Rapid droplet mixers for digital microfluidic systems

Paik, Phil; Pamula, Vamsee K.; Fair, Richard B.

doi:10.1039/b307628h

Cited by 501 publications

(434 citation statements)

References 13 publications

(18 reference statements)

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“…In several lab-on-a-chip applications, droplet manipulation has been demonstrated using electrohydrodynamic (EHD) forces. [13][14][15] Systems based on electrowetting [16][17][18] and dielectrophoresis 19,20 have also been used to dispense, transport, merge, and divide droplets. These approaches are not limited to unidirectional serial flow processes, where segregated samples are periodically generated and transported in the same direction through microchannels; rather, they allow droplets to be transported arbitrarily on a microfabricated control grid.…”

Section: Microfluidic Implementationmentioning

confidence: 99%

Digital microfluidics using soft lithography

et al. 2006

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Although microfluidic chips have demonstrated basic functionality for single applications, performing varied and complex experiments on a single device is still technically challenging. While many groups have implemented control software to drive the pumps, valves, and electrodes used to manipulate fluids in microfluidic devices, a new level of programmability is needed for end users to orchestrate their own unique experiments on a given device. This paper presents an approach for programmable and scalable control of discrete fluid samples in a polydimethylsiloxane (PDMS) microfluidic system using multiphase flows. An immiscible fluid phase is utilized to separate aqueous samples from one another, and a novel ''microfluidic latch'' is used to precisely align a sample after it has been transported a long distance through the flow channels. To demonstrate the scalability of the approach, this paper introduces a ''generalpurpose'' microfluidic chip containing a rotary mixer and addressable storage cells. The system is general purpose in that all operations on the chip operate in terms of unit-sized aqueous samples; using the underlying mechanisms for sample transport and storage, additional sensors and actuators can be integrated in a scalable manner. A novel high-level software library allows users to specify experiments in terms of variables (i.e., fluids) and operations (i.e., mixes) without the need for detailed knowledge about the underlying device architecture. This research represents a first step to provide a programmable interface to the microfluidic realm, with the aim of enabling a new level of scalability and flexibility for lab-on-a-chip experiments.

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Section: Microfluidic Implementationmentioning

confidence: 99%

Digital microfluidics using soft lithography

et al. 2006

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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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“…14,15 Of the various micromixers reported in the past years, passive mixers, which have included lamination, 16,17 intersecting or disturbing channels, 18,19 and droplet-based platforms, 20,21 have not required energy input or moving parts. Passive mixers are, however, difficult to integrate into organs-on-a-chip systems due to the complexity of their structures.…”

Section: Introductionmentioning

confidence: 99%

In-plane microvortices micromixer-based AC electrothermal for testing drug induced death of tumor cells

et al. 2016

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Herein, we first describe a perfusion chip integrated with an AC electrothermal (ACET) micromixer to supply a uniform drug concentration to tumor cells. The inplane fluid microvortices for mixing were generated by six pairs of reconstructed novel ACET asymmetric electrodes. To enhance the mixing efficiency, the novel ACET electrodes with rotating angles of 0 , 30 , and 60 were investigated. The asymmetric electrodes with a rotating angle of 60 exhibited the highest mixing efficiency by both simulated and experimental results. The length of the mixing area is 7 mm, and the mixing efficiency is 89.12% (approximate complete mixing) at a voltage of 3 V and a frequency of 500 kHz. The applicability of our micromixer with electrodes rotating at 60 was demonstrated by the drug (tamoxifen) test of human breast cancer cells (MCF-7) for five days, which implies that our ACET inplane microvortices micromixer has great potential for the application of drug induced rapid death of tumor cells and mixing of biomaterials in organs-on-a-chip systems. Published by AIP Publishing. [http://dx

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Rapid droplet mixers for digital microfluidic systems

Cited by 501 publications

References 13 publications

Digital microfluidics using soft lithography

Digital microfluidics using soft lithography

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

In-plane microvortices micromixer-based AC electrothermal for testing drug induced death of tumor cells

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