Micro- and nanoscale microelectrodes can directly oxidise or reduce cellular metabolites and quantify the concentration of metabolites based on the current value. It is also possible to quantify chemicals that are difficult to oxidise or reduce, such as glucose, by measuring the chemicals produced via enzymatic reactions. We have developed a system that enables the measurement of metabolites on the cell surface by miniaturising the size of these microelectrodes to the level of 1/100 of a single cell. Furthermore, scanning electrochemical microscopy (SECM), which utilises scanning probe microscopy technology to scan the microelectrode on the cell, has developed a simultaneous imaging technique for cell surface topography and metabolites.
　Furthermore, a similar cell surface imaging technique was established for nanopipettes, which are miniaturised glass pipettes used for patch clamping. Nanopipettes are easier to miniaturise than microelectrodes, and a nanopipette with a radius of 50 nm can be used for topography imaging of live cell surfaces with a resolution of 20 nm in the XY direction and 5 nm in the Z direction. Furthermore, a system for simultaneous imaging of pH and topography has been developed by modifying the tip of a glass nanopipette with a pH-sensitive polymer.