A lift-off routine in the VersaStudio software was employed to perform the SECM images. The pretreated tissue samples were immersed in an electrolyte containing 2 mM FcMeOH, 1 mM H2O2, and 50 mM PB, pH 5.5. The soft gold electrode was scanned at a speed of 35 μm/s. A voltage of -0.2 V was applied to reduce FcMeOH + generated from HRP. The measurement delay interval is 0.1 s. First, we checked the cyclic voltammetry to ensure the quality of the soft microelectrode. Then, the probe was scanned in the x-direction (x line scan) in contact mode to investigate the oral cancer tissues. Finally, the XY area mode was selected to image the sample and analyze the distribution of biomarkers.