Compartmentalized Dual Screen-Printed Carbon Electrode as Flexible Electrochemical Biosensors, CFEBCDSPCE

A Compartmentalized Dual Screen-Printed Carbon Electrode (Compartmentalized Dual-SPCE) solves the primary manufacturing bottleneck of dual-electrode biosensors: cross-contamination during localized surface functionalization. By physically or chemically isolating two adjacent working electrodes (WE1 and WE2) during the drop-casting or immobilization step, distinct enzymes, antibodies, or nanomaterials can be deposited independently without droplet coalescence. During testing, the barrier allows a single sample droplet (30–60 uL) or a continuous flow stream to bridge both working electrodes along with the shared counter (CE) and reference (RE) electrodes.

For Chip Layout and Electrical Topography: (1) Independent Working Electrodes (WE1 & WE2): Semicircular, rectangular microband, or disk geometry (Ф 1.5–2.5 mm). Centered within isolated wells separated by a non-conductive barrier band (≥ 0.8–1.2 mm width). (2) Shared Counter Electrode (CE): High-surface-area carbon band enclosing the working electrode perimeter (A_CE ≥ 3 * [A_WE1 + A_WE2). (3) Shared Reference Electrode (RE): Screen-printed Ag/AgCl track providing an identical potentiostatic reference for both channels. (4) Connection Interface: 4-pin or 4-track edge card connector interface (WE1, WE2, CE, RE) configured for standard boxed bipotentiostat connectors.

The Step-by-Step Sensor Fabrication Workflow: (1) Electrochemical Pre-Activation: Immerse the entire sensing area in 0.1 M H2SO4 and run cyclic voltammetry sweeps (-0.2 V to +1.2 V vs. Ag/AgCl at 100 mV/s for 10 cycles) to strip residual ink binders and generate carboxyl (-COOH) and hydroxyl (-OH) anchoring sites on both carbon disks. (2) Compartmentalized Dispensing: Well 1 (Target Channel): Dispense 0.8–1.5 uL of target probe solution (e.g., anti-Troponin I antibody + EDC/NHS coupling mix). Well 2 (Reference/Interference Channel): Dispense 0.8–1.5 uL of control solution (e.g., non-specific IgG, BSA, or secondary target enzyme such as Lactate Oxidase). Incubate in a humid chamber (4°C or 37°C) for 1–2 hours. The isolation barrier keeps the droplets mechanically separated. (3) Washing & Global Surface Blocking: Aspirate the micro-droplets using an automatic pipette tip directed away from the carbon center. Rinse with PBST (0.05% Tween-20 in PBS). Flood the entire chip well with 50 uL of 1wt% BSA or casein solution for 30 minutes to block unreacted sites across the whole sensing area, then rinse and dry under a gentle N2 stream. (4) Electrochemical Interrogation: Apply a single 40–60 uL drop of whole blood, serum, or running buffer bridging all four electrodes. Connect to a bipotentiostat for concurrent differential pulse voltammetry (DPV) or chronoamperometric reading.

References:

1. H. Beitollahi, et al., Applications of electrochemical sensors and biosensors based on modified screen-printed electrodes: a review, Anal. Methods (2020) 12 (12): 1547–1560.
2. Keiichiro Yamanaka, et al. Printable Electrochemical Biosensors: A Focus on Screen-Printed Electrodes and Their Application, Analytical and Bioanalytical Chemistry, 2005, 382, 884–886.