Error-calibrated sensing: ratiometric biosensor for carcinogenic formaldehyde in food safety monitoring

Ratiometric biosensor overcomes challenges of single-signal biosensors. • Dual-electrode design ensures self-calibration and compensates for errors. • Achieves a low detection limit (0.004 mM) and high accuracy (>97.29%). • Higher recovery compared to the Nash assay in real food matrices. • Demonstrates excellent reproducibility in a complex food matrix. Global food safety requires reliable biosensors in complex matrices. Yet, conventional single-signal electrochemical biosensors suffer from high inter-electrode variability (RSD <12.14%) and low accuracy (<87.84%) due to common-mode signal fluctuations. This study presents a ratiometric biosensor with a dual-electrode design that enables calculation of the current ratio (I WE2 /I WE1 ) between a formaldehyde dehydrogenase-functionalized sensing electrode and an inert graphene reference to mitigate systemic fluctuations. This self-calibrating configuration reduced variability (RSD of 6.92%), improved accuracy (>97.29%), and minimized interference effects (from 7.54% to 1.52%). Spanning a linear range of 0.02–0.50 mM with a LOD of 0.004 mM, the biosensor achieved 97.22–103.87% recovery in coffee samples (RSD = 0.21%). Validation against the Nash assay showed strong correlation (R 2  = 0.995) with comparable accuracy at 0.10–0.50 mM concentrations, yet up to nine-fold higher accuracy at 0.02 mM ( p  < 0.05), confirming its superior suitability for practical application in food safety monitoring. Download: Download high-res image (125KB) Download: Download full-size image