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Title: On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer

Abstract

Fast microfluidic mixers for use with line-of-sight integrating detection schemes pose unique challenges. Such detectors typically cannot discriminate signal from slow moving (e.g. near internal walls) and fast-moving portions of the fluid stream. This convolves reaction rate dynamics with fluid flow residence time dynamics. Further, the small cross sections of typical three-dimensional hydrodynamic focusing devices lead to lower detection signals. The current study focuses on achieving both small time scales of mixing and homogenous residence times. This is achieved by injecting sample through a center capillary and hydrodynamically focusing using a sheath flow within a tapered second capillary. The current design also features a third, larger coaxial capillary. The mixed stream flows into the large cross-section of this third capillary to decelerate and expand the stream by up to 14-fold to improve line-of-sight signal strength of reaction products. Hydrodynamic focusing, mixing, and expansion are studied using analytical and numerical models and also studied experimentally using a fluorescein-iodide quenching reaction. The experimentally validated models are used to explore trade-offs between mixing rate and uniformity. For the first time, this work presents detailed analysis of the Lagrangian time history of species transport during mixing inside coaxial capillaries to measure mixing nonuniformity. Themore » mixing region enables order 100 μs mixing times and residence time widths of the same order (140 μs).« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [2]; ORCiD logo [1]
  1. Stanford Univ., CA (United States)
  2. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1608308
Alternate Identifier(s):
OSTI ID: 1599966
Grant/Contract Number:  
AC02-76SF00515; P41GM103393
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Analytica Chimica Acta
Additional Journal Information:
Journal Volume: 1103; Journal Issue: C; Journal ID: ISSN 0003-2670
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; Microfluidics; Mixing; Hydrodynamic focusing; Coaxial capillaries; Kinetics

Citation Formats

Huyke, Diego A., Ramachandran, Ashwin, Oyarzun, Diego I., Kroll, Thomas, DePonte, Daniel P., and Santiago, Juan G. On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer. United States: N. p., 2020. Web. doi:10.1016/j.aca.2020.01.013.
Huyke, Diego A., Ramachandran, Ashwin, Oyarzun, Diego I., Kroll, Thomas, DePonte, Daniel P., & Santiago, Juan G. On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer. United States. doi:10.1016/j.aca.2020.01.013.
Huyke, Diego A., Ramachandran, Ashwin, Oyarzun, Diego I., Kroll, Thomas, DePonte, Daniel P., and Santiago, Juan G. Sun . "On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer". United States. doi:10.1016/j.aca.2020.01.013.
@article{osti_1608308,
title = {On the competition between mixing rate and uniformity in a coaxial hydrodynamic focusing mixer},
author = {Huyke, Diego A. and Ramachandran, Ashwin and Oyarzun, Diego I. and Kroll, Thomas and DePonte, Daniel P. and Santiago, Juan G.},
abstractNote = {Fast microfluidic mixers for use with line-of-sight integrating detection schemes pose unique challenges. Such detectors typically cannot discriminate signal from slow moving (e.g. near internal walls) and fast-moving portions of the fluid stream. This convolves reaction rate dynamics with fluid flow residence time dynamics. Further, the small cross sections of typical three-dimensional hydrodynamic focusing devices lead to lower detection signals. The current study focuses on achieving both small time scales of mixing and homogenous residence times. This is achieved by injecting sample through a center capillary and hydrodynamically focusing using a sheath flow within a tapered second capillary. The current design also features a third, larger coaxial capillary. The mixed stream flows into the large cross-section of this third capillary to decelerate and expand the stream by up to 14-fold to improve line-of-sight signal strength of reaction products. Hydrodynamic focusing, mixing, and expansion are studied using analytical and numerical models and also studied experimentally using a fluorescein-iodide quenching reaction. The experimentally validated models are used to explore trade-offs between mixing rate and uniformity. For the first time, this work presents detailed analysis of the Lagrangian time history of species transport during mixing inside coaxial capillaries to measure mixing nonuniformity. The mixing region enables order 100 μs mixing times and residence time widths of the same order (140 μs).},
doi = {10.1016/j.aca.2020.01.013},
journal = {Analytica Chimica Acta},
issn = {0003-2670},
number = C,
volume = 1103,
place = {United States},
year = {2020},
month = {3}
}

Journal Article:
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