Microstrip split ring resonator for microsphere detection and characterization

A new microwave microstrip sensor is presented in this paper for microsphere detection and dielectric characterization within a microfluidic channel. This comprises a 2.5 GHz split ring resonator with a 35 μm gap. To validate the sensor, two sizes of polystyrene microspheres (of diameters 15 and 25 μm) were tested. Measurements of changes in resonant frequency and insertion loss of the odd mode were related to the dielectric contrast provided by the microspheres and their host solvent, here water. COMSOL Multiphysics^® was used to model the sensor, and good agreements were found between the simulated and measured results.