Microfluidic devices fabricated using fast wafer-scale LED-lithography patterning

Challa, Pavan Kumar; Kartanas, Tadas; Charmet, Jérôme; Knowles, Tuomas P. J.

doi:10.1063/1.4976690

Cited by 53 publications

(43 citation statements)

References 18 publications

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“…Building up on a low cost UV light-emitting diode (LED) wafer scale mask aligner that enables sub-micron patterning with alignment resolution lower than 10 µm that we developed previously [10], we propose a low-cost version set-up with an Arduino based timer for single layer exposure.…”

Section: Photolithographymentioning

confidence: 99%

Low-Cost Microfabrication Tool Box

et al. 2020

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Microsystems are key enabling technologies, with applications found in almost every industrial field, including in vitro diagnostic, energy harvesting, automotive, telecommunication, drug screening, etc. Microsystems, such as microsensors and actuators, are typically made up of components below 1000 microns in size that can be manufactured at low unit cost through mass-production. Yet, their development for commercial or educational purposes has typically been limited to specialized laboratories in upper-income countries due to the initial investment costs associated with the microfabrication equipment and processes. However, recent technological advances have enabled the development of low-cost microfabrication tools. In this paper, we describe a range of low-cost approaches and equipment (below £1000), developed or adapted and implemented in our laboratories. We describe processes including photolithography, micromilling, 3D printing, xurography and screen-printing used for the microfabrication of structural and functional materials. The processes that can be used to shape a range of materials with sub-millimetre feature sizes are demonstrated here in the context of lab-on-chips, but they can be adapted for other applications. We anticipate that this paper, which will enable researchers to build a low-cost microfabrication toolbox in a wide range of settings, will spark a new interest in microsystems.

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Section: Photolithographymentioning

confidence: 99%

Low-Cost Microfabrication Tool Box

et al. 2020

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“…Polydimethylsiloxane (PDMS) devices were produced on SU-8 moulds fabricated via photolithographic processes as described elsewhere, 30;31 with UV exposure performed with custom-built LED-based apparatus. 32 Following development of the moulds, feature heights were verified by profilometer (Dektak, Bruker) and PDMS (Dow Corning, primer and base mixed in 1:10 ratio) applied and degassed before baking at 65°C overnight. Devices were cut from the moulds and holes for tubing connection (0.75 mm) and electrode insertion (1.5 mm) were created with biopsy punches, the devices were cleaned by application of Scotch tape and sonication in IPA (5 min).…”

Section: Microfluidic Device Fabricationmentioning

confidence: 99%

Rapid Fractionation and Characterisation of Alpha-Synuclein Oligomers in Solution

Arter

Castellana-Cruz

et al. 2020

Preprint

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Oligomeric intermediates are implicated as neurotoxins in the pathogenesis of protein misfolding diseases. Structural, biophysical and biochemical characterisation of these species is challenging due to their heterogeneous and transient nature, and their typically low abundance. Here, we show that microfluidic free-flow electrophoresis is capable of separating heterogeneous oligomer mixtures on a timescale of seconds, at least two orders of magnitude faster than conventional techniques. This enables analysis of oligomer structural heterogeneity, zeta-potential and immunochemistry with minimal sample perturbation under physiologicallyrelevant conditions.

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“…The replica mould for the two-dimensional (2D) microfluidic devices was fabricated through a single, standard soft-lithography step 20,21 by spinning SU-8 3050 (MicroChem Corp.) photoresist onto a polished silicon wafer to a height of 50 µm and using a custom-built LEDbased apparatus for performing the UV exposure step. 22 The mould was used to generate poly(dimethylsiloxane) (PDMS; Dow Corning) based chips and the channels were sealed with a quartz slide (Alfa Aesar, 76.2 x 25.4 x 1.0 mm) after the surface had been activated through oxygen plasma (Diener electronic; 40% power for 15 seconds). The chips were exposed to an additional plasma oxidation step (80% power for 500 seconds) to render the channel surfaces more hydrophilic.…”

Section: Fabrication Of Two-dimensional Microfluidic Devicesmentioning

confidence: 99%

Enhancing the Resolution of Micro Free Flow Electrophoresis through Spatially Controlled Sample Injection

Saar

Müller²,

Charmet

et al. 2018

Anal. Chem.

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Free flow electrophoresis is a versatile technique for the continuous separation of mixtures with both preparative and analytical applications. Microscale versions of free flow electrophoresis are particularly attractive strategies because of their fast separation times, ability to work with small sample volumes, and large surface area to volume ratios facilitating rapid heat transfer, thus minimizing the detrimental effects of Joule heating even at high voltages. The resolution of microscale free flow electrophoresis, however, is limited by the broadening of the analyte beam in the microfluidic channel, an effect that becomes especially pronounced when the analyte is deflected significantly away from its original position. Here, we describe and demonstrate how restricting spatially the sample injection and collection to the regions where the gradients in the velocity distribution of the carrier medium are the smallest allows this broadening effect to be substantially suppressed and hence the resolution of microscale free flow electrophoresis devices to be increased. To demonstrate this concept, we fabricated microfluidic free flow electrophoresis devices with spatially restricted injection nozzles implemented through the use of multilayer soft-photolithography and further integrated quartz based observation areas for fluorescent detection and imaging. With these devices, we demonstrated a 5-fold reduction in the extent of beam broadening relative to conventional free flow electrophoresis approaches with nonrestricted sample introduction. The manifold enhancement in the achievable resolution of microscale free flow electrophoresis devices opens up the possibility of rapid separation and analysis of complex mixtures.

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Microfluidic devices fabricated using fast wafer-scale LED-lithography patterning

Cited by 53 publications

References 18 publications

Low-Cost Microfabrication Tool Box

Low-Cost Microfabrication Tool Box

Rapid Fractionation and Characterisation of Alpha-Synuclein Oligomers in Solution

Enhancing the Resolution of Micro Free Flow Electrophoresis through Spatially Controlled Sample Injection

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