Microwave determination of liquid mixing ratio for microfluidics

This paper presents a microwave-based method for extracting liquid mixing ratio of two unknown liquids in microfluidics systems. The method is based purely on measurements, and no electromagnetic simulations nor liquid permittivity models are required. The method was successfully evaluated for three mixtures of isopropanol and water with varying concentration. The maximum error of extracting mixing ratio is 6.09%, which is probably mostly caused by fast isopropanol evaporation.