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

A sensor device for in-vivo monitoring of a glucose concentration in interstitial fluid and of a glycated hemoglobin concentration in venous blood of a subject, the sensor device comprising:

• a total internal reflection element comprising a top surface, two pairs of opposing side surfaces and a base surface and configured to be placed on a skin of the subject;
• a near infrared laser light source configured to emit a near-infrared laser beam at a near-infrared spectral region that encompasses an absorption region of glycated hemoglobin;
• a probe light source configured to emit a first probe beam at the near-infrared spectral region, the near-infrared laser beam and the first probe beam being configured to be transmitted under the skin through the top surface of the total internal reflection element;
• a spectrometer and an optical coherence tomography detector configured to, detect and analyze a returning reflection of the first probe beam using at least one of a fast Fourier transform and a Hilbert transform of a fringe pattern spectral signal indicating change in the glycated hemoglobin concentration;
• a mid-infrared laser source configured to emit a mid-infrared laser beam in a spectral region that encompasses absorption bands of glucose, and configured to enter through the top surface of the total internal reflection element;
• a heterodyne probe laser system that is configured to emit a second probe beam in a predetermined polarization state and that is positioned to be conveyed through one of the two pairs of side surfaces total internal reflection element and to exit through an opposite side surface after being reflected by the base surface of the total internal reflection element;
• a reflective optical element configured to reflect the second probe beam reflected by the base surface of the total internal reflection element;
• a beam splitting optical element configured to partially reflect and partially transmit the second probe beam after having been reflected by the reflective optical element;
• a phase detector configured to convert the second probe beam into an electric beat signal and determine a phase of the electric beat signal as a first measure of the glucose concentration;
• and
• a position sensing detector configured to detect and measure a change in position displacement of the second probe beam as a second measure of the glucose concentration.