Droplet position control in digital microfluidic systems

Bhattacharjee, Biddut; Najjaran, Homayoun

doi:10.1007/s10544-009-9366-9

Cited by 16 publications

(7 citation statements)

References 30 publications

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“…Given these nonlinear effects, implementing droplet manipulation tasks such as sorting and merging in fluidic networks can be quite challenging. As a result studies have resorted to manipulating droplets actively in devices using electric fields29–35 and elastomeric membrane valve actuation 36…”

Section: Introductionmentioning

confidence: 99%

Design of a model‐based feedback controller for active sorting and synchronization of droplets in a microfluidic loop

et al. 2011

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in Wiley Online Library (wileyonlinelibrary.com).The transport of confined droplets in fluidic networks can lead to complex spatiotemporal dynamics, precluding full control of the position of droplets in the network. Here, we report the design of a model-based feedback controller that can actively regulate droplet positions in a network. We specifically consider droplet dynamics in a microfluidic loop where a main channel splits into two and recombines. Consistent with previous studies, we find that without active control, the dynamics of droplets in the loop can range from periodic to chaotic behaviors. However, by implementing the model-based feedback controller, we show that the droplets can be made to sort alternately into the branches of the loop as well as to synchronize the times at which pairs of droplets exit the loop. In particular, our computations demonstrate that the controller is capable of executing remarkable droplet sort-synchronization tasks in the otherwise chaotic dynamics in the loop. The design of our controller incorporates a hydrodynamic network model, that is, capable of predicting droplet positions and subsequently delivering an actuation to the branches in the loop through elastomeric valves. Efficacy of the controller is discussed in terms of actuation characteristics and constraints imposed by elastomeric valves. The model-based feedback controller framework presented in this study is likely to promote the development of lab-on-chip technologies in which droplet manipulation tasks are executed with active control.The periodic dips in the actuation are shown in the inset. (f) Actuation frequency as a ratio of number of actuations at a particular value to the total number of actuations for synchronizing 35 pairs of droplets. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]The periodic dips in the actuation are seen in the inset. Interestingly in this case the upper branch also gets actuated consistently (f) Actuation frequency as a ratio of number of actuations at a particular value to the total number of actuations for synchronizing 35 pairs of droplets. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

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Section: Introductionmentioning

confidence: 99%

Design of a model‐based feedback controller for active sorting and synchronization of droplets in a microfluidic loop

et al. 2011

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“…Settling time estimates the upper bound of the time it would take to achieve a new equilibrium, following introduction of a changed sample into the device. 23 For FIG. 4.…”

Section: B Effects Of Device Design and Flow Rates On Photon Collectionmentioning

confidence: 99%

Sub-nanomolar detection of thrombin activity on a microfluidic chip

Gel

Dacres

et al. 2014

Biomicrofluidics

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Bioluminescence resonance energy transfer (BRET) is a form of Förster resonance energy transfer. BRET has been shown to support lower limits of detection than fluorescence resonance energy transfer (FRET) but, unlike FRET, has not been widely implemented on microfluidic devices for bioanalytical sensing. We recently reported a microscope-based microfluidic system for BRET-based biosensing, using a hybrid, high quantum-efficiency, form of BRET chemistry. This paper reports the first optical fiber-based system for BRET detection on a microfluidic chip, capable of quantifying photon emissions from the low quantum-efficiency BRET 2 system. We investigated the effects of varying core diameter and numerical aperture of optical fibers, as well as varying microfluidic channel design and measurement conditions. We optimized the set-up in order to maximize photon counts and minimize the response time. The optimized conditions supported measurement of thrombin activity, with a limit of detection of 20 pM, which is lower than the microscope-based system and more than 20 times lower than concentrations reported to occur in plasma clots. V C 2014 AIP Publishing LLC.

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“…The same concept of miniaturization was applied in biomedicine, which is disposable and can reduce the cross contamination on detection in a chip [2]. A digital microfluidic system (DMS), also called digital micro droplet system was recently developed to control the pico or micro-litter droplets [3]. Droplet can be actuated by using electro-wetting on dielectric (EWOD), which changes the surface energy between of two sides to move droplet.…”

Section: Introductionmentioning

confidence: 99%

Driving and controller design of digital microdroplet

Kang

Chen

2011

2011 6th IEEE International Conference on Nano/Micro Engineered and Molecular Systems

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The objective of this paper is to explore the control of digital microfluidic system (DMS), capable of manipulate individual microdroplet on a cell-based electrode structure. Electro-wetting on dielectric (EWOD) has been developed to driving droplet, which plays an important role on Lab on a chip and BioMEMS. In this work, two kinds of electrode patterns are proposed to make mircodroplet moving on one-dimensional (1D) and two-dimensional (2D) chip. The controller, consisting of the driving circuit, direct current (DC) power supply, spring probes array and LabView software, was design to manipulate microdroplet.

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Droplet position control in digital microfluidic systems

Cited by 16 publications

References 30 publications

Design of a model‐based feedback controller for active sorting and synchronization of droplets in a microfluidic loop

Design of a model‐based feedback controller for active sorting and synchronization of droplets in a microfluidic loop

Sub-nanomolar detection of thrombin activity on a microfluidic chip

Driving and controller design of digital microdroplet

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