Methods and apparatus for detecting motion via optomechanics
Methods and apparatus are described for facilitating the extraction of cleaner biometric signals from biometric monitors. A motion reference signal is generated independently from a biometric signal and then the motion reference signal is used to remove motion artifacts from the biometric signal.
1. A method of removing motion artifacts from a biometric signal generated by a sensor module worn by a subject, wherein the sensor module includes at least one optical emitter and at least one optical detector, the method comprising:
directing light from the at least one optical emitter:
at a first light guide along a first optical pathway, the first light guide configured to cause the light directed along the first optical pathway to enter into a body of the subject; and
at a second light guide along a second optical pathway, the second light guide configured to cause the light directed along the second optical pathway to be reflected from a skin surface of subject;
detecting light that has entered the body of the subject along the first optical pathway from the body of the subject and generating a first signal comprising subject physiological information via the at least one optical detector;
detecting light reflected by the skin surface of the subject along the second optical pathway and generating a second signal comprising subject motion information via the at least one optical detector; and
processing the first and second signals to remove motion artifacts from the first signal using the subject motion information.
2. The method of claim 1 , wherein the at least one optical emitter comprises first and second optical emitters, and wherein the method comprises directing light from the first optical emitter into the body of the subject via the first optical pathway, and directing light from the second optical emitter at the body along the second optical pathway.
3. The method of claim 1 , wherein the at least one optical detector comprises first and second optical detectors, and wherein the method comprises detecting light from the body of the subject and generating a first signal comprising subject physiological information via the first optical detector, and detecting light reflected by the skin surface and generating a second signal comprising subject motion information via the second optical detector.
4. The method of claim 1 , wherein the first and second optical pathways are optically isolated from each other.
5. The method of claim 1 , wherein the first optical pathway is configured such that light therefrom is directed towards the body at a first angle, wherein the second optical pathway is configured such that light therefrom is directed towards the body at a second angle different from the first angle, wherein the first angle encourages absorption of light from the first optical pathway by the body, and wherein the second angle discourages absorption of light from the second optical pathway by the body.
6. A device for sensing physiological and body motion information, the device comprising:
at least one optical emitter configured to emit light along at least two light pathways;
a first light guide configured to direct light along a first pathway that, wherein one pathway is configured to sense body motion information by sensing light scattered from a skin surface of the body, and wherein; and
a second light guide configured to direct light along a second pathway that at another pathway is configured to sense physiological information by sensing light that has entered the body and scattered from the body by blood flow;
a detector configured to:
detect light along the first pathway that is reflected by the skin surface of the subject and generate a first signal comprising subject motion information; and
detect light along the second pathway from the body of the subject and generating a second signal comprising subject physiological information; and
a processor configured to process the first and second signals to determine a physiological parameter of a user.
7. The device of claim 6 , wherein the device is a wearable device.
8. The device of claim 6 , wherein the device is configured to be positioned at or within an ear of the subject.
9. The device of claim 6 , wherein the device is configured to be secured to an appendage of the subject, integrated within a wearable device, integrated within clothing worn by the subject or a combination thereof.