Optical sensor and method for initializing and calibrating an optical sensor - Patents.com

Abstract

A method for calibrating an optical sensor (1) for measuring one or more physiological signs of a person after the device is attached to the person is provided. The sensor includes one or more detectors (15) and another light source (12, 14). The method includes, after the device is attached to the person, using the one or more light sources (12, 14) to emit one or more pulses of light at a plurality of different wavelengths, where each pulse of light at each wavelength is emitted at a known power level for a known length of time, recording signals of the pulses of light at each wavelength using the one or more detectors (15) to create an optical signature of the person, and selecting one or more wavelengths from the plurality of wavelengths to use in measuring the one or more physiological signs based on the optical signature of the person.

Description

[Technical Field]

[0001] The present invention relates to an optical sensor for use in measuring one or more physiological indicia of a person. The invention further extends to a method of initializing an optical sensor for use in measuring one or more physiological indicia of a person and / or a method of calibrating an optical sensor for use in measuring one or more physiological indicia of a person. [Background technology]

[0002] Optical sensors, such as photoplethysmography (PPG) sensors, are used in monitoring devices to monitor vital signs such as blood oxygen saturation, pulse rate, respiratory rate, etc. Physiological indicia can include one or more vital signs.

[0003] An exemplary vital signs monitoring device is disclosed in WO 2022 / 136438.

[0004] PPG sensors, such as pulse oximeters, typically include a photodetector and two LEDs, each emitting light of a known wavelength. The light is emitted to illuminate the skin and blood, which is then detected by the detector, which determines the varying absorbance at each wavelength, allowing the detector to determine the vital signs required.

[0005] The PPG sensor may be a transmission type sensor that can be used to monitor blood flow in a person's extremity, such as a fingertip or earlobe. In a transmission type sensor, the LED may be positioned on one side of the patient's extremity, while the photodetector is on the other side to receive the light immediately after it passes through the patient's tissue.

[0006] Alternatively, the PPG sensor may be a reflectance sensor used, for example, in a watch to monitor blood flow in a patient's wrist, where the photodetector and LED are positioned adjacent to each other on the same side of the patient's tissue so that light emitted by the sensor is reflected back toward the photodetector. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2022 / 136438 Summary of the Invention [Problem to be solved by the invention]

[0008] A significant issue identified with optical sensors for monitoring vital signs is that they do not always provide reliable measurements. This can have serious consequences because the output from the sensor may be relied upon in determining a patient's health status. For example, one possible issue is that the sensor may not be operating optimally, which may not be recognized by the sensor's user. Another known issue is that optical sensors may not perform as well on patients with certain skin tones or skin types.

[0009] Therefore, there is a need to provide sensors and accompanying methods that allow more accurate and reliable measurements to be made on a wider range of people. [Means for solving the problem]

[0010] Viewed from a first aspect, there is provided an optical sensor for measuring one or more physiological signs of a person, the sensor comprising a detector and a plurality of light sources surrounding the detector, the plurality of light sources for emitting light at a plurality of different wavelengths.

[0011] By using multiple light sources surrounding the detector, improved readings can be obtained using an optical sensor because the detector can be better positioned relative to the light source to record the signal from the light source. Light sources surrounding the detector can mean that the light sources are positioned around the detector. The light sources can surround the detector. The light sources can be positioned to provide a uniform light field that is detected by the detector.

[0012] By using multiple different wavelengths (e.g., three or more, six or more, seven or more, eight or more, ten or more, or just eight different wavelengths), readings may be taken using more than a minimum number of wavelengths, which may allow for more reliable readings. Additionally or alternatively, the optical sensor may be calibrated (i.e., adjusted) for different people, e.g., different skin profiles of different people. For example, an optimal selected combination of wavelengths and / or light intensities for each particular person may be determined before any measurements of their physiological signs are taken. This may therefore improve the accuracy of measurements of one or more physiological signs in people with different skin types, and correspondingly improve the safety of the people.

[0013] The optical sensor may measure (eg, monitor) one or more physiological signs of the person.

[0014] The one or more physiological indicia may include one or more vital signs, such as blood oxygen saturation, pulse rate, and respiratory rate.

[0015] The optical sensor may measure one or more physiological signs continuously, i.e., the sensor may monitor one or more physiological signs. The term "continuous" may be interpreted as one or more of the one or more physiological signs being monitored in discrete time steps over a continuous period of time. A discrete time step may include a time period in the range of 1 to 100 ms. Alternatively, a discrete time step may include a time period up to 2 minutes, e.g., 30 seconds, 45 seconds, 1 minute, or 90 seconds.

[0016] Additionally or alternatively, the optical sensor may measure one or more physiological signs at a single point in time. In other words, the optical sensor may perform a snapshot measurement of one or more physiological signs. The optical sensor may perform the snapshot measurement when instructed by an operator. The use of snapshot measurements may reduce the power requirements of the optical sensor because it does not need to continuously monitor one or more physiological signs.

[0017] The optical sensor may be a pulse oximeter and may comprise a photoplethysmogram (PPG) sensor. The sensor may be a reflectance sensor, such as a reflectance pulse oximeter.

[0018] The optical sensor may be a medical device for measuring one or more physiological symptoms of a patient. In this example, the person may be the patient. The medical device may be, for example, a pulse oximeter.

[0019] Alternatively, the optical sensor may be a wearable device for measuring one or more physiological signs of a person. The wearable device may be, for example, a smart watch or a sports watch. The wearable device may be attached to the person's wrist.

[0020] The detector may be or comprise a photodetector. The detector may be a camera. The camera may comprise one or more pixels.

[0021] The optical sensor may include a first surface, and the detector and each of the plurality of light sources may be positioned on the first surface, and the first surface may face toward tissue of the person during use, i.e., when the optical sensor is attached to a person.

[0022] The optical sensor may further include a second surface that may be on an opposite side of the optical sensor from the first surface. The second surface may face away from the human tissue during use. The second surface may include a display for displaying results of measurements made by the sensor.

[0023] The optical sensor may include a processor. The processor may determine one or more physiological signs. The processor may be located on or toward the second surface; i.e., the processor may not be located on the first surface. In other words, the processor may be on a surface of the optical sensor that is different from the detector and the plurality of light sources and / or within the optical sensor.

[0024] Each light source may be for emitting light of a specific wavelength. In practice, each light source may be for emitting light over a narrow band / peak of wavelengths, for example, over a range of up to 20 nm for a specific wavelength. Thus, throughout this specification and claims, references to wavelengths should be interpreted herein as referring to a single narrow band wavelength (i.e., within a range of up to 20 nm from the specified wavelength). A sensor may include one or more light sources for emitting light of each wavelength. For example, a sensor may include two light sources capable of emitting light at a first wavelength and two light sources capable of emitting light at a second wavelength.

[0025] The multiple light sources may include at least one separate light source for each wavelength of the multiple wavelengths. For example, if the optical sensor emits six wavelengths, the optical sensor may include at least six light sources, each for emitting a different one of the six wavelengths.

[0026] The multiple light sources may include two or more separate light sources (i.e., sets of light sources) for each wavelength of the multiple wavelengths. For example, if the multiple light sources emit six different wavelengths, the optical sensor may include 12 light sources, with each wavelength being emitted by two separate light sources. Optionally, the multiple light sources may include three or four separate light sources for each different wavelength of light (i.e., for each set of light sources). As a further example, the optical sensor may include 24 separate light sources, with each wavelength being emitted by four separate light sources. By providing multiple light sources for emitting each of the different wavelengths, the light sources can be positioned to provide a uniform light field to the detector.

[0027] The multiple light sources may be arranged in one or more loops surrounding the detector (i.e., the light sources may be in one or more ring / circular formations around the detector). There may be gaps between the light sources in each loop. Thus, rather than a continuous loop of light sources, the light sources may be positioned in one or more nominal loops that may be formed if the light sources were joined together. The loop(s) may each be concentric with each other and with the center of the detector. The light sources may be arranged such that all of the light sources in a loop are all equidistant from the center of the detector.

[0028] The multiple loops may include an inner loop and an outer loop. The outer loop may be arranged such that each light source in the outer loop is positioned farther from the center of the detector than the light sources in the inner loop. Each light source on the outer loop may be positioned a first distance from the center of the detector. Each light source on the inner loop may be positioned a second distance from the center of the detector. The second distance may be smaller than the first distance. The first distance may be constant around the outer loop such that each light source on the outer loop is positioned the same distance from the center of the detector as other light sources on the outer loop. Similarly, the second distance may be constant around the inner loop such that each light source on the inner loop is positioned the same distance from the center of the detector as other light sources on the inner loop. These distances may be from the center of the respective light source to the center of the detector.

[0029] The light sources may be arranged so that half the light sources form an inner loop and half the light sources form an outer loop.

[0030] The multiple light sources may be positioned on an inner loop with light sources emitting shorter wavelengths of light, and the multiple light sources may be positioned in an outer loop with light sources emitting longer wavelengths of light, in other words, the multiple light sources emitting shorter wavelengths may be positioned closer to the detector than the multiple light sources emitting longer wavelengths.

[0031] The multiple light sources may be positioned in a first group of light sources and a second group of light sources, where the first group of light sources is positioned closer to the detector than the second group of light sources and the light sources in the first group emit light at shorter wavelengths than the light sources in the second group of light sources. The first group of light sources may form an inner loop and the second group of light sources may form an outer loop.

[0032] It will be understood that references to "shorter" and "longer" are relative terms with respect to wavelengths selected from the plurality of wavelengths. As an example, in the case of a plurality of wavelengths consisting of six wavelengths, the light sources emitting the three shortest wavelengths may be positioned on the inner loop, while the light sources emitting the three longest wavelengths may be positioned on the outer loop. A similar interpretation applies when the plurality of wavelengths consists of eight wavelengths, i.e., the four shortest wavelengths are positioned on the inner loop and the four longest wavelengths are positioned on the outer loop.

[0033] This arrangement can be beneficial because light with longer wavelengths can typically travel farther through human tissue. Therefore, it can be positioned farther from the detector and still provide a satisfactory reading. Meanwhile, light with shorter wavelengths can be emitted from a position closer to the detector and therefore be adequately detected. This arrangement can allow for a more compact sensor design while ensuring good signal detection. Furthermore, the use of a compact sensor design can allow for a greater number of light sources, allowing for a greater number of wavelengths to be utilized for a given size sensor compared to other designs.

[0034] When there are multiple light sources (i.e., two or more) for each wavelength of light, the light sources of a particular wavelength may be positioned symmetrically around the detector. In other words, light sources that may be intended to emit the same wavelength may be positioned on either side of the detector at equal distances from the center of the detector. Light sources that may be intended to emit the same wavelength may be symmetric about a line of symmetry that extends through the center of the detector.

[0035] For example, if there are two light sources, each emitting the same wavelength, they may be positioned on either side of the detector at equal distances from the center of the detector. In this case, these two light sources may be symmetrical about a line of symmetry extending through the center of the detector between the two light sources. If there are four light sources, each emitting the same wavelength, they may be positioned on either side of the detector (e.g., if the detector has a square shape), and each light source may be equidistant from the center of the detector. In this case, the light sources may be symmetrical about two lines of symmetry extending through the center of the detector, each perpendicular to each other.

[0036] Each set of light sources of all different wavelengths can be positioned symmetrically around the detector.

[0037] Such a symmetrical arrangement may allow a more uniform light field to be emitted for detection by the detector.

[0038] The light sources may emit a uniform light field around the detector. For example, the light sources positioned diametrically opposite each other on either side of the detector may be mirror images. For example, a light source positioned on one side of the detector may emit light of the same wavelength as a light source positioned diametrically opposite the detector.

[0039] For example, one side of the detector may include four light sources, where two light sources are positioned on the inner loop and two light sources are positioned on the outer loop. In this example, the same configuration may exist on the opposite side of the detector, where the two light sources on the inner loop on one side may be for emitting light of the same wavelengths as the two light sources on the inner loop on the other side. Similarly, the two light sources in the outer loop on one side may be for emitting light of the same wavelengths as the two light sources on the outer loop on the other side.

[0040] The sensor may include multiple light sources for emitting light at multiple different wavelengths, although not all wavelengths may be used to monitor one or more physiological signs. Determining (e.g., measuring / monitoring) a physiological sign may be performed using one or more subsets of the multiple wavelengths that may be emitted by the sensor. However, not all wavelengths may be used when measuring a physiological sign of a person, but all of the available wavelengths may be used when initializing and / or calibrating the sensor. Calibrating the sensor may involve selecting a subset of wavelengths to be used when measuring a physiological sign of a person.

[0041] To monitor blood oxygen saturation, the optical sensor may be configured to emit and detect two or more of a plurality of different wavelengths of light. A first wavelength may be, for example, a wavelength at which optical absorption is substantially the same in oxygenated hemoglobin and deoxygenated hemoglobin (this may be referred to as an isosbestic wavelength), and a second wavelength may be a wavelength at which there is a substantial difference in optical absorption between oxygenated and deoxygenated hemoglobin (i.e., a non-isosbestic wavelength).

[0042] To measure pulse rate using an optical sensor, measuring the reflectance of a single wavelength of light may be sufficient. As the heart beats, blood pulsates through the capillaries at the same frequency as the heartbeat. This pulsation effectively means that the volume of blood within the capillaries is changing. This change in volume, in turn, causes a change in the amount of light absorbed by the blood, and therefore the amount reflected. Therefore, an estimate of pulse rate can be obtained with an optical sensor by measuring the time-dependent variation in the reflected light.

[0043] Because respiratory activity affects the photoplethysmographic waveform that may be acquired, it may also be possible to extract respiratory rate information using an optical sensor.

[0044] By providing a sensor that can emit multiple different wavelengths, the optimum wavelength, or optimum combination of wavelengths, can be selected for each measurement depending on factors such as the person's skin profile.

[0045] The detector may detect each of a plurality of different wavelengths. The detection of the different wavelengths using the detector may be time multiplexed corresponding to the different wavelengths of emission from the light source.

[0046] The detector may be an off-the-shelf known PPG photodetector, ie the sensor may comprise a known (eg not homemade) sensor unit.

[0047] The multiple light sources may emit light at six or more different wavelengths. For example, a sensor may be configured to emit light at just seven or eight different wavelengths. Each wavelength of light may be emitted from a different light source. Each wavelength may be enabled to emit at a different time than the other wavelengths. Each light source or set of light sources (e.g., a set of light sources for emitting a given wavelength) may be independently controllable. This may mean that each light source or each set of light sources may be turned on and off independently of the other light sources. The intensity of each light source (or set of light sources) may be controlled independently of the other light sources. The length of time each light source (or set of light sources) emits light may be controlled independently of the other light sources.

[0048] Each of the plurality of wavelengths may be in the range of 400 nm to 1300 nm, optionally in the range of 400 nm to 950 nm, and optionally in the range of 460 nm to 940 nm. The plurality of wavelengths may include one or more of blue light, dark green light, light green light, yellow light, red light, dark red light, and infrared light. The shortest wavelength of the plurality of wavelengths may include blue light. The longest wavelength of the plurality of wavelengths may include infrared light. The light source may emit at least one or more wavelengths considered to be isosbestic wavelengths of hemoglobin (e.g., 805 nm and / or 940 nm) and at least one or more wavelengths considered to be non-isosbestic wavelengths of hemoglobin (e.g., 660 nm).

[0049] In use, the optical sensor may monitor one or more physiological signs using any one or more of the multiple wavelengths. In use, the optical sensor may monitor one or more physiological signs using a combination of the multiple wavelengths. The combination may be a subset of the multiple wavelengths that may be emitted.

[0050] The plurality of light sources may include light emitting diodes (LEDs). Each light source may be a light emitting diode.

[0051] The optical sensor may include a screen (i.e., a shield) that optically separates the detector and the multiple light sources so that the detector does not directly detect light pulses from the multiple light sources (i.e., without first being reflected off a surface). The screen may be positioned between the detector and the multiple light sources. The screen may surround the detector. If the light sources form one or more loops, the screen may form a loop around the detector between the light sources and the detector. The screen loop may be within an inner loop of the light sources. The screen may be positioned around and / or extend around the detector.

[0052] The screen may be positioned on a first surface of the optical sensor. The screen may protrude from the first surface in a direction perpendicular to the first surface of the optical sensor. The screen may protrude a sufficient distance to prevent light emitted from the multiple light sources from being directly detected by the detector without reflection. The screen may be opaque to all wavelengths of light emitted by the light sources. The screen may include plastic. In this case, the plastic may be opaque.

[0053] The presence of the screen may be beneficial because it prevents any of the light emitted from the multiple light sources from being directly detected by the detector, thus ensuring that any light detected by the detector has traveled through and / or reflected from human tissue, which may improve the quality of the signal received by the detector.

[0054] As an alternative to or in addition to using a screen, the detector may be positioned within a cavity in the first surface of the optical sensor, in other words, within a recess on the surface of the optical sensor.

[0055] The sensor, for example the screen and / or cavity of the sensor, may block a direct line of sight from each of the multiple light sources and the detector.

[0056] The optical sensor may include a temperature sensor. The temperature sensor may be positioned on a first surface of the optical sensor. The temperature sensor may be positioned near the light source and / or the detector. This allows the temperature sensor to sense the temperature of an environment near the active portion of the optical sensor, such as human tissue.

[0057] The distance between the center of the detector and the center of the light source furthest from the center of the detector may be the same as or greater than the distance between the center of the temperature sensor and the center of the detector. The temperature sensor may be positioned in line with or within one or more loops of the light source. The temperature sensor may monitor the temperature of human tissue.

[0058] The use of a temperature sensor may enable the sensor to monitor tissue temperature rise resulting from use of the sensor. In particular, the temperature sensor may enable prevention of overheating of either the optical sensor or the human tissue. If the temperature of the human tissue and / or the optical sensor rises above an acceptable range, e.g., above 40°C, the optical sensor, e.g., a processor, may issue an alert. Additionally or alternatively, the processor may shut down the optical sensor.

[0059] The temperature sensor may also be used to verify whether the tissue is at a suitable temperature for accurate physiological sign readings to be obtained using the optical sensor. For example, if the tissue is too cold, accurate readings of one or more physiological signs may not be possible with the optical sensor. The optical sensor, e.g., the processor, may be configured to issue an alert and / or shut off the optical sensor if the measured temperature is below a certain temperature (e.g., below 35°C) when a physiological sign is being monitored.

[0060] The temperature sensor may also be used to check that the sensor is close enough to the person to obtain a physiological sign reading. This is because if the detected temperature differs from the expected temperature of the person's skin, it may be inferred that the first surface of the optical sensor is not close enough to the person's skin to obtain an accurate reading. The optical sensor, e.g., a processor, may be configured to issue an alert and / or shut off the optical sensor if the measured temperature is outside a predetermined range (e.g., outside of 35-40°C) when the optical sensor's physiological sign is being monitored.

[0061] The presence of a temperature sensor means that, in use, the sensor may be arranged to output a measurement of temperature.

[0062] The optical sensor may include a transparent surface covering the detector and the plurality of light sources. The surface may be transparent to all wavelengths that may be emitted by the light sources. The optical sensor and the transparent surface may contact human tissue during use. The transparent surface may be a flat surface. The transparent surface may be present to protect the detector and the light sources from damage and / or contamination. The transparent surface may be easily cleaned after use of the optical sensor.

[0063] The optical sensor may be part of a medical device for measuring one or more physiological signs, or may be part of a consumer wearable device such as a sports watch.

[0064] The optical sensor may be adapted for attachment to a person's skin, such as the person's neck. In other words, the optical sensor may be attached to the person's skin. The optical sensor may be used outside the patient's body, i.e., in contact with the outer surface of the skin. This allows for easy attachment and detachment of the device from the person and allows for viewing of the device during use. This is advantageous because the device is easy to attach so that it can be easily viewed by a medical professional without requiring constant attention. Furthermore, the neck may allow for accurate measurements of one or more physiological signs.

[0065] Alternatively, the optical sensor may be for attachment to a person's wrist, allowing the person to easily view their own physiological signs. The optical sensor may be attached to the person using an adhesive patch. The adhesive patch may include medical tape. The adhesive patch may include a base to which the optical sensor can be clipped and unclipped. Alternatively, or in combination with an adhesive patch, the optical sensor may be attached to the person using a strap.

[0066] The first aspect has been described above with respect to its use in measuring one or more physiological signs of a person. However, it will be appreciated that this use may form a separate aspect of the invention. In particular, according to a second aspect, there is provided a method of measuring one or more physiological signs of a person using an optical sensor according to the above first aspect. Furthermore, according to a third aspect, there is provided a physiological sign measuring device comprising an optical sensor according to the first aspect.

[0067] The second and third aspects of the invention may include any of the features described in relation to the first aspect above.

[0068] The method may include attaching an optical sensor to a person, e.g., to the person's skin, such that a first surface of the optical sensor faces and / or is proximate to the person's skin. The method may include emitting light at one or more wavelengths of light using one or more of a plurality of light sources. The method may include emitting light of different wavelengths at different times. The method may include recording a signal corresponding to the emitted light using a detector. The method may include determining one or more physiological signs using the sensor, e.g., a processor of the sensor, and / or outputting an indication of the one or more physiological signs.

[0069] When an optical sensor, such as that described in the first aspect above, includes a detector and emits multiple different wavelengths, it may be beneficial to check the functionality of the optical sensor before it is used to monitor one or more physiological signs. Such a process may be referred to as initializing the optical sensor for use.

[0070] Viewed from a fourth aspect, there is provided a method of initializing an optical sensor for measuring one or more physiological signs, the sensor comprising a detector and another light source, the method comprising, before the device is attached to a person, emitting (e.g., sequentially) one or more pulses of light at one or more different wavelengths using the one or more light sources, where each pulse of light is emitted at a known power level for a known length of time; recording (e.g., sequentially) signals of the one or more pulses of light at each wavelength using one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameters with stored values ​​of the parameters for each wavelength; and determining that the optical sensor is ready for use if the determined parameters for each wavelength are within a set tolerance range of the stored values ​​of the parameters for each wavelength.

[0071] This method is sometimes called the initialization method.

[0072] The optical sensor may be as described in the first aspect above. Accordingly, the method may be performed using the optical sensor described above, optionally including one or more or all of the optional features. Alternatively, the method may be performed using other known optical sensors, such as known PPG sensors. This may be, for example, an optical sensor that does not have multiple light sources surrounding the detector. The method may be performed using any known optical sensor for measuring one or more physiological signs, comprising a detector and another light source.

[0073] The method may be performed prior to using the optical sensor to monitor one or more physiological signs, i.e., before the optical sensor is attached to a person's skin. The method of initializing the optical sensor may be considered and / or referred to as a method of checking that the optical sensor is operating optimally and / or to a sufficient level before the optical sensor is used to monitor one or more physiological signs. The method may be performed during the manufacture of the optical sensor and / or by a consumer, immediately prior to its first use and / or before each use of the optical sensor on a person.

[0074] The method may include recording a signal received using a detector when no light is emitted by one or more light sources. This step may be performed before emitting a light pulse. Thus, the method may first include switching on the detector to receive light for a given integration time, and then recording a background signal before the light source is switched on. This may allow the sensor to monitor the background signal without any input from the one or more light sources of the optical sensor. This may be used to check that the detector is functioning satisfactorily and / or that the background noise is within an acceptable level for the recorded signal to be meaningful.

[0075] The method described in the fourth aspect above may ensure that each of the optical sensor, detector, and / or one or more light sources is operating accurately and / or in accordance with manufacturer specifications. This may improve the reliability of physiological signs monitored using the optical sensor because it may be ensured that the optical sensor is operating accurately before the optical sensor is used on a person.

[0076] The parameter may be or may include any quantifiable parameter associated with the recorded signal for each wavelength. Furthermore, the parameter may be a quantifiable parameter that is easily measurable or easily derived. For example, the parameter may be one of emitted irradiance, intensity, or intensity squared. The intensity and intensity squared may be the reflected intensity of the signal for each wavelength of light.

[0077] The parameter may be or may include the signal-to-noise ratio of each signal at each wavelength of light. Thus, each wavelength of light may include a stored signal-to-noise ratio that may be used in the comparison step of the method.

[0078] The signal-to-noise ratio may be the ratio of the signal power (ie, the power of the emitted light pulse) to the noise power (ie, the power of the detected signal).

[0079] The signal-to-noise ratio can be determined using standard methodologies, such as those described in "Signal-to-noise ratio as a quantitative measure for optical biosensors" (https: / / www.maximintegrated.com / en / design / technical-documents / app-notes / 6 / 6410.html).

[0080] For example, the signal-to-noise ratio can be determined by comparing the amplitude of the pulsating signal recorded for each wavelength to the noise floor of the device. The method can include recording a background signal for each wavelength using one or more detectors before emitting one or more light pulses of different wavelengths. The noise floor used in determining the signal-to-noise ratio for each wavelength can be the total signal recorded by the detector.

[0081] Alternatively, the signal-to-noise ratio for each of the plurality of wavelengths may be determined by comparing the intensity and / or fluctuating amplitude of the light pulse emitted from the light source with the intensity and / or fluctuating amplitude of the light pulse recorded by the detector. The intensity may include the power level of the signal. The fluctuating amplitude may include a pulsating signal corresponding to the emitted or detected light source.

[0082] The stored values ​​of the parameters for each wavelength may depend on the characteristics of the optical sensor. In particular, the stored values ​​of the parameters may be input and / or set by the manufacturer of the optical sensor. For example, the manufacturer of the optical sensor may determine the values ​​of the parameters used in the initialization method. The initialization method may then be used to verify that the optical sensor is operating as expected based on the settings by the manufacturer.

[0083] The stored values ​​of the parameters may be stored in a lookup table. The lookup table may be stored on the optical sensor. The stored data may be stored on the optical sensor, such as in a memory that may be accessible by a processor that may be housed in the optical sensor. The stored values ​​of the parameters, e.g., signal-to-noise ratio, may be bespoke for each manufactured optical sensor. The stored values ​​of the parameters may be stored accordingly so as to be accessible by the processor of each optical sensor. The stored values ​​of the parameters for each wavelength may be determined during the manufacture of the optical sensor, e.g., in the factory. This may be achieved by performing tests on the manufactured optical sensors. This may be before the optical sensors are supplied to consumers for use. The stored values ​​of the parameters, e.g., signal-to-noise ratio, may be determined when the optical sensor is known to be operating optimally, e.g., immediately after manufacture and / or under controlled conditions. Thus, a comparison between the determined parameters, e.g., the determined signal-to-noise ratio, and the stored values ​​of the parameters, e.g., the stored signal-to-noise ratio, may be used to check that the optical sensor is operating optimally or sufficiently close to optimally.

[0084] The determined parameters and the stored values ​​of the parameters may be verified under the same conditions so that an apples-to-apples comparison can be made.

[0085] The known power level and known length of time at which each light pulse of each wavelength is emitted may be the same as the power level and length of time of the light pulse used in determining the stored value of the parameter so that an apples-to-apples comparison can be made between the determined parameter and the stored value of the parameter for each wavelength.

[0086] The method may include indicating that the optical sensor is ready for use. This may occur when it is determined that the optical sensor is ready for use, for example, when the parameters for each wavelength are within a set tolerance range of the stored values ​​of the parameters for each wavelength. This indication may be by notification to the user and may also be an audible and / or visual alert. The step of indicating that the optical sensor is ready for use may occur after the step of determining that the optical sensor is ready for use (i.e., operating optimally or sufficiently close to optimally to be used (i.e., within a set tolerance range)).

[0087] The method may include determining that the optical sensor is not ready for use if the determined parameters for one or more of the wavelengths are outside a set tolerance range of the stored values ​​of the parameters for the respective wavelengths.

[0088] If the parameters for one or more of the wavelengths are determined to be outside a set tolerance range of the stored values ​​of the parameters for the respective wavelengths, the method may include repeating one or more times the steps of emitting (e.g., sequentially) one or more pulses of light at one or more different wavelengths using one or more light sources, recording (e.g., sequentially) signals of the one or more pulses of light at each wavelength using one or more detectors, determining parameters for each signal at each wavelength of light, and comparing the determined parameters to the stored values ​​of the parameters for each wavelength.

[0089] The method may include indicating that the optical sensor is not ready for use if the parameter for one or more wavelengths is outside a set tolerance range of the stored value of the parameter for the respective wavelength. The method may include indicating that the optical sensor is not ready for use if it is determined that the optical sensor is not ready for use.

[0090] Indicating that the optical sensor is not ready for use may include indicating that the sensor is faulty, in which case the initialization method may be run again (e.g., as directed by a user) and / or the sensor may be serviced.

[0091] If the parameter for one or more wavelengths is outside a set tolerance range of the stored value of the parameter for each wavelength, the method may be repeated a predetermined number of times, after which the method may include indicating that the optical sensor is not ready for use. The predetermined number of times may be defined by the manufacturer of the optical sensor. The predetermined number of times may be, for example, two, five, or ten times. In this case, the method may not be repeated continuously if there is an inherent error or malfunction detected in the sensor, for example, if it is determined that the detector is not picking up the signal accurately. Instead, the method may simply determine and / or indicate that the optical sensor is not ready for use.

[0092] If it is determined that the optical sensor is not ready for use, the method may include indicating that maintenance is required. The method may include indicating that the optical sensor is malfunctioning and / or has failed. This indication may be an alert to the user and may also be an audible and / or visual alert. In this example, the optical sensor may need to be returned to the manufacturer or some other specialist for repair. This step may be beneficial because it may prevent the malfunctioning optical sensor from being used to monitor physiological signs.

[0093] The set tolerance may be up to ±5%, optionally ±2%. In other words, for the optical sensor to be determined to be ready for use, the determined parameter should be within ±5%, or optionally ±2%, of the parameter's stored value for each wavelength. The set tolerance may be the same for each wavelength and / or each light source of one or more light sources. Alternatively, the set tolerance may be different for each wavelength and / or each light source. For example, a light source emitting light having a longer wavelength may have a larger set tolerance than a light source emitting light of a shorter wavelength, or vice versa.

[0094] The initialization method may be performed under specific, defined conditions. The initialization method may be performed when the optical sensor faces a reflective surface having specific reflective characteristics, such as a reflectance target with known characteristics. The reflective surface may be a standardized reflective surface, such as a white surface and / or a gray surface. For example, the steps of emitting light pulses of multiple different wavelengths using one or more light sources and recording signals of the light pulses of each wavelength using a detector may be performed when the detector and one or more light sources face a specific reflective surface, such as a reflective surface with specific, known reflective characteristics. The stored values ​​of the parameters may be determined when the detector and one or more light sources face the same reflective surface or a reflective surface with the same reflective characteristics. This may ensure an apples-to-apples comparison between the determined parameters and the stored values ​​of the parameters for each wavelength. The specific reflective surface may be provided, for example, by a reflective cover that may be fitted over the optical sensor. The reflective cover may comprise a reflective film or a reflective cap. The reflective cover may include any type of reflective material. The reflective cover may be a sticker that can be peeled off from the sensor after the initialization method is performed, for example, that can be peeled off just before the optical sensor is placed on a person's skin.

[0095] Additionally or alternatively, the sensor may be provided with a housing, for example a box, and the sensor may face a particular reflective surface when housed within the housing.

[0096] The initialization method may include orienting the detector and one or more light sources toward a particular reflective surface. This may include, for example, covering the detector and one or more light sources with a reflective cover and / or housing the optical sensor in a storage case. The step of orienting the detector and one or more light sources toward each other may be performed before the step of using the one or more light sources to emit light pulses of multiple different wavelengths and using the detector to record a signal for each light pulse of each wavelength.

[0097] This can be beneficial as it means that the determination of the parameters can be carried out under known conditions, and that these can be the same conditions under which the stored values ​​of the parameters are determined.

[0098] The term "sequential" herein should be interpreted such that the light pulses of each wavelength are emitted at different times, e.g., one after the other, and / or the recording of the signal of each wavelength is performed at different times. In the case where multiple light sources emit light pulses of the same wavelength, the method may include simultaneously emitting each of the light pulses of the same wavelength from different light sources. For example, in the case of one or more light sources including two light sources both emitting infrared light of the same wavelength, the method may include both of the infrared light sources simultaneously emitting their respective light pulses.

[0099] Alternatively, if the light sources emit light pulses of the same wavelength, the method may include emitting each of the light pulses of the same wavelength sequentially, i.e., at different times. For example, if the one or more light sources include both infrared light or two light sources that emit the same wavelength, the method may include both infrared light sources emitting their respective light pulses one after the other. This may allow each light source to be checked individually.

[0100] The detection of light pulses by one or more detectors can be time multiplexed according to the emission of each wavelength so that it can be determined exactly which wavelength of light gave rise to the detected signal.

[0101] The optical sensor may comprise one or more broadband light sources. The optical sensor may comprise one or more wavelength-sensitive detectors and / or one or more detectors provided with optical filters, whereby recording of signals at each wavelength may also be achieved with a broadband light source.

[0102] The present invention also extends to an optical sensor for carrying out the method described in the fourth aspect above.

[0103]

[0013] Accordingly, from a fifth aspect, there is provided an optical sensor for measuring one or more physiological signs, the sensor comprising one or more detectors and one or more light sources, and wherein the optical sensor is arranged to perform the method of the fourth aspect before the device is attached to the person. In other words, the optical sensor may: emit (e.g. sequentially, i.e. at different times) one or more pulses of light at one or more different wavelengths using one or more light sources, where each pulse of light is emitted at a known power level for a known length of time; record (e.g. sequentially) signals of the one or more pulses of light at each wavelength using one or more detectors; determine parameters for each signal for each wavelength of light; compare the determined parameters with stored values ​​of the parameters for each wavelength; and determine that the optical sensor is ready for use if the determined parameters for each wavelength are within a set tolerance range of the stored values ​​of the parameters for each wavelength.

[0104] The optical sensor may comprise a processor. The optical sensor and / or processor may perform any of the steps of the fourth aspect above, including one or more or all of the optional features.

[0105] It has been recognized that another method for improving the accuracy and reliability of an optical sensor for measuring one or more physiological signs is to perform one or more calibration methods once the sensor is attached to a person. The calibration method may involve one or more adjustments to the operation of the sensor based on how the light detected by the detector is affected by the particular conditions created by its attachment to the skin of a particular person. Thus, a method may be provided that involves calibrating the sensor for use with different people and / or various skin profiles.

[0106] Viewed from a sixth aspect, there is provided a method of calibrating an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and one or more light sources, the method comprising, after the device is attached to the person, emitting one or more light pulses of one or more different wavelengths using one or more of the one or more light sources, for example sequentially (i.e. at different times), where each light pulse of each wavelength is emitted at a known power level for a known length of time; recording the one or more light pulse signals of each wavelength using the one or more detectors; determining a parameter for each signal of each wavelength of light; comparing the determined parameter to a stored value of the parameter or each wavelength of light; and adjusting the power and / or length of time of the light pulse(s) of each wavelength to reduce a difference between the determined parameter and the stored value of the parameter.

[0107] The optical sensor may be as described in the first aspect above. Accordingly, the calibration method may be performed using the optical sensor of the first aspect (optionally including one or more or all of the optical features). Alternatively, the calibration method may be performed using any other known type of optical sensor for measuring a person's physiological signs (i.e., one in which the light source does not surround the detector). Such an optical sensor may comprise one or more detectors and one or more light sources.

[0108] Furthermore, the optical sensor may have been initialized according to the method described in the fourth aspect of the present invention. Thus, the calibration method may be performed after the initialization method of the fourth aspect. It may be that the optical sensor has been determined to be ready for use according to the fourth aspect.

[0109] Alternatively, the calibration method may be performed even if the initialization method is not performed.

[0110] The above method may allow the sensor to be calibrated for the specific person being monitored. This is because the method may calibrate the sensor to the person's specific skin profile. This calibration may be achieved by adjusting and / or optimizing the optical sensor, i.e., the power and / or duration of the light pulse(s) for each wavelength, depending on how the detected signal is affected when attached to a person. This may result in improved signal quality achievable for each wavelength for a given person / skin profile.

[0111] The calibration method may be performed before the optical sensor is used to monitor one or more physiological signs of a person. Additionally or alternatively, the calibration method may be performed during measurement of one or more physiological signs. For example, the calibration method may be performed after monitoring one or more physiological signs using the optical sensor for a period of time, e.g., five minutes. This may be a repeat of the calibration method performed before monitoring of one or more physiological signs begins. This may allow for ensuring that the optical sensor is calibrated throughout the sensor's lifetime, e.g., to accommodate adjustment or drift of any of the sensor's components over time.

[0112] The term "skin profile" should be understood to include multiple parameters related to various skin characteristics, such as blood content, skin thickness, amount of subcutaneous fat, skin pigmentation, scattering from connective tissue, etc. Skin profile may depend on factors such as skin tone / color, skin condition, and / or skin / tissue composition. Skin condition may be affected, for example, by a person's age. For example, older people may have different skin conditions than younger people, and older people's skin may cause more light scattering. Furthermore, skin condition may be affected by a person's lifestyle, for example, how much sunlight the skin has been exposed to over the person's lifetime. Skin / tissue composition, such as fat and moisture levels, may also affect how light is reflected and transmitted through a person's skin. By utilizing the above calibration method, optical sensors may provide more accurate measurements for most, if not all, different people, regardless of factors such as skin tone / color, skin condition, and / or skin / tissue composition. Each person may have a unique skin profile.

[0113] The optical sensor may include a single detector and a single light source. The detector may be capable of detecting multiple different wavelengths. The light source may be capable of emitting multiple distinct wavelengths of light.

[0114] In the most basic case (e.g., where the physiological sign being monitored can be so measured using a single wavelength of light), the method can include emitting a single pulse of light at a single wavelength using a single light source at a known power level for a known length of time. Such a case can be performed even if the optical sensor is capable of emitting multiple wavelengths of light and / or has multiple light sources.

[0115] The one or more physiological signs may include one or more vital signs, such as blood oxygen saturation, pulse rate, and respiratory rate. The person may be a patient.

[0116] The detector may be a photodetector. Alternatively, the detector may be a camera. The camera may comprise one or more individual pixels.

[0117] The calibration method does not necessarily need to be performed for all wavelengths that can be emitted by the sensor and / or for all light sources, as, for example, not all of the wavelengths that can be emitted will be used, or not all of the light sources will be used to monitor physiological signs of a particular person of interest.

[0118] The method may include emitting pulses of light at multiple different wavelengths. This may be particularly useful when the physiological sign being monitored requires the use of two or more different wavelengths, and therefore the ability to emit multiple wavelengths of light and to calibrate the sensor for multiple wavelengths of light may be beneficial. Even in this case, the multiple wavelengths may be a subset of the total number of discrete wavelengths that may be emitted by the sensor.

[0119] The stored parameters for each wavelength may be parameters recorded before the optical sensor is attached to a person. This may be parameters, such as the signal-to-noise ratio, recorded during setup (e.g., an initialization method) shortly before the optical sensor is attached to a person (e.g., within minutes or hours), or at some other time, such as during manufacturing before the optical sensor is provided to a user. The stored values ​​of the parameters for each wavelength may also be parameters determined under set, controlled conditions, such as at a given intensity, when the sensor faces a reflectance target with known characteristics. The stored values ​​of the parameters for each wavelength may also be parameters determined in the manner described in the fourth aspect above. In other words, the stored values ​​of the parameters, such as the signal-to-noise ratio for each wavelength, may be parameters determined during initialization of the optical sensor. Thus, the stored values ​​of the parameters may be different each time the optical sensor is calibrated.

[0120] Alternatively, the stored values ​​of the parameters for each wavelength may be predetermined parameters, which may be defined, for example, by the manufacturer. The predetermined parameters may depend on the characteristics and / or measurements of each of the one or more light sources obtained before the optical unit is delivered to the user, for example, by the manufacturer. Thus, the stored values ​​of the parameters may remain the same each time the optical sensor is calibrated. In other words, the stored parameters, such as the stored signal-to-noise ratio for each wavelength, may be expected values ​​for the recorded signal under ideal conditions.

[0121] The known power level and / or known time length of each light pulse may be a default power level and / or a default time length. The known power level and / or known time length of each light pulse may be the same each time the calibration method is performed. The known / default power level and / or known / default time length may be an initial power level and / or an initial time length. The known power level and / or known time length may be an average value. The average value may be determined by the manufacturer, for example, based on a database.

[0122] The known power level and / or known length of time of each light pulse may be a medium power level and / or a medium length of time, which may mean that the power level and / or length of time may be both increased and decreased from the known / default value.

[0123] The known power level and known length of time may be an average value over all expected skin profiles.

[0124] Adjusting the power and / or duration of the light pulses of each wavelength may include increasing or decreasing one or more of the power and / or duration. For example, the method may include increasing the power of the light pulses and decreasing the duration of the light pulses. As a further example, the method may include increasing the power of the light pulses and increasing the duration of the light pulses, or decreasing the power of the light pulses and decreasing the duration of the light pulses, or decreasing the power of the light pulses and increasing the duration of the light pulses.

[0125] It will thus be appreciated that the optical sensor may be configured to be able to adjust both the power of the light pulse and the time of the light pulse, however, even if the optical sensor is configured to be able to adjust both the power of the light pulse and the time of the light pulse, the method may only include adjusting one or both of the power of the light pulse or the time of the light pulse.

[0126] In other words, the optical sensor may be configured such that the power of the light pulse and the time of the light pulse are separate adjustable parameters for each of one or more wavelengths, which may provide greater adjustability and accuracy when calibrating the optical sensor to reduce differences between the determined parameters and the stored values ​​of the parameters.

[0127] The step of adjusting the power and / or duration of the light pulses of each wavelength may include selecting to adjust one or both of the power and duration of the light pulses of each wavelength. The step of selecting to adjust one or both of the power and duration of the light pulses of each wavelength may be based on one or more of the recorded signals for one or more light pulses of each wavelength and a comparison of the determined parameters of each signal at each wavelength with stored values ​​of the parameters at each wavelength.

[0128] It will be appreciated that in some instances, only the power of the light pulse may need to be adjusted, while in other instances, only the time of the light pulse may need to be adjusted, or both the power of the light pulse and the time of the light pulse may need to be adjusted. It is therefore beneficial for the optical sensor to be configured to be able to adjust both the power and the time of the light pulse so that the calibration method can determine accordingly. The method may include determining whether to adjust the power of the light pulse, the time of the light pulse, or both.

[0129] Adjusting the power and / or time length of each of the one or more light pulses can be used to adjust the light dose provided by each of the one or more light pulses.

[0130] The term light dose can be understood as the total energy of light absorbed by tissue for a given light pulse. In other words, light dose can be the product of the power of the light pulse absorbed by tissue and the length of time the light pulse is absorbed by tissue. Therefore, the same light dose can be achieved by increasing the power of the light source and decreasing the length of time the light source is emitting, or vice versa. For example, it may be possible to have the same light dose by increasing the power while keeping the length of time the light pulse is emitted constant, or by keeping the power of the light pulse constant and only increasing the length of time the light pulse is emitted.

[0131] The method may include adjusting only one of the power and / or duration of the light pulses. In particular, the method may include increasing or decreasing only one of the power and / or duration of the light pulses of each wavelength.

[0132] The method may include adjusting the power and / or duration of the light pulses of each wavelength in the same manner. For example, both the power and duration of the light pulses of each wavelength may be increased for each wavelength. Alternatively, the method may include adjusting the power and / or duration of the light of each wavelength in different manners, i.e., independently. In other words, one of the power and / or duration of the light pulses may be increased, and the other of the power and / or duration may be decreased. In particular, at some wavelengths, the power and duration of the light pulses may be increased, while at other wavelengths, the power may be increased and the duration may be decreased. This may depend on the difference between the determined parameters and the stored values ​​of the parameters for each wavelength. For example, at certain longer wavelengths, higher power and / or longer duration may be required to reduce the difference, while at shorter wavelengths, lower power and / or shorter duration may be required to reduce the difference.

[0133] For lighter skin tones, it may be necessary to decrease the power level and / or length of time of the emitted light pulse(s), and conversely, for darker skin tones, it may be necessary to increase the power level and / or length of time of the emitted light pulse(s).

[0134] The parameters for each of the multiple wavelengths may be determined by a processor within the optical sensor.

[0135] The parameter can be any quantifiable parameter related to the recorded signal for each wavelength. Furthermore, the parameter can be a quantifiable parameter that is easily measurable or easily derived. For example, the parameter can be one of emitted irradiance, intensity, or intensity squared. The intensity and intensity squared can be the reflected intensity of the signal for each wavelength of light.

[0136] In a preferred arrangement, the parameter may be a signal to noise ratio for each signal at each wavelength of light, and thus each wavelength of light may have a stored signal to noise ratio that may be used in the comparison step of the method.

[0137] The signal-to-noise ratio may be the ratio of the signal power (ie, the power of the emitted light pulse) to the noise power (ie, the power of the detected signal).

[0138] The signal-to-noise ratio can be determined using standard methodologies, one example of which is described in "Signal-to-noise ratio as a quantitative measure for optical biosensors" (https: / / www.maximintegrated.com / en / design / technical-documents / app-notes / 6 / 6410.html).

[0139] The signal-to-noise ratio can be determined by comparing the amplitude of the pulsating signal recorded for each wavelength to the noise floor of the device. The method can include recording a background signal for each wavelength using one or more detectors before emitting one or more light pulses of different wavelengths. The noise floor used in determining the signal-to-noise ratio for each wavelength can be the total signal recorded by the detector.

[0140] Alternatively, the signal-to-noise ratio for each of the plurality of wavelengths may be determined by comparing the intensity and / or fluctuating amplitude of the light pulse emitted from the light source with the intensity and / or fluctuating amplitude of the light pulse recorded by the detector. The intensity may include the power level of the signal. The fluctuating amplitude may include a pulsating signal corresponding to the emitted or detected light source.

[0141] The method may include attaching an optical sensor to the person's skin. The optical sensor may be attached such that one or more detectors and another light source face a surface of the person's skin. Thus, light pulses emitted by the multiple light sources may be directed into the person's tissue. The optical sensor may be a reflectance sensor (e.g., a reflectance pulse oximeter), in which case the one or more detectors and another light source may be positioned on / face the same surface of the person's tissue during use.

[0142] Alternatively, the optical sensor may be a transmission type sensor, in which case one or more detectors and another light source may be positioned on opposite sides of a person's tissue during use. For example, one or more light sources may be positioned on one side of a person's fingertip and one or more detectors may be positioned on the other side of the person's fingertip.

[0143] The steps of the method may be performed while the device is attached to the person whose physiological signs are being measured.

[0144] The method may include, for example, removing the optical sensor from an environment in which the initialization method (if performed) was performed. For example, the method may include removing the sensor from a housing and / or removing a cover. The optical sensor may be attached to a person's skin by any known means, such as tape, an adhesive base, and / or a strap.

[0145] The method may include turning on the sensor (if not done automatically when the sensor is attached to the person). The method may include the sensor indicating that the sensor is on and / or running a calibration method.

[0146] The terms "in sequence" or "sequentially" should be interpreted such that one or more light pulses of each wavelength are emitted at different times, e.g., one after the other, when multiple wavelengths are present, and / or the recording of the signal for each wavelength occurs at different times. If multiple light sources emit light pulses of the same wavelength, the method may include simultaneously emitting each of the light pulses of the same wavelength. For example, in the case of a light source including two light sources that both emit infrared light or the same wavelength, the method may include both infrared light sources simultaneously emitting their respective light pulses.

[0147] Alternatively, where the light sources emit light pulses of the same wavelength, the method may include sequentially emitting each of the light pulses of the same wavelength. For example, in the case of one or more light sources including two light sources both for emitting infrared light at the same wavelength, the method may include both infrared light sources sequentially emitting their respective light pulses.

[0148] The method may include determining a difference between the determined parameter and a stored value of the parameter for each wavelength of light. The method may include comparing the difference between the determined parameter and a stored value of the parameter for each wavelength to a predetermined tolerance. The method may include adjusting a power and / or a duration of the light pulses for each wavelength to reduce the difference to be within the predetermined tolerance.

[0149] The predetermined tolerance may be up to ±20% of the stored parameter, optionally up to ±15%, optionally up to ±10%, optionally up to ±5%, optionally up to ±2% of the stored value of the parameter. The tolerance may be the same or different for different light sources and / or wavelengths.

[0150] Following the step of adjusting the power and / or duration of one or more light pulses of each wavelength, the method may include one or more repeating steps of emitting one or more light pulses of one or more different wavelengths using one or more light sources (but in this case at the adjusted power and / or duration), recording the signal of the light pulses of each wavelength using a detector, determining parameters for each signal at each wavelength of light, and comparing the determined parameters with stored values ​​of the parameters for each wavelength. The repeating steps may include emitting one or more light pulses at an adjusted power level and for an adjusted duration, i.e., the power level and duration resulting from the last adjustment step of the last iteration of the method. The method may be repeated until the difference between the determined parameters and the stored values ​​of the parameters for each wavelength of light is within a predetermined tolerance and / or is as small as possible within a given number of iterations or a given duration. The method may be repeated up to a certain number of times, for example, up to 100 times. If the difference between the determined parameter and the stored value of the parameter for each wavelength of light is not within a predetermined tolerance within a certain number of iterations of the method, for example within 100 iterations, the optical sensor may be configured to provide, for example, an audible and / or visual indication that it is unsuitable for use, which may prevent the optical sensor from being used as it may not provide sufficiently accurate readings.

[0151] During operation, the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths may be within a predetermined tolerance, while the difference between the determined parameter and the stored value of the parameter for the remaining wavelengths of the plurality of wavelengths may be outside the predetermined tolerance.

[0152] For example, in the case of a plurality of different wavelengths including eight different wavelengths, for five of the different wavelengths, the difference between the determined parameter and the stored value of the parameter may be within a predetermined tolerance, while for the other three different wavelengths, the difference between the determined parameter and the stored value of the parameter may be outside the predetermined tolerance. In this case, the method may include adjusting the power and / or duration of the light pulses only for wavelengths for which the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths may be within the predetermined tolerance. Alternatively, in this case, the method may further include adjusting the power and / or duration of the light pulses for each of the plurality of wavelengths to further reduce the difference between the determined parameter and the stored value of the parameter.

[0153] If the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths is within a predetermined tolerance range, while the difference between the determined parameter and the stored value of the parameter for the remaining wavelengths of the plurality of wavelengths is outside the predetermined tolerance range, the method may include measuring a physiological sign of the person using only one or more of the wavelengths of light for which the difference between the determined parameter and the stored value of the parameter for the one or more of the plurality of wavelengths is within the predetermined tolerance range.

[0154] The method may include indicating that the optical sensor is calibrated and / or ready for use when a difference between the determined parameter and a stored value of the parameter for each wavelength is within a predetermined tolerance. The method may include indicating that the optical sensor is calibrated and / or ready for use when a difference between the determined parameter and a stored value of the parameter for sufficient wavelengths to be able to monitor one or more physiological signs is within a predetermined tolerance. The indication may include an audible and / or visual alert.

[0155] The method may be periodically re-iterated during use, for example, every five minutes. One reason for this may be that bodily fluids such as sweat may accumulate on the surface of one or more detectors or light sources, which may cause changes in parameters, such as the signal-to-noise ratio. This is particularly relevant when the optical sensor is a wearable device such as a sports watch. Therefore, the optical sensor may be recalibrated accordingly to account for any obstructions on the sensor's surface. If, upon re-iterating the method, it is found that the difference between the determined parameter and the parameter's stored value has increased, possibly outside a predetermined tolerance range, the method may include providing an alert. This may prompt the user to clean the surface of the optical sensor. The method may then be re-iterated to determine whether the difference between the determined parameter and the parameter's stored value is within a predetermined tolerance range.

[0156] The method may include using one or more detectors to record one or more light-plus signals at each wavelength to create an optical signature for the person.

[0157] A person's optical signature may be a signal recorded for each wavelength in an initial recording of the signal using a known / initial power and / or a known / initial time for each wavelength of the multiple wavelengths. In other words, the person's optical signature may be based on the light pulses before any adjustment of the power and / or time of the light pulses. The optical signature may include signals for each of the multiple wavelengths. A person's optical signature may provide an indication of how each emitted wavelength at a standard power and length of time is affected by the person's particular skin profile. This may provide an indication of the person's skin type.

[0158] The method may include storing an optical signature of the person.

[0159] The person's optical signature may be compared to a library of stored optical signatures to select one or more wavelengths to use when measuring one or more physiological signs.

[0160] The library of optical signatures may be organized into a plurality of skin profile categories. Each skin profile category may include one or more predetermined wavelengths to be used when measuring one or more physiological indicia. Comparing the person's optical signature to the library may include assigning a skin profile category to the person and selecting one or more wavelengths to be used when measuring the one or more physiological indicia based on the assigned skin profile category.

[0161] The assigned skin profile category may be a skin type category / class within which a person's particular skin type falls or best matches. For example, a library of optical signatures may include three skin profile categories that can be roughly considered as dark skin, medium-light skin, and light skin. A person's recorded optical signature may be analyzed to determine which skin profile category the person's skin falls into or best matches, i.e., which light affects it in the same or most similar way. This may be, for example, an evaluation of the degree to which light scattering and / or absorption occurs for each wavelength of light. A person's optical signature may be assigned to a particular skin profile category from the library. The skin profile category to which a given optical signature is assigned may be based on historical data. The historical data may have been collected by individual optical sensors, or historical data may be collected by many different optical sensors and collated in a central database. A given optical signature may be identified as falling into a given skin profile category.

[0162] The library of optical signatures may be stored for access by the processor. The library may be stored on memory within the optical sensor or on a separate device that may be in wireless or wired communication with the optical sensor.

[0163] Each skin profile category may have one or more predetermined wavelengths from a plurality of wavelengths that are used when measuring physiological signs of individuals having a skin type that falls within that skin profile category.

[0164] The method may be able to estimate a person's particular skin characteristics according to their optical signature and / or assigned skin profile category.

[0165] Based on the optical signature, the assigned skin profile category, and / or the estimated skin characteristics, a suitable selection or combination of one or more wavelengths can be selected to measure one or more physiological indicia. The suitable selection or combination of wavelengths to be used can be one or more wavelengths that will provide a sufficiently accurate and / or reliable reading of the one or more physiological indicia for that particular optical signature and / or skin profile category.

[0166] The selection of one or more wavelengths to use when measuring one or more physiological signs may be determined using a model using look-up tables, machine learning algorithms, based on light transport simulations and / or any other suitable method.

[0167] Once selected, the one or more wavelengths may be emitted using adjusted values ​​of power level and / or length of time (i.e., those that reduce or minimize the difference between the determined parameter and the stored value of the parameter to at least within a predetermined tolerance) when measuring one or more physiological signs.

[0168] The method may enable an optical sensor to record an initial optical signature of a person of a given skin type without any calibration.

[0169] The method may further include selecting one or more wavelengths from the plurality of wavelengths based on the person's optical signature or assigned skin profile category, where the selected one or more wavelengths should be used when measuring the one or more physiological signs. The selected one or more wavelengths may be the optimal wavelength(s) for measuring the person's assigned skin profile category, i.e., the wavelength(s) expected to provide the most accurate and / or reliable readings for the one or more physiological signs being monitored. The one or more wavelengths may be selected based on historical data from measuring the physiological signs of humans with assigned skin profiles. For example, for skin profile category A, a combination of green light and infrared light may be found to be an optimal combination of wavelengths based on data stored in a library of skin profiles.

[0170] The steps of creating an optical signature of the person and selecting one or more wavelengths from the plurality of wavelengths based on the optical signature of the person to be used when measuring one or more physiological signs may be performed before the steps of determining parameters for each signal at each wavelength of light, comparing the determined parameters to stored values ​​of the parameters for each wavelength of light, and adjusting the power and / or duration of the light pulses at each wavelength to reduce the difference between the determined parameters and the stored values ​​of the parameters. In other words, the steps of determining parameters for each signal at each wavelength of light, comparing the determined parameters to stored values ​​of the parameters for each wavelength of light, and adjusting the power and / or duration of the light pulses at each wavelength to reduce the difference between the determined parameters and the stored values ​​of the parameters may be performed only for the one or more selected wavelengths. In this case, the parameter, e.g., signal-to-noise ratio, may be determined only for the signals corresponding to the one or more wavelengths selected to be used when measuring one or more physiological signs.

[0171] This may be beneficial because it may reduce the computational requirements and / or time of the calibration method by only determining parameters and adjusting the power and / or duration of the light pulses corresponding to selected wavelengths, rather than for all wavelengths that may be emitted by the optical sensor.

[0172] The library of optical signatures may be organized into multiple categories, each containing multiple different optical profiles. For example, the stored library of optical signatures may include two to eight categories, with each category containing two to six optical signatures. Each category of optical signatures may have an assigned combination of one or more wavelengths that may form the basis for selection in the method. This assigned combination of one or more wavelengths may be one that is deemed optimal for that category.

[0173] The method may enable the use of the most suitable wavelengths when measuring physiological signs. The historical database may include information regarding the optimal wavelengths for each optical signature or group of optical signatures.

[0174] A method of selecting wavelengths to use for measuring physiological signs based on a skin profile, in combination with adjusting the power and / or duration of the light pulses of each wavelength to reduce the difference between the determined parameter and the stored value of the parameter, may improve the accuracy and reliability of the measurement of one or more physiological signs.

[0175] The number of wavelengths used to measure one or more physiological signs may depend on the physiological signs being monitored. When measuring one or more physiological signs, it may not be necessary to use all wavelengths that an optical sensor can emit, and therefore the above method may be useful for selecting wavelengths that are appropriate for a given skin or optical signature of a person when measuring one or more physiological signs.

[0176] If the physiological sign is respiratory rate (i.e., breathing rate) or pulse rate, one wavelength may be sufficient to monitor the physiological sign. In this case, there may be a specific wavelength for a given skin type or optical signature that provides the most accurate and / or reliable reading. For example, for individuals with lighter skin tones, selecting a shorter wavelength may provide more accurate results, while for individuals with darker skin tones, selecting a longer wavelength may provide more accurate results. A calibration method may provide an assessment or indication of skin type via the measured optical signature, allowing for a selection of one or more wavelengths to use. Also, even if it is possible to monitor a physiological sign using a single wavelength, signals from two or more different wavelengths may provide a more accurate and / or reliable reading. If the physiological sign is blood oxygen saturation, two or more different wavelengths may be required. Similarly, there may be a specific combination of wavelengths for a given skin type / optical signature that provides the most accurate and / or reliable reading. A calibration method may provide an assessment or indication of skin type, allowing for a selection of a combination of wavelengths to use.

[0177] After a calibration method is performed (i.e., after the power level and / or length of emission time of one or more wavelengths is adjusted and / or one or more wavelengths for use is selected), one or more physiological signs may be measured using the optical sensor. After one calibration method is completed, the sensor may indicate (e.g., visually and / or audibly) that the sensor is ready to measure one or more physiological signs of a person.

[0178] As with the previous aspects, the present invention also extends to an optical sensor operating in accordance with the method described in the sixth aspect above. The present invention may therefore provide an optical sensor carrying out a calibration method including one or more or all of the optional features. This may or may not be the optical sensor of the first aspect.

[0179] The optical sensor may include one or more broadband light sources, one or more wavelength-sensitive detectors, and / or one or more detectors equipped with optical filters.

[0180] Therefore, viewed from a seventh aspect, there is provided an optical sensor for measuring one or more physiological signs, the sensor comprising one or more detectors and one or more light sources, wherein when the optical sensor is attached to a person, the optical sensor emits one or more pulses of light of one or more different wavelengths using one or more of the one or more light sources, wherein each pulse of light of each wavelength is emitted at a known power level for a known length of time; records the one or more light pulse signals of each wavelength using the one or more detectors; determines a parameter for each signal of each wavelength of light; compares the determined parameter with stored values ​​of the parameter for each wavelength of light; and adjusts the power and / or duration of the one or more light pulses of each wavelength to reduce a difference between the determined parameter and the stored value of the parameter.

[0181] The optical sensor may comprise a processor, and the optical sensor and / or processor may perform (or cause to be performed) any of the steps of the invention of the sixth aspect above, including one or more or all of the optional features.

[0182] The optical sensor may be a medical device, such as a pulse oximeter, for measuring one or more vital signs of a patient, or a wearable device, such as a sports watch, for measuring one or more physiological symptoms of a person.

[0183] The calibration steps of creating an optical signature of the person and selecting one or more wavelengths of the plurality of wavelengths to use when measuring one or more physiological signs based on the optical signature of the person may be performed, and may be beneficial, even if other steps of determining parameters of each signal at each wavelength of light, comparing the determined parameters with stored values ​​of the parameters for each wavelength of light, and adjusting the power and / or duration of the light pulses at each wavelength to reduce differences between the determined parameters and the stored values ​​of the parameters are not performed.

[0184] Therefore, viewed from an eighth aspect, there is provided a method of calibrating an optical sensor for measuring one or more physiological signs of a person after the device is attached to the person, the sensor comprising one or more detectors and another light source, the method comprising: after the device is attached to the person, using the one or more light sources to emit one or more pulses of light at one or more different wavelengths, wherein each pulse of light at each wavelength is emitted at a known power level for a known length of time; recording signals of the one or more pulses of light at each wavelength using the one or more detectors to create an optical signature of the person; and selecting one or more wavelengths from the plurality of wavelengths to use in measuring the one or more physiological signs based on the optical signature of the person.

[0185] The method of calibrating an optical sensor may include any of the steps or features, including one or more or all of the optional features described in relation to the sixth aspect above. The calibration methods may be performed in parallel, and not necessarily sequentially.

[0186] The method may include comparing an optical signature of the person to a library of stored optical signatures to select one or more wavelengths to use when measuring the one or more physiological indicia, where selecting one or more wavelengths of the plurality of wavelengths to use when measuring the one or more physiological indicia may be based on the assigned skin profile.

[0187] The library of optical signatures may be organized into a plurality of skin profile categories. Each skin profile category may be associated with one or more predetermined wavelengths to be used when measuring one or more physiological indicia. Comparing the person's optical signature to the library may include assigning a skin profile category to the person and selecting one or more wavelengths to be used when measuring the one or more physiological indicia based on the assigned skin profile category.

[0188] The one or more wavelengths may be selected using a lookup table, a model using a machine learning algorithm, a light transport simulation, and / or any other known method.

[0189] The method may include storing an optical signature of the person.

[0190] The optical signature may provide a spectral profile of the person's skin on which the sensor is worn. The optical signature may give an indication of the bulk properties of the person's skin / tissue in proximity to the optical sensor, i.e., where the measurement is being taken.

[0191] A person's optical signature can be compared to a library of stored optical signatures, which can be used to assign a skin profile category to the person.

[0192] The assigned skin profile category may be the skin type category / class to which a person's particular skin type falls or best matches. For example, a skin profile may include three skin profile categories A, B, and C, which may be roughly considered, for example, dark skin, medium-light skin, and light skin. A person's recorded optical signature may be analyzed to determine which skin profile category the person's skin falls into or best matches, i.e., which emitted light affects it in the same or most similar way. This may be, for example, an assessment of how much light scattering and / or absorption occurs for each wavelength of light when an optical sensor is attached to a particular person. A person's optical signature may be assigned to a particular skin profile category from a library.

[0193] Library historical data may be collected by individual optical sensors, or historical data may be collected by many different optical sensors and collated in a central database.

[0194] The library may be stored for access by the processor. The library may be stored on memory within the optical sensor or on a separate device that may be in wireless or wired communication with the optical sensor.

[0195] The method may include determining a skin profile category for the person, wherein each skin profile category in the library may have one or more predetermined wavelengths of a plurality of wavelengths to be used when measuring physiological indicia for people having a skin type / optical signature that corresponds to the skin profile category.

[0196] The method may include using machine learning to create a library of stored optical signatures and skin profile categories and / or to select one or more wavelengths to use when measuring one or more physiological signs. The skin profile category may be determined based on the intensity of the detector readings at multiple or all wavelengths and / or by looking at one or more ratios of the readings at two or more of the wavelengths.

[0197] The method may be capable of estimating certain skin characteristics of a person according to their optical signature and / or assigned skin profile category. Based on the estimated skin characteristics, a suitable selection or combination of one or more wavelengths may be selected for measuring one or more physiological signs. The suitable selection or combination of wavelengths used may be one or more wavelengths known to provide sufficiently accurate and / or reliable readings of one or more physiological signs for that particular skin profile category. The selected one or more wavelengths may be emitted using adjusted values ​​of power level and / or length of time (i.e., those that reduce the difference between the determined parameters and the stored values ​​of the parameters to at least within a predetermined tolerance) when measuring the one or more physiological signs.

[0198] The method may comprise an optical sensor that records an initial optical signature of a person of a given skin type / profile without any calibration, i.e., adjustment.

[0199] The one or more wavelengths selected may be the optimal wavelength(s) for measuring one or more physiological signs of a person, i.e., the wavelength(s) that are expected to give the most accurate and / or reliable readings for the one or more physiological signs being monitored. The one or more wavelengths may be selected based on historical data from measuring human physiological signs of the assigned skin profile category. For example, for skin profile A, a combination of green light and infrared light may be found to be the optimal combination of wavelengths based on data stored in the library.

[0200] Selecting one or more wavelengths of the plurality of wavelengths when measuring one or more physiological signs based on the person's optical signature or assigned skin profile category to be used may include looking up one or more wavelengths to use for that optical signature or assigned skin profile category from a lookup table. Additionally or alternatively, the one or more wavelengths may be selected using a model using a machine learning algorithm, based on light transport simulations, or using any other known method.

[0201] The library of optical signatures may be organized into multiple categories. For example, the library of optical signatures may include two to eight categories, and each category may include two to six optical profiles. Each category of skin profile may have an assigned combination of one or more wavelengths that may form the basis for selection in the method. This assigned combination of one or more wavelengths may be one that is deemed optimal or sufficient for that skin profile category.

[0202] The method may enable wavelengths appropriate for a given skin profile category to be used when measuring physiological signs. The historical database may include information regarding optimal wavelengths for each optical signature or group of skin profiles.

[0203] A method of selecting wavelengths to use for measuring physiological signs based on optical signatures and / or skin profile categories, in combination with adjusting the power and / or duration of light pulses for each wavelength to reduce differences between determined parameters and stored values ​​of the parameters, may improve the accuracy and reliability of measurements of one or more physiological signs.

[0204] The number of wavelengths used to measure one or more physiological signs may depend on the physiological signs being monitored. When measuring one or more physiological signs, it may not be necessary to use all wavelengths that the optical sensor can emit, and therefore the above method may be useful for selecting wavelengths that are appropriate for a given skin profile category of a person when measuring one or more physiological signs.

[0205] If the physiological sign is respiratory rate or pulse rate, one wavelength may be sufficient to monitor the physiological sign. In this case, there may be a specific wavelength for a given optical signature or skin type that provides the most accurate and / or reliable reading. For example, for individuals with lighter skin tones, selecting a shorter wavelength may provide more accurate results, while for individuals with darker skin tones, selecting a longer wavelength may provide more accurate results. A calibration method may provide an assessment or indication of skin type (e.g., from the optical signature) that allows for the selection of one or more wavelengths to use. Also, even if it is possible to monitor a physiological sign using a single wavelength, signals from two or more different wavelengths may provide a more accurate and / or reliable reading. If the physiological sign is blood oxygen saturation, two or more different wavelengths may be required. Similarly, there may be a specific combination of wavelengths for a given skin type that provides the most accurate and / or reliable reading. The calibration method may provide an assessment or indication of skin type (eg, from the optical signature) that allows a selection of wavelength combinations to be made.

[0206] After a calibration method is performed (i.e., after the power level and / or length of emission time of one or more wavelengths is adjusted and / or one or more wavelengths for use is selected), one or more physiological signs may be measured using the optical sensor. After the calibration method is completed, the sensor may indicate (e.g., visually and / or audibly) that the sensor is ready to measure one or more physiological signs of a person.

[0207] This calibration method may be performed before the optical sensor is used to monitor one or more physiological signs of a person. Additionally or alternatively, the calibration method may be performed during measurement of one or more physiological signs. For example, the calibration method may be performed after the optical sensor has been used to monitor one or more physiological signs for a period of time, e.g., five minutes. This may be a repeat of the calibration method performed before monitoring of one or more physiological signs began. This may ensure that the optical sensor is calibrated throughout the sensor's lifetime, for example, to accommodate adjustment or drift of any of the sensor's components and / or changes in the person's condition.

[0208] Although not required, the calibration method of the eighth aspect may include one or more or all of the steps of the calibration method of the sixth aspect, and therefore the above description of the sixth aspect is applicable to this eighth aspect.

[0209] Thus, the method may include determining a parameter (e.g., a signal-to-noise ratio) for each signal at each wavelength of light. This step of determining the parameter may be performed after the step of selecting one or more wavelengths of the plurality of wavelengths when measuring one or more physiological signs based on the person's optical signature and / or assigned skin profile category to be used. Thus, the method may include determining a parameter for each signal corresponding to the one or more wavelengths selected for use in measuring only one or more physiological signs.

[0210] The method may include comparing the determined parameter to a stored value of the parameter for each wavelength of light. The method may include comparing the determined parameter to a stored value of the parameter for each of the one or more wavelengths selected for use in measuring only the one or more physiological signs.

[0211] The method may include determining a difference between the determined parameter and a stored value of the parameter for each wavelength of light. The method may include comparing the difference between the determined parameter and a stored value of the parameter for each wavelength to a predetermined tolerance range.

[0212] The method may include adjusting the power and / or duration of one or more light pulses of each wavelength to reduce a difference between the determined parameter and a stored value of the parameter. The adjustment of the power and / or duration of the light pulses of each wavelength may be to reduce the difference to within a predetermined tolerance.

[0213] This is advantageous because it can ensure that light pulses of each wavelength of light used to measure one or more physiological signs are emitted using suitable characteristics so that the recorded signals have acceptable parameters, such as signal-to-noise ratio, which can improve the quality of the recorded signals for each wavelength, such that more accurate and / or reliable measurements of one or more physiological signs can be recorded using one or more selected wavelengths for a particular optical signature and / or skin profile category of a person.

[0214] The parameter can be any quantifiable parameter related to the recorded signal for each wavelength. Furthermore, the parameter can be a quantifiable parameter that is easily measurable or easily derived. For example, the parameter can be one of emitted irradiance, intensity, or intensity squared. The intensity and intensity squared can be the reflected intensity of the signal for each wavelength of light.

[0215] The parameter may be a signal-to-noise ratio for each signal at each wavelength of light. Thus, each wavelength of light may include a stored signal-to-noise ratio that may be used in the comparison step of the method.

[0216] The steps of determining a parameter for each signal at each wavelength of light, including comparing the determined parameter to a stored value of the parameter for each wavelength of light and adjusting the power and / or time of the light pulses at each wavelength to reduce the difference between the determined parameter and the stored value of the parameter ratio, may be performed only for the one or more wavelengths selected for use in measuring the one or more physiological signs. Similarly, the steps of determining a difference between the determined parameter and the stored value of the parameter for each wavelength of light and comparing the difference between the determined parameter and the stored value of the parameter for each wavelength with a predetermined tolerance may be performed only for the one or more wavelengths selected for use in measuring the one or more physiological signs.

[0217] This is beneficial because it may reduce the amount of adjustment required during the calibration method. Instead of adjusting the power and / or duration of the light pulses at each wavelength, the process can be performed more efficiently by first selecting one or more wavelengths that will be used to measure physiological signs and then adjusting the power and / or duration of only those wavelengths.

[0218] The predetermined tolerance may be up to ±20% of the stored signal-to-noise ratio, optionally up to ±15%, optionally up to ±10%, optionally up to ±5%, optionally up to ±2% of the stored signal-to-noise ratio.

[0219] The known power level and / or known time length of each light pulse may be a default power level and / or a default time length. The known / default power level and / or known / default time length may be an initial power level and / or an initial time length. The default power level and / or default time length may be an average value. The average value may be determined by the manufacturer based on a database.

[0220] The known power level and / or known length of time of each light pulse may be a medium power level and / or a medium length of time, which may mean that the power level and / or length of time may be both increased and decreased from the known / default.

[0221] The known power level and known time length may be average values ​​across all skin profiles. Adjusting the power and / or time of the light pulses of each wavelength may include increasing or decreasing one or more of the power and / or time. For example, the method may include increasing the power of the light pulses and decreasing the time of the light pulses. As a further example, the method may include increasing the power of the light pulses and increasing the time of the light pulses, or decreasing the power of the light pulses and decreasing the time of the light pulses, or decreasing the power of the light pulses and increasing the time of the light pulses.

[0222] It will thus be appreciated that the optical sensor may be configured to be able to adjust both the power of the light pulse and the time of the light pulse, however, even if the optical sensor is configured to be able to adjust both the power of the light pulse and the time of the light pulse, the method may only include adjusting one or both of the power of the light pulse or the time of the light pulse.

[0223] In other words, the optical sensor may be configured such that the power of the light pulse and the time of the light pulse are separate adjustable parameters for each of one or more wavelengths, which may provide greater adjustability and accuracy when calibrating the optical sensor to reduce differences between the determined parameters and the stored values ​​of the parameters.

[0224] The step of adjusting the power and / or duration of the light pulses of each wavelength may include selecting to adjust one or both of the power and duration of the light pulses of each wavelength. The step of selecting to adjust one or both of the power and duration of the light pulses of each wavelength may be based on one or more of the recorded signals for one or more light pulses of each wavelength and a comparison of the determined parameters of each signal at each wavelength with stored values ​​of the parameters at each wavelength.

[0225] It will be appreciated that in some instances, only the power of the light pulse may need to be adjusted, while in other instances, only the time of the light pulse may need to be adjusted, or both the power of the light pulse and the time of the light pulse may need to be adjusted. It is therefore beneficial for the optical sensor to be configured to be able to adjust both the power and the time of the light pulse so that the calibration method can determine accordingly. The method may include determining whether to adjust the power of the light pulse, the time of the light pulse, or both.

[0226] Adjusting the power and / or time length of each of the one or more light pulses can be used to adjust the light dose provided by each of the one or more light pulses.

[0227] The term light dose can be understood as the total energy of light absorbed by tissue for a given light pulse. In other words, light dose can be the product of the power of the light pulse and the length of time the light pulse is absorbed. Therefore, the same light dose can be achieved by increasing the power of the light source and decreasing the length of time the light source is emitting, or vice versa. For example, it may be possible to have the same light dose by increasing the power while keeping the length of time the light pulse is emitted constant, or by keeping the power of the light pulse constant and only increasing the length of time the light pulse is emitted.

[0228] The method may include adjusting only one of the power and / or duration of the light pulses. In particular, the method may include increasing or decreasing only one of the power and / or duration of the light pulses of each wavelength.

[0229] The method may include adjusting the power and / or time of the light pulses of each wavelength in the same manner. For example, both the power and time of the light pulses of each wavelength may be increased for each wavelength. Alternatively, the method may include adjusting the power and / or time of the light of each wavelength in different manners, i.e., independently. In particular, at some wavelengths, the power and time of the light pulses may be increased, while at other wavelengths, the power may be increased and the time may be decreased. This may depend on the difference between the determined parameters and the stored values ​​of the parameters for each wavelength. For example, at certain longer wavelengths, higher power and / or longer time may be required to reduce the difference, while at shorter wavelengths, lower power and shorter time may be required to reduce the difference.

[0230] Lighter skin tones may require a decrease in the power level and / or length of time of the emitted signal compared to the known / initial power level and known / initial length of time. Conversely, darker skin tones may require an increase in the power level and / or length of time compared to the known / initial power level and known / initial length of time.

[0231] Following the step of adjusting the power and / or duration of one or more light pulses at each wavelength, the method may include repeating one or more times the following steps: emitting one or more light pulses at one or more different wavelengths (e.g., sequentially) using one or more light sources; recording (e.g., sequentially) signals of the light pulses at each wavelength using a detector; determining parameters for each signal at each wavelength of light; and comparing the determined parameters with stored values ​​of the parameters for each wavelength. The repeating steps may include emitting one or more light pulses at an adjusted power level for an adjusted length of time, i.e., the power level and length of time resulting from the last adjustment step of the last iteration of the method. The method may be repeated until the difference between the determined parameters and the stored values ​​of the parameters for each wavelength of light is within a predetermined tolerance. The method may be repeated up to a certain number of times, for example, up to 100 times. If the difference between the determined parameter and the stored value of the parameter for each wavelength of light is not within a predetermined tolerance within a certain number of iterations of the method, for example within 100 iterations, the optical sensor may be configured to provide, for example, an audible and / or visual indication that it is unsuitable for use, which may prevent the optical sensor from being used as it may not provide sufficiently accurate readings.

[0232] During operation, the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths may be within a predetermined tolerance, while the difference between the determined parameter and the stored value of the parameter for the remaining wavelengths of the plurality of wavelengths may be outside the predetermined tolerance.

[0233] For example, in the case of a plurality of different wavelengths including eight different wavelengths, for five of the different wavelengths, the difference between the determined parameter and the stored value of the parameter may be within a predetermined tolerance, while for the other three different wavelengths, the difference between the determined parameter and the stored value of the parameter may be outside the predetermined tolerance. In this case, the method may include adjusting the power and / or duration of the light pulses only for wavelengths for which the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths is outside the predetermined tolerance. Alternatively, in this case, the method may further include adjusting the power and / or duration of the light pulses for each of the plurality of wavelengths to further reduce the difference between the determined parameter and the stored value of the parameter.

[0234] If the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths is within a predetermined tolerance range, while the difference between the determined parameter and the stored value of the parameter for the remaining wavelengths of the plurality of wavelengths is outside the predetermined tolerance range, the method may include measuring a physiological sign of the person using only one or more of the wavelengths of light for which the difference between the determined parameter and the stored value of the parameter for the one or more of the plurality of wavelengths is within the predetermined tolerance range.

[0235] The method may include indicating that the optical sensor is calibrated and / or ready for use when a difference between the determined parameter and a stored value of the parameter for each wavelength is within a predetermined tolerance. The method may include indicating that the optical sensor is calibrated and / or ready for use when a difference between the determined parameter and a stored value of the parameter for sufficient wavelengths to be able to monitor one or more physiological signs is within a predetermined tolerance. The indication may include an audible and / or visual alert.

[0236] The term "sequential" should be interpreted such that one or more light pulses of each wavelength are emitted at different times, e.g., one after the other, and / or the recording of signals at each wavelength is performed at different times. If multiple light sources emit light pulses of the same wavelength, the method may include simultaneously emitting each of the light pulses of the same wavelength. For example, if the one or more light sources include two light sources that both emit infrared light, the method may include both infrared light sources simultaneously emitting their respective light pulses.

[0237] Alternatively, if the light sources emit light pulses of the same wavelength, the method may include sequentially emitting each of the light pulses of the same wavelength. For example, if the one or more light sources include two light sources that both emit infrared light, the method may include both infrared light sources sequentially emitting their respective light pulses.

[0238] As with the previous aspects, the present invention also extends to an optical sensor operating in accordance with the method described in the eighth aspect above. The present invention may therefore provide an optical sensor performing a calibration method including one or more or all of the optional features. This may be the optical sensor of the first aspect.

[0239] The optical sensor may include one or more broadband light sources, one or more wavelength-sensitive detectors, and / or one or more detectors equipped with optical filters.

[0240] Viewed from a ninth aspect, there is provided an optical sensor for measuring one or more physiological signs, the sensor comprising one or more detectors and one or more light sources, wherein when the device is attached to a person, the optical sensor is for emitting (e.g. sequentially) one or more pulses of light of a plurality of different wavelengths using one or more of the one or more light sources, wherein each pulse of light of each wavelength is emitted at a known power level for a known length of time; recording (e.g. sequentially) the light plus signal of each wavelength using one or more detectors to create an optical signature of the person; and selecting one or more wavelengths of the plurality of wavelengths when measuring the one or more physiological signs based on the optical signature of the person to be used.

[0241] The optical sensor may compare the person's optical signature to a library of stored optical signatures to select one or more wavelengths to be used when measuring one or more physiological signs.

[0242] The library of optical signatures may be organized into a plurality of skin profile categories. Each skin profile category may include one or more predetermined wavelengths to be used when measuring one or more physiological indicia. Comparing the person's optical signature to the library may include assigning a skin profile category to the person and selecting one or more wavelengths to be used when measuring the one or more physiological indicia based on the assigned skin profile category.

[0243] The optical sensor may comprise a processor, and the optical sensor and / or processor may perform (or cause to be performed) any of the steps of the invention of the eighth aspect above, including one or more or all of the optional features.

[0244] Furthermore, the optical sensor may be the optical sensor of the first aspect, including one or more or all of the optional features.

[0245] The present invention may provide an optical sensor according to the first aspect for carrying out the methods of the fourth, sixth and eighth aspects of the invention.

[0246] As will be appreciated by the various optional features described therein, the steps of each calibration method may be combined to increase the accuracy and / or reliability of the measurement of the physiological sign.

[0247] Therefore, viewed from a tenth aspect, there is provided a method of calibrating an optical sensor for measuring one or more physiological signs of a person after the device is attached to the person, the sensor comprising one or more detectors and another light source, the method comprising: after the device is attached to the person, emitting one or more pulses of light at one or more different wavelengths using the one or more light sources, wherein each pulse of light at each wavelength is emitted at a known power level for a known length of time; recording signals of the light pulses of each wavelength using the one or more detectors to create an optical signature of the person; determining parameters for each wavelength of light; comparing the determined parameters to stored values ​​of the parameters for each wavelength of light; adjusting the power and / or duration of the light pulses of each wavelength to reduce a difference between the determined parameters and the stored values ​​of the parameters; and selecting one or more wavelengths from the plurality of wavelengths to use in measuring the one or more physiological signs based on the optical signature of the person.

[0248] The method according to the tenth aspect may include any of the features described in the sixth and eighth aspects above. Furthermore, the optical sensor used in the tenth aspect may be as described in the first aspect above.

[0249] The invention also extends in particular to an optical sensor for carrying out the steps of the method according to the tenth aspect.

[0250] Therefore, viewed from an eleventh aspect, there is provided an optical sensor for measuring one or more physiological signs, the sensor comprising one or more detectors and one or more light sources, wherein when the device is attached to a person, the optical sensor: emits (e.g., sequentially) one or more pulses of light at a plurality of different wavelengths using the one or more light sources, wherein each pulse of light at each wavelength is emitted at a known power level for a known length of time; records signals of the light pulses at each wavelength using the one or more detectors to create an optical signature of the person; determines parameters for each signal at each wavelength of light; compares the determined parameters with stored values ​​of the parameters for each wavelength of light; adjusts the power and / or duration of the light pulses at each wavelength to reduce differences between the determined parameters and the stored values ​​of the parameters; and selects one or more wavelengths from the plurality of wavelengths to use when measuring the one or more physiological signs based on the optical signature of the person.

[0251] The optical sensor may comprise a processor, and the optical sensor and / or processor may perform (or cause to be performed) any of the steps of the invention of the tenth aspect above, including one or more or all of the optional features.

[0252] Further, according to a twelfth aspect, there is provided a method of calibrating an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and another light source, the method comprising: after the device is attached to the person, emitting (e.g., sequentially) one or more pulses of light of a plurality of different wavelengths using the one or more light sources, wherein each pulse of light of each wavelength is emitted at a known power level for a known length of time; recording a signal of light of each wavelength using the one or more detectors to create an optical signature of the person; selecting one or more wavelengths of the plurality of wavelengths to use in measuring the one or more physiological signs based on the optical signature of the person; determining parameters for each signal of the one or more wavelengths of light selected to be used in measuring the one or more physiological signs; comparing, for each of the one or more selected wavelengths of light, the determined parameters with stored values ​​of the parameters; and adjusting a power and / or duration of each of the light pulses of the one or more selected wavelengths to reduce a difference between the determined parameters and the stored values ​​of the parameters.

[0253] The method can be beneficial because the calculation step of determining parameters (e.g., signal-to-noise ratio) for each wavelength can be performed only for wavelengths selected for use according to the person's optical signature.

[0254] The method according to the twelfth aspect may include any of the features described in the sixth and eighth aspects above. Furthermore, the optical sensor used in the twelfth aspect may be as described in the first aspect above.

[0255] Viewed from a thirteenth aspect, there is provided an optical sensor for measuring one or more physiological signs, the sensor comprising one or more detectors and one or more light sources, wherein when the device is attached to a person, the optical sensor performs the following steps: emit (e.g., sequentially) one or more pulses of light of one or more different wavelengths using the one or more light sources, wherein each pulse of light of each wavelength is emitted at a known power level for a known length of time; record signals of the pulses of light of each wavelength using the one or more detectors to create an optical signature of the person; select one or more wavelengths from the plurality of wavelengths to be used in measuring the one or more physiological signs based on the optical signature of the person; determine parameters for each signal of the one or more wavelengths of light selected to be used in measuring the one or more physiological signs; compare the determined parameters with stored values ​​of the parameters for each of the one or more selected wavelengths of light; and adjust the power and / or duration of the light pulses of each of the one or more selected wavelengths to reduce a difference between the determined parameters and the stored values ​​of the parameters.

[0256] It should be noted that while thirteen independently claimable aspects of the present invention are listed above, all of these are sensors and methods that may be used together. For example, a particular optical sensor of the first aspect may be used to perform one or more or all of the disclosed methods, and any of the disclosed methods may be performed by any of the disclosed sensors. Consequently, any feature of one aspect described herein, including optional features of that aspect, may be applicable to any of the other aspects. Thus, even if any feature is disclosed only with respect to one or more of the aspects, such feature may be equally applicable to any of the other aspects. Therefore, any disclosure herein should not be read as being disclosed solely in conjunction with the aspect to which it follows, but rather should be understood as relating to (and therefore disclosed in combination with) any of the enumerated aspects of the present invention.

[0257] Certain preferred embodiments of the present invention will now be described, by way of example only, with reference to the following drawings: [Brief explanation of the drawings]

[0258] [Figure 1] 1 shows an optical sensor. [Figure 2a] 1 shows an optical sensor unit attached to an adhesive patch. [Figure 2b] 1 shows the optical sensor unit detached from the adhesive patch. [Figure 3a] 1 shows the underside of the optical sensor unit. [Figure 3b] 1 shows the underside of the optical sensor unit. [Figure 4a] 1 shows an optical sensor as part of a smartwatch. [Figure 4b] 1 shows an optical sensor as part of a smartwatch. [Figure 5] 1 shows a method for initializing an optical sensor. [Figure 6] 1 illustrates a first method for calibrating an optical sensor. [Figure 7] 1 illustrates a second method for calibrating an optical sensor. [Figure 8] A third method for calibrating an optical sensor is shown. [Figure 9] A fourth method for calibrating an optical sensor is shown. DETAILED DESCRIPTION OF THE INVENTION

[0259] FIG. 1 illustrates a printed circuit board (PCB) 10 for an optical sensor 1 (such as the optical sensor shown in FIGS. 2a, 2b, 3a, 3b, 4a, or 4b) for measuring one or more physiological signs of a person. The physiological signs may include the person's vital signs, such as pulse rate, respiratory rate, and blood oxygenation level. When the optical sensor 1 is attached to a person and in use, the PCB 10 faces the person's skin. The PCB 10 includes multiple light sources 12, 14 surrounding a detector 15. The optical sensor 1 including the PCB 10 may be a PPG sensor or any other known optical sensor for measuring one or more physiological signs of a person. The optical sensor is a reflectance-type device in which the detector 15 is positioned to detect reflected light from the light sources 12, 14. Thus, the detector 15 is on the same surface as the light sources 12, 14.

[0260] The multiple light sources 12, 14 are LEDs, each configured to emit light at multiple different wavelengths. The optical sensor 1 of FIG. 1 includes 28 light sources 12, 14. Each light source 12, 14 emits light at a specific wavelength (i.e., a narrowband wavelength). In this particular example, the light sources are configured to emit light pulses at seven different wavelengths, each of which is emitted by four light sources 12, 14. In other words, there are four light sources 12, 14 that emit each wavelength.

[0261] The detector 15 shown is a photodetector, but may also be another type of detector, such as a camera.

[0262] As shown in Figure 1, multiple light sources 12, 14 are arranged in two concentric loops 16, 18. The outer loop 16 includes a light source 12 that emits light pulses having a longer wavelength compared to the light pulses in the inner loop. The inner loop 18 includes a light source 14 that emits light pulses having a shorter wavelength compared to the light pulses in the outer loop. In other words, the longest wavelength of light emitted by the LED 14 in the inner loop 18 may be shorter than the shortest wavelength of light emitted by the LED 12 in the outer loop 16.

[0263] The seven different wavelengths in this example may be, in ascending order of wavelength, blue, dark green, light green, yellow, red, dark red, and infrared. The wavelengths emitted by the light sources may be in the range of 400 to 1300 nm, such as in the range of 460 nm to 940 nm. Thus, light sources 12 for emitting red light, dark red light, and infrared light are positioned on outer loop 16, and light sources 14 for emitting blue light, dark green light, light green light, and yellow light are positioned on inner loop 18.

[0264] In addition to the inner loop 18 and outer loop 16, multiple light sources are arranged in four groups 22, 23, 24, and 25 surrounding the detector 15. Each group 22, 23, 24, and 25 is positioned on a different side of the detector 15, and each group contains seven light sources. In each group 22, 23, 24, and 25, each light source emits light pulses at all seven different wavelengths. Each light source in each group 22, 23, 24, and 25 may be positioned the same distance from the center of the detector as a comparable light source in another group. In other words, the blue light source in each group 22, 23, 24, and 25 may be the same distance from the center of the detector as the blue light source in each other group. The multiple light sources 12 and 14 on each side of the detector 15 are positioned symmetrically around the detector. For example, in each group of light sources 22, 23, 24, and 25, the light source 12 on the outer loop 16 emits red light, dark red light, and infrared light. Similarly, the light sources on the inner loop 18 in each group 22, 23, 24, 25 emit blue, dark green, and light green light. The light sources in one group may be mirror images of the light sources on the opposite side of the detector, both in terms of the wavelengths they emit and their location relative to the photodetector. The illustrated arrangement may ensure that the emitted light field around the detector 15 is uniform, which may help improve the accuracy and strength of the signal detected by the detector 15.

[0265] Optical sensor 1 is attached to the skin, such as at a person's neck or wrist, using attachment means such as an adhesive patch and / or strap to monitor one or more physiological signs. Specific physiological signs typically measured using optical sensor 1 include pulse rate, respiratory rate, and blood oxygen saturation. To monitor blood oxygen saturation, at least two different wavelengths are required. However, while a single wavelength is sufficient to monitor respiratory rate and pulse rate, the accuracy of pulse rate and respiratory rate measurements can be improved by using a combination of wavelengths.

[0266] The optical sensor may include a screen 26 (see FIGS. 3a and 4a) that optically separates the multiple light pulses 12, 14 from the detector 15. The screen 26 is present to prevent the light pulses from the light sources 12, 14 from being directly detected by the detector 15 before they are reflected from human tissue. The screen 26 forms a loop around the detector 15 between the light sources 12, 14 and the detector 15. The screen 26 is formed from an opaque material that is opaque to all wavelengths of light emitted by the light sources 12, 14. The screen 26 may be, for example, plastic. Additionally, the detector 15 may be positioned within a recess in the first surface of the optical sensor 1. This may also be to prevent the light pulses from the light sources from being directly detected by the detector 15 before they are reflected from human tissue.

[0267] The optical sensor 1 further includes a temperature sensor 20 positioned on the PCB 10. The temperature sensor 20 monitors the temperature of the environment proximate the first surface of the optical sensor. When the optical sensor is attached to a person, this may be the temperature of the person's skin. The temperature may be monitored to detect overheating of the person's skin due to the emission of light pulses to the skin. If the temperature rises above a predetermined amount while the optical sensor is in use on a person, an alert may be issued and the optical sensor 1 will stop emitting light pulses from the multiple light sources 12, 14. The temperature sensor 20 may also be used to determine whether the person's tissue is at a temperature appropriate for accurate physiological sign readings obtained using the optical sensor and / or to check that the optical sensor is sufficiently close to the person's skin to obtain accurate readings. For example, if the detected temperature is not within a certain temperature range, an alert may be issued and / or the optical sensor 1 may not output a physiological sign reading. This may indicate that the person is not in an appropriate condition for an accurate reading and / or that the sensor 1 is not properly attached to the person.

[0268] The optical sensor 1 further includes a processor that is not present on the first surface of the optical sensor and therefore not shown in Figure 1. The processor may be housed, for example, on a second surface opposite the first surface. The processor may be used to control the operation of the optical sensor.

[0269] 2a and 2b show perspective views of a monitoring device 30 for monitoring a physiological sign of a patient. The monitoring device 30 comprises a sensor unit 40 (see FIGS. 3a and 3b) that includes a display 44 and the optical sensor shown in FIG. 1. The display 44 is used to display values ​​and / or indications of the measured physiological signs.

[0270] The sensor unit 40 may be connected to a frame 46 that is attached to an adhesive patch 42. The underside of the adhesive patch 42 (see FIG. 3a) may be attached to a person's skin. For example, the adhesive patch may be attached to a person's skin to monitor one or more physiological signs.

[0271] Adhesive patch 42 and frame 46 may remain attached to the patient's skin while the patient is hospitalized, at which time sensor unit 40 may be removed or attached as needed, as shown in Figure 2b. Sensor unit 40 may be attached to the frame by applying sufficient force to the sensor unit in a direction toward frame 46 so that the flanges of frame 46 clip over the outer edge of sensor unit 40.

[0272] Figures 3a and 3b show the underside of monitoring device 30 of Figure 2a. In particular, Figure 3a shows the underside 48 of adhesive patch 42 that can be used to attach monitoring device 35 to a person's skin. Sensor unit 40 comprises optical sensor 1 as shown in Figure 1, including screen 26 that blocks detector 15 from receiving direct light from multiple light sources 12. Sensor unit 40 further comprises a separate acoustic sensor 2.

[0273] As shown in Figure 3b, monitoring device 35 includes a reflective cover 52 that may be positioned over the lower surface 48 of adhesive patch 42. Reflective cover 52 may cover optical sensor 1 for use as part of the initialization method described below in Figure 5. Additionally, reflective cover 52 may be used to protect the adhesiveness of lower surface 48 of adhesive patch 42.

[0274] 4a and 4b show a smartwatch 35 comprising a watch portion 48 and a strap portion 50 for attaching the smartwatch 35 to a person's wrist. The smartwatch 35 comprises an optical sensor 1 as shown in FIG. 1 and including all the features described therefor. The optical sensor 1 measures one or more physiological signs of the person wearing the smartwatch 35.

[0275] Similar to monitoring device 35, the lower surface 54 of watch portion 48 includes a reflective cover 52. Reflective cover 52 is positioned to cover optical sensor 1 during an initialization method described in more detail below in connection with FIG.

[0276] 5 illustrates a method for initializing an optical sensor before use on a person. Initialization occurs before optical sensor 1 is used and can occur in the manufacturer's packaging and / or in a set, known environment with reflective covers 52 fitted over light sources 12, 14 and detector 15. In either case, this should occur before optical sensor 1 is secured to a person and typically involves first surface 10 being covered by reflective cover 52 with known properties to ensure maximum good reflectivity of the light pulse under controlled conditions. This has the added benefit of preventing any other signals from being detected by detector 15 and affecting its readings.

[0277] The method includes activating (i.e., turning on) 100 the optical sensor and recording 110 a background signal. The background signal is recorded 110 before the multiple light sources 120 are activated, so the optical sensor 1 records a signal at the detector 15 in the absence of a light pulse. This step 110 can be used to check that the detector is operating as expected and to provide a reading of the detected background light. Once the background signal is recorded 110, the method includes activating (i.e., turning on) 120 the multiple light sources 12, 14 and sequentially emitting one or more light pulses of different wavelengths. Typically, light pulses of the same wavelength but from different light sources are emitted simultaneously, while light pulses of different wavelengths are emitted sequentially, i.e., at different times. For example, four light sources 14 emitting light pulses of blue light will emit them simultaneously. If this is done for a certain period of time, four light sources 14 emitting dark green light will simultaneously emit their pulses after the blue light has been emitted by each light source 14.

[0278] The method includes recording 130 a signal corresponding to a light pulse from each wavelength in detector 15. This is achieved by time multiplexing the signal detected in detector 15 corresponding to the emission of light at each wavelength to obtain a reading for each wavelength. Additionally or alternatively, signals at each different wavelength may be detected sequentially, for example using wavelength-sensitive detectors and / or one or more detectors equipped with optical filters.

[0279] The processor then determines a parameter for the signal recorded at each wavelength 140. In this example, the parameter is the signal-to-noise ratio (SNR) of the signal, but may also be or include other measurable and determinable quantities such as the emitted irradiance, intensity, or intensity squared of the detected signal.

[0280] The signal-to-noise ratio may be the ratio of the signal power (ie, the power of the emitted light pulse) to the noise power (ie, the power of the detected signal).

[0281] The SNR for each wavelength can be determined using any known technique. However, in this case, the SNR is determined by comparing the fluctuations in the intensity and / or amplitude of the light pulses emitted from the light source to the fluctuations in the intensity and / or amplitude of the light pulses recorded by the detector 15. One alternative is to compare the amplitude of the pulsating signal recorded for each wavelength to the noise floor of the device. The noise floor in this example is the background signal recorded by the detector before the light pulses are activated. In this example, the noise floor is effectively the total signal recorded by the detector 15 when detecting the emitted signal.

[0282] The determined SNR for each wavelength is then compared 150 with the stored SNR for each wavelength (or other parameters, if parameters other than SNR are used). The stored SNR depends on the characteristics of the optical sensor, e.g., each light source 12, 14 and detector 15, and their precise placement on the optical sensor 1. The stored SNR for a particular optical sensor 1 may be determined under controlled conditions during manufacturing when the sensor 1 is known to be operating optimally. Thus, the SNR may be determined and set by the manufacturer of the sensor 1. The stored SNR is stored in a stored lookup table for access by the processor of the optical sensor 1. Each optical sensor 1 has a custom lookup table of stored SNR values ​​due to the different characteristics and operating parameters of the optical sensor 1 and its components. The stored SNR is determined during performance testing before the optical sensor 1 is delivered to a consumer. To allow an apples-to-apples comparison between the determined SNR and the stored SNR (or other parameter, if used), the light pulse is emitted with the same parameters and ideally under the same conditions as those used in determining the stored SNR (or other parameter) value (so initialization is performed with the sensor in the box or with the cap on).

[0283] The method then includes determining 160 whether the determined SNR is within a predetermined tolerance of the stored SNR, e.g., within + / - 2% of the stored SNR for each wavelength. If so, this indicates that the light source is operating correctly. In this case, the method includes indicating 170 that the optical sensor 1 is ready for use. If the determined SNR for one or more wavelengths is outside a predetermined tolerance of the stored SNR, e.g., outside + / - 2% of the stored SNR for each wavelength, the method includes indicating 180 that the optical sensor 1 is not ready for use. The indication in each case may be a visual or audible alert, such as text, indicating that the optical sensor 1 is ready for use.

[0284] Although not shown, steps 120, 130, 140, 150, and 160 of the method can be repeated if the SNR for one or more wavelengths is determined to be outside a predetermined tolerance of the stored SNR. These steps may be repeated a given number of times, for example, five times. If one or more of the determined SNRs for a wavelength are still outside the tolerance of the stored SNR for that wavelength, the method includes indicating 180 that optical sensor 1 is not ready for use. This may indicate that one or more of light sources 12, 14 and / or detectors is not operating correctly. The user may then check the optical sensor's environment—for example, ensure that the optical sensor is properly placed in its box or covered by a cover—and repeat the initialization method. However, optical sensor 1 may be broken or malfunctioning and need to be returned to the manufacturer for servicing.

[0285] The initialization method may be performed, ie repeated, before each use of the optical sensor.

[0286] Once the optical sensor has been initialized according to the method shown in FIG. 5 and is indicated as ready for use, the optical sensor may then be attached to a person to monitor one or more physiological signs. Optical sensor 1 for measuring one or more physiological signs may be designed to work with a specific skin type and, therefore, may be less accurate when measuring people with skin types different from this specific skin type. For example, darker skin tones may filter out more of certain wavelengths of light, and the skin profile of elderly people may result in changes in light scattering, both of which may reduce the accuracy and reliability of readings unless taken into account. Therefore, it may be desirable to calibrate optical sensor 1 to a specific person's skin to improve the accuracy of measuring physiological signs.

[0287] FIG. 6 illustrates a first calibration method used by the optical sensor 1. As a first step, the method includes attaching the sensor to a person's skin (200). In this step, the optical sensor 1 is attached to a part of the person, such as the person's neck or wrist, using a known attachment means, such as an adhesive patch. Additionally or alternatively, the optical sensor 1 may be provided with a band or strap that wraps around a part of the person. In either case, the optical sensor 1 is attached to the person so that a first surface of the sensor, including the multiple light sources 12, 14 and the detector 15, faces and is close to the person's skin, for example, within 5 mm of the person's skin. If the sensor was in a box or covered with a cap / cover for the initialization method, the sensor is removed from the box and / or the cap / cover is removed.

[0288] The optical sensor 1 can then be turned on, for example by pressing a button on the device. At this stage, the optical sensor may indicate that it is on and calibrating.

[0289] 6 involves sequentially emitting 210 one or more pulses of light at different wavelengths using multiple light sources 12, 14. Each pulse of light is emitted at a known (initial) power level for a known (initial) length of time.

[0290] The method then includes recording 220 a signal for each wavelength of light pulse using detector 15. The recorded signal is from the light pulse reflected from tissue, including the person's skin. The method then includes determining 230 a parameter for each wavelength of light and comparing 240 the determined parameter to a stored value of the parameter for each wavelength of light. Similar to the initialization method, in this example of the first calibration method, the parameter used is the signal-to-noise ratio (SNR) of the signal.

[0291] If the initialization method of Figure 5 has been performed, the stored SNR may be the SNR 140 determined during the initialization process shown in Figure 5, i.e., the stored SNR may be the SNR of the signal for each wavelength under certain controlled conditions before the optical sensor 1 is attached to the person 200.

[0292] The difference between the determined SNR and the stored SNR for each wavelength is calculated in comparing the determined SNR with the stored SNR for each wavelength 240. If the difference between the determined SNR and the stored SNR is determined to be within a predetermined tolerance, the sensor is considered to be calibrated 260. The optical sensor may indicate that this is the case.

[0293] If it is determined that the difference between the determined SNR and the stored SNR is outside a predetermined tolerance, the method includes adjusting 250 the power level and / or length of time of the emitted light pulses to reduce the difference between the determined SNR value and the stored SNR value for each wavelength. Steps 210, 220, 230, and 240 of the method are then repeated using the adjusted values ​​for the power and / or time of each light pulse. The method may be repeated multiple times, for example, up to 100 times, and / or continuously or for a given length of time, for example, 1 minute, until the difference between the determined SNR and the stored SNR for each wavelength is within a predetermined tolerance.

[0294] The predetermined tolerance may be set to an appropriate level depending on the known values ​​that allow a sufficiently accurate reading of one or more physiological signs to be obtained, for example, the predetermined tolerance may be up to ±20% of the stored signal-to-noise ratio.

[0295] In certain cases, the difference between the determined SNR and the stored SNR for some of the plurality of different wavelengths may be within a predetermined tolerance, while the difference for other wavelengths may be outside the predetermined tolerance, in which case the method may include adjusting the power and / or time only for light pulses emitting wavelengths where the difference is outside the predetermined tolerance.

[0296] Figure 7 shows another method for calibrating optical sensor 1. This may be in addition to or an alternative to the calibration method shown in Figure 6 (as shown in Figures 5 and 6 below). This calibration method, like Figure 6, begins with attaching optical sensor 1 to a person's skin 300. If the calibration methods of Figures 6 and 7 are performed in combination, the step of attaching the sensor to the skin may be a single step performed once. In either case, the above description of the step 200 of attaching the sensor to the skin described above is equally applicable to this calibration method.

[0297] The calibration method of Figure 7 then involves sequentially emitting 310 pulses of light at different wavelengths using multiple light sources 12, 14. Each pulse of light is emitted at a known power level for a known length of time, again similar to the method described in Figure 6.

[0298] The method includes recording 320 the signal of the light pulse at each wavelength using detector 15 to create an optical signature for the person. This optical signature is based on the signal recorded for an initial light pulse using an initial power level and length of time, and provides an initial representation of how the person's skin and tissue affect the reflectance of light at each wavelength.

[0299] The optical signature for the person is compared 330 to a library of stored optical signatures (which is based on historical data collected and used to compile a database of how the reflectance of each wavelength is affected by different skin profiles) to select 350 one or more wavelengths to be used when measuring one or more physiological signs.

[0300] The library of optical signatures is organized into a plurality of skin profile categories 340. Each skin profile category consists of a plurality of different optical signatures, each of which may be similar in nature. Furthermore, each of these skin profile categories has a predetermined set of one or more wavelengths to use when measuring physiological signs that provide the most accurate reading.

[0301] A skin profile category is assigned to the person in step 330 of comparing the person's optical signature to a library of optical signatures. The assigned skin profile category is based on the person's optical signature and may be the skin profile category to which the person's optical signature best matches or falls.

[0302] In this case, the stored optical signatures are organized 340 into categories A, B, and C. The method then includes selecting 350 a combination of one or more wavelengths from the plurality of wavelengths based on the assigned skin profile category to be used when measuring the one or more physiological indicia.

[0303] The library may also include optimal wavelengths or wavelength combinations to be used for optical signatures within each skin profile category for measuring each particular physiological sign. For example, for an optical signature assigned to skin profile category A, a combination of dark green and dark red may be an optimal wavelength combination to use when measuring a person's respiratory rate, and therefore, the wavelengths selected for measuring respiratory rate may be dark green and dark red wavelengths. Furthermore, for the same optical signature that falls into skin profile category A, an optimal wavelength combination for measuring blood oxygen saturation may be red and infrared.

[0304] The methods of calibrating optical sensors shown in Figures 6 and 7 can be performed independently, each providing the advantage of improving the accuracy of physiological sign measurements (even if other calibration methods are not performed), but they can also be combined to form further calibration methods such as those shown in Figures 8 or 9.

[0305] The method according to Figure 8 includes attaching 400 an optical sensor 1 to a person, which may be as described above with respect to step 200 of Figure 6. Light pulses of each different wavelength are then emitted at an initial known power level for an initial known length of time 410. The method then includes recording 420 an initial signal of each light pulse for each wavelength when emitted at the known initial power level and for the initial known length of time to create an optical signature for the particular person to whom the optical sensor is attached.

[0306] The SNR (or other parameter) of the signal for each wavelength is then determined 430, and the determined SNR for each wavelength is compared 440 to a stored SNR (or other parameter), as in the calibration method shown in FIG. 6. If the difference between the determined SNR and the stored SNR is greater than a predetermined tolerance, the method includes adjusting the power level and / or length of time of each light pulse to reduce the difference between the determined SNR and the stored SNR 450. Method steps 410, 430, and 440 are then repeated (a given number of times, such as up to 100 times, and / or for a given length of time, such as up to 1 minute) until the difference between the determined SNR and the stored SNR for each wavelength is within a predetermined tolerance. As discussed above in connection with FIG. 6, the stored SNR may be that determined during the initialization method shown in FIG. 5 or may be some other stored SNR, for example, set by the manufacturer. If after a given number of repetitions, such as 100, and / or after a given length of time, such as up to 1 minute, the SNR signal determined for each wavelength is not within a predetermined tolerance, the optical sensor 1 may indicate that it cannot be used to record one or more physiological signs with the person.

[0307] If / when the difference between the determined SNR and the stored SNR is within a predetermined tolerance, the signal is determined to be sufficient to obtain an accurate reading of one or more physiological signs, and the method then compares 460 the person's optical signature determined in 420 to a library of stored optical signatures, such as the calibration method shown in FIG. 7, described in more detail above.

[0308] Based on a comparison 460 of the person's optical signature to the library of stored optical signatures, a skin profile category is assigned 470 to the person. The method then includes selecting 480 a suitable combination of one or more wavelengths to be used to measure one or more physiological indicia based on the assigned skin profile category. Again, this is described in more detail above in connection with FIG. 7.

[0309] A combination of the calibration methods of both Figures 6 and 7 can be particularly beneficial because it allows for achieving suitable parameters for the light pulses of each wavelength (Figure 6) and selecting an optimal and suitable combination of wavelengths based on the assigned skin profile category (Figure 7), thereby maximizing the likelihood that an accurate and reliable reading of one or more physiological signs can be achieved for a particular person to whom the physiological sign measurement device is attached.

[0310] Figure 9 shows an alternative method for calibrating the optical sensor 1, which includes substantially the same steps as the method shown in Figure 8. However, the order in which the steps of the method are performed is different.

[0311] Similar to the method of Figure 5, the method of Figure 9 involves attaching 500 a sensor to a person's skin and emitting 510 pulses of light at each wavelength at an initial known power level for an initial known length of time. The signals are recorded 520 by detector 15 for each wavelength to create an initial optical signature of the person. Similar to the method of Figure 7, the person's initial optical signature is compared 530 to a library of stored optical signatures to assign 540 a skin profile category to the person.

[0312] Based on this comparison, the method then includes selecting 550 a combination of one or more wavelengths of light to be used to measure one or more physiological signs.

[0313] The method then includes determining 560 an SNR (or other parameter) for only each of the one or more wavelengths selected for use in measuring the one or more physiological signs. The determined SNR is then compared 570 to a stored SNR (or other parameter) for each of the one or more selected wavelengths. As explained above, the stored SNR may be that determined during the initialization method shown in FIG. 5 or some other stored SNR for the optical sensor. If the determined SNR is within a predetermined tolerance, the sensor is determined to be calibrated 580. If the determined SNR is outside the predetermined tolerance, the power level and / or duration of the optical pulses for each of the one or more wavelengths selected for use in measuring the one or more physiological signs is adjusted 590 in a manner similar to the method according to FIG. 6 and / or FIG. 5.

[0314] At this time, determining 560 the SNR for each wavelength and comparing 570 the determined SNR to the stored SNR is repeated using adjusted values ​​for the power level and duration of each optical pulse until the determined SNR for each wavelength falls within a predetermined tolerance of the stored SNR value.

[0315] 9 may have the additional advantage of reducing the computational requirements and / or time of the calibration method, because the steps of analyzing the signal, determining the SNR, and then adjusting the power and / or time of the light pulses are performed only for one or more wavelengths selected for use, rather than for all possible wavelengths that may be emitted by the optical sensor, which may therefore increase the speed and efficiency of the calibration process.

[0316] While the methods of Figures 5-9 are described herein as being performed by optical sensor 1, it should be understood that these methods are not limited to being performed by such sensors, and in fact may be performed using any optical sensor that includes one or more light sources and one or more detectors capable of emitting and detecting one or more wavelengths to measure one or more physiological signs of a person.

[0317] The following sections describe aspects of the present disclosure that may not be currently claimed, but may form the basis of future amended and / or divisional applications.

[0318] 1. A method of initializing an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and another light source, the method comprising, before the device is attached to the person: emitting one or more pulses of light at one or more different wavelengths using one or more light sources, each pulse of light being emitted at a known power level for a known length of time; recording a signal of one or more light pulses at each wavelength using one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameter with stored values ​​of the parameter for each wavelength; determining that the optical sensor is ready for use if the determined parameter for each wavelength is within a set tolerance range of the stored value of the parameter for each wavelength; A method comprising:

[0319] 2. The method of clause 1, wherein the method further comprises recording received signals using one or more detectors when no light is emitted by the one or more light sources.

[0320] 3. The method of clause 1 or 2, wherein the stored values ​​of the parameters are determined and stored before the optical sensor is supplied to the user.

[0321] 4. The method of any of clauses 1, 2, or 3, wherein the determined parameter and the stored value of the parameter are verified under the same conditions.

[0322] 5. The method of any preceding clause, wherein the method includes, after determining that the optical sensor is ready for use, indicating that the optical sensor is ready for use.

[0323] 6. The method of any preceding clause, wherein the method further includes determining that the optical sensor is not ready for use if the determined parameters for one or more of the wavelengths are outside a set tolerance range of the stored values ​​of the parameters for the respective wavelengths.

[0324] 7. A method according to any preceding clause, wherein if the parameter for one or more of the wavelengths is determined to be outside a set tolerance range of the stored value of the parameter for the respective wavelength, the method comprises repeating one or more times the steps of emitting one or more pulses of light at one or more different wavelengths using one or more light sources, recording signals of the one or more pulses of light at each wavelength using one or more detectors, determining parameters for each signal at each wavelength of light, and comparing the determined parameters with the stored value of the parameter for each wavelength.

[0325] 8. A method according to clause 7, comprising the steps of emitting one or more pulses of light at one or more different wavelengths using one or more light sources, recording signals of the one or more pulses of light at each wavelength using one or more detectors, determining parameters of each signal at each wavelength of light, and comparing the determined parameters with stored values ​​of the parameter for each wavelength, if a parameter for at least one of the one or more wavelengths is outside a set tolerance range of the stored values ​​of the parameter, repeated a predetermined number of iterations, after which if the parameter for at least one of the one or more wavelengths is still outside a set tolerance range of the stored values ​​of the parameter, the method indicating that the optical sensor is not ready for use.

[0326] 9. The method described in any preceding clause where the tolerance set is up to ±5%.

[0327] 10. The method of any preceding clause, wherein the method includes directing one or more detectors and one or more light sources at a reflective surface having known characteristics. 11. The method of any preceding clause, wherein the method includes covering the one or more detectors and the one or more light sources with a reflective cover.

[0328] 12. The method of clause 11, wherein the method includes covering the one or more detectors and the one or more light sources with a reflective cover before the steps of using one or more light sources to emit one or more light pulses at one or more different wavelengths and using one or more detectors to record signals of the one or more light pulses at each wavelength.

[0329] 13. The method of any preceding clause, wherein the detection of one or more light pulses of a plurality of different wavelengths by one or more detectors is time multiplexed according to the emission of each wavelength of light.

[0330] 14. A method according to any preceding clause, wherein when the optical sensor comprises several light sources for emitting light pulses of the same wavelength, the method includes emitting light pulses of the same wavelength simultaneously from different light sources.

[0331] 15. A method according to any of clauses 1 to 13, wherein when the optical sensor comprises several light sources for emitting light pulses of the same wavelength, the method comprises sequentially emitting each of the light pulses of the same wavelength.

[0332] 16. The method of any preceding clause, wherein the optical sensor is a medical device for measuring one or more physiological signs of a patient.

[0333] 17. The method of clause 16, wherein the medical device is a pulse oximeter.

[0334] 18. The method of any preceding clause, wherein the optical sensor is a wearable device for measuring one or more physiological signs of a person.

[0335] 19. The method of clause 18, wherein the wearable device is a smart watch or a sports watch.

[0336] 20. The method of any preceding clause, wherein the one or more detectors include a photodetector.

[0337] 21. The method of any preceding clause, wherein the one or more detectors include a camera.

[0338] 22. The method of any preceding clause, wherein the parameter is a signal-to-noise ratio.

[0339] 23. The method of any preceding clause, wherein the one or more physiological signs include one or more vital signs.

[0340] 24. An optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and one or more light sources, wherein, before the device is attached to the person, the optical sensor: emitting one or more pulses of light at one or more different wavelengths using one or more light sources, each pulse of light being emitted at a known power level for a known length of time; recording the signal of one or more light pulses at each wavelength using one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameter with stored values ​​of the parameter for each wavelength; determining that the optical sensor is ready for use if the determined parameter for each wavelength is within a set tolerance range of the stored value of the parameter for each wavelength; Optical sensor.

[0341] 25. An optical sensor as described in clause 24, wherein the optical sensor performs any of the methods of clauses 1 to 23.

[0342] 26. A method of calibrating an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and one or more light sources, the method comprising, after the device is attached to the person: emitting one or more pulses of light at one or more wavelengths using one or more of the one or more light sources, wherein each pulse of light at each wavelength is emitted at a known power level for a known length of time; recording one or more light-positive signals at each wavelength using one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameter with stored values ​​of the parameter for each wavelength of light; adjusting the power and / or duration of one or more light pulses of each wavelength to reduce the difference between the determined parameter and the stored value of the parameter; A method comprising:

[0343] 27. The method of clause 26, wherein the method includes emitting pulses of light of a plurality of different wavelengths.

[0344] 28. The method according to clause 26 or 27, wherein the stored values ​​of the parameters depend on one or more light sources and / or one or more detectors and are determined under predetermined conditions.

[0345] 29. The method of clause 26, 27, or 28, wherein the known power level and the known length of time are values ​​from which the power can be both increased or decreased, and from which the length of time can be both increased or decreased.

[0346] 30. The method of any of clauses 26 to 29, wherein the method includes adjusting only one of the power and / or time length of the light pulse(s) of each wavelength.

[0347] 31. The method of any of clauses 26 to 30, wherein the method includes independently adjusting the power and / or time length of the light pulses of each wavelength.

[0348] 32. The method of clause 31, wherein one of the power and / or the time is increased and the other of the power and / or the time is decreased. 33. A method according to any of clauses 26 to 32, wherein the method comprises attaching an optical sensor to the skin of the person.

[0349] 34. A method according to any of clauses 26 to 33, wherein the optical sensor comprises a number of light sources emitting light pulses of the same wavelength, and the method comprises simultaneously emitting each of the light pulses of the same wavelength from the different light sources.

[0350] 35. A method according to any of clauses 26 to 34, wherein the method comprises determining the difference between the determined parameter and a stored value of the parameter for each wavelength of light.

[0351] 36. A method according to clause 35, wherein the method includes comparing the difference between the determined parameter and the stored value of the parameter for each wavelength with a predetermined tolerance range.

[0352] 37. A method according to clause 36, wherein the method comprises adjusting the power and / or duration of the light pulses of each wavelength to reduce the difference to be within a predetermined tolerance.

[0353] 38. The method of clause 36 or 37, wherein the method includes adjusting the power and / or time length of the light pulse only for wavelengths where the difference between the determined parameter and the stored value of the parameter for one or more of the plurality of wavelengths is outside a predetermined tolerance range.

[0354] 39. The method of clause 36, 37, or 38, wherein the predetermined tolerance is up to ±20% of the stored value of the parameter.

[0355] 40. A method according to any one of clauses 36 to 39, wherein the method comprises indicating that the optical sensor is calibrated and / or ready for use when the difference between the determined parameter and the stored value of the parameter for each wavelength is within a predetermined tolerance.

[0356] 41. A method according to any of clauses 26 to 40, wherein following the step of adjusting the power and / or duration of the light pulses of each wavelength, the method comprises repeating one or more times the steps of emitting one or more light pulses of one or more different wavelengths using one or more light sources, recording signals of the one or more light pulses of each wavelength using a detector, determining parameters for each signal of each wavelength of light, and comparing the determined parameters with stored values ​​of the parameters for each wavelength.

[0357] 42. The method of clause 41, wherein the repeating step includes emitting one or more pulses of light at an adjusted power level and / or for an adjusted length of time.

[0358] 43. A method according to any of clauses 26 to 42, wherein the method includes using one or more detectors to record one or more light-plus signals at each wavelength to create an optical signature of the person.

[0359] 44. The method of clause 43, wherein the method includes comparing the person's optical signature to a library of stored optical signatures to select one or more wavelengths to be used in measuring one or more physiological signs. 45. The method of clause 44, wherein the library of optical signatures is organized into a plurality of skin profile categories, each skin profile category having one or more predetermined wavelengths to be used when measuring one or more physiological signs, and wherein comparing the person's optical signature to the library includes assigning a skin profile category to the person and selecting one or more wavelengths to be used when measuring the one or more physiological signs based on the assigned skin profile category.

[0360] 46. ​​The method of clause 45, wherein the steps of determining a parameter for each signal at each wavelength of light, comparing the determined parameter with a stored value of the parameter for each wavelength of light, and adjusting the power and / or duration of the light pulses at each wavelength to reduce the difference between the determined parameter and the stored value of the parameter are performed only for one or more selected wavelengths.

[0361] 47. A method according to any of clauses 26 to 46, wherein the optical sensor is a medical device, such as a pulse oximeter, for measuring one or more vital signs of a patient, or a wearable device, such as a sports watch, for measuring one or more physiological signs of a person.

[0362] 48. The method of any of clauses 26 to 47, wherein the parameter is a signal-to-noise ratio.

[0363] 49. An optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and one or more light sources, wherein when the device is attached to the person, the optical sensor: emitting one or more pulses of light at one or more different wavelengths using one or more of the one or more light sources, each pulse of light at each wavelength being emitted at a known power level for a known length of time; recording the light plus signal at each wavelength using one or more detectors; determining a parameter for each signal at each wavelength of light and comparing the determined parameter with stored values ​​of the parameter for each wavelength of light; adjusting the power and / or duration of the light pulses of each wavelength to reduce the difference between the determined parameter and the stored value of the parameter; Optical sensor.

[0364] 50. An optical sensor according to clause 49, wherein the optical sensor performs a method according to any one of clauses 26 to 48.

Claims

1. 1. A method of calibrating an optical sensor for measuring one or more physiological signs of a person after the device is attached to the person, the sensor comprising one or more detectors and another light source, the method comprising, after the device is attached to the person: emitting one or more pulses of light at a plurality of different wavelengths using one or more light sources, each pulse of light at each wavelength being emitted at a known power level for a known length of time; recording the signal of the light pulses at each wavelength using one or more detectors to create an optical signature of the person; selecting one or more wavelengths from the plurality of wavelengths for use in measuring the one or more physiological signs based on the optical signature of the person; A method comprising:

2. 10. The method of claim 1, wherein the method comprises comparing the optical signature of the person to a library of stored optical signatures to select the one or more wavelengths to use when measuring the one or more physiological signs.

3. 3. The method of claim 2, wherein the library of optical signatures is organized into a plurality of skin profile categories, each skin profile category having one or more predetermined wavelengths to be used when measuring the one or more physiological signs, and wherein comparing the optical signature of the person to the library comprises: assigning a skin profile category to the person; and selecting the one or more wavelengths to be used when measuring the one or more physiological signs based on the assigned skin profile category.

4. 4. The method of claim 1, wherein the method comprises determining a parameter for each recorded signal at each wavelength.

5. The method of claim 4 , wherein the method includes comparing the determined parameter to stored values ​​of the parameter for each wavelength of light.

6. The method of claim 5 , wherein the method includes determining a difference between the determined parameter and the stored value of the parameter for each wavelength of light.

7. 7. The method of claim 5 or 6, wherein the method comprises adjusting the power and / or time of one or more of the light pulses of each wavelength to reduce a difference between the determined parameter and the stored value of the parameter.

8. 8. The method of claim 7, wherein the steps of determining the parameter for each wavelength, comparing the determined parameter to a stored value of the parameter for each wavelength of light, determining a difference between the determined parameter and the stored value of the parameter for each wavelength of light, and adjusting the power and / or time of the light pulses for each wavelength to reduce the difference between the determined parameter and the stored value of the parameter are performed only for the one or more wavelengths selected to be used in measuring the one or more physiological signs.

9. The method of claim 1 , wherein the optical sensor is a medical device for measuring one or more physiological signs of a patient.

10. The method of claim 9 , wherein the medical device is a pulse oximeter.

11. The method of claim 1 , wherein the optical sensor is a wearable device for measuring one or more physiological signs of a person.

12. The method of claim 11 , wherein the wearable device is a smart watch or a sports watch.

13. The method of claim 1 , wherein the one or more detectors include a photodetector.

14. The method of claim 1 , wherein the one or more detectors include a camera.

15. 15. The method of any one of claims 1 to 14, wherein the parameter is a signal-to-noise ratio.

16. 1. An optical sensor for measuring one or more physiological signs of a person, the optical sensor comprising: one or more detectors; one or more light sources; Equipped with When the device is attached to the person, the optical sensor: emitting light pulses of a plurality of different wavelengths using one or more light sources, each light pulse of each wavelength being emitted at a known power level for a known length of time; using the one or more detectors to record a light-plus signal at each wavelength to create an optical signature of the person; selecting one or more wavelengths from the plurality of wavelengths for use in measuring the one or more physiological indicia based on the optical signature of the person; Optical sensor.

17. 17. The optical sensor of claim 16, wherein the optical sensor performs the method of any one of claims 1 to 15.

18. 1. A method of initializing an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and another light source, the method comprising, before the device is attached to the person: emitting one or more pulses of light at one or more different wavelengths using one or more light sources, each pulse of light being emitted at a known power level for a known length of time; recording a signal of the one or more light pulses at each wavelength using the one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameters with stored values ​​of the parameters for each wavelength; determining that the optical sensor is ready for use if the determined parameter for each wavelength is within a set tolerance of the stored value of the parameter for each wavelength; A method comprising:

19. 1. A method of calibrating an optical sensor for measuring one or more physiological signs of a person, the sensor comprising one or more detectors and one or more light sources, the method comprising, after a device is attached to the person: emitting one or more pulses of light at one or more wavelengths using one or more of the one or more light sources, each pulse of light at each wavelength being emitted at a known power level for a known length of time; recording one or more light-positive signals at each wavelength using the one or more detectors; determining parameters for each signal at each wavelength of light; comparing the determined parameter with stored values ​​of the parameter for each wavelength of light; adjusting the power and / or duration of the one or more light pulses of each wavelength to reduce the difference between the determined parameters and the stored values ​​of the parameters; A method comprising:

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