Complementary Split Ring Resonator Based Fluidic Microwave Sensor

Abstract

A microwave filter composed of a microstrip waveguide and a complementary split ring resonator is assembled with a microfluidic channel placed below the ground plane. The near field of the complementary split ring resonator is sensitive to the electric permittivity of the fluid, which flows in the channel, therefore this setup can be applied as fluidic sensor. It is shown that the frequency shift of the first two resonances introduced by the complementary double split ring resonator can be utilized for sensing. The advantage of placing the microfluidic channel below the ground plane is that the guided electromagnetic wave can be well separated from the fluidic flow, which can simplify the measurement setup. The electromagnetic design of the sensor is discussed, and a prototype is presented. Simulations for different water temperatures reveals the sensitivity of the setup.