Abstract: In order to meet the challenging requirements of high-precision measurement of internal structures such as deep holes and grooves in high-end/cutting-edge instruments and equipments such as inertial gyroscopes and aerospace engines using non-contact sensing methods,research has been conducted on the sensitive mechanisms in the metal/air/metal micro-interface formed by probing a measured part with a spherical sensitive element.From the perspectives of the electron transport mechanism in the thin layer of insulating medium and the change of the insulating medium properties leading to electron transport,various electron transport mechanisms,including electron tunneling,were analyzed in terms of formation conditions and current density characteristics.It was revealed that the Fowler-Nordheim tunneling effect was the main mechanism for the generation of sensing current in the metal/air/metal micro-interface formed by probing with the spherical sensitive element,laying the foundation for exploring a new principle of three-dimensional non-contact nano-sensing methods.

Key words: Electron tunneling, Metal-Air-Metal microinterfaces, Microsphere probing, Nano-sensing