:10.3390/mi2020129
Received: 21 February 2011 / Revised: 5 April 2011 / Accepted: 8 April 2011 / Published: 15 April 2011
Cited by 9 | PDF Full-text (1167 KB) | HTML Full-text | XML Full-text | Correction
Abstract
The purpose of this paper is to present a simple micromechanics-based model to estimate the effective thermal conductivity of macroscopically isotropic materials of matrix-inclusion type. The methodology is based on the well-established Mori-Tanaka method for composite media reinforced with ellipsoidal inclusions, extended [...] Read more.
The purpose of this paper is to present a simple micromechanics-based model to estimate the effective thermal conductivity of macroscopically isotropic materials of matrix-inclusion type. The methodology is based on the well-established Mori-Tanaka method for composite media reinforced with ellipsoidal inclusions, extended to account for imperfect thermal contact at the matrix-inclusion interface, random orientation of particles and particle size distribution. Using simple ensemble averaging arguments, we show that the Mori-Tanaka relations are still applicable for these complex systems, provided that the inclusion conductivity is appropriately modified. Such conclusion is supported by the verification of the model against a detailed finite-element study as well as its validation against experimental data for a wide range of engineering material systems. Full article
(This article belongs to the Special Issue Advances in Micromechanics and Microengineering)
Open AccessArticle Focusing Light with Curved Guided-Mode Resonance Reflectors
Micromachines 2011, 2(2), 150-156; doi:10.3390/mi2020150
Received: 2 March 2011 / Revised: 12 April 2011 / Accepted: 14 April 2011 / Published: 28 April 2011
Cited by 5 | PDF Full-text (208 KB) | HTML Full-text | XML Full-text
Abstract
Employing numerical simulations, we investigate the possibility of using curved guided-mode resonance (GMR) elements to focus light in reflection. We treat GMR reflectors with a parabolic shape and show that they are capable of focusing light effectively across wavelength bands that extend [...] Read more.
Employing numerical simulations, we investigate the possibility of using curved guided-mode resonance (GMR) elements to focus light in reflection. We treat GMR reflectors with a parabolic shape and show that they are capable of focusing light effectively across wavelength bands that extend several hundred nanometers. The spatially infinite reflector model is simulated with a finite-element method, whereas the spatially finite reflector is treated with a finite-difference-time-domain method. The numerical results demonstrate that light intensity at the focal point is 8.6 dB stronger than the incident intensity when the GMR reflector’s size is on the order of 10 wavelengths. The results indicate potential applicability of wideband-focusing devices in electromagnetics and photonics using compact resonance elements. Full article
(This article belongs to the Special Issue Nano-photonic Devices)
Open AccessArticle Ultrasonic Hot Embossing
Micromachines 2011, 2(2), 157-166; doi:10.3390/mi2020157
Received: 31 March 2011 / Revised: 3 May 2011 / Accepted: 9 May 2011 / Published: 11 May 2011
Cited by 23 | PDF Full-text (282 KB) | HTML Full-text | XML Full-text
Abstract
Ultrasonic hot embossing is a new process for fast and low-cost production of micro systems from polymer. Investment costs are on the order of 20.000 € and cycle times are a few seconds. Microstructures are fabricated on polymer foils and can be [...] Read more.
Ultrasonic hot embossing is a new process for fast and low-cost production of micro systems from polymer. Investment costs are on the order of 20.000 € and cycle times are a few seconds. Microstructures are fabricated on polymer foils and can be combined to three-dimensional systems by ultrasonic welding. Full article
(This article belongs to the Special Issue Polymer MEMS)
Open AccessArticle Effect of the Detector Width and Gas Pressure on the Frequency Response of a Micromachined Thermal Accelerometer
Micromachines 2011, 2(2), 167-178; doi:10.3390/mi2020167
Received: 25 March 2011 / Revised: 18 May 2011 / Accepted: 19 May 2011 / Published: 23 May 2011
Cited by 5 | PDF Full-text (408 KB) | HTML Full-text | XML Full-text
Abstract
In the present work, the design and the environmental conditions of a micromachined thermal accelerometer, based on convection effect, are discussed and studied in order to understand the behavior of the frequency response evolution of the sensor. It has been theoretically and [...] Read more.
In the present work, the design and the environmental conditions of a micromachined thermal accelerometer, based on convection effect, are discussed and studied in order to understand the behavior of the frequency response evolution of the sensor. It has been theoretically and experimentally studied with different detector widths, pressure and gas nature. Although this type of sensor has already been intensively examined, little information concerning the frequency response modeling is currently available and very few experimental results about the frequency response are reported in the literature. In some particular conditions, our measurements show a cut-off frequency at −3 dB greater than 200 Hz. By using simple cylindrical and planar models of the thermal accelerometer and an equivalent electrical circuit, a good agreement with the experimental results has been demonstrated. Full article
Open AccessArticle Optimization of Liquid DiElectroPhoresis (LDEP) Digital Microfluidic Transduction for Biomedical Applications
Micromachines 2011, 2(2), 258-273; doi:10.3390/mi2020258
Received: 5 April 2011 / Revised: 22 May 2011 / Accepted: 25 May 2011 / Published: 3 June 2011
Cited by 17 | PDF Full-text (823 KB) | HTML Full-text | XML Full-text
Abstract
Digital microfluidic has recently been under intensive study, as an effective method to carry out liquid manipulation in Lab-On-a-Chip (LOC) systems. Among droplet actuation forces, ElectroWetting on Dielectric (EWOD) and Liquid DiElectroPhoresis (LDEP) are powerful tools, used in many LOC platforms. Such [...] Read more.
Digital microfluidic has recently been under intensive study, as an effective method to carry out liquid manipulation in Lab-On-a-Chip (LOC) systems. Among droplet actuation forces, ElectroWetting on Dielectric (EWOD) and Liquid DiElectroPhoresis (LDEP) are powerful tools, used in many LOC platforms. Such digital microfluidic transductions do not require integration of complex mechanical components such as pumps and valves to perform the fluidic operations. However, although LDEP has been proved to be efficient to carry and manipulate biological components in insulating liquids, this microfluidic transduction requires several hundreds of volts at relatively high frequencies (kHz to MHz). With the purpose to develop integrated microsystems µ-TAS (Micro Total Analysis System) or Point of Care systems, the goal here is to reduce such high actuation voltage, the power consumption, though using standard dielectric materials. This paper gives key rules to determine the best tradeoff between liquid manipulation efficiency, low-power consumption and robustness of microsystems using LDEP actuation. This study leans on an electromechanical model to describe liquid manipulation that is applied to an experimental setup, and provides precise quantification of both actuation voltage Vth and frequency fc thresholds between EWOD and LDEP regimes. In particular, several parameters will be investigated to quantify Vth and fc, such as the influence of the chip materials, the electrodes size and the device configurations. Compared to current studies in the field, significant reduction of both Vth and fc is achieved by optimization of the aforementioned parameters. Full article
(This article belongs to the Special Issue Biomedical Microdevices)
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Open AccessCommunication Jitterbot: A Mobile Millirobot Using Vibration Actuation
Micromachines 2011, 2(2), 295-305; doi:10.3390/mi2020295
Received: 6 May 2011 / Revised: 7 June 2011 / Accepted: 14 June 2011 / Published: 15 June 2011
Cited by 5 | PDF Full-text (476 KB) | HTML Full-text | XML Full-text
Abstract
Microrobotics is a rapidly growing field with promising applications in microsurgery and microassembly. A challenge in these systems is providing power and control signals to the robot. This project explores crawling robots that are powered and controlled through a global mechanical vibration [...] Read more.
Microrobotics is a rapidly growing field with promising applications in microsurgery and microassembly. A challenge in these systems is providing power and control signals to the robot. This project explores crawling robots that are powered and controlled through a global mechanical vibration field. Structures within the robot will cause it to respond to particular frequencies with different motion modalities. A prototype, dubbed the “jitterbot”, was cut out of a 0.75 mm sheet of steel using electric discharge machining (EDM), and has a total footprint of approximately 30 mm × 20 mm in the xy-plane. The “robot” has a tripod body (8 mm × 16 mm) with three small legs, and two suspended masses that are designed for specific resonance frequencies. The robot was tested on a plate that was vibrated vertically at frequencies ranging from 20 to 2,000 Hz. For particular resonant frequencies, the robot moves forward and turns in either a clockwise or counterclockwise direction. Finite element modeling confirms that the mechanism for motion is a rocking mode that is influenced by two arms that are suspended mass springs tuned to different frequencies. This lays the groundwork for further miniaturization. Full article
(This article belongs to the Special Issue Microrobots)
Open AccessArticle Infrared Ellipsometric Study of Hydrogen-Bonded Long-Chain Thiolates on Gold: Towards Resolving Structural Details
Micromachines 2011, 2(2), 306-318; doi:10.3390/mi2020306
Received: 29 April 2011 / Revised: 18 June 2011 / Accepted: 19 June 2011 / Published: 22 June 2011
Cited by 1 | PDF Full-text (357 KB) | HTML Full-text | XML Full-text
Abstract
A set of newly synthesized aryl-substituted amides of 16-mercaptohexadecanoic acid (R = 4-OH; 3,5-di-OH) are self-assembled on Au(111) substrate. Self assembled monolayers (SAMs) formed by these molecules are studied by ellipsometry from infrared to visible spectral range. Best fit calculations based on [...] Read more.
A set of newly synthesized aryl-substituted amides of 16-mercaptohexadecanoic acid (R = 4-OH; 3,5-di-OH) are self-assembled on Au(111) substrate. Self assembled monolayers (SAMs) formed by these molecules are studied by ellipsometry from infrared to visible spectral range. Best fit calculations based on the three-phase optical model are employed in order to determine the average tilt angle of the hydrocarbon chains. The data revealed that the SAMs reside in a crystalline-like environment as the long methylene chains predominantly exist in all-trans conformation. The calculated tilt angle of the hydrocarbon chain is decreased by approximately 12° in comparison with the one for the correspondent long-chain n-alkyl thiols. Strong hydrogen bonded networks were detected between the amide proton and the carbonyl oxygen as well as between hydroxyl groups in the end aryl substituents. The transition dipole moments of the C=O, N-H and O-H modes are oriented almost parallel to the gold surface. Full article
(This article belongs to the Special Issue Self-Assembly)

Review

Jump to: Research

Open AccessReview Modeling Self-Assembly Across Scales: The Unifying Perspective of Smart Minimal Particles
Micromachines 2011, 2(2), 82-115; doi:10.3390/mi2020082
Received: 1 February 2011 / Revised: 22 March 2011 / Accepted: 24 March 2011 / Published: 31 March 2011
Cited by 8 | PDF Full-text (2589 KB) | HTML Full-text | XML Full-text
Abstract
A wealth of current research in microengineering aims at fabricating devices of increasing complexity, notably by (self-)assembling elementary components into heterogeneous functional systems. At the same time, a large body of robotic research called swarm robotics is concerned with the design and [...] Read more.
A wealth of current research in microengineering aims at fabricating devices of increasing complexity, notably by (self-)assembling elementary components into heterogeneous functional systems. At the same time, a large body of robotic research called swarm robotics is concerned with the design and the control of large ensembles of robots of decreasing size and complexity. This paper describes the asymptotic convergence of micro/nano electromechanical systems (M/NEMS) on one side, and swarm robotic systems on the other, toward a unifying class of systems, which we denote Smart Minimal Particles (SMPs). We define SMPs as mobile, purely reactive and physically embodied agents that compensate for their limited on-board capabilities using specifically engineered reactivity to external physical stimuli, including local energy and information scavenging. In trading off internal resources for simplicity and robustness, SMPs are still able to collectively perform non-trivial, spatio-temporally coordinated and highly scalable operations such as aggregation and self-assembly (SA). We outline the opposite converging tendencies, namely M/NEMS smarting and robotic minimalism, by reviewing each field’s literature with specific focus on self-assembling systems. Our main claim is that the SMPs can be used to develop a unifying technological and methodological framework that bridges the gap between passive M/NEMS and active, centimeter-sized robots. By proposing this unifying perspective, we hypothesize a continuum in both complexity and length scale between these two extremes. We illustrate the benefits of possible cross-fertilizations among these originally separate domains, with specific emphasis on the modeling of collective dynamics. Particularly, we argue that while most of the theoretical studies on M/NEMS SA dynamics belong so far to one of only two main frameworks—based on analytical master equations and on numerical agent-based simulations, respectively—alternative models developed in swarm robotics could be amenable to the task, and thereby provide important novel insights. Full article
(This article belongs to the Special Issue Self-Assembly)
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Open AccessReview Microvalves and Micropumps for BioMEMS
Micromachines 2011, 2(2), 179-220; doi:10.3390/mi2020179
Received: 20 March 2011 / Revised: 10 May 2011 / Accepted: 12 May 2011 / Published: 24 May 2011
Cited by 72 | PDF Full-text (6745 KB) | HTML Full-text | XML Full-text
Abstract
This review presents an extensive overview of a large number of microvalve and micropump designs with great variability in performance and operation. The performance of a given design varies greatly depending on the particular assembly procedure and there is no standardized performance [...] Read more.
This review presents an extensive overview of a large number of microvalve and micropump designs with great variability in performance and operation. The performance of a given design varies greatly depending on the particular assembly procedure and there is no standardized performance test against which all microvalves and micropumps can be compared. We present the designs with a historical perspective and provide insight into their advantages and limitations for biomedical uses. Full article
(This article belongs to the Special Issue Micromixers)
Open AccessReview Multi-Beam Interference Advances and Applications: Nano-Electronics, Photonic Crystals, Metamaterials, Subwavelength Structures, Optical Trapping, and Biomedical Structures
Micromachines 2011, 2(2), 221-257; doi:10.3390/mi2020221
Received: 14 April 2011 / Revised: 25 May 2011 / Accepted: 27 May 2011 / Published: 3 June 2011
Cited by 27 | PDF Full-text (3857 KB) | HTML Full-text | XML Full-text
Abstract
Research in recent years has greatly advanced the understanding and capabilities of multi-beam interference (MBI). With this technology it is now possible to generate a wide range of one-, two-, and three-dimensional periodic optical-intensity distributions at the micro- and nano-scale over a [...] Read more.
Research in recent years has greatly advanced the understanding and capabilities of multi-beam interference (MBI). With this technology it is now possible to generate a wide range of one-, two-, and three-dimensional periodic optical-intensity distributions at the micro- and nano-scale over a large length/area/volume. These patterns may be used directly or recorded in photo-sensitive materials using multi-beam interference lithography (MBIL) to accomplish subwavelength patterning. Advances in MBI and MBIL and a very wide range of applications areas including nano-electronics, photonic crystals, metamaterials, subwavelength structures, optical trapping, and biomedical structures are reviewed and put into a unified perspective. Full article
(This article belongs to the Special Issue Nano-photonic Devices)
Open AccessReview Recent Progress in Piezoelectric Conversion and Energy Harvesting Using Nonlinear Electronic Interfaces and Issues in Small Scale Implementation
Micromachines 2011, 2(2), 274-294; doi:10.3390/mi2020274
Received: 2 April 2011 / Revised: 23 May 2011 / Accepted: 25 May 2011 / Published: 3 June 2011
Cited by 50 | PDF Full-text (725 KB) | HTML Full-text | XML Full-text
Abstract
This paper aims at providing an up-to-date review of nonlinear electronic interfaces for energy harvesting from mechanical vibrations using piezoelectric coupling. The basic principles and the direct application to energy harvesting of nonlinear treatment of the output voltage of the transducers for [...] Read more.
This paper aims at providing an up-to-date review of nonlinear electronic interfaces for energy harvesting from mechanical vibrations using piezoelectric coupling. The basic principles and the direct application to energy harvesting of nonlinear treatment of the output voltage of the transducers for conversion enhancement will be recalled, and extensions of this approach presented. Latest advances in this field will be exposed, such as the use of intermediate energy tanks for decoupling or initial energy injection for conversion magnification. A comparative analysis of each of these techniques will be performed, highlighting the advantages and drawbacks of the methods, in terms of efficiency, performance under several excitation conditions, complexity of implementation and so on. Finally, a special focus of their implementation in the case of low voltage output transducers (as in the case of microsystems) will be presented. Full article
(This article belongs to the Special Issue Energy Harvesting)

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