Microwave Liquid Sensing Based on Interferometry and Microscopy Techniques

Abstract

A microwave technique based on the high spatial resolution of microscopy tools and the unique measurement accuracy of interferometric methods is demonstrated. In particular, we have investigated the sodium chloride concentration in an aqueous solution volume of 144 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> at the test frequency of 2.45 GHz. By measuring the reflection coefficient, we have observed a measurement sensitivity of 78 dB/(mol/l) in the range of 0-0.22 mol/l. This method provides a unique approach for high sensitive liquid sensing applications.