Young 4ever—the use of capillarity for passive flow handling in lab on a chip devices

doi:10.1039/b613839j

Cited by 20 publications

(4 citation statements)

References 24 publications

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“…Passive flow control employs everyday forces such as gravity, suction, and capillary action to manipulate fluids in microdevices [12]. For example, microfluidic channel resistance can be exploited to tune fluidic flow rates passively, so that no external syringe pumps or power supplies are needed in the operation of these devices [4,5,9,11,13].…”

Section: Introductionmentioning

confidence: 99%

Measurement of microchannel fluidic resistance with a standard voltage meter

Godwin

Deal

Hoepfner

et al. 2013

Analytica Chimica Acta

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A simplified method for measuring the fluidic resistance (Rfluidic) of microfluidic channels is presented, in which the electrical resistance (Relec) of a channel filled with a conductivity standard solution can be measured and directly correlated to Rfluidic using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine Rfluidic to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ~40 – 600 kPa s mm−3) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic Rfluidic measurements were possible in more complex microfluidic designs. Microchannel Relec was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems.

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Section: Introductionmentioning

confidence: 99%

Measurement of microchannel fluidic resistance with a standard voltage meter

Godwin

Deal

Hoepfner

et al. 2013

Analytica Chimica Acta

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“…5l). From these experiments, we can conclude that the channel restriction in the higher resistance channel acts as a capillary valve/diode 63, 64 , and that the specific fork design is critical for the splitting profile at low capillary number. We can effectively employ capillary effects to tailor the splitting profile at low capillary number.…”

Section: Resultsmentioning

confidence: 91%

Rapid and continuous magnetic separation in droplet microfluidic devices

et al. 2015

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We present a droplet microfluidic method to extract molecules of interest from a droplet in a rapid and continuous fashion. We accomplish this by first marginalizing functionalized super-paramagnetic beads within the droplet using a magnetic field, and then splitting the droplet into one droplet containing the majority of magnetic beads and one droplet containing the minority fraction. We quantitatively analysed the factors which affect the efficiency of marginalization and droplet splitting to optimize the enrichment of magnetic beads. We first characterized the interplay between the droplet velocity and the strength of the magnetic field and its effect on marginalization. We found that marginalization is optimal at the midline of the magnet and that marginalization is a good predictor of bead enrichment through splitting at low to moderate droplet velocities. Finally, we focused our efforts on manipulating the splitting profile to improve the enrichment provided by asymmetric splitting. We designed asymmetric splitting forks that employ capillary effects to preferentially extract the bead-rich regions of the droplets. Our strategy represents a framework to optimize magnetic bead enrichment methods tailored to the requirements of specific droplet-based applications. We anticipate that our separation technology is well suited for applications in single-cell genomics and proteomics. In particular, our method could be used to separate mRNA bound to poly-dT functionalized magnetic microparticles from single cell lysates to prepare single-cell cDNA libraries.

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“…19 The third device type included 60 μm × 20 μm supporting lines that were arranged in vertical rows with an inter-row pitch of 40 μm (Figure 3c). The corners of the individual lines were rounded to avoid fluidic pinning 35 or edge flow. 19 The supporting structures in the S.R., C.W., and C.P.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Injection Molding of Thermoplastics for Low-Cost Nanofluidic Devices

Mortelmans

Kazazis

Werder

et al. 2022

ACS Appl. Nano Mater.

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Thermoplastic micro- and nanofluidics are increasing in popularity due to their favorable chemical and physical properties as an alternative to poly(dimethyl siloxane) (PDMS)-based devices, which are more widely used in academia. Additionally, their fabrication is compatible with industrial processes, such as hot embossing and injection molding. Nevertheless, producing devices with sub-micrometer channel heights and low roughness while retaining high-throughput molding remains challenging. This article details the combination of grayscale e-beam lithography (g-EBL) and injection molding as a fabrication route for capillary 3D thermoplastic nanofluidic devices with unprecedented accuracy in the sub-micrometer range. We employed g-EBL to pattern the device profile in a poly(methyl methacrylate) (PMMA)-based resist, which served as a substrate for the subsequent fabrication of a negative nickel mold by using electroforming. These molds are used to fabricate devices in PMMA and cyclic olefin polymers (COP) using injection molding. We show that the 3D height profile of the nanofluidic devices is maintained throughout the entire replication cycle within very tight tolerances, retaining its nanoscale topography on a millimeter-length scale. Moreover, somewhat surprisingly, the roughness in the inflow section of the devices was significantly reduced, which we attribute to the nickel mold fabrication. Last, we show that the capillary-driven devices can be used to size-dependently trap nanoparticles of various sizes in a reliable and facile manner while only requiring a 4 μL sample volume. The presented device and fabrication procedure paves the way for applications in various scientific fields, ranging from immunology to neurology and material science, in a cost-effective manner.

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Young 4ever—the use of capillarity for passive flow handling in lab on a chip devices

Cited by 20 publications

References 24 publications

Measurement of microchannel fluidic resistance with a standard voltage meter

Measurement of microchannel fluidic resistance with a standard voltage meter

Rapid and continuous magnetic separation in droplet microfluidic devices

Injection Molding of Thermoplastics for Low-Cost Nanofluidic Devices

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