Electrowetting on Dielectric Based Droplet Transport Inside a Closed-Channel

2010 ◽  
Author(s):  
Mohammed Jalal Ahamed ◽  
Ridha Ben-Mrad ◽  
Pierre Sullivan
Keyword(s):  
Constant Velocity ◽  
Actuation Voltage ◽  
Design Parameters ◽  
Channel Height ◽  
Closed Channel ◽  
Droplet Motion ◽  
Electrowetting On Dielectric ◽  
Droplet Transport ◽  
Open Plane ◽  
Peak Value

The paper reports Electrowetting on Dielectric (EWOD) actuated droplet transport characteristics inside a closed-channel. Traditional EWOD devices are open-plane wall-less devices within which droplets are either sitting on a substrate or sandwiched between top and bottom substrates. We investigated droplet motion by EWOD actuation inside a sealed closed-channel. Closed-channel EWOD actuation is useful for interfacing open-plane EWOD (digital) designs to closed continuous (analog) microfluidic devices. Some transport characteristics of the closed-channel EWOD actuation were investigated. Actuation voltage was varied between 85–120 VRMS. Channel height was varied between 90–150 μm. The electrodes were square shaped and 2 mm across. Within these range of design parameters the droplet velocity profile showed no steady state constant velocity. And it accelerated to the peak value near the midpoint of the energized electrode then decelerated for the rest of the travel.

Investigation of the Effect of Geometric Parameters on EWOD Actuation in Rectangular Microchannels

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Sajad Pooyan ◽  
Mohammad Passandideh-Fard
Keyword(s):  
Theoretical Model ◽  
High Speed ◽  
Channel Width ◽  
Circuit Board ◽  
Design Parameters ◽  
Channel Height ◽  
Liquid Slug ◽  
Electrowetting On Dielectric ◽  
Transport Velocity ◽  
The Mean

Efficient actuation of liquid slugs in microfluidic circuits is a matter of interest in droplet-based microfluidic (DMF) applications. In this paper, the electrowetting on dielectric (EWOD) actuation of a liquid slug fully confined in a microchannel is studied. A set of experiments are conducted in which the mean transport velocity of a liquid slug enclosed in a microchannel of rectangular cross section and actuated by EWOD method is measured. A printed circuit board-based (PCB-based) microfluidic chip is used as the platform, and the transport velocity of the slug is measured by processing the images recorded by a high-speed camera while the slug moves in the channel. To investigate the effect of microchannel geometry on the mean transport velocity of the slugs, different channel heights and widths (ranging between 250−440μm and 1–2 mm, respectively) as well as different liquid volumes (ranging between 2.94and5.15μL) are tested and slug velocities up to 14.9 mm/s are achieved. A theoretical model is also developed to analyze the effect of involved parameters on the transport velocity. The results show that, within the range of design parameters considered in this study, for a constant slug volume and channel width, increasing the channel height enhances the velocity. Moreover, keeping the slug volume and channel height fixed, the transport velocity is increased by enlarging the channel width. An inverse proportionality between the slug length and velocity is also observed. These results are also shown to agree with the theoretical model developed.

Steam Turbine Overspeed Scenarios: Comparison Between API Energy Method and Dynamic Simulation

2021 ◽  
Author(s):  
Fabrizio Piras ◽  
Federico Bucciarelli ◽  
Damaso Checcacci ◽  
Filippo Ingrasciotta
Keyword(s):  
Design Parameters ◽  
Steam Turbines ◽  
Analysis Method ◽  
Design Constraint ◽  
Rotating Speed ◽  
Critical Design ◽  
Operating Stress ◽  
Technological Challenge ◽  
Rotor Dynamic ◽  
Peak Value

Abstract In turbomachinery applications the possibility to reduce size and costs of main flow-path components, by increasing shaft rotating speed, has always been appealing. The technological challenge in increasing this power density capability is typically related to performance prediction, to operating stress in blades and shafts, as well as to the need for a more accurate rotor-dynamic analysis. Yet another aspect, often reduced to standard assessments in less demanding applications, is related to the analysis of overspeed scenarios where, following a sudden loss of load and/or driven inertia, the turbomachine shall maintain its mechanical integrity. Especially in steam turbines applications, where the behavior of the machine is strongly affected by the plant conditions, valves intervention time and connected volumes, the reduction of the rotor inertia, against comparable power, may produce overspeed scenarios that can become a primary design constraint and, if overlooked, may have both availability and safety implications. In this paper several approaches to the analysis of overspeed scenarios are discussed, with increasing level of detail. The energy-based overspeed analysis method, as required by API612, is first discussed against practical design cases. A more accurate dynamic model is then presented, and its results compared with those of the energy-based approach. Finally, the sensitivity analysis of the overspeed peak value with respect to critical design parameters is discussed. With respect to previous works, mostly based on load rejection scenarios, the main focus is on the scenario of sudden coupling loss.

scholarly journals Design and Optimization of Germanium-Based Gate-Metal-Core Vertical Nanowire Tunnel FET

Micromachines ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 749 ◽  
Author(s):  
Jang ◽  
Yoon ◽  
Cho ◽  
Jung ◽  
Lee ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Design Parameters ◽  
Channel Height ◽  
Logic Device ◽  
Metal Core ◽  
Design And Optimization ◽  
Channel Thickness ◽  
Effect Transistor ◽  
Tunnel Field Effect Transistor ◽  
Aided Design

In this paper, a germanium-based gate-metal-core vertical nanowire tunnel field effect transistor (VNWTFET) has been designed and optimized using the technology computer-aided design (TCAD) simulation. In the proposed structure, by locating the gate-metal as a core of the nanowire, a more extensive band-to-band tunneling (BTBT) area can be achieved compared with the conventional core–shell VNWTFETs. The channel thickness (Tch), the gate-metal height (Hg), and the channel height (Hch) were considered as the design parameters for the optimization of device performances. The designed gate-metal-core VNWTFET exhibits outstanding performance, with an on-state current (Ion) of 80.9 μA/μm, off-state current (Ioff) of 1.09 × 10−12 A/μm, threshold voltage (Vt) of 0.21 V, and subthreshold swing (SS) of 42.8 mV/dec. Therefore, the proposed device was demonstrated to be a promising logic device for low-power applications.

CFD Modeling of a Catalytic Flat Plate Fuel Reformer for Hydrogen Generation

2010 ◽  
Author(s):  
Kranthi K. Gadde ◽  
Panini K. Kolavennu ◽  
Susanta K. Das ◽  
K. J. Berry
Keyword(s):  
Flat Plate ◽  
Catalytic Combustion ◽  
Reaction Rates ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Design Parameters ◽  
Practical Implementation ◽  
Channel Height ◽  
Inlet Temperature ◽  
Two Dimensional

In this study, steam reforming of methane coupled with methane catalytic combustion in a catalytic plate reactor is studied using a two-dimensional mathematical model for co-current flow arrangement. A two-dimensional approach makes the model more realistic by increasing its capability to capture the effect of parameters such as catalyst thickness, reaction rates, inlet temperature and velocity, and channel height, and eliminates the uncertainties introduced by heat and mass transfer coefficients used in one-dimensional models. In our work, we simulate the entire flat plate reformer (both reforming side and combustion side) and carry out parametric studies related to channel height, inlet velocities, and catalyst layer thickness that can provide guidance for the practical implementation of such design. The operating conditions chosen make possible a comparison of the catalytic plate reactor and catalytic combustion analysis with the conventional steam reformer. The CFD results obtained in this study will be very helpful to understand the optimization of design parameters to build a first generation prototype.

3D Droplet Transportation by EWOD Actuations on Flexible Polymer Films

2005 ◽  
Author(s):  
Hanping Yang ◽  
Shih-Kang Fan ◽  
Chan-Pau Lin ◽  
Chien Tai Wu ◽  
Wensyang Hsu
Keyword(s):  
Polymer Film ◽  
Glass Substrate ◽  
Flexible Substrate ◽  
Current Model ◽  
Actuation Voltage ◽  
Experiment Data ◽  
Electrowetting On Dielectric ◽  
Flexible Polymer ◽  
Out Of Plane ◽  
Better Than

3-D droplet transportation of ElectroWetting On Dielectric (EWOD) actuation with flexible substrate is proposed. Instead of glass substrate, a polymer film is taken to fabricate the microfluidic device for the droplet demonstrating out of plane motions. Two kinds of tests, tilted test and curved test, are performed, and a model of minimum required actuation voltage is presented, and compared with the results of tilted test. The current model matches experiment data much better than the conventional ones. In the curved test, the droplet successfully transports from bottom to the top.

Experimental Performance Evaluation of a Catalytic Flat Plate Fuel Reformer for Fuel Cell Grade Reformate

2014 ◽  
Author(s):  
Susanta K. Das ◽  
K. Joel Berry
Keyword(s):  
Fuel Cell ◽  
Flat Plate ◽  
Reaction Rates ◽  
Design Parameters ◽  
Channel Height ◽  
Inlet Temperature ◽  
Cfd Model ◽  
Current Voltage ◽  
Study Results ◽  
Current Voltage Characteristics

Compact and efficient fuel reforming system design is a major challenge because of strict requirements of efficient heat distribution on both the reforming and combustion side. As an alternative to traditional packed bed tubular reformers, catalytic flat plate fuel reformer offers better heat integration by combining the combustion reaction on one side and reforming reaction on the other side. In this study, with the help of a two-dimensional computational fluid dynamics (CFD) model, a catalytic flat plate fuel reformer is built and investigated its performance experimentally. The CFD model simulation results help to capture the effect of design parameters such as catalyst layer thickness, reaction rates, inlet temperature and velocity, and channel height. The CFD model study results also help to design and built the actual reformer in such a way that eliminate the limitations or uncertainties of heat and mass transfer coefficients. In our study, we experimentally evaluated the catalytic flat plate fuel reformer performance using natural gas. The effect of reformate gas on the current-voltage characteristics of a 5kW high temperature PEM fuel cell (HTPEMFC) stack is investigated extensively. The results shows that the overall system performance increases in terms of current-voltage characteristics of HTPEMFC while fed with reformate directly from the catalytic flat plate reformer.

Design, Evaluation and Analysis of a Novel H-Shaped Capacitive RF MEMS Switch

2021 ◽  
Author(s):  
Shoukathvali Khan ◽  
K. Srinivasa ◽  
Koushik Guha
Keyword(s):  
Rf Mems ◽  
Actuation Voltage ◽  
Element Model ◽  
Parameter Analysis ◽  
Design Parameters ◽  
Rf Mems Switch ◽  
Lumped Model ◽  
Mems Switch ◽  
Novel Structure ◽  
Micro Electromechanical System

Abstract In this paper, absolute evaluation of Radio Frequency Micro Electromechanical System (RF MEMS) to improve parameters like high actuation voltage and low switching time, by introducing a new fixed - fixed RF MEMS capacitive switch. The proposed switch designed step-by-step evaluation of the plane beam, a novel structure of beam, and deposit the perforations and meanders to reducethe pull-in voltage. All the RF MEMS switch design parameters arestudy using the COMSOL Multiphysics FEM (Finite Element Model) tool. The proposed RF MEMS switch express low pull-in voltageof 4.75V and good return, insertion, and isolation losses in both upstate and downstate conditions are >10dB, below 0.1dB and 60dB, respectively. The dielectric layer as silicon nitride (Si3N4), beam as a gold material. The RLC values are extracted by using lumped model design. The RF MEMS shunt switch (capacitance, inductance, and resistance) of the MEMS bridge are accurately evaluated from the S-parameter analysis. The computational and simulated results are good agreement with each other, which indicates the validity of the proposed switch for K (18-26) GHz band applications.

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