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 sensor module configured to be worn by a subject, the sensor module comprising:
a housing;
at least one optical emitter and at least one optical detector supported by the housing; and
a stabilizer member movably supported by the housing, wherein the stabilizer member comprises a portion that extends through a first aperture in the housing and that is configured to engage a body of the subject;
wherein the at least one optical emitter is configured to direct light through a second aperture in the housing and into the body of the subject via a first optical pathway and to direct light at a portion of the stabilizer member within the housing along a second optical pathway, and
wherein the at least one optical detector is configured to detect light from the body of the subject via a third aperture in the housing and generate a first signal comprising subject physiological information, and wherein the at least one optical detector is configured to detect light scattered by the stabilizer member and generate a second signal comprising subject motion information.
2. The sensor module of claim 1 , wherein the at least one optical emitter comprises at least one first optical emitter configured to direct light into the body of the subject via the first optical pathway, and at least one second optical emitter configured to direct light at the stabilizer member along the second optical pathway.
3. The sensor module of claim 1 , wherein the first and second optical pathways are optically isolated from each other, and/or wherein the housing comprises substantially opaque material.
4. The sensor module of claim 1 , further comprising a light guide supported by the housing and wherein the at least one optical emitter is configured to direct light into the body of the subject via the light guide.
5. The sensor module of claim 4 , wherein the light guide comprises a plurality of portions that extend through respective apertures in the housing and are configured to engage portions of the body of the subject.
6. The sensor module of claim 1 , further comprising at least one signal processor configured to process the first and second signals so as to remove motion artifacts from the first signal.
7. The sensor module of claim 1 , wherein the sensor module is configured to be positioned at or within an ear of the subject, secured to an appendage of the subject, integrated within a wearable device, and/or integrated within clothing worn by the subject.
8. The sensor module of claim 1 , further comprising a blood flow stimulator configured to increase blood perfusion at a location of the body of the subject receiving light via the first optical pathway.
9. A method of removing motion artifacts from a biometric signal generated by a sensor module worn by a subject, wherein the sensor module includes a stabilizer member, at least one optical emitter, and at least one optical detector, the method comprising:
directing light from the at least one optical emitter into a body of the subject via a first optical pathway;
directing light from the at least one optical emitter at the stabilizer member along a second optical pathway;
detecting light from the body of the subject and generating a first signal comprising subject physiological information;
detecting light scattered by the stabilizer member and generating a second signal comprising subject motion information; and
processing the first and second signals so as to remove motion artifacts from the first signal.
10. The method of claim 9 , 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 stabilizer member along the second optical pathway.
11. The method of claim 9 , 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 physically modulated light scattered by the stabilizer member and generate a second signal comprising subject motion information via the second optical detector.
12. The method of claim 9 , wherein the first and second optical pathways are optically isolated from each other.