pH change in electroosmotic flow hysteresis
Electroosmotic flow (EOF) or electro-osmosis has been shown to exhibit a hysteresis effect under displacement flow involving two solutions with different concentrations, i.e. the flow velocity for a high-concentration solution displacing a low-concentration solution is faster than the flow velocity...
| Main Authors: | , , |
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| Format: | Journal Article |
| Language: | English |
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2018
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| Online Access: | https://hdl.handle.net/10356/89027 http://hdl.handle.net/10220/44842 |
| _version_ | 1811680431761784832 |
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| author | Lim, Chun Yee Lim, An Eng Lam, Yee Cheong |
| author2 | School of Mechanical and Aerospace Engineering |
| author_facet | School of Mechanical and Aerospace Engineering Lim, Chun Yee Lim, An Eng Lam, Yee Cheong |
| author_sort | Lim, Chun Yee |
| collection | NTU |
| description | Electroosmotic flow (EOF) or electro-osmosis has been shown to exhibit a hysteresis effect under displacement flow involving two solutions with different concentrations, i.e. the flow velocity for a high-concentration solution displacing a low-concentration solution is faster than the flow velocity in the reverse direction involving the same solution pair. On the basis of our recent numerical analysis, a pH change initiated at the interface between the two solutions has been hypothesized as the cause for the observed anomalies. We report the first experimental evidence of EOF hysteresis induced by a pH change in the bulk solution. pH-sensitive dye was employed to quantify the pH changes in the microchannel during EOF. The electric-field gradient across the boundary of two solutions generates an accumulation or depletion of a minority of pH-governing ions such as hydronium (H3O+) ions, thus inducing pH variations across the microchannel. When a high-concentration solution displaced a lower-concentration solution, a pH increase was observed, while the flow in the reverse direction induced a decrease in pH. This effect causes significant changes to the zeta potential and flow velocity. The experimental results show good quantitative agreement with numerical simulations. This work presents the experimental proof which validates the hypothesis of a pH change during electroomostic flow hysteresis as predicted by numerical analysis. The understanding of pH changes during EOF is crucial for accurate flow manipulation in microfluidic devices and maintenance of constant pH in biological and chemical systems under an electric field. |
| first_indexed | 2024-10-01T03:24:57Z |
| format | Journal Article |
| id | ntu-10356/89027 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T03:24:57Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | ntu-10356/890272023-03-04T17:16:19Z pH change in electroosmotic flow hysteresis Lim, Chun Yee Lim, An Eng Lam, Yee Cheong School of Mechanical and Aerospace Engineering Hysteresis Electroosmotic Flow Electroosmotic flow (EOF) or electro-osmosis has been shown to exhibit a hysteresis effect under displacement flow involving two solutions with different concentrations, i.e. the flow velocity for a high-concentration solution displacing a low-concentration solution is faster than the flow velocity in the reverse direction involving the same solution pair. On the basis of our recent numerical analysis, a pH change initiated at the interface between the two solutions has been hypothesized as the cause for the observed anomalies. We report the first experimental evidence of EOF hysteresis induced by a pH change in the bulk solution. pH-sensitive dye was employed to quantify the pH changes in the microchannel during EOF. The electric-field gradient across the boundary of two solutions generates an accumulation or depletion of a minority of pH-governing ions such as hydronium (H3O+) ions, thus inducing pH variations across the microchannel. When a high-concentration solution displaced a lower-concentration solution, a pH increase was observed, while the flow in the reverse direction induced a decrease in pH. This effect causes significant changes to the zeta potential and flow velocity. The experimental results show good quantitative agreement with numerical simulations. This work presents the experimental proof which validates the hypothesis of a pH change during electroomostic flow hysteresis as predicted by numerical analysis. The understanding of pH changes during EOF is crucial for accurate flow manipulation in microfluidic devices and maintenance of constant pH in biological and chemical systems under an electric field. ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version 2018-05-18T08:41:48Z 2019-12-06T17:16:14Z 2018-05-18T08:41:48Z 2019-12-06T17:16:14Z 2017 2017 Journal Article Lim, C. Y., Lim, A. E., & Lam, Y. C. (2017). pH Change in Electroosmotic Flow Hysteresis. Analytical Chemistry, 89(17), 9394–9399. 0003-2700 https://hdl.handle.net/10356/89027 http://hdl.handle.net/10220/44842 10.1021/acs.analchem.7b02219 207778 en Analytical Chemistry © 2017 American Chemical Society. This is the author created version of a work that has been peer reviewed and accepted for publication by Analytical Chemistry, American Chemical Society. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1021/acs.analchem.7b02219]. 14 p. application/pdf |
| spellingShingle | Hysteresis Electroosmotic Flow Lim, Chun Yee Lim, An Eng Lam, Yee Cheong pH change in electroosmotic flow hysteresis |
| title | pH change in electroosmotic flow hysteresis |
| title_full | pH change in electroosmotic flow hysteresis |
| title_fullStr | pH change in electroosmotic flow hysteresis |
| title_full_unstemmed | pH change in electroosmotic flow hysteresis |
| title_short | pH change in electroosmotic flow hysteresis |
| title_sort | ph change in electroosmotic flow hysteresis |
| topic | Hysteresis Electroosmotic Flow |
| url | https://hdl.handle.net/10356/89027 http://hdl.handle.net/10220/44842 |
| work_keys_str_mv | AT limchunyee phchangeinelectroosmoticflowhysteresis AT limaneng phchangeinelectroosmoticflowhysteresis AT lamyeecheong phchangeinelectroosmoticflowhysteresis |