Feasibility Study on Direct Counting of Viruses and Bacteria by Using Microelectrode Array

A concept of a system is proposed for counting viruses (∼100 nm) and bacteria (∼1 µm) using a sensor array with microelectrodes that are almost the same size as the target. A finite element method simulation theoretically clarified that single targets can be detected using the microelectrode as an 8 % increase in resistance in impedance spectroscopy and a 10 % decrease in redox current in amperometry. In experiments, the polystyrene beads used as model targets were successfully detected in both impedance spectroscopy and amperometry. The results showed that even a 100‐nm target can be detected by optimizing measurement conditions.