Abstract: In this study, a bipolar - electrode electrochemiluminescence (BPE-ECL) sensing platform based on the regulation of conductivity was constructed for the detection of urea. An independent sensing cell and a reporting cell were constructed on the patterned BPE, and ruthenium bipyridine / tri-n-propylamine [Ru(bpy)32+/TPrA] was used as the ECL – signal resource. When urea at different concentrations is present in the sensing cell, urease specifically catalyzes the decomposition of urea, generating ions that promote an increase in the conductivity. Based on the charge balance of BPE, the intensity of ECL in the reporting cell increases. The higher the concentration of urea, the greater the intensity of ECL. Therefore, a BPE-ECL platform based on regulation of conductivity was established for the detection of urea. Under optimal conditions, this sensing platform exhibits a good linear relationship for urea within the range of 10 nM – 1 mM, and the limit of detection is 0.19 nM (S/N = 3). The sensing platform was further applied to the spiked recovery detection in human urine samples, showing good accuracy and anti - interference ability. The sensing strategy based on the regulation of conductivity not only eliminates the need for the addition of exogenous electroactive indicators, but also effectively avoids the interference of complex biological samples with the signal reaction through the sensing - signal separation of BPE.

Key words: Bipolar electrode, Electrochemiluminescence , ; Conductivity regulation, Sensing-signal separation, Urea