SSP based Coplanar Waveguide Filter for Sensing Applications

This paper proposes a compact spoof surface plasmon (SSP) filter for dielectric sensing. The sensor configuration comprises a coplanar waveguide line (CPW) positioned at top of the substrate, while dumbbell-shaped metallic SSP transmission line is etched at the bottom ground plane. The magnetic field of the CPW effectively couples with the SSP line, wherein defects within the SSP structure induce stop bands, concentrating energy for dielectric sensing. These defects amplify electromagnetic field interactions, leading to frequency changes. Placing a sample where the electric field is maximal allows effective material interaction. The sensor, validated through simulations in CST-MWS, conforms to planar geometry for easy integration into modern RF systems and the sensor is experimentally tested in the GHz frequency range with varied dielectric constants demonstrates the sensor's ability to differentiate samples possessing closely spaced dielectric constants. This compact design exhibits high sensitivity extending to biosensing applications.