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Open AccessArticle

A Diffusion-Based pH Regulator in Laminar Flows with Smartphone-Based Colorimetric Analysis

1
ASIC and System State Key Laboratory, School of Microelectronics, Fudan University, Shanghai 200433, China
2
State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences, Changchun 130033, China
3
School of Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China
*
Authors to whom correspondence should be addressed.
Micromachines 2018, 9(12), 616; https://doi.org/10.3390/mi9120616
Received: 20 October 2018 / Revised: 7 November 2018 / Accepted: 19 November 2018 / Published: 23 November 2018
(This article belongs to the Special Issue Optofluidics 2018)
A strategy for an on-chip pH regulator is demonstrated computationally and experimentally, based on the diffusion characteristics of aqueous ionic solutions. Micro-flows with specific pH values are formed based on the diffusion behaviors of hydrogen and hydroxide ions in laminar flows. The final achieved pH value and its gradient in the channel can be regulated by the amount of ions transported between laminar flows, and the experimental results can be further generalized based on the normalized Nernst-Planck equation. A smartphone was applied as an image capture and analysis instrument to quantify pH values of liquids in a colorimetric detection process, with monotonic response range of ~1–13. View Full-Text
Keywords: pH regulator; diffusion; laminar flows; smartphone; colorimetric analysis pH regulator; diffusion; laminar flows; smartphone; colorimetric analysis
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MDPI and ACS Style

Wang, W.; Zeng, Z.; Xu, W.; Wu, W.; Liang, W.; Zhou, J. A Diffusion-Based pH Regulator in Laminar Flows with Smartphone-Based Colorimetric Analysis. Micromachines 2018, 9, 616.

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