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Title: Electronic desalting for controlling the ionic environment in droplet-based biosensing platforms

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.
Authors:
 [1] ; ;  [2] ; ; ;  [3] ;  [4] ;  [5] ;  [6] ;  [1] ;  [7] ;  [7]
  1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
  2. School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)
  3. Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
  4. Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
  5. Abbott Laboratories, 1921 Hurd Drive, Dept. 8482 LC2 M/S 2-33, Irving, Texas 75038 (United States)
  6. Taiwan Semiconductor Manufacturing Company, Hsinchu 300-78, Taiwan (China)
  7. (United States)
Publication Date:
OSTI Identifier:
22420263
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 5; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AQUEOUS SOLUTIONS; DESALINATION; DROPLETS; ELECTROCHEMISTRY; ELECTRODES; PLATINUM; SIMULATION; SURFACE TREATMENTS