Interferometric optical sensor for measuring glucose concentration

With a specially designed probe, the phase difference between s and p polarization of light reflected under surface-plasmon resonance is measured by use of a common-path heterodyne interferometer. For specific ratios of phase difference to glucose concentration, the glucose concentration can be estimated as a function of the measured phase data. A prototype was set up to demonstrate the feasibility of this sensor, which was experimentally tested in the range 40–500 mg/dl with a small quantity of solution and had a measurement resolution of 1.41 mg/dl at 25 °C.