A highly sensitive, easy-and-rapidly-fabricable microfluidic electrochemical cell with an enhanced three-dimensional electric field.

An NP-μFEC is a reusable, novel microfluidic electrochemical cell with multiple non-planar interdigitated microelectrode arrays, minimal sample volume, and enhanced electric field penetration for highly sensitive electrochemical analysis. (i) The NP-μFEC features spatial 3-electrode architecture, and a small sample volume (∼4 μL). (ii) Here, [Fe(CN)] redox couple are used as an electrochemical reporter. The effects on the electrochemical properties of NP-μFEC due to the change in the reference electrode (RE) and counter electrode (CE)'s position with respect to the working electrode (WE) position are analyzed. For NP-μFEC, the position of the RE with respect to the WE does not affect the CV, DPV electrochemical profiles. However, the spacing between the CE and WE plays a significant role. (iii) The enhanced three-dimensional electric field penetration in NP-μFEC is validated by finite element analysis simulation using COMSOL Multiphysics. (iv) Without electrode surface modifications, NP-μFEC shows a detection limit (DL) of ∼2.54 × 10 M for aqueous [Fe(CN)] probe. (v) The DL for Cu, Fe, and Hg are 30.5±9.5 μg L, 181±58.5 μg L, and 12.4±1.95 μg L, respectively, which meets the US Environmental Protection Agency (EPA)'s water contamination level for Cu, Fe, and is close to that for Hg (EPA limits are 1300 μg L, 300 μg L, and 2 μg L, respectively). (vi) Further, using a pressure-sensitive adhesive layer to form the channel and create the NP-μFEC configuration simplifies the manufacturing process, making it cost-effective and allowing for rapid adoption in any research lab. NP-μFEC is used to detect heavy metal ions in water. This demonstrates that cost-effective, easy-to-fabricate NP-μFEC can be a new sensitive electrochemical platform.