Diffusion along microfluidic channels

Heeren, A.; Luo, Cheng-Ping; Roth, Günter; Ganser, Alexander; Brock, Roland; Wiesmueller, Karl-Heinz; Henschel, W.; Kern, D. P.

doi:10.1016/j.mee.2006.01.187

Cited by 10 publications

(6 citation statements)

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“…Pixel intensity (a.u.) at a specified point in the resulting image must now be converted into a concentration, and this is usually achieved using a direct calibration done, for example, by measuring intensities of a dilution series of the fluorescein 31 . However, as bounding fluid walls/ceilings are not flat and morph as flow rates change, this induces the same concentration to correspond to multiple intensities depending on z -location and flow velocity.…”

Section: Resultsmentioning

confidence: 99%

Stable diffusion gradients in microfluidic conduits bounded by fluid walls

Nebuloni,

Deroy,

Cook

et al. 2024

Microsyst Nanoeng

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Assays mimicking in vitro the concentration gradients triggering biological responses like those involved in fighting infections and blood clotting are essential for biomedical research. Microfluidic assays prove especially attractive as they allow precise control of gradient shape allied to a reduction in scale. Conventional microfluidic devices are fabricated using solid plastics that prevent direct access to responding cells. Fluid-walled microfluidics allows the manufacture of circuits on standard Petri dishes in seconds, coupled to simple operating methods; cell-culture medium sitting in a standard dish is confined to circuits by fluid walls made of an immiscible fluorocarbon. We develop and experimentally validate an analytical model of diffusion between two or more aqueous streams flowing at different rates into a fluid-walled conduit with the cross-section of a circular segment. Unlike solid walls, fluid walls morph during flows as pressures fall, with wall shape changing down the conduit. The model is validated experimentally for Fourier numbers < 0.1 using fluorescein diffusing between laminar streams. It enables a priori prediction of concentration gradients throughout a conduit, so allowing rapid circuit design as well as providing bio-scientists with an accurate way of predicting local concentrations of bioactive molecules around responsive and non-responsive cells.

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Section: Resultsmentioning

confidence: 99%

Stable diffusion gradients in microfluidic conduits bounded by fluid walls

Nebuloni,

Deroy,

Cook

et al. 2024

Microsyst Nanoeng

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“…[ 53 ] The mixing of reagents and cell‐secreted compounds in simple microfluidic devices and conventional well plates is passive, making the mass transport of components limited by diffusion. [ 54 , 55 ] According to Fick's law of diffusion, the diffusion time is proportional to the square of the distance in a passive system with diffusion limitation. [ 56 , 57 ] In the case of a conventional well plate (≈8 mm), the average distance traveled is much longer than in the microfluidic chips (0.4 mm), making it up to 25 times faster to get an even distribution of a generic compound in the chip.…”

Section: Resultsmentioning

confidence: 99%

On‐Chip Neural Induction Boosts Neural Stem Cell Commitment: Toward a Pipeline for iPSC‐Based Therapies

Jain,

Voulgaris,

Thongkorn

et al. 2024

Advanced Science

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The clinical translation of induced pluripotent stem cells (iPSCs) holds great potential for personalized therapeutics. However, one of the main obstacles is that the current workflow to generate iPSCs is expensive, time‐consuming, and requires standardization. A simplified and cost‐effective microfluidic approach is presented for reprogramming fibroblasts into iPSCs and their subsequent differentiation into neural stem cells (NSCs). This method exploits microphysiological technology, providing a 100‐fold reduction in reagents for reprogramming and a ninefold reduction in number of input cells. The iPSCs generated from microfluidic reprogramming of fibroblasts show upregulation of pluripotency markers and downregulation of fibroblast markers, on par with those reprogrammed in standard well‐conditions. The NSCs differentiated in microfluidic chips show upregulation of neuroectodermal markers (ZIC1, PAX6, SOX1), highlighting their propensity for nervous system development. Cells obtained on conventional well plates and microfluidic chips are compared for reprogramming and neural induction by bulk RNA sequencing. Pathway enrichment analysis of NSCs from chip showed neural stem cell development enrichment and boosted commitment to neural stem cell lineage in initial phases of neural induction, attributed to a confined environment in a microfluidic chip. This method provides a cost‐effective pipeline to reprogram and differentiate iPSCs for therapeutics compliant with current good manufacturing practices.

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“…Both of them were charged with a fluorescein solution. The fluorescein molecule has an approximate diameter of about 1 nm, 33 which means that should be able to diffuse out through the 2 nm mesh size microworm but not through the 0.5 nm one. Microworms were placed in a DI water solution and Fig.…”

Section: Resultsmentioning

confidence: 99%