Highly Sensitive Microwave-Based Biosensor for Electrolytic Level Measurement in Water

This paper presents a microwave microfluidic sensor for determination of electrolytic content in the distilled water. The sensor is made of series LC resonator, which is connected in parallel with a microstrip transmission line. A microfluidic channel is designed to deliver the test liquid samples to the most sensitive area of the device. The operation principle of the device is based on the change of the transmission coefficient (S
₂₁
) level as function of the electrolytic concentration, where the distilled water is considered as a reference sample. The sensing principle is validated by testing the sensor with NaCl electrolytic solutions of various concentrations. The measurements show a maximum sensitivity of 0.1 g/L.