Fig. 4. Analysis of the potential-corrected cross-points under various tip–bulk concentration gradient combinations. The error bars on each point show the standard deviations from five repeated scans under each condition. Between each asymmetric concentration measurement, symmetric ones with the same tip concentration were measured to validate the efficacy of loading and replacing the solutions, particularly inside the tip. Data from repeated measurements in the same concentration combination (both symmetric and representative asymmetric) are circled to highlight the reproducibility of the measurements.
