Noise shielding for a noninvaise device
A noninvasive physiological sensor for measuring one or more physiological parameters of a medical patient can include a bump interposed between a light source and a photodetector. The bump can be placed in contact with body tissue of a patient and thereby reduce a thickness of the body tissue. As a result, an optical pathlength between the light source and the photodetector can be reduced. In addition, the sensor can include a heat sink that can direct heat away from the light source. Moreover, the sensor can include shielding in the optical path between the light source and the photodetector. The shielding can reduce noise received by the photodetector.
1. A noninvasive optical medical sensor configured to detect light attenuated by body tissue of a patient, the sensor comprising:
a sensor housing comprising:
a detector shell, and
an emitter shell pivotably coupled with the detector shell;
an emitter disposed within the emitter shell and configured to emit light;
a plurality of detectors disposed on a detector submount within the detector shell;
a shielding enclosure disposed within the detector shell, the shielding enclosure comprising:
a metal cage that at least partially encloses the detector, and
a first window in the metal cage, the first window positioned over the detectors and configured to permit at least a portion of the light emitted from the emitter to pass to the detectors; and
a noise shield separate from the shielding enclosure and disposed above the shielding enclosure within the detector shell and below a digit bed shaped to receive tissue, the noise shield comprising:
a glass or plastic sheet comprising an electrically-conductive material configured to reduce noise received by the detectors, and
a second window comprising glass or plastic disposed in the sheet, the second window configured to pass more of the light emitted from the emitter than a portion of the sheet surrounding the second window; and
a partially cylindrical protrusion disposed on the second window, the partially cylindrical protrusion comprising a curved surface shaped to receive tissue, wherein the partially cylindrical protrusion acts as a lens to focus light on the detectors.
2. The sensor of claim 1 , wherein the first window comprises glass or plastic.
3. The sensor of claim 1 , wherein the first window comprises an opening.
4. The sensor of claim 1 , wherein the shielding enclosure is oblong.
5. The sensor of claim 1 , further comprising a cylindrical housing surrounding the detectors.
6. The sensor of claim 1 , wherein the noise shield is supported by the shielding enclosure.
7. The sensor of claim 1 , wherein the sheet further comprises a stop configured to position the tissue within the sensor.
8. The sensor of claim 1 , further comprising a thermistor protruding through the first and second windows and above the noise shield.