A novel passive micromixer with modified asymmetric lateral wall structures

Wang, Hanlin; Shi, Liuyong; Zhou, Teng; Xu, Chao; Deng, Yongbo

doi:10.1002/apj.2202

Cited by 11 publications

(8 citation statements)

References 51 publications

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“…The digitally captured intensity images are usually stored in the format of three 8‐bit monochromatic red, green, and blue colors (RGB), which can be converted to the grayscale, cyan/magenta/yellow/key or hue/saturation/intensity (HSI) color model. The mixing index can be calculated using grayscale images as follows:

italicMixing index = 1 - \sqrt{\frac{1}{N} \sum_{i = 1}^{N} {(\frac{{\overset{false¯}{I}}_{italicgray, normali} - I^{*}}{I^{*}})}^{2}},

where N is the total number of pixels i analyzed, I * is the expected normalized pixel intensity that equals 0.5, and

\overset{I}{true}

gray ,i is

{\overset{false¯}{I}}_{italicgray, normali} = \frac{((), I_{italicgray, i} - I_{italicgray, italicmin})}{((), I_{italicgray, italicmax} - I_{italicgray, italicmin})},

where

\overset{I}{true}

gray ,i is the normalized pixel intensity inside the image, whereas I gray, min and I gray, max are the minimum and maximum local pixel intensity, respectively, and I gray, i is

I_{gray, normali} = ((), 0.299 normalR + 0.587 normalG + 0.114 normalB) / 3,

where I gray, i is the local pixel intensity.…”

Section: Introductionmentioning

confidence: 99%

“…12,13 Several quantitative mixing indices have been defined based on intensity images recorded using typical digital video microscopes. 9,12,14,15 The digitally captured intensity images are usually stored in the format of three 8-bit monochromatic red, green, and blue colors (RGB), which can be converted to the grayscale, cyan/magenta/yellow/key or hue/saturation/intensity (HSI) color model. The mixing index can be calculated using grayscale images as follows 7,9,[14][15][16] :…”

Section: Introductionmentioning

confidence: 99%

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Method for determining mixing index in microfluidics by RGB color model

Mahmud

Tamrin

2020

Asia-Pacific J Chem Eng

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Microfluidic mixing is a key process in miniaturized analysis system. Achieving adequate mixing performance is considerably difficult in microfluidic micromixer, as the flow is always associated with unfavorable laminar flow and dominated by molecular diffusion. The mixing performance of these micromixers are generally characterized as a function of mixing index based on dispersion (homogeneity) information, leading to either an overestimated or underestimated mixing index. This paper presents a new method for determining the mixing index of micromixers based on RGB color model by decoding mixing images to their respective red, green, and blue pixel intensities. Several digital composite images were used to perform initial benchmarking, and the proposed method accurately quantified the mixing index significantly better than previously adopted methods. The practicality of the method was further demonstrated by characterizing mixing of well‐known micromixers, namely T‐ and Y‐ micromixers, at varying Reynolds numbers of 5 ≤ Re ≤ 100. The results show that the mixing index decreases with the increase in Reynolds number, whereas the mixing index of the T‐micromixer was superior to that of Y‐micromixer, both agreeing well with the literature. The mixing index of these micromixers at varying Reynolds numbers of 5 ≤ Re ≤ 100 calculated using other methods were also compared and discussed. The proposed method is foreseen handy and robust in characterizing mixing in real time for gradient mixing in networked microchannels and multivortex mixing for the manipulation of fluids, particles, and biological substances.

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italicMixing index = 1 - \sqrt{\frac{1}{N} \sum_{i = 1}^{N} {(\frac{{\overset{false¯}{I}}_{italicgray, normali} - I^{*}}{I^{*}})}^{2}},

where N is the total number of pixels i analyzed, I * is the expected normalized pixel intensity that equals 0.5, and

\overset{I}{true}

gray ,i is

{\overset{false¯}{I}}_{italicgray, normali} = \frac{((), I_{italicgray, i} - I_{italicgray, italicmin})}{((), I_{italicgray, italicmax} - I_{italicgray, italicmin})},

where

\overset{I}{true}

gray ,i is the normalized pixel intensity inside the image, whereas I gray, min and I gray, max are the minimum and maximum local pixel intensity, respectively, and I gray, i is

I_{gray, normali} = ((), 0.299 normalR + 0.587 normalG + 0.114 normalB) / 3,

where I gray, i is the local pixel intensity.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Method for determining mixing index in microfluidics by RGB color model

Mahmud

Tamrin

2020

Asia-Pacific J Chem Eng

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“…Generally, these methods can be divided into two categories: active methods and passive methods [4]. Passive methods usually utilize various geometries [5–17] of microchannels and different shapes of obstacles [18–23] or grooves [24–27] placed in microchannels to disturb the laminar flow for vortex formation. Passive methods do not need external energy sources, but the channels of such methods usually need to be designed with complex structures, thereby increasing the fabrication difficulty.…”

Section: Introductionmentioning

confidence: 99%

Electrokinetic‐vortex formation near a two‐part cylinder with same‐sign zeta potentials in a straight microchannel

2020

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Vortex formation near a two-part cylinder with zeta potentials of different values but the same sign under an external DC electric field is numerically investigated in this paper. The cylinder, inserted in a straight microchannel filled with an aqueous solution, is composed of an upstream part and a downstream part. When a DC electric field is applied in the channel, under certain conditions, the vortex will form near the cylinder due to the different velocities of electroosmotic flow generated on the cylinder surface. The numerical results reveal that the larger the velocity difference of electroosmotic flow generated on the two-part cylinder and the smaller the channel width, the more conducive to vortex formation in the channel. In addition, if the zeta potential ratios of cylinder downstream part to upstream part and channel wall to cylinder upstream part are unchanged, the DC electric field strength and the zeta potential value do not affect the pattern of vortices formed in the channel. This study provides a way for vortex formation in microchannels and has the potential application in microfluidic devices.

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“…O glioxal (CH(O)CHO) e o metilglioxal (CH3C(O)CHO) são as mais prevalentes alfa-carbonilas encontradas na atmosfera, sendo mensurados em partes por trilhão em volume (pptv) e suas taxas de mistura podem apresentar desde dezenas a centenas de partes por trilhão ZHOU;HALLOCK, 1995;BIKKINA et al, 2014;PANG et al, 2014). Diversos estudos têm relatado uma variação de 15 a 1820 pptv para o GLI e de 50 a 320 pptv para o MGLI em áreas urbanas, rurais e oceanos abertos (Lee et al, 1995;Volkamer et al, 2005a;Fu et al, 2008;Huisman et al, 2008;Sinreich et al, 2010;Vrekoussis et al, 2009;Munger et al, 1995;Spaulding et al, 2003;Washenfelder et al, 2011;Apud PANG et al, 2014 2006a;FU et al, 2008).…”

Section: Glioxal (Gli) E Metilglioxal (Mgli) Formação E Impactos Na Aunclassified

“…Claramente, diversos trabalhos têm abordado a importância do desenvolvimento e novos estudos de aplicabilidade no seguimento dos misturadores passivos, sejam eles para síntese, análises bioquímicas, microrreatores e etc., (LEE et al, 2016;HERMANN et al, 2018;WANG et al, 2018;HUSSAIN;PÖSCHEL;MÜLLER, 2019;MONDAL et al, 2019).…”

Section: Introductionunclassified

Desenvolvimento de um circuito microfluídico para análise atmosférica através de microusinagem com laser de pulsos ultracurtos

Gomes¹

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Gomes, A. Arleques. Development of a microfluidic circuit for atmospheric analysis through ultra-short laser pulse micromachining. 2020. 188 p. Dissertação (Mestrado em Tecnologia Nuclear)-Instituto de Pesquisas Energéticas e Nucleares-IPEN-CNEN/SP. São Paulo. This work presents an improvement and qualitative validation of a method for obtaining glyoxal-GLY (gas), on a laboratory scale through a 40% aqueous solution of GLY, which is also applied in obtaining methylglioxal-MGLY under the same conditions. The successful obtainment of GLY, as well as the probable acquisition of the other species, will be used for future testing in microfluidic microreactors. For this, two types of microcircuits, with mixers, were proposed and produced for a two-phase system (gas-liquid), these being a Double-T circuit (with serpentine mixer) and the microcircuit-II (composed by Mixed Speed and Recombination-MSAR). The mixers developed were able to reduce the size of the bubbles formed in certain flows applicable to the kinetics of the reaction of a microreactor, which, through the derivatization technique, will make it possible to identify and quantify GLY and MGLY in the gaseous sample. The ultra-short laser pulses ablation technique was applied to make the proposed microcircuits. Improvements in the micromachining of complex geometries on the surfaces of BK7 borosilicate optical glass were also developed for this technique, which presented excellent results. Subsequently, a technique of validating and analyzing speeds, size, and number of bubbles was implemented using an image capture system (Embedded Supervisory Optical System "ESOS"). The validated capture system was the main tool in the characterization and definition of the type of circuit that can best be applied to the microreactor due to its maximum volume and the residence time for the derivatization technique. Finally, a microfluidic random laser was developed with the same micromachining process on a translucent surface, being presented as a candidate for analysis of the derivatized material containing GLY at the outlet of the microreactor.

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A novel passive micromixer with modified asymmetric lateral wall structures

Cited by 11 publications

References 51 publications

Method for determining mixing index in microfluidics by RGB color model

Method for determining mixing index in microfluidics by RGB color model

Electrokinetic‐vortex formation near a two‐part cylinder with same‐sign zeta potentials in a straight microchannel

Desenvolvimento de um circuito microfluídico para análise atmosférica através de microusinagem com laser de pulsos ultracurtos

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