ENHANCED VISIBLE NEAR-INFRARED PHOTODIODE AND NON-INVASIVE PHYSIOLOGICAL SENSOR

• US 20160081552A1
• Filed: 09/18/2015
• Published: 03/24/2016
• Est. Priority Date: 09/18/2014
• Status: Active Grant

• Current Assignee: Masimo Semiconductor Inc. (Masimo Corporation)
• Original Assignee: Masimo Semiconductor Inc. (Masimo Corporation)
• Inventors: Wojtczuk, Steven J., Zhang, Xuebing, MacNeish, William J. III
• Granted Patent: US 10,383,520 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: H01L 31/02162 for filtering or shielding light, e.g. multicolour filters for photodetectors
• CPC Class Codes: H01L 31/03046 including ternary or quaternary compounds, e.g. GaAlAs, InGaAs, InGaAsP
• CPC Class Codes: H01L 31/105 the potential barrier being of the PIN type
• CPC Class Codes: Y02E 10/544 Solar cells from Group III-V materials

Abstract

Embodiments of the present disclosure include a photodiode that can detect optical radiation at a broad range of wavelengths. The photodiode can be used as a detector of a non-invasive sensor, which can be used for measuring physiological parameters of a monitored patient. The photodiode can be part of an integrated semiconductor structure that generates a detector signal responsive to optical radiation at both visible and infrared wavelengths incident on the photodiode. The photodiode can include a layer that forms part of an external surface of the photodiode, which is disposed to receive the optical radiation incident on the photodiode and pass the optical radiation to one or more other layers of the photodiode.

Claims

1. A non-invasive physiological sensor which measures physiological parameters of a monitored patient, the sensor comprising:

an input configured to receive a drive signal from a driver circuit;

an emitter electrically coupled to the input and configured to emit optical radiation at one or more wavelengths responsive to the drive signal;

one or more detectors configured to be positioned proximate to the emitter and tissue of a patient by a sensor housing, the one or more detectors comprising one photodiode that is part of an integrated semiconductor structure, the one photodiode being configured to detect the optical radiation after attenuation by the tissue of the patient and generate a detector signal responsive to the detected optical radiation; and

an output electrically coupled to the one or more detectors and configured to output the detector signal,

wherein the one photodiode has an external quantum efficiency of at least 20% at wavelengths ranging from 450 nm to 1400 nm.

2. The sensor of claim 1, wherein the one photodiode is configured to generate the detector signal with a signal strength sufficient for the detector signal to be usable to determine measurement values for one or more physiological parameters of the patient from the optical radiation detected by the one photodiode at the wavelengths ranging from 450 nm to 1400 nm.

3. The sensor of claim 1, wherein the one photodiode has an external quantum efficiency of at least 60% at wavelengths ranging from 500 nm to 1400 nm.

4. The sensor of claim 3, wherein the one photodiode has an external quantum efficiency of at least 70% at wavelengths ranging from 600 nm to 1400 nm.

5. The sensor of claim 4, wherein the one photodiode has an external quantum efficiency of at least 80% at wavelengths ranging from 800 nm to 1400 nm.

6. The sensor of claim 1, wherein the one photodiode has an external quantum efficiency of about 40% at a wavelength of 450 nm, an external quantum efficiency of about 75% at a wavelength of 550 nm, an external quantum efficiency of about 80% at a wavelength of 700 nm, and an external quantum efficiency of about 95% at a wavelength of 1250 nm.

7. The sensor of claim 1, wherein the one photodiode has an external quantum efficiency greater than 70% at wavelengths ranging from 1400 nm to 1700 nm.

8. The sensor of claim 1, wherein the one photodiode comprises indium, gallium, and arsenic, and the one photodiode comprises a window layer comprising indium, aluminum, and arsenic.

9. A non-invasive physiological sensor which measures physiological parameters of a monitored patient, the sensor comprising:

an input configured to receive a drive signal from a driver circuit;

an emitter electrically coupled to the input and configured to emit optical radiation at one or more wavelengths responsive to the drive signal;

one or more detectors configured to be positioned proximate to the emitter and tissue of a patient by a sensor housing, the one or more detectors comprising one photodiode that is part of an integrated semiconductor structure, the one photodiode being configured to detect the optical radiation after attenuation by the tissue of the patient and generate a detector signal responsive to the detected optical radiation; and

an output electrically coupled to the one or more detectors and configured to output the detector signal,

wherein the one photodiode is configured to generate the detector signal with a signal strength sufficient for the detector signal to be usable to determine measurement values for one or more physiological parameters of the patient from the optical radiation detected by the one photodiode at the wavelengths ranging from 450 nm to 1400 nm, the one photodiode comprising a window layer having a thickness ranging from about 25 nm to about 150 nm, the window layer forming part of an external surface of the one photodiode and being disposed to receive the optical radiation incident on the one photodiode before the optical radiation passes to one or more other layers of the one photodiode.

10. The sensor of claim 9, wherein the thickness ranges from about 50 nm to about 100 nm.

11. The sensor of claim 9, wherein the thickness is about 50 nm.

12. The sensor of claim 9, wherein the window layer has a bandgap of about 1.52 eV at 25°

C.

13. The sensor of claim 9, wherein the window layer has a bandgap of about 1.68 eV at 25°

C.

14. The sensor of claim 9, wherein the window layer has a bandgap ranging from about 1.7 eV to about 1.9 eV at 25°

C.

15. The sensor of claim 9, wherein the one photodiode comprises indium, gallium, and arsenic, and the window layer comprises indium, aluminum, and arsenic.

16. The sensor of claim 9, wherein the one photodiode comprises indium, gallium, and arsenic, and the window layer comprises indium and phosphorus.

17. The sensor of claim 9, wherein the window layer is not lattice matched to a substrate of the one photodiode.

18. A non-invasive physiological sensor which measures physiological parameters of a monitored patient, the sensor comprising:

an input configured to receive a drive signal from a driver circuit;

an emitter electrically coupled to the input and configured to emit optical radiation at one or more wavelengths responsive to the drive signal;

one or more detectors configured to be positioned proximate to the emitter and tissue of a patient by a sensor housing, the one or more detectors comprising one photodiode that is part of an integrated semiconductor structure, the one photodiode being configured to detect the optical radiation after attenuation by the tissue of the patient and generate a detector signal responsive to the detected optical radiation; and

an output electrically coupled to the one or more detectors and configured to output the detector signal,

wherein the one photodiode is configured to generate the detector signal with a signal strength sufficient for the detector signal to be usable to determine measurement values for one or more physiological parameters of the patient from the optical radiation detected by the one photodiode at the wavelengths ranging from 450 nm to 1400 nm, the one photodiode comprising indium, gallium, and arsenic.

19. The sensor of claim 18, wherein the one photodiode comprises a window layer comprising indium, aluminum, and arsenic.

20. The sensor of claim 18, wherein the one photodiode comprises a window layer comprising indium and phosphorus.