Bulletin of the American Physical Society
66th Annual Meeting of the APS Division of Fluid Dynamics
Volume 58, Number 18
Sunday–Tuesday, November 24–26, 2013; Pittsburgh, Pennsylvania
Session H6: Microfluids: Fluidic Devices I |
Hide Abstracts |
Chair: Thomas Cubaud, Stony Brook University Room: 328 |
Monday, November 25, 2013 10:30AM - 10:43AM |
H6.00001: Foam imbibition in a Hele-Shaw cell via laminated microfluidic ``T-junction'' device Dina Parra, Thomas Ward In this talk we analyze experimental results of a novel microfluidic ``T-junction'' device, made from laminated plastic, that is used to produce foam in porous media. The fluids, both Newtonian and non-Newtonian liquids and air, are driven using constant-static pressure fluid pumping. For the T-junction geometry studied there are novel observations with this type of pumping: 1) at low pressure ratios there is an increase in the liquid and total flow rates and 2) at higher pressure ratios there is a decrease in the liquid flow rate. To understand this phenomenon we visualize the drop production process near the T-junction. Furthermore, flow rates for the liquid and total volume are estimated by imbibing the foam into a Hele-Shaw cell. Foam is produced by using a mixture containing aqueous polyacrylamide of concentrations ranging from 0.01-0.10\% by weight and several solution also containing a sodium-lauryl-sulfate (SLS) surfactant at concentrations ranging 0.01-0.1\% by weight. [Preview Abstract] |
Monday, November 25, 2013 10:43AM - 10:56AM |
H6.00002: Gas rivulets on a submerged solid surface: a new microfluidic technique to produce microbubbles Miguel A. Herrada, Alfonso M. Ga\~n\'an-Clavo, Jos\'e M. Montanero A general microfluidic technique is proposed to produce microbubbles from gas micro-rivulets formed on the surface of a solid over which a liquid is flowing. In the particular geometry considered in this work, a gaseous stream is injected through a T-junction into a channel transporting a liquid current. The gas adheres to a hydrophobic strip printed on the channel surface. When the gas and liquid flow rates are set appropriately, a gaseous rivulet flows over that strip. The rivulet breaks up downstream due to a capillary pearling instability, which leads to a monodisperse collection of microbubbles. The physics of the process is described from both the numerical simulation of the Navier-Stokes equations, and the linear stability analysis of an infinite gaseous rivulet driven by a coflowing liquid stream. This analysis allows one to determine a necessary condition to get this effect in a T-junction device. It also provides reasonably good predictions for the size of the produced microbubbles. [Preview Abstract] |
Monday, November 25, 2013 10:56AM - 11:09AM |
H6.00003: Utilizing chemo-mechanically functionalized oscillating fins to ``catch and release'' nanoparticles in binary flow Ya Liu, Yongting Ma, Amitabh Bhattacharya, Olga Kuksenok, Ximin He, Joanna Aizenberg, Anna Balazs In biomimetics, designing an effective ``catch and release'' device for the selective removal of target species from the surrounding solution is critical for developing autonomous sensors and sorters. Using computational simulation, we model an array of oscillating fins that are tethered on the floor of a microchannel and immersed in a binary-fluid stream. During the oscillation, the fins with the specific chemical wetting reach the upper fluid when they are upright and are entirely within the lower stream when they are tilted. We introduce specific adhesive interactions between the fins and particulates in the solution and determine conditions where the oscillating fins can selectively bind (``catch'') target nanoparticles within the upper fluid stream and then release these particles into the lower stream. We isolate the effects of chemical wetting on the fins (e.g., wetting contact angle between fins and fluid) and mechanical parameters (e.g., frequency of fins' oscillations) that lead to the efficient extraction of target species from the upper stream and placement into the lower fluid. Our understanding provides fundamental insights into the system's complex dynamics and mechanism for detection, separation, and purification of multi-component mixtures. [Preview Abstract] |
Monday, November 25, 2013 11:09AM - 11:22AM |
H6.00004: Transporting Janus Nanoparticles Using Self-Healing Vesicles Xin Yong, Emily Crabb, Nicholas Moellers, Isaac Salib, Gerald McFarlin, Olga Kuksenok, Anna Balazs Using dissipative particle dynamics (DPD) simulations, we model the interaction between nanoscopic lipid vesicles and Janus nanoparticles in the presence of an imposed flow. Both the vesicle and Janus nanoparticles are localized on a hydrophilic substrate and immersed in a hydrophilic solution. The fluid-driven vesicle successfully picks up Janus particles on the substrate and transports these particles as cargo along the surface. With the introduction of a ``sticky'' domain or a nanoscale crack onto the otherwise flat substrate, the vesicles can robustly drop off and deposit the particles at the targeted places. For Janus particles with a large hydrophobic region, the vesicle tears and deposits the particle with a few lipids covering its hydrophobic region. This lipids coating can protect the particle from the outer solution after deposition. The vesicle then heals itself after tearing off the lipids, and could be reused for transporting particles. These environmentally adaptive and self-healing vesicles can play an important role in drug-delivery and microfluidic applications. [Preview Abstract] |
Monday, November 25, 2013 11:22AM - 11:35AM |
H6.00005: Life after wetting: Transport and concentration in paper-based microfluidics using ion concentration polarization Brendan MacDonald, Max Gong, Pei Zhang, David Sinton In this talk, we present a method for active transport and concentration in paper-based microfluidic devices using ion concentration polarization. Paper-based devices rely on wicking for fluid transport and therefore have limited transport capacity upon reaching a wetted state. We present two methods, one external, and one embedded within the paper to enable transport after wetting is complete. The external device contains a nano-porous membrane and electrical connections required for ion concentration polarization. The device can be placed against the paper surface for transport and concentration. The imbedded method involves patterning the nano-porous membrane within the paper layer and electrical connections in contact with the wetted paper. We demonstrate transport and concentration in paper-based devices using both methods for dyes (fluorescent and non fluorescent), and for biological analytes in a lateral flow device. [Preview Abstract] |
Monday, November 25, 2013 11:35AM - 11:48AM |
H6.00006: Buckling of Dielectric Elastomeric Plates for Electrically Active Microfludic Pumps Douglas Holmes, Behrouz Tavakol, Michael Bozlar, Guillaume Froehlicher, Howard Stone, Ilhan Aksay Fluid flow can be directed and controlled by a variety of mechanisms within industrial and biological environments. Advances in microfluidic technology have required innovative ways to control fluid flow on a small scale, and the ability to actively control fluid flow within microfluidic devices is crucial for advancements in nanofluidics, biomedical fluidic devices, and digital microfluidics. In this work, we present a means for microfluidic control via the electrical actuation of thin, flexible valves within microfluidic channels. These structures consist of a dielectric elastomer confined between two compliant electrodes that can be actively and reversibly buckle out of plane to pump fluids from an applied voltage. The out-of-plane deformation can be quantified using two parameters: net change in surface area and the shape of deformation. Change in surface area depends on the voltage, while the deformation shape, which significantly affects the flow rate, is a function of voltage, and the pressure and volume of the chambers on each side of the thin plate. The use of solid electrodes enables a robust and reversible pumping mechanism that will have will enable advancements in rapid microfluidic diagnostics, adaptive materials, and artificial muscles. [Preview Abstract] |
Monday, November 25, 2013 11:48AM - 12:01PM |
H6.00007: Towards 2D field-flow fractionation - Vector separation over slanted open cavities Jorge A. Bernate, Mengfei Yang, Hong Zhao, Sumedh Risbud, Colin Paul, Matthew Dallas, Konstantinos Konstantopoulos, German Drazer, Eric S.G. Shaqfeh Planar microfluidic platforms for vector chromatography, in which different species fan out in different directions and can be continuously sorted, are particularly promising for the high throughput separation of multicomponent mixtures. We carry out a computational study of the vector separation of dilute suspensions of rigid and flexible particles transported by a pressure-driven flow over an array of slanted open cavities. The numerical scheme is based on a Stokes flow boundary integral equation method. The simulations are performed in a periodic system without lateral confinement, relevant to microfluidic devices with negligible recirculation in the main channel. We study the deflection of rigid spherical particles, of flexible capsules as a model of white and red blood cells, and of rigid discoidal particles as a model of platelets. We characterize the deflection of different particles as a function of their size, shape, shear elasticity, their release position, and the geometric parameters of the channel. The simulations provide insight into the separation mechanism and allow the optimization of specific devices depending on the application. Good agreement with experiments is observed. [Preview Abstract] |
Monday, November 25, 2013 12:01PM - 12:14PM |
H6.00008: Large modulation of light beams by surface acoustic waves Byung Hang Ha, Kang Soo Lee, Ghulam Destgeer, Jin Ho Jung, Hyung Jin Sung We present a refraction-based method for light beam deflection with up to 20 degrees deflection angle and modulation bandwidth on the order of ten hertz. The mechanism utilizes sharp focusing of acoustic energy to produce a steep gradient of refractive index inside an optically-transparent media. The medium, fluid or solid, is subject to bulk acoustic waves (leaky Rayleigh waves) which is transmitted from piezo-actuated surface acoustic waves. The wavelets interfere to form a vertical gradient of acoustic energy density in the media as well as a refractive index gradient accordingly. Given the input acoustic energy, the biggest deflection angle is obtained when the light beam is given at the area where the refractive index gradient is largest. The device is based on lens effect and free from numerous limitations that acousto-optic deflector has: precise alignment of the incident angle of light beam is unnecessary, 100{\%} deflection is achieved, the device is modulated by amplitude, not frequency and the deflection efficiency is not dependent on the polarity and the wavelength of light beam. The device can deflect, switch, and scan light beams and is applicable to pre-press, radar, laser imaging and displays, instrumentation and research. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700