Microfluidic Flow Cell for Screen-Printed Electrodes (SPEs) Testing, CSPETMFC

A Microfluidic Flow Cell for Screen-Printed Electrodes (SPEs) interfaces planar, disposable three-electrode strips (carbon, gold, or platinum on PET/ceramic) with microfluidic plumbing. It converts static drop-cast analysis into automated flow injection analysis (FIA), continuous monitoring, and controlled hydrodynamic electrochemical sensing.

The main components are: (1) Manifold Block: Machined from transparent PMMA (acrylic) or polycarbonate to permit optical verification of air bubble clearance and flow profiles, or from PEEK for aggressive organic solvents and high chemical resistance. Standard fluidic ports with 1/4-28 UNF or M6 flat-bottom threads for 1/16-inch (1.58 mm) OD PTFE/FEP capillary tubing. (2) Gasket & Microchannel Chamber: Laser-cut silicone, Viton (FKM), or double-sided adhesive tape (50–250 um thick). Outlines a micro-chamber (typically 1 to 15 uL internal volume) directly over the working, counter, and reference areas, eliminating dead volume and vortex stagnation zones. (3) Clamping & Interconnect Mechanism: Spring-loaded gold-plated pins contact the rear edge-connector pads of the SPE, routing WE, CE, and RE signals to shielded BNC/banana cables hooked to a potentiostat.

The operation cautions are: (1) Fluid Flow Direction: Orient flow such that analyte encounters the Working Electrode (WE) first, followed by the Counter (CE) and Reference Electrode (RE). This prevents trace silver ions (Ag+) leaching from the printed Ag/AgCl ink from plating onto or fouling the working surface. (2) Degassing & Bubble Control: Microbubbles pinned to gasket edges or electrode rough spots cause sudden open-circuit spikes or surface blockage. Always degas buffers (ultrasonication or vacuum filtration) and prime lines with a low-surface-tension fluid (e.g., 10–20% ethanol in buffer) before running experiments. (3) Mechanical Clamping Pressure: Over-tightening screw-based clamps can distort flexible PET substrates or shear the dielectric ink layer, producing short circuits between silver tracks and the electrolyte.

References:

1. A. René, et al., Elaboration of screen-printed microelectrodes working as generator/collector and their use in a flow cell system, Sensors and Actuators B: Chemical, 2012, 174, 225-230
2. J. M. Mohan, et al. Emerging trends in miniaturized and microfluidic electrochemical sensing platforms, Current Opinion in Electrochemistry, 2022, 33, 100930.