Optical device for non-invasive continuous monitoring of blood glucose level and HbA1c concentration

A sensor device for in-vivo use and continuous monitoring of a glucose concentration and a glycated hemoglobin concentration, comprising:

• a total internal reflection element comprising of a top surface, four side surfaces and a bottom or a base surface and is configured to be placed on a skin of a subject to monitor the glucose concentration and the glycated hemoglobin concentration;
• a first near infrared light source is configured to emit a first laser beam at a near-infrared spectral region that encompasses absorption region of a glycated hemoglobin;
• the first near infrared light source is further configured to emit a broadband first probe beam at the near-infrared spectral region selected to measure the glycated hemoglobin in the venous blood, wherein the first laser beam and the broadband probe beam are positioned to be conveyed under the skin through the total internal reflection element;
• a spectrometer and an Optical coherence tomography detector are configured to detect, and analyze a returning reflected broadband probe beam resulting from the probe beam using at least one of a fast Fourier transform and a Hilbert transform of a spectral signal to report a fringe pattern indicating change in the glycated hemoglobin concentration in the venous blood;
• a second mid-infrared laser source including a quantum cascade laser is configured to emit a mid-infrared region laser beam in a spectral region that encompasses an absorption band of the glucose and is positioned to enter the total internal reflection element;
• a heterodyne probe laser system that is configured to emit a second probe beam in a predetermined polarization state is positioned to be conveyed through the total internal reflection element and exit after being reflected by the base surface of the total internal reflection element;
• a wire grid polarizer configured to receive the second probe beam reflected by the total internal reflection element and reflect one predetermined polarization state and transmit another predetermined polarization state;
• a phase detector configured to convert the second probe beam from the heterodyne probe laser system into an electric beat signal and read the phase of the electric beat signal as one measure of the glucose concentration in the interstitial fluid;
• a grating element configured to receive the transmitted predetermined polarization state of the second probe beam and diffract that beam, wherein the diffracted beam undergoes phase shift, when a relative displacement occurs between the diffraction element and the received diffracted second probe beam;
• and
• a position sensing detector configured to detect and measure change in position displacement of the diffracted second probe beam as a second measure of the glucose concentration in the interstitial fluid.