Department of Chemistry and the Texas Materials Institute, The University of Texas at Austin, 105 E. 24th Street, Stop A5300, Austin, Texas 78712-1224, USA.
Lab Chip. 2022 Feb 1;22(3):632-640. doi: 10.1039/d1lc00952d.
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, 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.
我们报告了一种在微流控装置中生成的微滴中电化学调节 pH 值的方法。关键发现是可以在受约束的移动微滴中电化学生成定量的试剂，这些微滴被限制在微流道内。此外，在阳极和阴极生成的产物可以在衍生的微滴内被隔离。具体来说，在 T 形 Junction 处生成约 5 nL 的油包水微滴，然后将其分裂成两个衍生的微滴。在分裂过程中，地板图案化的微电极在水微滴内驱动水电解以产生 H 和 OH。这会导致衍生微滴的 pH 值发生变化。通过向微滴中注入定量的电荷，可以在 5.9 到 7.7 的范围内调节微滴的 pH 值。当注入的电荷量在-6.3 到 54.5 nC nL 之间时，所得到的微滴的测量 pH 值与根据注入电荷量预测的 pH 值相差在±0.1 个 pH 单位内。该技术可能适用于在微滴中电化学生成其他试剂。
