Microstrip Resonator Technique for Measuring Dielectric Permittivity of Liquid Solvents and for Solution Sensing

A simple planar circuit method has been applied for the first time to measure the dielectric permittivity of solvents in trace amounts (0.3mul to 5mul) at multiple frequencies. It has been shown that due to the high sensitivity of the device it can be used effectively to characterize the quantity of dissolved impurities in a given solution. For relative dielectric permittivity measurements a square ring resonator prototype has been fabricated. Three solvents have been used as standards to measure seven unknowns at 1GHz, 2GHz and 3GHz. The measured results show excellent agreement with theoretical. An open loop resonator has also been developed to characterize glucose-water solutions of various concentrations at 1GHz.