Electrochemical pH regulation in droplet microfluidics

Wilder, Logan M.; Thompson, Jonathan R.; Crooks, Richard M.

doi:10.1039/d1lc00952d

Title: Electrochemical pH regulation in droplet microfluidics

Journal Article · 12 January 2022 · Lab on a chip (Print)

DOI: https://doi.org/10.1039/d1lc00952d · OSTI ID:1978800

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University of Texas, Austin, TX (United States)

Here we report a method for electrochemical pH regulation in microdroplets generated in a microfluidic device. The key finding is that controlled quantities of reagents can be generated electrochemically in moving microdroplets confined within a microfluidic channel. Additionally, products generated at the anode and cathode can be isolated within descendant microdroplets. Specifically, ~5 nL water-in-oil microdroplets are produced at a T-junction and then later split into two descendant droplets. During splitting, floor-patterned microelectrodes drive water electrolysis within the aqueous microdroplets to produce H⁺ and OH^-. This results in a change in the pHs of the descendant droplets. The droplet pH can be regulated over a range of 5.9 to 7.7 by injecting controlled amounts of charge into the droplets. When the injected charge is between -6.3 and 54.5 nC nL^-1, the measured pH of the resulting droplets is within ±0.1 pH units of that predicted based on the magnitude of the injected charge. This technique can likely be adapted to electrogeneration of other reagents within microdroplets.

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Research Organization:: Univ. of Texas, Austin, TX (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB); Robert A. Welch Foundation; USDOE

Grant/Contract Number:: FG02-06ER15758; F-0032

OSTI ID:: 1978800

Alternate ID(s):: OSTI ID: 1839464

Journal Information:: Lab on a chip (Print), Vol. 22, Issue 3; ISSN 1473-0197

Publisher:: Royal Society of ChemistryCopyright Statement

Country of Publication:: United States

Language:: English

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