Photoplethysmographs

• US 4,015,595 A
• Filed: 09/15/1975
• Issued: 04/05/1977
• Est. Priority Date: 09/15/1975
• Status: Expired due to Term

• Current Assignee: Benjamin J. Malvern Jr
• Original Assignee: Benjamin J. Malvern Jr
• Inventors: Benjamin, J. Malvern Jr.
• Primary Examiner(s): Howell, Kyle L.
• Application Number:
  US05/613,301
• Time in Patent Office: 568 Days
• Field of Search: 128/2.05 V, 128/2.05 P, 128/2.05 T, 128/2 L, 128/2 A, 356/39
• US Class Current: 600/479
• CPC Class Codes: A61B 5/02427 Details of sensor

Abstract

A photoplethysmograph probe including a light source, a photo-sensitive cell and a light control film positioned in front of the light source and photo-sensitive cell for collimating the light emitted from the light source and reflected back to the photo-sensitive cell.

Claims

1. A probe for use with a photoplethysmograph for the measurement of peripheral pulsatile blood flow comprising:

a casing having a window therein,

a light source and a photo-sensitive cell mounted in said casing to overlie said window,

said light source being arranged to direct light through said window,

said photo-sensitive cell being arranged adjacent said light source to respond to light passing through said window as it is reflected from a field in line with said light source, and

a light control film mounted to extend across said window for collimating the light emitted from said light source to direct the same toward said field and for collimating the light reflected to said photo-sensitive cell and passing through said window.

2. A probe according to claim 1 wherein said light control film is made of a clear cellulose acetate butyrate film.

3. A probe according to claim 2 wherein said light source comprises an incandescent lamp.

4. A probe according to claim 1 wherein said light source comprises an incandescent lamp.

5. A probe according to claim 1 wherein said light source is constructed to emit light in a narrow band of green wave lengths.

6. A probe according to claim 2 wherein said light source is constructed to emit light in a narrow band of green wave lengths.

7. A probe for use with a photoplethysmograph for the measurement of peripheral pulsatile blood flow by application to the surface of the patient'"'"'s skin comprising:

a casing having a window therein,

a light source and a photo-sensitive cell mounted in said casing to overlie said window,

said light source being arranged to direct light through said window to a field of blood,

said photo-sensitive cell being arranged adjacent said light source to respond to light reflected from a field of blood in line with said light source, and

said light source being constructed to emit light in a narrow band of green wave lengths so that substantially all of said light is absorbed by the blood so as to minimize the motion artifact.