Renewable Solid Electrodes in Microfluidics: Recovering the Electrochemical Activity without Treating the Surface

Area of Science:

• Electrochemistry
• Microfluidics
• Analytical Chemistry

Background:

• Electrode contamination, passivation, and fouling significantly degrade electroanalytical device performance.
• Current electrode regeneration methods require time-consuming, complex, and chemical-intensive surface treatments.

Purpose of the Study:

• To introduce a reproducible, surface-treatment-free method for renewing solid electrodes in microfluidic devices.
• To present a microfluidic platform that mimics the renewability of mercury drop electrodes.
• To address the critical issue of electrode modification in microfluidic systems.

Main Methods:

• Developed a microfluidic chip from polydimethylsiloxane (PDMS) with interconnected channels.
• Integrated metal-coated microwires as working, counter, and pseudoreference electrodes within the channels.
• Implemented a renewal process by manually sliding microwires, effectively refreshing electrode surfaces.

Main Results:

• Demonstrated successful renewal of all three electrodes by simply pulling the microwires.
• Achieved leak-free operation at high flow rates (up to 40.0 mL min^-1) due to the PDMS elastomeric nature and absence of interfaces.
• Validated the method's reproducibility and effectiveness in microfluidic applications.

Conclusions:

• The proposed microwire renewal technique offers a powerful alternative to conventional electrode cleaning methods.
• This approach eliminates operational complexity and chemical usage, paving the way for more robust and precise electroanalytical measurements.
• Facilitates the development of advanced microfluidic platforms for simplified and reliable real-world sample analysis.