Determination of sugar concentration in aqueous solutions using ultra-wideband microwave impedance spectroscopy

This paper describes the concept of combining pseudo random noise sequences and a microstrip sensor for measurement of glucose in aqueous solutions. The propagation characteristics of the microstrip sensor are variables dependent of the glucose concentration in contact with. These are measured as a function of the frequency using a maximal length sequence that in contrast with other frequency sweep based methods, offers a shorter measurement time. The presented system uses low-power microwave energy over the frequency range between 23 MHz and 12 GHz. With the implemented system glucose concentrations from 5000 mg/dl to 100 mg/dl can be estimated by detecting the changes of phase on the microstrip sensor. One potential future application for this system is the measurement of blood glucose levels in a noninvasive way.