Swaminathan Vikhram Vilasur, Dak Piyush, Reddy Bobby, Salm Eric, Duarte-Guevara Carlos, Zhong Yu, Fischer Andrew, Liu Yi-Shao, Alam Muhammad A, Bashir Rashid
Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, USA.
Appl Phys Lett. 2015 Feb 2;106(5):053105. doi: 10.1063/1.4907351.
The ability to control the ionic environment in saline waters and aqueous electrolytes is useful for desalination as well as electronic biosensing. We demonstrate a method of electronic desalting at micro-scale through on-chip micro electrodes. We show that, while desalting is limited in bulk solutions with unlimited availability of salts, significant desalting of ≥1 mM solutions can be achieved in sub-nanoliter volume droplets with diameters of ∼250 m. Within these droplets, by using platinum-black microelectrodes and electrochemical surface treatments, we can enhance the electrode surface area to achieve >99% and 41% salt removal in 1 mM and 10 mM salt concentrations, respectively. Through self-consistent simulations and experimental measurements, we demonstrate that conventional double-layer theory over-predicts the desalting capacity and, hence, cannot be used to model systems that are mass limited or undergoing significant salt removal from the bulk. Our results will provide a better understanding of capacitive desalination, as well as a method for salt manipulation in high-throughput droplet-based microfluidic sensing platforms.
控制盐水和水性电解质中离子环境的能力对海水淡化以及电子生物传感都很有用。我们展示了一种通过芯片上的微电极进行微尺度电子脱盐的方法。我们表明，虽然在盐供应不受限的本体溶液中脱盐受到限制，但在直径约为250微米的亚纳升体积液滴中，可以实现对≥1 mM溶液的显著脱盐。在这些液滴中，通过使用铂黑微电极和电化学表面处理，我们可以增大电极表面积，在1 mM和10 mM盐浓度下分别实现>99%和41%的盐分去除。通过自洽模拟和实验测量，我们证明传统的双层理论对脱盐能力预测过高，因此不能用于对受质量限制或正在从本体中大量去除盐分的系统进行建模。我们的结果将有助于更好地理解电容式脱盐，以及为基于高通量液滴的微流控传感平台中的盐分操控提供一种方法。
