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Micromachines, Volume 3, Issue 3 (September 2012), Pages 542-603

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Research

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Open AccessArticle Characterization of Kink Actuators as Compared to Traditional Chevron Shaped Bent-Beam Electrothermal Actuators
Micromachines 2012, 3(3), 542-549; doi:10.3390/mi3030542
Received: 10 May 2012 / Revised: 19 June 2012 / Accepted: 3 July 2012 / Published: 6 July 2012
Cited by 4 | PDF Full-text (1963 KB) | HTML Full-text | XML Full-text
Abstract
This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs
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This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs. Full article
(This article belongs to the Special Issue Thermal Switches and Control of Heat Transfer in MEMS)
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Open AccessCommunication Very High Throughput Electrical Cell Lysis and Extraction of Intracellular Compounds Using 3D Carbon Electrodes in Lab-on-a-Chip Devices
Micromachines 2012, 3(3), 574-581; doi:10.3390/mi3030574
Received: 25 June 2012 / Revised: 30 July 2012 / Accepted: 3 August 2012 / Published: 16 August 2012
Cited by 12 | PDF Full-text (1716 KB) | HTML Full-text | XML Full-text
Abstract
Here we present an electrical lysis throughput of 600 microliters per minute at high cell density (108 yeast cells per ml) with 90% efficiency, thus improving the current common throughput of one microliter per minute. We also demonstrate the extraction of intracellular
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Here we present an electrical lysis throughput of 600 microliters per minute at high cell density (108 yeast cells per ml) with 90% efficiency, thus improving the current common throughput of one microliter per minute. We also demonstrate the extraction of intracellular luciferase from mammalian cells with efficiency comparable to off-chip bulk chemical lysis. The goal of this work is to develop a sample preparation module that can act as a stand-alone device or be integrated to other functions already demonstrated in miniaturized devices, including sorting and analysis, towards a true lab-on-a-chip. Full article
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Open AccessArticle Nonlinear Modeling for Distortion Analysis in Silicon Bulk-Mode Ring Resonators
Micromachines 2012, 3(3), 582-603; doi:10.3390/mi3030582
Received: 6 July 2012 / Revised: 6 August 2012 / Accepted: 16 August 2012 / Published: 22 August 2012
PDF Full-text (615 KB) | HTML Full-text | XML Full-text
Abstract
A distributed modeling approach has been developed to describe the dynamic behavior of ring resonators. The model includes the effect of large amplitudes around primary resonance frequencies, material and electrostatic nonlinearities. Through a combination of geometric and material nonlinearities, closed-form expression for third-order
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A distributed modeling approach has been developed to describe the dynamic behavior of ring resonators. The model includes the effect of large amplitudes around primary resonance frequencies, material and electrostatic nonlinearities. Through a combination of geometric and material nonlinearities, closed-form expression for third-order nonlinearity in mechanical stiffness of bulk-mode ring resonators is obtained. Moreover, to avoid dynamic pull-in instability, the choices of the quality factor, ac-drive and DC-bias voltages of the ring resonators, with a given geometry are limited by a resonant pull-in condition. Using the perturbation technique and the method of harmonic balance, the expressions for describing the effect of nonlinearities on the resonance frequency and displacement are derived. The results are discussed in detail, showing the effect of varying operating conditions and the quality factor on the harmonic distortions and third-order intermodulation distortion. The detailed nonlinear modeling and distortion analysis are applied as appropriate tools to design bulk-mode ring resonators with low motional resistance and high linearity. Full article

Review

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Open AccessReview Micromachined Thermal Flow Sensors—A Review
Micromachines 2012, 3(3), 550-573; doi:10.3390/mi3030550
Received: 13 June 2012 / Revised: 3 July 2012 / Accepted: 16 July 2012 / Published: 23 July 2012
Cited by 81 | PDF Full-text (683 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Microfabrication has greatly matured and proliferated in use amongst many disciplines. There has been great interest in micromachined flow sensors due to the benefits of miniaturization: low cost, small device footprint, low power consumption, greater sensitivity, integration with on-chip circuitry, etc. This paper
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Microfabrication has greatly matured and proliferated in use amongst many disciplines. There has been great interest in micromachined flow sensors due to the benefits of miniaturization: low cost, small device footprint, low power consumption, greater sensitivity, integration with on-chip circuitry, etc. This paper reviews the theory of thermal flow sensing and the different configurations and operation modes available. Material properties relevant to micromachined thermal flow sensing and selection criteria are also presented. Finally, recent applications of micromachined thermal flow sensors are presented. Detailed tables of the reviewed devices are included. Full article
(This article belongs to the Special Issue Micro Flow Controllers)
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