Novel physical sensors using evanescent microwave probes

Abstract

Local probes, such as electron and photon tunneling, atomic force, and capacitance probes, are excellent sensing means for displacement and other related sensors. Here we introduce applications of a new local probe using evanescent microwave probe (EMP) in displacement sensing with a very high vertical spatial resolution (0.01 μm at 1 GHz), very high bandwidth (100 MHz), and stability. The EMP has been used in the characterization and mapping of the microwave properties of a variety of materials in the past and its application in gas sensing and thermography was recently explored and reported. The interesting feature of the EMP is that its characteristics can be easily altered for a specific sensing application by changing its geometry and frequency of operation.