Continuous noninvasive measurement of analyte concentration using an optical bridge

A method for measuring an analyte in blood within tissue of a subject, comprising:

• directing a radiation beam at the tissue, the beam including at least two periods of radiation having different wavelengths, the analyte having different absorption coefficients for the two different wavelengths;
• detecting the beam with a detector when the tissue is in a first blood state having a first amount of blood, wherein the detector is configured to generate an output signal proportional to an intensity of the beam at each of the two different wavelengths;
• obtaining an estimate of the first amount of blood;
• detecting the beam with the detector when the tissue is in a second blood state having a second amount of blood, wherein the tissue transitions from the first blood state to the second blood state by a pulse from a heartbeat of the subject;
• obtaining an estimate of the second amount of blood;
• and
• determining an estimate of a concentration of the analyte in the blood based on the output signal, the estimate of the first amount of blood, and the estimate of the second amount of blood.

A method for measuring an analyte in a fluid within a sample, comprising:

• directing a radiation beam at the sample, the beam including at least two periods of radiation having different wavelengths, the analyte having different absorption coefficients for the two different wavelengths;
• detecting the beam with a detector when the sample is in a first sample fluid state having a first amount of fluid, wherein the detector is configured to generate an output signal proportional to an intensity of the beam at each of the two different wavelengths;
• obtaining an estimate of the first amount of fluid;
• detecting the beam with the detector when the sample is in a second sample fluid state having a second amount of fluid, wherein the sample transitions from the first sample fluid state to the second sample fluid state by pulsations of the sample;
• obtaining an estimate of the second amount of fluid;
• and
• determining estimates of a concentration of the analyte in the fluid for a predetermined number of pulsations based on the output signals, the estimate of the first amount of fluid, and the estimate of the second amount of fluid.