Compared to normal tissues, the current values of cancer tissues were higher (more negative), representing more EGFR in cancer biopsies. Therefore, we speculate that EGFR is a better biomarker than IL-6 in these cases. However, the microelectrodes were fabricated manually, so it was difficult to compare the current values of different experiments. Besides, although the sample-probe distance may be slightly different for each microelectrode, the trend of the x-line scan results was similar. In the x-line scans in figure and figure 2, the current value over the cancerous tissue was approximately 400 pA higher than that for the normal tissues. Hence, the slight variation of each microelectrode might cause some bias of the baseline, but it did not affect the results of the measurements.