Electrowetting (EW)-Based Valve Combined with Hydrophilic Teflon Microfluidic Guidance in Controlling Continuous Fluid Flow

Cheng, Ji-Yen; Hsiung, Lo-Chang

doi:10.1023/b:bmmd.0000048565.59159.c1

Cited by 30 publications

(24 citation statements)

References 11 publications

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“…Passive microfluidic logic gates can also be based on the surface tension of bubbles moving in a liquid (Prakash and Gershenfeld 2007) or liquid droplets (Cheow et al 2007). Actuated valves that have no moving parts such as electrowetting-based valves (Cheng and Hsiung 2004) might also be integrated in CSs, but require additional fabrication steps and electric circuits to operate the valve which might be costly for ultimately disposable CSs.…”

Section: Introductionmentioning

confidence: 99%

Valves for autonomous capillary systems

Zimmermann

Hunziker

Delamarche

2008

Microfluid Nanofluid

157

153

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Autonomous capillary systems (CSs) are microfluidic systems inside which liquids move owing to capillary forces. CSs can in principle bring the high-performances of microfluidic-based analytical devices to near patient and environmental testing applications. In this paper, we show how wettable capillary valves can enhance CSs with novel functionalities, such as delaying and stopping liquids in microchannels. The valves employ an abruptly changing geometry of the flow path to delay a moving liquid filling front in a wettable microchannel. We show how to combine delay valves with capillary pumps, prevent shortcuts of liquid along the corners of microfluidic channels, stop liquids filling microchannels from a few seconds to over 30 min, trigger valves using two liquid fronts merging, and time a liquid using parallel microfluidic paths converging to a trigger valve. All together, these concepts should add functionality to passive microfluidic systems without departing from their initial simplicity of use.

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Section: Introductionmentioning

confidence: 99%

Valves for autonomous capillary systems

Zimmermann

Hunziker

Delamarche

2008

Microfluid Nanofluid

157

153

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“…The solution passes the valve area by applying pressure in various manners. Although the hydrophobic valve has been realized in various forms [78][79][80][81], some attempts using electrowetting to pass the stopped solution through the valve area have also been reported [82,83]. Figures 3d-f show such an example.…”

Section: Microfluidic Transport Based On Electrowettingmentioning

confidence: 99%

Electrochemical techniques for microfluidic applications

et al. 2008

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Electrochemical principles provide key techniques to promote the construction of bio/chemical microsystems of the next generation. There is a wealth of technology for the microfabrication of bio/chemical sensors. In addition, microfluidic transport in a network of flow channels, pH regulation, and automatic switching can be realized by electrochemical principles. Since the basic components of the devices are electrode patterns, the integration of different components is easily achieved. With these techniques, bio/chemical assays that require the exchange of solutions can be conducted on a chip. Furthermore, autonomous microanalysis systems that can carry out necessary procedures are beginning to be realized. In this article, techniques developed in our group will be comprehensively introduced.

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“…[6][7][8] Among these methods, EWOD has become a popular topic and a useful technology in academic research worldwide relative to other driving forces or control methods due to special advantages, such as straightforward fabrication, low cost, compatibility with conductive or polar fluids, and convenient programmable control. The effect changes the electron distribution in droplets, and the force of static electricity changes the contact angle of droplets, enabling diverse applications, such as micro-valves, 9 focal lenses, [10][11][12][13] fibers, 14,15 screens, 16,17 transport, [18][19][20][21][22][23][24] printing, 25 transistors, 26 electrical switches, 27,28 thermal control 29,30 and thermal management. 31 An increasing number of studies have applied the advantage of EWOD to be amplified in micro-systems, particularly for micro-optical devices, because droplets can adjust the focal length by changing the radius of curvature, using the properties of droplet flexibility with an applied voltage.…”

Section: Introductionmentioning

confidence: 99%

Optimization and limit of a tilt manipulation stage based on the electrowetting-on-dielectric principle

et al. 2017

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This work designed a new tilt manipulation stage based on the electrowetting-on-dielectric (EWOD) principle as the actuating mechanism and investigated the performance of that stage. The stage was fabricated using a universal MEMS (Micro-Electro-Mechanical System) fabrication method. In the previously demonstrated form of this device, the tilt stage consisted of a top plate that functions as a mirror, a bottom plate that was designed for changing the shape of water droplets, and supporters that were fixed between the top and bottom plate. That device was actuated by a voltage applied to the bottom plate, resulting in a static electric force actuating the shape change in the droplets by moving the top plate in the vertical direction. Previous experimental results indicated that that device can tilt at up to ±1.8°, with a resolution of 7 μm in displacement and 0.05° in angle. By selecting the best combination of the dielectric layer, the tilt angle was maximized. The new device, fabricated using a common and straightforward fabrication method, avoids deflection of the top plate and grounding in the bottom plate. Because of the limit of Teflon and other MEMS materials, this device has a tilt angle in the range of 3.2-3.5° according to the experimental data for friction and the EWOD device limit, which is close to 1.8°. This paper also describe the investigation of the effects of various parameters, e.g., various dielectric materials, thicknesses, and droplet type and volume, on the performance of the stage. The results indicate that the apparent frictions coefficient of the solid-liquid interface may remain constant, i.e., the friction force is proportional to the normal support force and the apparent frictions coefficient.

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Electrowetting (EW)-Based Valve Combined with Hydrophilic Teflon Microfluidic Guidance in Controlling Continuous Fluid Flow

Cited by 30 publications

References 11 publications

Valves for autonomous capillary systems

Valves for autonomous capillary systems

Electrochemical techniques for microfluidic applications

Optimization and limit of a tilt manipulation stage based on the electrowetting-on-dielectric principle

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