Open-Channel Capillary Trees and Capillary Pumping

Dostie

et al. 2022

Preprint

Self Cite

The search for efficient capillary pumping has led to two main directions for investigation: first, assembly of capillary channels to provide high capillary pressures, and second, imbibition in absorbing fibers or paper pads. In the case of open microfluidics (i.e., channels where the top boundary of the fluid is in contact with air instead of a solid wall), the coupling between capillary channels and paper pads unites the two approaches and provides enhanced capillary pumping. In this work, we investigate the coupling of capillary trees–networks of channels mimicking the branches of a tree–with paper pads placed at the extremities of the channels, mimicking the small capillary networks of leaves. It is shown that high velocities and flow rates (18 mm3/s or 30 μL/s for more than 30 seconds using 50% (v/v) isopropanol, which has a 3–fold increase in viscosity in comparison to water; >3.5 mm3/s or 5 μL/s for more than 200 seconds with nonanol, which has a 3–fold increase in viscosity in comparison to water) can be reached in the root channel, enabling higher sustained flow rates than are achievable with capillary trees alone.

Section: Fabrication Of Capillary Tree Channelsmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

mentioning

confidence: 91%

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Enhanced capillary pumping using open-channel capillary trees with integrated paper pads

Dostie

et al. 2022

Preprint

Self Cite

“…Additionally, SCF can be observed in open microfluidic or mesofluidic channels where at least one side of the channel is open to the air. [12][13][14][15][16][17] Unlike conventional droplet microfluidics, our system has one side of the channel exposed, literally removing the ceiling to create an open air-liquid interface. The open surface of the channel gives access to the channel that conventional droplet microfluidics with closed, walled off channels does not provide; for example, a researcher can directly pipette into the channel or add/retrieve droplets, solid objects such as magnetic beads, or tissue samples.…”

Section: Introductionmentioning

confidence: 99%

“…(1, 2, [5][6][7][8][9][10][11] In our system, we autonomously generate droplets in an open channel without pumps or tubing by leveraging the inherent hydrostatic pressure difference between two immiscible fluids (the fluorinated carrier phase and aqueous phase), capillary pressure, and spontaneous capillary flow (SCF) -flow induced by capillary action. (12)(13)(14)(15)(16)(17) In our autonomous droplet generating system, the top side of the channel is exposed to air, rather than being enclosed by a ceiling, which gives access to the channel where conventional droplet microfluidics with enclosed channels does not. Open channels are advantageous because a researcher can directly pipette into the channel or add/retrieve droplets, solid objects such as magnetic beads, or tissue samples as they wish.…”

Section: Introductionmentioning

confidence: 99%

Interfacial tension driven open droplet microfluidics

Theberge

2021

Preprint

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We developed an open channel droplet microfluidics system that autonomously generates droplets by utilizing competing hydrostatic and capillary pressure. With only our open channel PTFE device, pipettes, and commercially available carrier fluid, we produce hundreds of microliter droplets; tubing, electronics, or pumps are not required, making droplet technology feasible for research labs without external flow generators. Furthermore, we demonstrated conceptual applications that showcase the process of droplet generation, splitting, transport, incubation, mixing, and sorting in our system. Unlike conventional droplet microfluidics, the open nature of the device enables the use of physical tools such as tweezers and styli to directly access the system; with this, we developed a new method of droplet sorting and transfer that capitalizes on the Cheerios effect, the aggregation of buoyant objects along a liquid interface. Our open channel platform offers enhanced usability, direct access to the droplet contents, easy manufacturability, compact footprint, and high customizability.

Interfacial Tension Driven Open Droplet Microfluidics

Berthier

et al. 2023

Adv Materials Inter

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droplet generating system, the top side of the channel is exposed to air, rather than being enclosed by a ceiling, which gives access to the channel where conventional droplet microfluidics with enclosed channels does not. Open channels are advantageous because a researcher can directly pipette into the channel or add/retrieve droplets, solid objects such as magnetic beads, or tissue samples as they wish. We demonstrate downstream manipulations such as sorting, splitting, and mixing that are uniquely enabled by the open nature of the system and the ability to access droplets with simple tools such as styli, tweezers, and a needle. The ability to move and manipulate droplets with simple tools through the open surface allows our method to be used in chemistry and biology labs without microfluidics experience and allows faster prototypingthat is, it is easy to add in new processing steps or workflows that require droplets to be relocated to a different space on-or off chip. Prior methods for moving droplets within microfluidic devices such as electrowetting on dielectric [1][2][3] optical tweezers, [4,5] and complex valving systems [6,7] require significant expertise; our system provides a "plug and play" approach for prototyping and executing new experimental workflows. This work has potential to open new avenues in droplet microfluidics, a field which has grown immensely in the past decade. [8][9][10][11][12][13][14][15][16][17][18] Droplet microfluidics is an attractive technology because it miniaturizes and compartmentalizes chemical and biological processes, reduces reagent waste, and enables the use of precious or expensive reagents. The microliter to picoliter droplets act as chambers to conduct biological or chemical analyses and have many important applications in DNA sequencing, directed evolution, materials chemistry, and chemical reactions. [8][9][10][11][12][13][14][15][16][17][18] Additionally, droplet manipulations such as sorting, mixing, and splitting are empowering for expanding the versatility and potential applications of droplet microfluidics. [8,9,[12][13][14][15][16][17][18] Our open channel droplet generator presented here is distinct from prior work in that it shows autonomous generation of droplets from an open capillary flow without the direct actuation of a pipette to generate each droplet. In our system, we autonomously generate droplets in an open channel without pumps or tubing by leveraging spontaneous capillary flow (SCF -flow induced by capillary action), [19][20][21][22][23][24] capillary pressure, and the hydrostatic pressure difference between two immiscible fluids (the fluorinated carrier phase and aqueous phase). Previous work in open droplet microfluidics includes the analysis of different modes of immiscible fluid plug flow in anDroplet microfluidics enables compartmentalized reactions in small scales and is utilized for a variety of applications across chemical analysis, material science, and biology. While droplet microfluidics is a successful technology, barriers include h...