Faradaic and non-faradaic depletions by anodic electrode corrosion with strong electrolytes on tautochrone curve interdigitated electrodes

By integrating conventional parallel electrodes with two semi-circular curves, a new tautochrone curve interdigitated electrodes (TCIDE) biosensor was fabricated to be compatible for Faradaic and non-Faradaic measurements. Scanning electron microscopy affirmed the immaculate fabrication, as multiple scans showed that both the width and gap of electrodes were 50.0 μm, with a maximum percentage error of ∼8.0 %. A maximum current of 29.54 μA was generated with a strong electrolyte (pH 2), signifying the weak adaptability of the device to a highly acidic medium. The stability of the biosensor was further evaluated by prolonging the exposure duration to different pH levels for 5 min. Substantial increases in current were recorded under extreme pH environments (pH 2, 3, and 12) over the duration at 2.0 V, while others maintained excellent stability. A high-power microscope revealed that the anodic aluminium transducers experienced surface corrosion, elucidating the unusual current fluctuations. The mechanisms of anodic corrosion caused by the strong electrolytes were additionally proposed and discussed. As validated by electrochemical impedance spectroscopy, this study provides valuable insights into the declined biosensing performances of corroded anodes.