Patterning liquid flow on the microscopic scale

Kataoka, Dawn E.; Troian, Sandra M.

doi:10.1038/45521

Cited by 317 publications

(256 citation statements)

References 25 publications

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“…Because each droplet can be independently controlled, highly integrated, scalable and flexible architectures can be implemented. 10 A number of techniques have been described for the actuation of droplets on solid surfaces including the use of thermocapillary effects, 14 photochemical effects, 15 electrochemical gradients, 16 surface tension gradients, 17 temperature gradients, 18 air pressure, 19 structured surfaces, 20 dielectrophoresis, 21 and electrostatic methods. 8 An extension of this approach is a liquid-liquid microfluidic system for manipulating freely suspended microliter or nanoliter droplets.…”

Section: Introductionmentioning

confidence: 99%

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

et al. 2006

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This paper describes a method for local heating of discrete micro-liter scale liquid droplets. The droplets are covered with magnetic porous Si microparticles, and heating is achieved by application of an external alternating electromagnetic field. The magnetic porous Si microparticles consist of two layers: the top layer contains a photonic code and it is hydrophobic, with surfacegrafted dodecyl moieties. The bottom layer consists of a hydrophilic Si oxide host layer that is infused with Fe 3 O 4 nanoparticles. The amphiphilic microparticles spontaneously align at the interface of a water droplet immersed in mineral oil, allowing manipulation of the droplets by application of a magnetic field. Application of an oscillating magnetic field (338 kHz, 18A RMS current in a coil surrounding the experiment) generates heat in the superparamagnetic particles that can raise the temperature of the enclosed water droplet to >80 °C within 5 min.A simple microfluidics application is demonstrated: combining complementary DNA strands contained in separate droplets and then thermally inducing dehybridization of the conjugate. The complementary oligonucleotides were conjugated with the cyanine dye fluorophores Cy3 and Cy5 to quantify the melting/re-binding reaction by fluorescence resonance energy transfer (FRET). The magnetic porous Si microparticles were prepared as photonic crystals, containing spectral codes that allowed the identification of the droplets by reflectivity spectroscopy. The technique demonstrates the feasibility of tagging, manipulating, and heating small volumes of liquids without the use of conventional microfluidic channel and heating systems.

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Section: Introductionmentioning

confidence: 99%

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

et al. 2006

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“…1,2 Many techniques have been developed to pump liquids in microdevices, including micromechanical methods, 3 electroosmosis, 4 electrowetting, 5 thermocapillary pumping, 6 electrohydrodynamic ͑EHD͒ pumping, 7 and ac electroosmosis. 8 In the latter, electrolytic solutions are pumped using asymmetric pairs of microelectrodes subjected to a low potential ac signal of the order of kilohertz.…”

Section: Introductionmentioning

confidence: 99%

Pumping of liquids with traveling-wave electroosmosis

Ramos

Morgan

Green

et al. 2005

Journal of Applied Physics

163

180

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Net flow of electrolyte induced by a traveling-wave electric potential applied to an array of microelectrodes is reported. Two fluid flow regimes have been observed: at small-voltage amplitudes the fluid flow follows the direction of the traveling wave, and at higher-voltage amplitudes the fluid flow is reversed. In both cases, the flow seems to be driven at the level of the electrodes. The experiments have been analyzed with a linear electroosmotic model based upon the Debye-Huckel theory of the double layer. The electrical problem for the experimental interdigitated electrode array is solved numerically using a truncated Fourier series. The observations at low voltages are in qualitative accordance with the electroosmotic model.

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“…Since the surface tension of liquids typically decreases monotonically with increasing temperature, small quantities of liquids can be moved along a solid substrate bearing an inhomogeneous temperature distribution. [9][10][11][12] Thermocapillary transport is due to the shear stress induced at the air-liquid interface by the applied thermal gradient. The flow direction is from warmer to cooler regions on the substrate.…”

Section: Introductionmentioning

confidence: 99%

Generation of high-resolution surface temperature distributions

Darhuber

Troian

Wagner

2002

Journal of Applied Physics

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We have performed numerical calculations to study the generation of arbitrary temperature profiles with high spatial resolution on the surface of a solid. The characteristics of steady-state distributions and time-dependent heating and cooling cycles are examined, as well as their dependence on material properties and device geometry. Ideally, low-power consumption and fast response times are desirable. The simulations show that the achievable spatial resolution is on the order of the substrate thickness and that the response time t ϩ depends on the width of the individual heating elements. Moreover, the rise time t ϩ can be significantly shortened by deposition of a thermal insulation layer, which also reduces the power consumption and increases lateral resolution.

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Patterning liquid flow on the microscopic scale

Cited by 317 publications

References 25 publications

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

Local Heating of Discrete Droplets Using Magnetic Porous Silicon-Based Photonic Crystals

Pumping of liquids with traveling-wave electroosmosis

Generation of high-resolution surface temperature distributions

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