Laser-Induced Mixing in Microfluidic Channels

Hellman, Amy N.; Rau, Kaustubh R.; Yoon, Helen H.; Bae, Jung-In; Palmer, John; Phillips, K. Scott; Allbritton, Nancy L.; Venugopalan, Vasan

doi:10.1021/ac070081i

Cited by 160 publications

(107 citation statements)

References 46 publications

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“…This feature may be useful for creating a shear flow near bubble 1. The complicated flow generated by the jetting of the antiphase bubble pair may also be used for laser-induced mixing in microfluidic systems (Hellman et al 2007) by extending their single-bubble scheme to bubble pairs.…”

Section: Jet Dynamicsmentioning

confidence: 99%

Dynamics of laser-induced bubble pairs

et al. 2015

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The interaction of two laser-induced bubbles in bulk water is investigated. The strength and direction of the emerging liquid jets can be controlled by adjusting the relative bubble positions, the time difference between bubble generation, and the laser pulse energies determining the bubble sizes. Experimental and numerical studies are performed for millimetre-sized bubble pairs. Taking bubbles of equal energy, a maximum jet velocity is found for close anti-phase bubbles, i.e. when the second bubble is produced at the maximum volume of the first one and the bubble walls are almost touching and not merging. Under these conditions, one bubble produces a fast jet with a peak velocity of about 150 m s −1 that reaches a distance into the surrounding liquid of at least three times the maximum bubble radius. Collapse of the other bubble results in a slow jet of large mass that rapidly converts into a ring vortex. Correspondingly, the interaction with adjacent structures is dominated either by localized jet impact or by shear stresses extending over a larger area. Furthermore, interactions between micrometre-sized bubble pairs are investigated numerically to understand and predict how the effects of the physical parameters on bubble dynamics would change when the bubbles become smaller. The results are discussed with respect to micropumping and opto-injection.

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Section: Jet Dynamicsmentioning

confidence: 99%

Dynamics of laser-induced bubble pairs

et al. 2015

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“…These bubbles can be generated with a focused laser pulse [1][2][3], acoustically excited capillary waves [4], or through spark discharges [5]. Applications of these transient pulsating flows span cell stretching [6,7], liquid pumping [8], switching and sorting [9,10], mixing [11], and droplet generation [12].…”

Section: Introductionmentioning

confidence: 99%

Shearing flow from transient bubble oscillations in narrow gaps

Mohammadzadeh

Ohl

2017

Phys. Rev. Fluids

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The flow driven by a rapidly expanding and collapsing cavitation bubble in a narrow cylindrical gap is studied with the volume of fluid method. The simulations reveal a developing plug flow during the early expansion followed by flow reversal at later stages. An adverse pressure gradient leads to boundary layer separation and flow reversal, causing large shear stress near the boundaries. Analytical solution to a planar pulsating flow shows qualitative agreement with the CFD results. The shear stress close to boundaries has implications to deformable objects located near the bubble: experiments reveal that thin, flat biological cells entrained in the boundary layer become stretched, while cells with a larger cross-section are mainly transported with the flow.

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“…However, the microfabrication process involved in this approach is sophisticated and considerably challenging. Alternatively, active microfluidic mixers utilize external energy to stir or agitate the fluid flow to promote the mixing performance, such as, acoustic/ultrasonic [17,18], electro-hydrodynamic [19][20][21][22][23], magnetic [24,25], and laser techniques [26][27][28], et.al. Among them, electrokinetic flow has been extensively employed in microfluidic devices to accomplish pumping and mixing, which refers to generate the flow stream instabilities on the surface of the micromachined electrodes activated by electric field [29].…”

Section: Introductionmentioning

confidence: 99%

Fluid Flow and Mixing Induced by AC Continuous Electrowetting of Liquid Metal Droplet

Ren

Liu

et al. 2017

Preprint

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Abstract:In this work, we proposed a novel design of microfluidic mixer utilizing the amplified Marangoni chaotic advection induced by AC continuous electrowetting of a metal droplet situated in electrolyte solution, due to the linear and quadratic voltage-dependence of flow velocity at small or large voltages, respectively. Unlike previous researchers exploiting the unidirectional surface stress with DC bias at droplet/medium interface for pumping of electrolyte where the resulting flow rate is linearly proportional to the field intensity, dominance of another kind of dipolar flow pattern caused by local Marangoni stress at the drop surface in sufficiently intense AC electric field is demonstrated by both theoretical analysis and experimental observation, which exhibits a quadratic growth trend as a function of the applied voltage. The dipolar shear stress merely appears at larger voltages and greatly enhances the mixing performance by inducing chaotic advection between the neighboring laminar flow. The mixer design developed herein, on the basis of amplified Marangoni chaotic advection around a liquid metal droplet at larger AC voltages, has great potential for chemical reaction and MEMS actuator applications, because of generating high-throughput and excellent mixing performance at the same time.

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Laser-Induced Mixing in Microfluidic Channels

Cited by 160 publications

References 46 publications

Dynamics of laser-induced bubble pairs

Dynamics of laser-induced bubble pairs

Shearing flow from transient bubble oscillations in narrow gaps

Fluid Flow and Mixing Induced by AC Continuous Electrowetting of Liquid Metal Droplet

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