INTEGRATED PULSE OXIMETRY SENSOR

• US 20090240125A1
• Filed: 12/05/2005
• Published: 09/24/2009
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Pinter, Robert, Such, Olaf, Lauter, Josef, Mühlsteff, Jens
• Granted Patent: US 8,315,682 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: G01N 2021/3133 with selection of wavelengths before the sample
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 2201/062 LED's
• CPC Class Codes: G01N 2201/0623 Use of a reference LED
• CPC Class Codes: G01N 2201/0625 Modulated LED
• CPC Class Codes: G01N 2201/0627 Use of several LED's for spectral resolution

Abstract

In a medical pulse oximetry sensor (10) at least two light emitting diodes (16, 18) are disposed to emit red light and infrared light through a portion of a subject'"'"'s anatomy with a typically high oxygenated blood throughput. Typically, this area is also relatively narrow, to allow the light to pass through the area with acceptable attenuation, such as a finger or an earlobe. Light emitted from the LEDs (16, 18) is incumbent upon an integrated circuit (22) printed from a single CMOS substrate (21). The integrated circuit (22) includes all preprocessing and post-processing elements needed to convert the detected light signals into a pulse oximetry measurement. These elements include a photodetector (20), a photo pre-amplifier (40), a sampler/holder (42), an analog to digital converter (44), a microprocessor (46) a rangefinder (48), a timing control circuit (50) and an LED control circuit (52). By integrating all pre and post processing functions into the carriage housing (12), the system becomes more efficient, less expensive to manufacture, and more robust to ambient light and x-ray radiation.

Claims

1. A medical pulse oximetry sensor comprising:

a carriage housing adapted to fit snugly about a portion of a subject'"'"'s anatomy with a relatively high oxygenated blood throughput;

a first light emitting diode mounted in the housing for emitting light in the electromagnetic spectrum of the red wavelengths;

a second light emitting diode mounted in the housing emitting light in the electromagnetic spectrum of the infrared wavelengths;

at least one photodiode for detecting incumbent light from the first and second light emitting diodes after the emitted light has passed through a blood oxygenated portion of a subject and generating electrical signals indicative thereof;

a processing circuit integrally formed on an integrated semiconducting component chip mounted in the carriage housing, the processing circuit processing the signals into one of a pulse oximetry value and plethysmographic waveforms from at least one of the wavelengths.

2. The medical pulse oximetry sensor as set forth in claim 1, wherein the processing circuit of the semiconducting chip includes:

an amplifier for amplifying the signals from the at least one photodiode.

3. The medical pulse oximetry sensor as set forth in claim 2 wherein processing circuit of the semiconducting chip includes:

a sigma delta modulator for sampling the amplified signals and converting the signals into digital format.

4. The medical pulse oximetry sensor as set forth in claim 3, further including:

a current to voltage converter for analog modulation and one of frequency and phase multiplexed LED modulation of the signals from the photodiode.

5. The medical pulse oximetry sensor as set forth in claim 2, wherein processing circuit of the semiconducting chip includes:

a sample and hold operatively connected to the amplifier for sampling and holding the amplified signals.

6. The medical pulse oximetry sensor as set forth in claim 5, wherein the processing circuit of the semiconducting chip includes:

an analog to digital converter for digitizing sampled and held amplified signals.

7. The medical pulse oximetry sensor as set forth in claim 6, wherein the processing circuit of the semiconducting chip includes:

a microprocessing unit operationally connected to the analog to digital converter for processing the digitized signals into the pulse oximetry value and for controlling operation of the light emitting diodes.

8. The medical pulse oximetry sensor as set forth in claim 7, wherein the processing circuit of the semiconducting chip includes:

a light emitting diode control portion operationally connected to the microprocessing unit that controls light emissions from the first and second light emitting diodes.

9. The medical pulse oximetry sensor as set forth in claim 7, wherein the processing circuit of the semiconducting chip includes:

a timing circuit that coordinates signal processing by the microprocessing unit, the analog to digital converter, and the sample and hold, and the emission of light by the first and second light emitting diodes.

10. The medical pulse oximetry sensor as set forth in claim 2, wherein the processing circuit of the semiconducting chip includes:

a range finder that selects an amplification range or the amplifier.

11. The medical pulse oximetry sensor as set forth in claim 1, further including:

additional light emitting diodes, each emitting additional wavelengths of electromagnetic radiation.

12. The medical pulse oximetry sensor as set forth in claim 1, wherein the photodiode is integrally formed in the semiconductor chip.

13. The medical pulse oximetry sensor as set forth in claim 1, wherein the photodiode is electrically connected to the semiconductor chip.

14. The medical pulse oximetry sensor as set forth in claim 1, wherein the semiconductor chip is a CMOS chip.

15. The medical pulse oximetry sensor as set forth in claim 14, wherein the CMOS chip includes:

an amplifier for amplifying the signals from the photodiode;

a current to voltage converter for analog modulation and one of frequency and phase multiplexed LED modulation of the signals from the photodiode;

a circuit for digitizing the signal from the photodiode;

a microprocessing unit for processing the digitized segments into the pulse oximetry value;

a light emitting diode control portion operationally connected to the microprocessing unit that controls light emissions from the first and second light emitting diodes;

a timing circuit that coordinates digitizing and processing the signals and operations of the light emitting diodes.

16. The medical pulse oximetry sensor as set forth in claim 14, further including:

a wireless transmitter for transmitting the calculated pulse oximetry value to at least one of a display console and a recordation means;

a battery for providing power to the pulse oximetry sensor.

17. The medical pulse oximetry sensor as set forth in claim 14, further including:

a cable for providing power to the pulse oximetry sensor and for transmitting the calculated pulse oximetry value to at least one of a display console and a recordation means.

18. A method manufacturing a pulse oximetry sensor comprising:

embedding at least first and second light emitting diodes into a carriage housing adapted to fit snugly about a portion of a subject'"'"'s anatomy with a relatively high oxygenated blood throughput;

embedding an integrated circuit opposite the light emitting diodes, such that light emitted by the diodes must pass through the portion of the subject'"'"'s anatomy before impinging upon the integrated circuit, the integrated circuit including;

at least one photodiode for detection of light signals from the at least two light emitting diodes and generating signals indicative thereof;

an amplifier for amplifying the signals from the photodiode;

digital conversion elements for digitizing the signals from the photodiode;

a processing unit for processing the digital signals into the pulse oximetry value.

19. The method of manufacturing a pulse oximetry sensor as set forth in claim 18, wherein the integrated circuit is formed on a single CMOS substrate.

20. A method of measuring blood oxygen comprising:

emitting pulses of red light from a first LED (16) mounted in a carriage housing adapted to fit snugly about a portion of a subject'"'"'s anatomy with a relatively high oxygenated blood throughput;

emitting pulses of infrared light from a second LED mounted in the carriage housing;

receiving light from the LEDs which has traversed a blood oxygenated portion of a person with a photodiode mounted in the carriage housing and generating electrical signals;

processing the electrical signals from the photodiode into a blood oximetry value with a processing circuit integrally formed on a semiconductor chip that is mounted in the carriage housing.

21. The method of measuring blood oxygen as set forth in claim 20, wherein the photodiode is an integral part of the semiconductor chip.