Abstract: A method may include directing a radiation beam at a sample, the beam including two periods of radiation having different wavelengths, an analyte in a fluid within the sample having different absorption coefficients for the two different wavelengths, detecting the beam with a detector when the sample is in a first fluid state, the detector configured to generate an output signal proportional to an intensity of the beam at each of the two different wavelengths, detecting the beam with the detector when the sample is in a second fluid state, the sample transitioning from the first fluid state to the second fluid state by a pulsation of the sample, obtaining estimates of an amount of fluid at the first and second fluid states, and determining an analyte concentration estimate based on the output signal and the estimate of the amount of fluid at the first and second fluid states.

Abstract: An improved method for non-invasively measuring a concentration of a target analyte dissolved in a fluid flowing through a sample is presented. It includes directing a probe beam of electromagnetic radiation, having time multiplexed components of different wavelengths, where at least one of the time-multiplexed components consists of two different simultaneous wavelengths through the sample and measuring the difference of the absorption of the radiation of the time-multiplexed components at different sample states. During sample state changes, the amount of fluid containing the target analyte within the sample is changing, varying the total amount of target analyte in the sample, and the absorption properties of the sample. The sample states may be produced by compressing and uncompressing the tissue sample. The method is useful in measuring the concentration of a target analyte, such as glucose, in tissue containing blood.