Reconfigurable Dual-Type Sensor for Resonant and Broadband Liquid Materials Characterization

A novel sensor is proposed featuring a reconfigurable dual-type operation offering both resonant and broadband liquid materials characterization. Advantageously, both types of measurements are carried out for the same liquid sample without disconnecting the measurement setup. The sensor is realized in Printed Circuit Board (PCB) technology as a microstrip transmission line (MSL) loaded with a Complementary Split Ring Resonator (CSRR) with an accompanying 3D printed liquid container. The default type is the resonant measurement offering a robust characterization in the vicinity of a single frequency well suited for the detection of even small material parameters change from the resonant frequency and quality factor deviation in the reflection coefficient of the CSRR loaded MSL submerged in the liquid. For broadband type measurement, the CSRR is shorted with a stamper to create a uniform ground plane while the relative permittivity of the liquid is determined from the S-parameters of an MSL having a dielectric cover on top. An exemplary sensing setup was developed with resonance at 1.5 GHz, fabricated, and experimentally tested for a set of alcohol samples. The obtained results proved the features of the proposed technique.