title: Electronic desalting for controlling the ionic environment in droplet-based biosensing platforms.
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 ∼250μm. 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.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
authors.forename: Vikhram Vilasur
authors.identifier: 0000-0001-5359-3784
authors.initials: VV
authors.lastname: Swaminathan
authors.affiliation: School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, USA.
authors.forename: Piyush
authors.initials: P
authors.lastname: Dak
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
authors.forename: Bobby
authors.initials: B
authors.lastname: Reddy
authors.affiliation: Department of Bioengineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Salm
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Duarte-Guevara
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhong
authors.affiliation: Abbott Laboratories , 1921 Hurd Drive, Dept. 8482 LC2 M/S 2-33, Irving, Texas 75038, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Fischer
authors.affiliation: Taiwan Semiconductor Manufacturing Company , Hsinchu 300-78, Taiwan.
authors.forename: Yi-Shao
authors.initials: YS
authors.lastname: Liu
authors.affiliation: School of Electrical and Computer Engineering, Purdue University , West Lafayette, Indiana 47907, USA.
authors.forename: Muhammad A
authors.initials: MA
authors.lastname: Alam
authors.forename: Rashid
authors.initials: R
authors.lastname: Bashir