Digital microfluidics: is a true lab-on-a-chip possible?

Fair, Richard B.

doi:10.1007/s10404-007-0161-8

Cited by 963 publications

(773 citation statements)

References 109 publications

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“…Common kinetic actuation methods include electrokinetic (EK), 15 magnetohydrodynamic, 16 electrochemical, 17 electrothermal, 18,19 and electrowetting. 20 EK flows are a popular class of low-volume, low-power micropumps, and can serve as a useful alternative to mechanical micropumps. 13 EK pumps, however, typically require direct contact between electric field-generating electrodes and a working fluid.…”

Section: Introductionmentioning

confidence: 99%

Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

Gagnon

2015

Biomicrofluidics

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The ability to pump and manipulate fluid at the micron-scale is a basic requirement for microfluidic platforms. Many current manipulation methods, however, require expensive and bulky external supporting equipment, which are not typically compatible for portable applications. We have developed a contactless metal electroosmotic micropump capable of pumping conductive buffers. The pump operates using two pairs of gallium metal electrodes, which are activated using an external voltage source and separated from a main flow channel by a thin micron-scale polydimethylsiloxane (PDMS) membrane. The thin contactless membrane allows for field penetration and electro-osmotic flow within the microchannel, but eliminates electrode damage and sample contamination commonly associated with traditional DC electro-osmotic pumps that utilize electrodes in direct contact with the working fluid. Our previous work has demonstrated the effectiveness of this method in pumping deionized water. However, due to the high resistivity of PDMS, this method proved difficult to apply towards manipulating conductive buffers. To overcome this limitation, we fabricated conductive carbon black (CB) powder directly into the contactless PDMS membranes. The increased electrical conductivity of the contactless PDMS membrane significantly increased micropump performance. Using a microfluidic T-channel device and an electro-osmotic flow model, we determined the influence that CB has on pump pressure for CB weight percents varying between 0 and 20. The results demonstrate that the CB increases pump pressure by two orders of magnitude and enables effective operations with conductive buffers. V C 2015 AIP Publishing LLC. [http://dx

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Section: Introductionmentioning

confidence: 99%

Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

Gagnon

2015

Biomicrofluidics

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“…The manipulation of liquids in the form of individually controlled discrete ('digitized') droplets, referred to as digital microfluidics [1], has gained tremendous interest over the last decade. Manipulation (e.g.…”

Section: Introductionmentioning

confidence: 99%

On-demand droplet loading for automated organic chemistry on digital microfluidics

et al. 2013

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Organic chemistry applications on digital microfluidic devices often involve reagents that are volatile or sensitive and must be introduced to the chip immediately before use. We present a new technique for automated, on--demand loading of 1 µL droplets from large (~1 mL), sealed off--chip reservoirs to a digital microfluidic chip in order to address this challenge. Unlike aqueous liquids which generally are non--wetting to the hydrophobic surface and must be actively drawn into the electrowetting--on--dielectric (EWOD) chip by electrode activation, organic liquids tend to be wetting and can spontaneously flood the chip, and hence require a retracting force for controlled liquid delivery. Using a combination of compressed inert gas and gravity to exert driving and retracting forces on the liquid, the simple loading technique enables precise loading of droplets of both wetting and non--wetting liquids in a reliable manner. A key feature from a practical point of view is that all of the wetted parts are inexpensive and potentially disposable, thus avoiding cross--contamination in chemical and biochemical applications. We provide a theoretical treatment of the underlying physics, discuss the effect of geometry and liquid properties on its performance, and show repeatable reagent loading using the technique. Its versatility is demonstrated with the loading of several aqueous and non--aqueous liquids on an EWOD digital microfluidic device.

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“…EWOD is based on modulating of the interfacial tension between a liquid and an electrode buried underneath a hydrophobic dielectric layer. By establishing an electric field in the dielectric layer on one side of the droplet, the contact angle is locally changed from hydrophobic to hydrophilic, causing the droplet to move [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Silicon photonic sensors incorporated in a digital microfluidic system

et al. 2012

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Label-free biosensing with silicon nanophotonic microring resonator sensors has proven to be an excellent sensing technique for achieving high-throughput and high sensitivity, comparing favorably with other labeled and label-free sensing techniques. However, as in any biosensing platform, silicon nanophotonic microring resonator sensors require a fluidic component which allows the continuous delivery of the sample to the sensor surface. This component is typically based on microchannels in PDMS or other materials which add cost and complexity to the system. The use of microdroplets in a digital microfluidic system, instead of continuous flows, is one of the recent trends in the field, where micro-to picoliter-sized droplets are generated, transported, mixed and split, thereby creating miniaturized reaction chambers which can be controlled individually in time and space. This avoids cross-talk between samples or reagents and allows fluid plugs to be manipulated on reconfigurable paths, which cannot be achieved using the more established and more complex technology of microfluidic channels where droplets are controlled in series. It has great potential for high-throughput liquid handling, while avoiding on-chip cross contamination.We present the integration of two miniaturized technologies: label-free silicon nanophotonic microring resonator sensors and digital microfluidics, providing an alternative to the typical microfluidic system based on microchannels. The performance of this combined system is demonstrated by performing proof-of-principle measurements of glucose, sodium chloride and ethanol concentrations. These results show that multiplexed real-time detection and analysis, great flexibility, and portability make the combination of these technologies an ideal platform for easy and fast use in any laboratory.

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Digital microfluidics: is a true lab-on-a-chip possible?

Cited by 963 publications

References 109 publications

Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

Contactless microfluidic pumping using microchannel-integrated carbon black composite membranes

On-demand droplet loading for automated organic chemistry on digital microfluidics

Silicon photonic sensors incorporated in a digital microfluidic system

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