Fig. 6: Tests of long-term electrochemical stability and experiments of real-time single-cell intracellular pH detection of DLC-UME.

a Schematic diagram of three-electrode system for electrochemical characterization of the UME. b Impedance-frequency curves of the DLC-UME under different aging time. c CV curves of the DLC-UME under different aging time. d Curves of the changes in current and impedance within 60 days. e Microscopic images before and after UME insertion into a cell. f Microscopic images of three cells inserted by the UME. g Equivalent circuit diagram of the UME inserted into the cytoplasm in a dual electrode system. h Potential curves and corresponding pH curves of the DLC-UME when the UME is sequentially inserted from extracellular to intracellular of the three cells in DMEM in f. i Potential curves and corresponding pH value inside and outside the cell 1 before and after adding NaOH into the DMEM