Patient sensor for optical cerebral oximeter and the like

• US 5,217,013 A
• Filed: 06/06/1991
• Issued: 06/08/1993
• Est. Priority Date: 10/14/1983
• Status: Expired due to Term

• Current Assignee: Somanetics Corporation (Medtronic Plc)
• Original Assignee: Somanetics Corporation (Medtronic Plc)
• Inventors: Klose, Peter H., Lewis, Gary D., Messing, Wayne P.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): NASSER, ROBERT L
• Application Number:
  US07/711,452
• Time in Patent Office: 733 Days
• Field of Search: 128/664-666, 128/633-634, 356/40, 356/41
• US Class Current: 600/342
• CPC Class Codes: A61B 5/0091 for mammography
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/4312 Breast evaluation or disorder diagnosis A61B5/0091 takes precedence
• CPC Class Codes: A61B 5/6814 Head

Abstract

A sensor for use in medical patient examination and monitoring by spectrophotometric apparatus, including a main body having a soft, resilient outer cover on at least one side for conformably contacting a selected area on the patient, in particular the forehead, also having and an electro-optical light source and a plurality of electro-optical light detectors spaced from the source and from one another, and exposed to the selected site on the patient by light-transmissive passages extending through the resilient cover, in which the resilient cover is formed of a thin, softly compressible member of light-absorbing and moisture-transmissible material, preferably of resilient cellular polymeric foam.

Claims

1. An optical sensor unit for use as a patient interface device in conducting in vivo spectrophotometric examination procedures, comprising in combination:

a body having at least limited longitudinal flexibility and a softly resilient outer cover carried on at least one side, for comfortably and contiguously contacting a selected surface area on a patient;

an electro-optical light source carried with said body and exposed through said resilient cover, for emitting light of at least two selected wavelengths and introducing such light into said patient through said surface area;

a plurality of electro-optical light detectors carried with said body and maintained at particular spacings from one another and from said light source thereby, said detectors being exposed through said resilient cover to receive light from said patient resulting from said introduced light from said source;

electrical conductors coupled to said light source and light detectors to energize said source and to convey output signals from said detectors representative of the resultant light received from said patent, said conductors extending outwardly from said body for coupling to a remotely located signal-processing device;

said resilient cover comprising a thin, softly compressible member of light-absorbing and moisture-transmissible material which helps isolate said source from said detectors with respect to light traveling directly therebetween as well as from ambient light while also acting to convey moisture away from said patient surface area, to enhance the fidelity and accuracy of said detector output signals.

2. The optical sensor unit as recited in claim 1, further including means for shielding said light detectors and at least portions of their said electrical conductors from ambient sources of electrical noise and/or like distortion, to help maintain the fidelity of said signals to the detected representative light;

said shielding means including at least one thin layer of lightly flexible and longitudinally resilient, electrically conductive sheet metal, said layer overlying said body throughout the portion thereof carrying said detectors to provide a shielding for them and the immediately adjacent electrical conductors to which they are directly coupled;

wherein said thin layer of said sheet metal is disposed on the inside of said body and extends alongside at least portions of said detectors.

3. The optical sensor unit as recited in claim 2, wherein said means for shielding further includes a sheath substantially surrounding at least portions of said conductors extending outward beyond said body.

4. The optical sensor unit as recited in claim 3, wherein said thin sheet member is electrically coupled to said sheath.

5. The optical sensor unit as recited in claim 2, wherein said body includes a circuit board underlying and supporting said detectors, said circuit board comprising a generally planar member carrying electrically-conductive strips comprising at least in part said conductors coupled to said detectors, said thin sheet metal shielding member overlying at least portions of said circuit board adjacent said detectors.

6. The optical sensor unit as recited in claim 5, wherein said means for shielding includes a thin sheet-like member which substantially envelopes said circuit board and is disposed in juxtaposition to at least portions of said detectors.

7. The optical sensor unit as recited in claim 6, wherein said thin sheet-like shielding member overlies the side of said circuit board carrying said detectors and is apertured to expose the latter for operation.

8. The optical sensor unit as recited in claim 5, wherein said thin sheet member is substantially coextensive with and overlies said circuit board and said conductive strips.

9. The optical sensor unit as recited in claim 8, wherein said means for shielding further includes a sheath surrounding at least portions of said conductors extending outwardly from said body, and wherein said thin sheet member is electrically coupled to said sheath.

10. The optical sensor unit as recited in claim 5, wherein said shielding means comprises a sheet of conductive foil wrapped about and substantially enveloping said circuit board and its conductor strips.

11. The optical sensor unit as recited in claim 1, wherein said light detectors comprise photodiodes having a sensitivity on the order of about 500 milliamps per watt, and are of a low-noise type.

12. The optical sensor unit as recited in claim 1, wherein said light source comprises at least one L.E.D. having an output on the order of about three milliwatts and an output light solid angle of about ninety degrees.

13. The optical sensor unit as recited in claim 1, wherein said amplifier unit is located at least three feet away from said electro-optical light source and detectors.

14. The optical sensor unit as recited in claim 1, wherein said source and said detectors comprise low-power components requiring only low levels of current and voltage essentially negligible to human comfort and safety;

and electric signal amplification means coupled to receive said output signals from said light detectors via their said electrical conductors for amplification of said signals prior to processing thereof, said amplification means comprising an amplifier unit which is physically located between said patient and said signal-processing device, to protect said patient from higher power levels.

15. The optical sensor unit as recited in claim 1, wherein said body further includes a flexible sheet disposed on the rearward side thereof opposite the cover contacting said patient, to sandwich at least portions of said electro-optical source and detectors therebetween, said sheet being of light-reflective material and generally opaque in nature to further isolate said source and detectors from ambient light.

16. The optical sensor unit as recited in claim 1, wherein said cover comprises a resilient foam material having vapor-transmissive characteristics.

17. The optical sender-receiver unit as recited in claim 16, wherein said foam is of open-cell form.

18. The optical sender-receiver unit as recited in claim 16, wherein said foam is black in color and highly light-absorbing.