Low power pulse oximeter
First Claim
Patent Images
1. A low-power pulse oximeter that comprises:
- a sensor further comprising a source of light configured to generate pulses of light in at least two wavelengths of light and a photodetector configured to receive the pulses of light and to generate an analog electrical signal indicative of the amplitude of light in each of the pulses;
at least one amplifier that is coupled to the photodetector to amplify the analog electrical signal;
a power supply that is coupled to the at least one amplifier to provide power to the at least one amplifier;
an analog to digital converter that is coupled to the amplifier to receive and convert the amplified analog electrical signal to a digital signal;
a microcomputer configured to receive the digital signal and to calculate a blood oxygenation level therefrom; and
a switching circuit disposed between the at least one amplifier and the power supply to selectively interrupt a flow of electrical power from the power supply to the at least one amplifier.
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Abstract
A low power pulse oximeter includes an input stage for amplifying a signal received from a light detector that is switchably connected to the power supply that powers the amplifier. The oximeter also includes an output stage with an LED driver circuit that is switchably connected to the power supply that powers the LED driver circuit. The input and output stages are switchably connected to the power supply when measurements need to be taken. When measurements do not need to be taken, they are switched off to reduce the power consumption of the oximeter.
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Citations
24 Claims
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1. A low-power pulse oximeter that comprises:
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a sensor further comprising a source of light configured to generate pulses of light in at least two wavelengths of light and a photodetector configured to receive the pulses of light and to generate an analog electrical signal indicative of the amplitude of light in each of the pulses;
at least one amplifier that is coupled to the photodetector to amplify the analog electrical signal;
a power supply that is coupled to the at least one amplifier to provide power to the at least one amplifier;
an analog to digital converter that is coupled to the amplifier to receive and convert the amplified analog electrical signal to a digital signal;
a microcomputer configured to receive the digital signal and to calculate a blood oxygenation level therefrom; and
a switching circuit disposed between the at least one amplifier and the power supply to selectively interrupt a flow of electrical power from the power supply to the at least one amplifier. - View Dependent Claims (2, 3, 4, 5)
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6. A low power pulse oximeter for driving and monitoring an oximeter sensor, the sensor comprising at least one LED configured to generate pulses of light at two different wavelengths and at least one photodetector responsive to the two wavelengths of light, the oximeter comprising:
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a power supply configured to provide electrical power;
first and second switching circuits coupled to the power supply to selectively enable and disable first and second flows, respectively, of the electrical power from the power supply between successive pulses of light thereby reducing power consumption;
an amplifier circuit configured to be coupled to the at least one photodetector to receive an electrical signal from the photodetector representative of an amount of light impinging on the photodetector and to amplify that electrical signal, wherein the amplifier circuit is coupled to the first switching circuit to receive at least a portion of the first flow of electrical power; and
an LED driver circuit configured to be coupled to the at least one LED to receive an analog electrical signal indicative of a desired light magnitude of the at least one LED and configured to control the current flow through the at least one LED to provide that desired light magnitude, wherein the LED driver circuit is coupled to the second switching circuit to receive at least a portion of the second flow of electrical power. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. A method for reducing the power consumption of a pulse oximeter having a photodetector for detecting pulsatile variations in light transmission through perfused tissue, an amplifier circuit to amplify electrical analogues of the pulsatile variations, an analog-to-digital converter for converting an output of the amplifier circuit into a corresponding digital value, and a microcomputer configured to generate an oxygen saturation based at least upon the digital value, the method comprising the steps of:
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(a) generating a pulse of infrared light;
(b) converting at least a portion of the pulse of infrared light into an infrared electrical signal;
(c) connecting the amplifier circuit to a source of electrical power;
(d) amplifying at least a portion of the infrared electrical signal in the amplifier circuit;
(e) transmitting the amplified infrared signal to the analog to digital converter circuit;
(f) disconnecting the amplifier circuit from the source of electrical power after step (e);
(g) generating a pulse of red light;
(h) converting at least a portion of the pulse of red light into a red electrical signal;
(i) connecting the amplifier circuit to the source of electrical power after step (g);
(j) amplifying at least a portion of the red electrical signal in the amplifier circuit after step (i);
(k) transmitting the amplified red signal to the analog-to-digital converter; and
(l) disconnecting the amplifier circuit from the source of electrical power after step (k). - View Dependent Claims (14, 15, 16)
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17. A low-power pulse oximeter, comprising:
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a microcomputer configured to generate a digital signal indicative of a desired amount of light;
a digital to analog converter circuit coupled to the microcomputer to convert the digital signal into an analog signal indicative of a desired amount of light;
at least one source amplifier circuit coupled to the digital to analog converter circuit to amplify the analog signal to an amplitude sufficient to generate the desired amount of light;
a power supply coupled to the at least one source amplifier circuit to provide power to the at least one LED amplifier/driver circuit;
a switching circuit electrically interposed between the power supply and the at least one source amplifier circuit to selectively interrupt a flow of electrical power from the power supply to the at least one source amplifier circuit; and
a light source coupled to the at least one source amplifier circuit and configured to generate the desired amount of light upon receipt of the amplified analog signal. - View Dependent Claims (18, 19)
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20. A medical monitoring system, comprising:
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a sensor configured to sense a physical parameter of a patient and to generate a sensor signal;
at least one amplifier that is coupled to the sensor to amplify the sensor signal;
a battery that is coupled to the at least one amplifier to provide power to the at least one amplifier;
an analog to digital converter that is coupled to the amplifier to receive and convert the amplified signal to a digital signal;
a microcomputer circuit configured to receive the digital signal and to calculate a value indicative of the physical parameter therefrom; and
a switching circuit disposed between the at least one amplifier and the battery to selectively interrupt a flow of electrical power from the battery to the at least one amplifier. - View Dependent Claims (21, 22, 23, 24)
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Specification