SYSTEMS AND METHODS FOR MEASURING RESPIRATORY BIOMETRICS
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.
1 . A method for determining a concentration (Xe) of a gas component in breath exhaled by a subject, the method comprising acts of:
(A) providing an at least partially enclosed compartment, adapted to hold a mixture of air exhaled by a subject and ambient air, the compartment allowing for air travel along a flow path such that in response to exhalation by the subject, at least a portion of exhaled air flows into the compartment via the flow path, and in response to inhalation by the subject, air flows out of the compartment via the flow path;
(B) receiving one or more readings, by at least one sensor disposed in, or in fluid communication with, the compartment, of the concentration of the gas component;
(C) based at least in part on the one or more readings, determining a time-averaged value X of the concentration of the gas component;
(D) based at least in part on the time-averaged value X of the concentration of the gas component, determining the concentration Xe of the gas component in air exhaled by the subject; and
(E) determining at least one respiratory or metabolic value concerning the subject based at least in part on the determined concentration Xe of the gas component.
2 . The method of claim 1 , wherein determining the concentration Xe in the act (D) employs a linear function of X comprising a multiplicative coefficient of X equal to 2, reflecting substantially equal amounts of exhaled and ambient air being exposed to the at least one sensor over the time period.
3 . The method of claim 1 , wherein determining the concentration Xe in the act (D) 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 ambient air being exposed to the at least one sensor over the time period.
4 . The method of claim 1 , wherein determining the concentration Xe in the act (D) 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 (Xe) 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 Xe 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 Xe 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 Xe 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 Xe 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, comprising:
an at least partially enclosed compartment, adapted to hold a mixture of air exhaled by a subject and ambient air, the compartment allowing for air travel along a flow path such that in response to exhalation by the subject, at least a portion of exhaled air flows into the compartment via the flow path, and in response to inhalation by the subject, air flows out of the compartment via the flow path;
at least one sensor, disposed in, or in fluid communication with, the compartment, configured to measure a concentration of a gas component in the flow path; and
at least one processor programmed to:
receive, over time, one or more readings by the at least one sensor of the concentration of the gas component;
based at least in part on the one or more readings, determine a time-averaged value X of the concentration of the gas component;
based at least in part on the time-averaged value X of the concentration of the gas component, determine the concentration Xe of the gas component in air exhaled by the subject; and
determine at least one respiratory or metabolic value concerning the subject based at least in part on the determined concentration Xe of the gas component in the air exhaled by the subject.
12 . The method of claim 11 , wherein the at least one processor is programmed to determine the concentration Xe using a linear function of X comprising a multiplicative coefficient of X equal to 2, reflecting substantially equal amounts of exhaled and ambient air being exposed to the at least one sensor over the time period.
13 . The system of claim 11 , wherein the at least one processor is programmed to determine the concentration Xe 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 ambient air being exposed to the at least one sensor over the time period.
14 . The system of claim 11 , wherein the at least one processor is programmed to determine the concentration Xe 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.
15 . The system of claim 11 , wherein the flow path comprises a space configured to hold a mix of air exhaled by the subject and ambient air.
16 . The system of claim 11 , wherein the gas component is one of oxygen and carbon dioxide.