Universal Parafilm®-Mediated Thermal Bonding for Gold Leaf Electrode Patterning and Microfluidic Assembly on Diverse Substrates

Gold leaf electrodes offer a low-cost, substrate-versatile strategy for electrochemical sensing and microfluidic systems. Herein, we demonstrate a unified Parafilm®-mediated platform in which the Parafilm® layer serves as both the adhesive for gold-leaf electrode patterning and the bonding/channel-defining layer for microfluidic assembly via heat-activated bonding. Gold leaf electrodes were patterned on diverse substrates by laser ablation, achieving a minimum achieved linewidth of 53 ± 3 μm on polyethylene terephthalate (PET) sheets. Electrochemical characterization showed stable CV responses after 40 manual bending cycles and good batch reproducibility. Leveraging Parafilm’s hydrophobicity and thermoplasticity, we integrated electrodes into hierarchical microfluidic architectures on paper and PET. Paper-based hybrid devices with asymmetric self-driven channels enabled dual-zone measurements. Structured PET microchannels yielded microfluidic devices with sequential flow control and selective loading. In a proof-of-concept H2O2 assay, on-chip Prussian blue electrodeposition followed by amperometry gave a detection limit of 0.44 mg/L and ~85% recovery in spiked pond water. This Parafilm®-mediated strategy provides a low-cost route for cross-substrate microfluidic–electrochemical integration, unifying electrode fabrication and device assembly on a single thermoplastic bonding platform.