1. Electronic desalting for controlling the ionic environment in droplet-based biosensing platforms
- Author
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Vikhram V. Swaminathan, Yi Shao Liu, Yu Zhong, Piyush Dak, Carlos Duarte-Guevara, Eric Salm, Bobby Reddy, Muhammad A. Alam, Rashid Bashir, and Andrew T. Fischer
- Subjects
chemistry.chemical_classification ,Aqueous solution ,Physics and Astronomy (miscellaneous) ,Chemistry ,Nanoscale Science and Technology ,Microfluidics ,Salt (chemistry) ,Nanotechnology ,Electrolyte ,Lab-on-a-chip ,Desalination ,law.invention ,Microelectrode ,law ,Biosensor - Abstract
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 μm. 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.
- Published
- 2014