Experimental optimization of a passive planar rhombic micromixer with obstacles for effective mixing in a short channel length

Bernacka-Wojcik, Iwona; Ribeiro, Susana; Wójcik, P.; Alves, Pedro Urbano; Busani, Tito; Fortunato, Elvira; Baptista, Pedro V.; Covas, J. A.; Águas, Hugo; Hilliou, L.; Martins, Rodrigo

doi:10.1039/c4ra10160j

Cited by 15 publications

(20 citation statements)

References 33 publications

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“…In the next step of the setup optimization, the mixing of reagents should be performed in the microfluidic chip (Bernacka‐Wojcik et al, ) to reduce the risk of sample contamination. Furthermore, waveguides should be incorporated to facilitate the chip exchange towards the point of care use.…”

Section: Discussionmentioning

confidence: 99%

Single nucleotide polymorphism detection using gold nanoprobes and bio‐microfluidic platform with embedded microlenses

Bernacka-Wojcik

Águas²,

Carlos³

et al. 2015

Biotech & Bioengineering

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The use of microfluidics platforms combined with the optimal optical properties of gold nanoparticles has found plenty of application in molecular biosensing. This paper describes a bio-microfluidic platform coupled to a non-cross-linking colorimetric gold nanoprobe assay to detect a single nucleotide polymorphism associated with increased risk of obesity fat-mass and obesity-associated (FTO) rs9939609 (Carlos et al., 2014). The system enabled significant discrimination between positive and negative assays using a target DNA concentration of 5 ng/µL below the limit of detection of the conventionally used microplate reader (i.e., 15 ng/µL) with 10 times lower solution volume (i.e., 3 µL). A set of optimization of our previously reported bio-microfluidic platform (Bernacka-Wojcik et al., 2013) resulted in a 160% improvement of colorimetric analysis results. Incorporation of planar microlenses increased 6 times signal-to-loss ratio reaching the output optical fiber improving by 34% the colorimetric analysis of gold nanoparticles, while the implementation of an optoelectronic acquisition system yielded increased accuracy and reduced noise. The microfluidic chip was also integrated with a miniature fiber spectrometer to analyze the assays' colorimetric changes and also the LEDs transmission spectra when illuminating through various solutions. Furthermore, by coupling an optical microscope to a digital camera with a long exposure time (30 s), we could visualise the different scatter intensities of gold nanoparticles within channels following salt addition. These intensities correlate well to the expected difference in aggregation between FTO positive (none to small aggregates) and negative samples (large aggregates).

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Section: Discussionmentioning

confidence: 99%

Single nucleotide polymorphism detection using gold nanoprobes and bio‐microfluidic platform with embedded microlenses

Bernacka-Wojcik

Águas²,

Carlos³

et al. 2015

Biotech & Bioengineering

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“…The geometry sketched in Figure 3 is based on the design presented by Bernacka-Wojcik et al, [22] although not exactly with the same dimensions. The width and height of the channels containing obstructions are 200 and 125 mm, respectively.…”

Section: Geometry and Mesh Independence Studymentioning

confidence: 99%

“…In an attempt to take advantage of various passive techniques for mixing enhancement, Bernacka-Wojcik et al [22] proposed a passive micromixer that incorporated a rhombic SAR design with diamond-shaped obstacles and a rectangular contraction between the rhombi. Mixing length in the channel is dependent on the diffusion coefficient, width and height of the channel, inlet velocities of the fluid, viscosity of the fluids, and geometric layout of micromixer.…”

Section: Introductionmentioning

confidence: 99%

“…Mixing length in the channel is dependent on the diffusion coefficient, width and height of the channel, inlet velocities of the fluid, viscosity of the fluids, and geometric layout of micromixer. In an attempt to take advantage of various passive techniques for mixing enhancement, Bernacka-Wojcik et al [22] proposed a passive micromixer that incorporated a rhombic SAR design with diamond-shaped obstacles and a rectangular contraction between the rhombi. Their design was optimized experimentally through varying geometrical parameters, such as the number of rhombi, the distance between obstacles, and the contraction width, and employing statistical methods to analyze the obtained results.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion and convection mixing of non‐Newtonian liquids in an optimized micromixer

2018

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An optimized planar micromixer has been employed to study its performance in mixing liquids with various rheological behaviours. This design takes advantage of a number of passive techniques, including split-and-recombination of the channel, contraction of the channel, and embedding diamond-shaped obstacles in the main channels. Three-dimensional Navier-Stokes equations, along with an advection-diffusion model are solved by means of a finite-element scheme. Numerical simulations are performed for species with power law indexes ranging from 0.6-1.4, and the resulting mixing efficiencies are compared for different cases. Pressure drop is also evaluated and compared by taking into account the rheological behaviour of the fluids. The results revealed that in the studied range of Reynolds numbers, shear-thickening fluids present higher efficiencies in the diffusion-dominated regimes by 5 % at the best case. Shear-thinning flows have a better performance at higher Reynolds numbers and expedite the diffusion-advection transition point compared to other regimes. Transition occurs at a Reynolds number of 0.1 for the shear-thinning regime, while for Newtonian fluids this point is at a Reynolds number equal to 1. Moreover, it is found that the variation of mixing efficiency for shear-thickening flows with different fluid behaviour indexes is not significant in the studied Reynolds number range.

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“…Undistorted convex corners lead toward a novel design method for angle deflection from the standard <100> direction by forcing the sides of mask patterns along predetermined <n10> crystallographic directions. The analyzed parallelograms could be used for future designs of lab-on-chip platforms based on obstacle mechanisms (micromixers, deterministic lateral displacement (DLD) separators, cell peg) [40][41][42][43][44][45][46][47][48][49][50], microfluidic diodes [51] and quality microfluidic bifurcations. This paper will provide guidance on novel micromachining of bosses, convex corner compensation, microfluidic channels with obstacles, etc.…”

Section: Introductionmentioning

confidence: 99%

Etching of Uncompensated Convex Corners with Sides along <n10> and <100> in 25 wt% TMAH at 80 °C

et al. 2020

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This paper presents etching of convex corners with sides along <n10> and <100> crystallographic directions in a 25 wt% tetramethylammonium hydroxide (TMAH) water solution at 80 °C. We analyzed parallelograms as the mask patterns for anisotropic wet etching of Si (100). The sides of the parallelograms were designed along <n10> and <100> crystallographic directions (1 < n < 8). The acute corners of islands in the masking layer formed by <n10> and <100> crystallographic directions were smaller than 45°. All the crystallographic planes that appeared during etching in the experiment were determined. We found that the obtained types of 3D silicon shape sustain when n > 2. The convex corners were not distorted during etching. Therefore, no convex corner compensation is necessary. We fabricated three matrices of parallelograms with sides along crystallographic directions <310> and <100> as examples for possible applications. Additionally, the etching of matrices was simulated by the level set method. We obtained a good agreement between experiments and simulations.

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Experimental optimization of a passive planar rhombic micromixer with obstacles for effective mixing in a short channel length

Abstract: A short passive planar micromixer was experimentally optimised using statistical methods to determine parameter significance and most desirable geometry.

Cited by 15 publications

References 33 publications

Single nucleotide polymorphism detection using gold nanoprobes and bio‐microfluidic platform with embedded microlenses

Single nucleotide polymorphism detection using gold nanoprobes and bio‐microfluidic platform with embedded microlenses

Diffusion and convection mixing of non‐Newtonian liquids in an optimized micromixer

Etching of Uncompensated Convex Corners with Sides along <n10> and <100> in 25 wt% TMAH at 80 °C

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