Effect of Lithium Manganese Oxide on Lithium Detection in Microfluidic Electrochemical Sensor

This paper presents a novel, low-cost and easy-to-fabricate Microfluidic Electrochemical Sensor (MES) capable of detecting LiCl-based lithium (Li) ions in water. The MES consisted of inexpensive Pressure Sensitive Adhesive (PSA) and Polyethylene Terephthalate (PET) sheets to fabricate a curved microchannel over three carbon-based electrodes. The MES was tested with various concentrations of Lithium Manganese Oxide (LMO) in 1 mL N-methyl-2-pyrrolidone (NMP), mixed in a 1:1 mass ratio with Graphene Carbon Paste (GCP) to create the Li-specific electrodes. The electrodes formed in a mixture of 300 mg/mL LMO in NMP performed the best, with Cyclic Voltammetry (CV) currents indicating a reduction peak of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$265 \ \mu \mathrm{A}$</tex> at 1.0 M LiCI and no significant reduction for competitive 1.0 M NaCl and KCl salts. These results demonstrate the MESs strong selectivity towards Li. Due to the use of low-cost and readily available materials, the MES used in this study has a high potential to be a reliable, portable, and efficient sensor for Li detection.