Biocathode prepared at low anodic potentials achieved a higher response for water biotoxicity monitoring after polarity reversal

Microbial electrochemical sensors equipped with biocathode sensing elements have attracted a growing interest, but their startup and recovery properties remain unclear. In this study, the approach of polarity reversal was applied for the biocathode sensing element fabrication and biosensor recovery. The stimulating/suppressing effect of formaldehyde was determined by the anode potential before polarity reversal as well as the increased trials of toxic exposure. Increasing anode potential from -0.3 V to +0.3 V before polarity reversal, the baseline electric signal was changed from -0.028 ± 0.001 mA to -0.005 ± 0.003 mA, while the maximum normalized electrical signal (NES) was increased from 1.1 ± 0.1 to 4.1 ± 1.9, and thus a general downtrend was observed for Response as a newly induced indicator. Polarity reversal failed to recover the electroactivity of these poisoned bioelectrodes. This study demonstrated that electrode potential was critical when using the approach of polarity reversal to construct the biocathode sensing element, and revealed an urgent need for strategies toward high recoverability of such biosensors.