Electro-inductive Wave Transmission Line based Microfluidic Microwave Sensor

We propose the use of electro-inductive wave (EIW) transmission lines based on complementary split-ring resonators (CSRR) to implement a differential-mode microwave sensor for biological fluid sensing purposes. Differential-mode operation is achieved by comparing the response of the device loaded with a reference (REF) sample to the one of the sensor loaded with a sample under test (SUT). By this means, any alteration or difference in the SUT as compared to the REF sample (seen as an asymmetry) can be detected. The designed and fabricated device has been validated by considering ethanol and glucose solutions in pure deionized (DI) water. The main relevant aspect of the proposed sensor is the high sensitivity and resolution. Thus, this device is especially useful for the characterization of solute content in very diluted solutions.