Method and apparatus for hemodynamically characterizing a neurological or fitness state by dynamic light scattering (DLS)

A method for optically measuring state and/or status information or changes therein about a warm-blooded subject, the method comprising:

• a. illuminating a portion of the subject's skin or tissue by a VCSEL (vertical cavity surface emitting laser) or a diode laser to scatter partially or entirely coherent light off of the subject's moving red blood cells (RBCs) to induce a scattered-light time-dependent optical response;
• b. receiving the scattered light by a photodetector(s) to generate an electrical signal descriptive of the induced scattered-light time-dependent optical response or an AC component thereof;
• c. processing the scattered-light-optical-response-descriptive electrical signal or a derived-signal thereof to compute therefrom at least two or at least three or at least four blood-shear-rate-descriptive (BSRD) signals selected from the BSRD signal group, each blood-rate-descriptive BSRD signal characterized by a different respective frequency-selection profile, the BSRD signal group consisting of the following signals:
• (i) a [sub −200 Hz, ˜300 Hz] BSRD signal;
• (ii) a [˜300 Hz, ˜1000 Hz] BSRD signal;
• (iii) a [˜1000 Hz, ˜4000 Hz] BSRD signal and (iv) a [˜4000 Hz, z Hz] (z>=7,000) BSRD signal;
• d. electronically analyzing features of the at least two or at least 3 or at least 4 BSRD signals of the BSRD signal group;
• e. in accordance with the results of the electronically analyzing of the at least two or at least 3 or at least 4 BSRD signals, computing the state and/or status information or changes therein.

Apparatus for optically measuring state and/or status information or changes therein about a warm-blooded subject the apparatus comprising:

• a. a diode laser or VCSEL configured to illuminate the subject's skin so as to scatter partially or entirely coherent light off of moving red blood cells (RBCs) of the subject to induce a scattered-light time-dependent optical response;
• b. photodetector(s) configured to generate an electrical signal descriptive of the induced scattered-light time-dependent optical response;
• and
• c. electronic circuitry configured to:
• i. process the scattered-light-optical-response-descriptive electrical signal or a derived-signal thereof to compute therefrom one or more blood-shear rate-descriptive (BSRD) signal(s), each BSRD signal characterized by a respective frequency-selection profile;
• ii. electronically analyze features of the BSRD signal(s) of the BSRD signal group;
• iii. in accordance with the results of the electronically analyzing of the at least two frequency-interval-specific shear-rate-descriptive signals, perform at least one of the following of subject-status-classification operation(s):
• A. classify a stress-state (e.g. type of stress or level of stress) of the subject;
• B. classify a mood-state of the subject;
• C. classify a stress-resistance of the subject;
• D. classify a cardiovascular fitness-status of the subject;
• wherein a frequency-selection profile of the BSRD(s) signal is computed dynamically so to adaptively maximize a prominence of a predetermined non-pulsatile physiological signal within the BSRD(s) and/or wherein the classification operation is performed dynamically so that a weight assigned to a BSRD signal is adaptively determined to increase a weight of BSRD signal(s) whose frequency-selection profile correspond to a greater prominence of the predetermined non-pulsatile physiological signal at the weight-expense of BSRD signal(s) whose frequency-selection profile correspond to a lesser prominence of the predetermined non pulsatile physiological signal.