Patent ID: 11937906
Assignee: ALIO, INC.
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 8:
9. A system for monitoring blood flow metrics comprising:
a patch of a flexible substrate configured to attach to an area of skin over a blood vessel;
a plurality of light emitting diodes (LEDs) arranged on the substrate to form a R×C matrix and a row of C photodetectors (PDs) disposed on the substrate substantially in parallel with R rows of LEDs extending to form C columns substantially co-linear with each photodetector;
an optical signal interface mounted on the substrate and configured to drive each LED for an on-period and to input an optical signal at one of the photodetectors during the on-period to receive an intensity measurement for an optical path, OPrc, formed by LEDs in rows r=1 to R in columns c=1 to C and the photodetector receiving the optical signal;
a processing system comprising a memory for storing program instructions for execution by the processing system to:
determine an AC component, Irc,AC, and a DC component, Irc,DC, as a function of a plurality of intensity measurements, Irc, for each optical path, OPrc, over a period of time;
determine an AC-to-DC component ratio, R_(r,c)=I_(rc,AC)/I_(rc,DC), for each optical path;
determine a plurality of ratio-of-ratios, RoR values, by dividing a first plurality of selected AC-to-DC component ratios by a second plurality of selected AC to DC component ratios; and
using at least a subset of the RoR values to determine a biological metric;
the plurality of LEDs is a plurality of infrared (IR) LEDs for emitting light at a first wavelength in the infrared, the system further including a plurality of red LEDs for emitting light at a second wavelength in the red,
where each of the plurality of red LEDs is arranged on the substrate adjacent to each of the plurality of IR LEDs in the R×C matrix,
where the optical signal interface is configured to drive each IR LED and each red LED independently to form independent IR and red optical paths, OPIR,r,c and OPred,r,c,
where the processing system is configured to measure an oxygen saturation metric by:
receiving a plurality of red intensity measurements, Ired,rc, corresponding to the optical paths, OPred,rc, and a plurality of IR intensity measurements, IIR,rc, corresponding to the optical paths, OPIR,rc, for a period of time to receive a plurality of intensity measurements for each optical path at each wavelength;
determining a red AC component, Ired,rc,DC, and a red DC component, Ired,rc,DC, as a function of the plurality of intensity measurements, Irc, for each red optical path, OPred,rc, over the period of time;
determining an IR AC component, IIR,rc,AC, and an IR DC component, IIR,rc,DC, as a function of the plurality of intensity measurements, Irc, for each IR optical path, OPIR,rc, over the period of time;
determining a red AC-to-DC component ratio,, R
    
     red
     ,
     r
     ,
     c
    
   
   =
   
    
     I
     
      red
      ,
      rc
      ,
      
       a
       ⁢
       c
      
     
    
    
     I
     
      red
      ,
      rc
      ,
      dc
     
    
   
  
  ,, for each red optical path;

determining an IR AC-to-DC component ratio,, R
    
     IR
     ,
     r
     ,
     c
    
   
   =
   
    
     I
     
      IR
      ,
      rc
      ,
      
       a
       ⁢
       c
      
     
    
    
     I
     
      IR
      ,
      rc
      ,
      dc
     
    
   
  
  ,, for each IR optical path;

determining a plurality of composite ratio-of-ratios by dividing each of either red or IR AC-to-DC component ratios by each of either IR or red AC-to-DC component ratios until all of the red and IR AC-to-DC components are incorporated;
determining a plurality of ratio-of-ratios, RoR values, by dividing a first plurality of selected composite ratio-of-ratios by a second plurality of selected composite ratio-of-ratios; and
using at least a subset of the RoR values to determine a biological metric.