Systems and methods for measuring respiratory biometrics

Abstract

Some embodiments are directed to a self-contained breathing mask for measuring and monitoring the breath of a human subject. The mask may be lightweight, self-contained, and physically untethered to any test or measurement equipment, providing the subject full mobility, and allowing him/her to perform almost any daily activity during use. The mask may include integrated sensors for measuring properties of the subject's breath, over any length of time, providing respiratory information like breath count, rate and volume, oxygen consumption, and carbon dioxide production, as well as various biometric information.

What is claimed is: 
     
         1 . A method for determining a concentration (X e ) of a gas component in breath exhaled by a subject, the method being for use in a system comprising a flow path through which flows air exhaled by the subject and air to be inhaled by the subject, the flow path comprising at least one sensor configured to measure the concentration of the gas component, the method comprising acts of:
 (A) receiving a plurality of readings by the at least one sensor of the concentration of the gas component;   (B) based at least in part on the plurality of readings, determining a time-averaged value X of the concentration of the gas component;   (C) based at least in part on the time-averaged value X of the concentration of the gas component, determining the concentration X e  of the gas component in air exhaled by the subject; and   (D) determining at least one respiratory or metabolic value concerning the subject based at least in part on the determined concentration X e  of the gas component.   
     
     
         2 . The method of  claim 1 , wherein determining the concentration X e  in the act (C) employs a linear function of X comprising a multiplicative coefficient of X equal to 2, reflecting similar amounts of exhaled and inhaled air being exposed to the at least one sensor over the time period. 
     
     
         3 . The method of  claim 1 , wherein determining the concentration X e  in the act (C) employs a linear function of X comprising a multiplicative coefficient of X that is not equal to 2, reflecting an asymmetry in amounts of exhaled and inhaled air being exposed to the at least one sensor over the time period. 
     
     
         4 . The method of  claim 1 , wherein determining the concentration X e  in the act (C) employs a linear function of X comprising subtraction of a constant X i  associated with a predetermined concentration of the gas component in ambient air. 
     
     
         5 . The method of  claim 1 , wherein the gas component is one of oxygen and carbon dioxide. 
     
     
         6 . A method for enabling determination of a concentration (X e ) of a gas component in exhaled air without separating the exhaled air from inhaled air, method comprising acts of:
 (A) providing a sensing space configured so as to be in fluid communication with both air exhaled by a subject and air to be inhaled by the subject, such that, when employed by the subject, the sensing space contains a mix of the air exhaled by a subject and air to be inhaled by the subject;   (B) providing at least one sensor in fluid communication with the sensing space; and   (C) providing at least one processor programmed to:
 receive readings by the at least one sensor of the concentration of the gas component; 
 determine a time-averaged value X of the concentration of the gas component; and 
 determine, based at least in part on the time-averaged value X, the concentration X e  of the gas component in air exhaled by the subject. 
   
     
     
         7 . The method of  claim 6 , wherein the at least one processor is programmed to determine the concentration X e  using a linear function of X comprising a multiplicative coefficient of X equal to 2, reflecting similar amounts of exhaled and inhaled air being exposed to the at least one sensor over the time period. 
     
     
         8 . The method of  claim 6 , wherein the at least one processor is programmed to determine the concentration X e  using a linear function of X comprising a multiplicative coefficient of X that is not equal to 2, reflecting an asymmetry in amounts of exhaled and inhaled air being exposed to the at least one sensor over the time period. 
     
     
         9 . The method of  claim 6 , wherein the at least one processor is programmed to determine the concentration X e  using a linear function of X comprising subtraction of a constant X i  associated with a predetermined concentration of the gas component in ambient air. 
     
     
         10 . The method of  claim 6 , wherein the gas component is one of oxygen and carbon dioxide. 
     
     
         11 . A system for enabling determination of a concentration (X e ) of a gas component in exhaled air without separating the exhaled air from inhaled air, the system comprising:
 at least one sensor configured to measure a concentration of the gas component in mixed respiratory air comprising exhaled air and ambient air; and   at least one processor programmed to receive readings by the at least one sensor of the concentration of the gas component in the mixed respiratory air, determine a time-averaged value X of the concentration of the gas component, and determine, as a linear function of X, the concentration X e  of the gas component in air exhaled by the subject.   
     
     
         12 . The system of  claim 11 , wherein the at least one processor is programmed to determine the concentration X e  at least in part by producing a product by multiplying X by 2, and subtracting from the product a constant X i  approximately equal to a concentration of the gas component in ambient air. 
     
     
         13 . The system of  claim 11 , wherein the at least one sensor comprises an oxygen sensor. 
     
     
         14 . The system of  claim 11 , wherein the at least one sensor comprises a CO 2  sensor. 
     
     
         15 . The system of  claim 11 , comprising a mask to which one or more of the at least one sensor and the at least one processor is attached.