Inline Liquid Concentration Measurement in Nanoliter Volume Using Fiber-Optic Low-Coherence Interferometry

A method for inline measurement of composition of binary liquid mixture in a nanoliter volume is presented. Low-coherence interferometric technique, based on fiber-optic Mach-Zehnder interferometer, is applied for measuring the liquid refraction index, from which its volume fractions are found. The accuracy of volume fractions measurement, of about , was predominantly determined by the accuracy of reading the position of mechanical scanner. The data rate of about 1.5 Hz was also limited by mechanical scanning.