Physiological monitoring system for measuring blood oxygen concentration

Abstract

A wearable device is described. The wearable device includes a housing having a back cover and an optical shield on a first portion of the back cover. The back cover includes a set of windows, wherein a first subset of windows in the set of windows is defined by a second portion of the back cover without the optical shield thereon, and a second subset of windows in the set of windows is inserted into a set of openings in the back cover. An optical barrier surrounds each window in the second subset of windows. A set of light emitters is configured to emit light through at least some of the windows in the set of windows. A set of light detectors is configured to receive light passing through at least some of the windows in the set of windows.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This Patent Cooperation Treaty patent application claims priority to U.S. Provisional Patent Application No. 62 / 907,445, filed on September 27, 2019, and U.S. Non-Provisional Patent Application No. 17 / 018,850, filed on September 11, 2020, which are incorporated herein by reference in their entireties. Technical Field

[0003] Some described embodiments generally relate to physiological monitoring systems for measuring blood oxygen concentration, and more specifically to reflective devices and systems for measuring blood oxygen concentration. Some described embodiments also or alternatively relate to emitting and receiving light through a housing of a wearable device. Background Art

[0004] The use of technologies that monitor a user's heart rate or other types of biometric information has increased in the medical community and among the general public as sensing technology has advanced. In some examples, a sensing device (e.g., a chest strap heart rate monitor or a watch) may be able to measure a person's heart rate while performing physical activity (such as running) and may alert the user if the heart rate changes outside of an expected range.

[0005] In some cases, the sensing device may be used for pulse oximetry, which may be an effective and rapid way to monitor a person's cardiopulmonary function. Since the amount of oxygen carried by hemoglobin may affect the color of the blood, these pulse oximetry devices may be able to assess the color of the blood. In some examples, a pulse oximetry device may be placed on a person's finger to measure the oxygenation in the person's blood. Generally, these device measurements may be reliable because of the homogeneous nature of the small tissue area of ​​the person that the device measures. Summary of the invention

[0006] Embodiments of the systems, devices, methods, and apparatus described in the present disclosure relate to a wearable device for pulse oximetry. Systems, devices, methods, and apparatus are also described for a wearable device having a set of openings and a set of protrusions adjacent to the set of openings. The wearable device may include a set of windows in such openings and adjacent to the set of protrusions. The wearable device may include a light detector that can receive light through a window of the set of windows. Such protrusions and materials around the perimeter of such windows can at least partially serve as a barrier to undesirable light detected by such sensors, because such windows can be at least partially isolated from undesirable light sensed by such sensors.

[0007] In some examples, the present disclosure describes a wearable device that may include a housing having a back cover and an optical shield (e.g., at least one of an ink, a film, a coating, or a surface treatment) on a first portion of the back cover. The back cover may include a set of windows, wherein a first subset of windows in the set of windows is defined by a second portion of the back cover on which the optical shield is absent, and a second subset of windows in the set of windows is inserted into a set of openings in the back cover. An optical barrier may surround each window in the second subset of windows. A set of light emitters may be configured to emit light through at least some of the windows in the set of windows. A set of light detectors may be configured to receive light through at least some of the windows in the set of windows.

[0008] In some examples, the present disclosure describes a wearable device that may include a first group of emitters, a second group of emitters, and a group of detectors, the first group of emitters being configured to emit a red light range wavelength, and the second group of emitters being configured to emit an infrared light range wavelength. Each detector in the group of detectors may be configured to detect an amount of at least the red light range wavelength and the infrared light range wavelength. The wearable device may also include a processor configured to: operate the first group of emitters and the second group of emitters; receive an indicator of such amount of at least the red light range wavelength and the infrared light range wavelength detected by the group of detectors; and determine a blood oxygenation level using at least a subset of such indicators.

[0009] In some examples, the present disclosure describes a wearable device that may include a housing, a display, and a skin-facing cover, the display being viewable through a front side of the housing, the skin-facing cover being on a back side of the housing. The skin-facing cover may have an inner surface, an outer surface, and a set of protrusions adjacent to a set of openings. The set of openings may extend through the skin-facing cover from the inner surface to the outer surface of the skin-facing cover. The wearable device may also include a set of windows and a set of light detectors, the set of windows being disposed in the set of openings and adjacent to the set of protrusions, the set of light detectors being disposed within the housing and configured to receive light passing through the set of windows.

[0010] In some examples, the present disclosure describes a wearable device. The wearable device may include a skin side cover. The skin side cover may include: an inner surface; an outer surface; and a set of protrusions, the set of protrusions adjacent to a set of openings, such openings extending through the inner surface and the outer surface; a set of windows, the set of windows disposed in such openings and adjacent to the set of protrusions; and a light detector, which is configured to receive light through a window in the set of windows. In some examples, the skin side cover may be optically opaque. In some examples, the set of protrusions may include a stepped protrusion and / or the set of protrusions may include a conical protrusion. In some examples, the skin side cover may be optically transparent, and the set of windows may be optically transparent. In some examples, one or more protrusions in the set of protrusions may be coated with an optically opaque material, wherein the optically opaque material may be an optically opaque ink. In some examples, one or more protrusions of one or more windows in the set of windows may be coated with an optically opaque material.

[0011] In yet a further example, the light detector may be a first light detector, and the window may be a first window, and the wearable device may further include: a second light detector configured to receive light through a second window of the set of windows; a first light emitter configured to emit light through a third window in the set of windows, wherein the third window is closer to the first window than the second window; and each of the first light detector and the second light detector is configured to receive a reflection or backscatter of the light emitted by the first light emitter. In some examples, the wearable device may further include a second light emitter configured to emit light through a fourth window in the set of windows, wherein each of the first light detector and the second light detector is configured to receive a reflection or backscatter of the light emitted by the second light emitter. In some examples, the first light emitter can be configured to emit red light, wherein each window in the set of windows can be optically transparent to at least red and infrared range wavelengths; and each protrusion of the set of protrusions extends from an edge of one of such openings in a general direction parallel to a plane of the inner surface, and each opening has a smaller diameter at the inner surface than at the outer surface. In some examples, each window of the set of windows can be circular in shape.

[0012] In some examples, the present disclosure describes a reflective sensing device that may include: a first emitter configured to emit a red range wavelength; a second emitter configured to emit an infrared range wavelength; a first detector; a second detector, wherein both the first detector and the second detector are configured to detect at least the red range wavelength emitted by the first emitter and the infrared range wavelength emitted by the second emitter; and a processor configured to receive indicators of the amount of the detected red range wavelength and the detected infrared range wavelength received from each of the first detector and the second detector, the processor further configured to determine a blood oxygenation level using at least a subset of such indicators. In some examples, the first detector may detect such red light wavelength emitted by the first emitter on a first optical path, and the second detector may detect such red light wavelength emitted by the first emitter on a second optical path, and the first optical path and the second optical path may be of different lengths. In some examples, the reflective sensing device may further include: a third emitter configured to emit a green light range wavelength; and a third detector configured to detect the emitted green light range wavelength from at least the third emitter, wherein the processor is configured to receive the detected green light range wavelength from at least the third detector. In some examples, the processor may be configured to sum an indicator of the amount of the detected wavelength range from the first detector, the second detector, and the third detector. In some examples, the first emitter, the second emitter, and the third emitter may emit light sequentially. In some examples, the processor may be configured to determine the subset of received red light and infrared light for determining blood oxygenation level based at least in part on the received green light.

[0013] In some examples, the present disclosure describes a wearable device that may include: a back cover including a set of windows disposed around a central portion of the back cover; a set of light emitters disposed below a first subset of the set of windows included in the back cover, the set of light emitters being configured to emit at least red light and infrared light; a set of light detectors disposed below a second subset of the set of windows included in the back cover, the set of light detectors being configured to detect at least the red light and the infrared light emitted by the set of light emitters. In some examples, the set of windows may be adjacent to a set of protrusions that are adjacent to a set of openings extending through the back cover. In some examples, the distance between at least one first window of the first window subset and the second subset of the set of windows may be different from the distance between a second window of the first window subset and the second subset of the set of windows.

[0014] In some examples, the present disclosure describes a reflective sensing device that may include: a housing having a back cover; a group of emitters disposed within the housing and may include: a first subset of emitters configured to emit red light through the back cover; and a second subset of emitters configured to emit infrared light through the back cover; a group of detectors disposed within the housing and configured to detect red light received through the back cover and infrared light received through the back cover; and a group of optical barriers forming part of the back cover and extending through the back cover, the group of optical barriers being configured to block the emitted light emitted by the group of emitters from striking the group of detectors before the light passes through an outer surface of the back cover.

[0015] In some examples, the reflective sensing device may further include: a processor that may be configured to determine a blood oxygenation level of a user of the reflective sensing device, wherein the blood oxygenation level is determined using the amount of reflected red light and reflected infrared light detected by the set of detectors. In some examples, the set of optical barriers may define an optically closed wall around at least one opening of a set of openings in the back cover, wherein such openings extend through the back cover. In some examples, the set of optical barriers may include a hollow sleeve disposed in the set of openings of the back cover of a wearable device. In some examples, at least one emitter may be positioned to emit light in an opening defined by one of such hollow sleeves. In some examples, at least one detector of the set of detectors may be positioned to receive light through an opening defined by one of such hollow sleeves, and / or at least one of such hollow sleeves may have an outer perimeter wall coated with an opaque material. In some examples, the opaque material may be an opaque ink.

[0016] In yet further examples, at least one of such hollow sleeves may have an inner perimeter wall coated with an opaque material. In some examples, the reflective sensing device may further include a set of windows that may be disposed in the set of openings of the back cover. In some examples, the set of windows may be optically transparent windows. In some examples, the back cover may be an optically transparent back cover. Additionally, in some examples, the set of optical barriers may reflect at least the red range wavelengths and may reflect at least the infrared range wavelengths. In some examples, the set of optical barriers may be optically opaque. In some examples, the set of optical barriers includes black glass.

[0017] In some examples, the present disclosure describes a wearable device that may include: a back cover having: a substrate that defines a portion of an inner surface and an outer surface of the wearable device; and a set of frits extending through the substrate from the inner surface to the outer surface of the substrate and defining a portion of the outer surface of the back cover, wherein such frits of the set of frits have frit openings extending through the inner surface and the outer surface; a set of windows that are disposed in such frit openings and define a portion of the outer surface of the back cover; and a set of photodetectors that are disposed to receive light through a subset of windows of the set of windows. In some examples, the subset of windows may be a first subset of windows; and the set of windows may further include a second subset of windows of the set of windows; and the wearable device may further include a set of emitters configured to emit light through the second subset of windows. In some examples, the back cover and the set of windows may be optically transparent. In some examples, at least one window of the set of windows has an outer diameter wall coated with an optically opaque material.

[0018] In some examples, the present disclosure describes a method of forming an optical barrier in a reflective sensing device, which may include: inserting a hollow cylinder into a back cover opening of a wearable device, wherein the hollow cylinder has a centrally located opening; fusing the hollow cylinder to the back cover to form a mechanical bond between the hollow cylinder and the material of the back cover; inserting an optically transparent window into the centrally located opening of the hollow cylinder; and fusing the optically transparent window and the hollow cylinder together to form a mechanical bond between the hollow cylinder and the material of the optically transparent window, wherein: the hollow cylinder may be an optically opaque material, and it may form an optical barrier between light emitted by an emitter configured to emit light through the back cover and a detector, which may be configured to receive light through the back cover and be positioned on the same side of the back cover as the emitter. In some examples, the optically opaque material includes black glass. In some examples, each of the back cover and such window may be sapphire.

[0019] In some examples, the present disclosure describes a reflective sensing device that may include: a housing; a first set of emitters that may be configured to emit infrared light through the housing; a second set of emitters that may be configured to emit red light through the housing; a first set of waveguides that may be configured to direct infrared light emitted by the first set of emitters toward the housing; a second set of waveguides that may be configured to direct red light emitted by the second set of emitters toward the housing; a set of detectors that may be configured to detect reflections or backscatter of the infrared light emitted by the first set of emitters and the red light emitted by the second set of emitters; and a processor that may be configured to determine a blood oxygenation level of a user of the reflective sensing device, wherein the blood oxygenation level is determined using the amount of reflected or backscattered red light and reflected or backscattered infrared light detected by the set of detectors. In some examples, the first set of waveguides may internally reflect infrared light, and / or the second set of waveguides may internally reflect red light. In some examples, the first set of waveguides and the second set of waveguides can be solid materials, and / or the core of the solid material can internally reflect infrared light and red light.

[0020] In some examples, the reflective sensing device may further include: a set of windows, wherein the set of windows may include: four emitter windows, which may be configured to allow infrared light and red light emitted by the first set of emitters and the second set of emitters to pass through such emitter windows; and four detector windows, which may be configured to allow reflected infrared light and reflected red light to pass through the four detector windows and pass to the set of detectors. In some examples, the reflective sensing device may further include: a third set of emitters, which may be configured to emit green light; a third set of waveguides, which may be configured to guide green light to a third set of windows of the set of windows; and the set of detectors, which may be further configured to detect reflected or backscattered green light emitted by the third set of emitters.

[0021] In some examples, the present disclosure describes a wearable device that may include: a back cover; a group of emitters that may be configured to emit light; a first group of waveguides that are optically coupled to the group of emitters and that may be configured to guide the emitted light through the back cover; and a light detector of a group of light detectors that is configured to receive reflected or backscattered light emitted by the group of emitters. In some examples, at least one first waveguide of the first group of waveguides may be configured to guide light from a first group of emitters of the group of emitters, wherein the first group of emitters may be configured to emit red light. In some examples, at least one second waveguide of the first group of waveguides may be configured to guide light from a second group of emitters of the group of emitters, wherein the second group of emitters may be configured to emit infrared light.

[0022] In yet a further example, the wearable device may further include: a second set of waveguides that may be configured to receive reflected red light and reflected infrared light. In some examples, the second set of waveguides may be configured to direct light to the set of detectors. In some examples, the first set of waveguides and the second set of waveguides may be hardened glass. In some examples, the second set of waveguides may internally reflect infrared light and red light. In some examples, the first set of waveguides may internally reflect red light and may internally reflect infrared light. In some examples, the wearable device may further include: a third set of emitters of the set of emitters, the third set of emitters may be configured to emit green light, wherein the first set of waveguides and the second set of waveguides may internally reflect green light. In some examples, the first set of waveguides and the second set of waveguides may be fiber optic waveguides.

[0023] In some examples, the present disclosure describes a reflective sensing device that may include: a first emitter that may be configured to emit a red range wavelength; a second emitter that may be configured to emit an infrared range wavelength; a first detector; a second detector, wherein both the first detector and the second detector may be configured to detect at least the reflected red range wavelength from the first emitter and on a first optical path, and both the first detector and the second detector may be configured to detect at least the reflected infrared range wavelength from the second emitter and on a second optical path, wherein the first optical path and the second optical path may be of different lengths. In some examples, the reflective sensing device may further include: a first waveguide that may be configured to guide the emitted red wavelength; and a second waveguide that may be configured to guide the emitted infrared wavelength. In some examples, the detected red and infrared range wavelengths may be detected on a first optical path and a second optical path of different lengths, and such red and infrared range wavelengths may provide a mapping of arterial or venous blood flow for pulse oximetry.

[0024] In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the accompanying drawings and by study of the following descriptions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present disclosure may be more easily understood through the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals refer to like structural components, and wherein:

[0026] Figure 1A An example of a wearable device is shown;

[0027] Figure 1B An example of a wearable device is shown;

[0028] Figure 2 shows an example layout of emitters and detectors;

[0029] Figure 3 shows an example layout of emitters and detectors;

[0030] Figure 4 shows an example layout of emitters and detectors;

[0031] Figure 5A An example of the back side of a wearable device is shown;

[0032] Figure 5B An example of a back cover of a wearable device is shown from a side view;

[0033] Figure 5C An example of a back cover of a wearable device is shown;

[0034] Figure 5D An example of a back cover of a wearable device is shown from a side view;

[0035] Fig. 6A An example of the back side of a wearable device is shown;

[0036] Figure 6B An example of a back cover of a wearable device is shown from a side view;

[0037] Figure 6C An example of a back cover of a wearable device is shown;

[0038] Figure 7 An example of a back cover, a transmitter, a detector, and a waveguide of a wearable device is shown from a side view;

[0039] Fig. 8A An example of a back cover of a wearable device is shown;

[0040] Figure 8B An example of a back cover of a wearable device is shown;

[0041] Figure 8C An example of a back cover of a wearable device is shown;

[0042] Fig.8D An example of a back cover of a wearable device is shown;

[0043] Fig. 9A shows the layout of the back cover of the wearable device;

[0044] Fig. 9B showing the layout of the back cover of the wearable device; and

[0045] Fig.10 A sample electrical block diagram of an electronic device is shown.

[0046] Cross-hatching or shading used in the drawings is generally provided to clarify boundaries between adjacent components and also to aid in identification of the drawings in the specification. Thus, the presence or absence of cross-hatching or shading does not express or indicate a preference or requirement for a particular material, material property, component ratio, component size, commonality of similarly illustrated components, or any other characteristic, attribute, or property of any component shown in the drawings.

[0047] Furthermore, it should be understood that the proportions and sizes (relative or absolute) of the various features and components (and collections and groups thereof) and the boundaries, distances, and positioning relationships presented therebetween are provided in the drawings merely to facilitate understanding of the various embodiments described herein, and therefore, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for the embodiments illustrated to exclude embodiments described with reference thereto. DETAILED DESCRIPTION

[0048] Reference will now be made in detail to the representative embodiments shown in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. On the contrary, it is intended to cover various alternatives, modifications and equivalents that may be included within the spirit and scope of the described embodiments as defined by the appended claims.

[0049] Typically, different types of biometric information (such as heart rate and / or blood oxygenation level) can be monitored for a person. Biometric information can be monitored using sensing devices that do not require invasive procedures to be performed on the person. This information can be monitored using sensing devices, such as a thermometer that can be placed in the ear or forehead of a person, or a heart rate and / or blood oxygenation device that can be placed on the index finger of a person. One characteristic of these devices is that they are pass-through measurement type devices. When these devices are used, light can be emitted onto one side of a finger or earlobe, and the light can be detected on the other side of the finger or earlobe. The light can generally penetrate about 0.5 cm to 1.0 cm of tissue before it is detected. These sensing devices can be effectively used in controlled environments, for example, during medical examinations. To measure the blood oxygenation level of a person, a sensing device (such as a pulse oximeter) can be placed on the index finger of a person. A pulse oximeter can measure changes in the color of blood in a small tissue area, and therefore a single emitter and a single detector can be used. Further, because a small tissue area is measured, the tissue in the small area (e.g., an index finger or earlobe) may be relatively homogeneous, which may make the measurement reasonably reliable. The index finger or earlobe may be a confined area and an area with abundant tissue, which may additionally make the measurement reasonably reliable. Further, the fingertips are rich in blood vessels and generally provide a strong pulsating light signal for pulse oximetry, which may also contribute to reasonably reliable measurements. While these techniques may provide accurate measurements, these devices are not conducive to performing measurements while the user is moving or engaging in daily activities. Therefore, sensing devices (such as heart rate monitors) are integrated into wearable devices so that a person can monitor biometric data (such as heart rate) on a daily basis while engaging in various activities.

[0050] Some heart rate monitors are incorporated into chest straps, watches, and other types of fitness bands that a person may wear to monitor biometric data while performing daily activities or to monitor and / or maximize performance while exercising, training, and / or competing. Furthermore, in situations where the device is worn on the wrist or strapped to the user's chest or forehead or elsewhere, the tissue depth or structures within the tissue may significantly limit the amount of light that passes through and out of the tissue. Sensors (such as heart rate monitors or pulse oximeters) may therefore be configured as reflective devices that emit light into one side of a wrist or limb and receive reflections of the light through the same side of the wrist or limb. Additionally, in situations where the device is attached to the user via a band, it may be useful to implement the biometric sensor system as a reflective sensor to avoid having to incorporate portions of the sensor system into the band of the device (which may be necessary if the sensor system is implemented as a penetration or transmission type sensor system). Because these sensing devices may be integrated into devices such as wristbands, watches, and smart watches, various difficulties may arise due to the heterogeneous nature of the tissue in a person's wrist. For example, wrist tissue may include a dense network of blood vessels, tendons, ligaments, and bones, all or some of which may reflect, scatter, and / or absorb light, thus making measurements at the wrist difficult.

[0051] Alternatively and as discussed herein, the measurement can be implemented in an improved manner, thereby improving the accuracy and reliability of the measurement. In some examples, the sensing device may be a wearable device, such as a watch or smart watch that can be worn on a person's wrist. The watch may include multiple emitters and multiple detectors to image and / or optically detect wrist tissue, which can address the heterogeneous nature of wrist tissue and provide accurate measurements by collecting light passing through multiple regions. Further, the watch may include multiple emitters and multiple detectors to sample light that has passed through multiple tissue regions, which can address the reduced vascular density and heterogeneous nature of wrist tissue. By utilizing multiple emitters and detectors, light paths of different lengths can be propagated through the tissue and can ensure that the light travels through the tissue rather than simply reflecting off the surface of the tissue. In some less desirable situations, if the strap that can secure the device to the user is not tight, tilted, or deliberately worn loosely, the light may be reflected off the surface of the tissue. Multiple emitters and multiple detectors can provide sufficient data so that the processor may be able to identify erroneous readings and invalid or useless measurements from the data. In some examples, signals from the detectors (e.g., indicators of the amount of detected light) may be summed before processing, and in some cases, areas of suspected data corruption may be excluded. Corrupted data may result from crosstalk caused by the watch lifting off the user's skin and / or excessive tissue heterogeneity.

[0052] In order for light from the emitter to reach the wrist tissue of a person, a window may be provided on the inner side or skin-facing side of the wearable device. The window may also provide an aperture so that light reflected and / or backscattered from the wrist tissue can be detected by the detector through the aperture. The window may be anchored in the back cover and may be a feature through which one or more wavelengths of electromagnetic radiation can propagate. Further, the window may be set in an opening extending through the back cover, and in some examples, the window may be a sapphire window. These windows may be anchored in various ways that will be discussed in further detail herein on the skin-facing side of the wearable device, and in some cases, may be mounted in or on the back cover also formed of sapphire. Further, the method for fixing the window in the back cover of the wearable device may also include an optical isolation method to reduce and / or eliminate internal crosstalk between the emitter and the detector.

[0053] In some examples, light may be emitted to reach the wrist tissue of the user via a waveguide. The waveguide may guide the emitted light through the skin side cover or back cover and to the wrist tissue. Similarly, reflected light may be received or detected via a waveguide that may guide the reflected light to one or more detectors. The waveguide may guide light through a window that may be anchored in the back cover and / or receive reflected light through such a window. Alternatively, the waveguide may guide light through the back cover and / or receive reflected light through the back cover directly via an opening in the back cover, wherein there may be no window in the back cover. The opening in the back cover may extend through the inner and outer surfaces of the back cover.

[0054] Various configurations for maximizing the use of emitters and detectors for pulse oximetry are described herein.In some implementations, the window can be secured by utilizing a method that provides an optical barrier between the emitter and the detector.

[0055] refer to Figures 1A to 10 These and other implementations are discussed below. However, those skilled in the art will appreciate that the detailed description given herein with respect to these figures is for illustrative purposes only and should not be construed as limiting.

[0056] Directional terms such as "top", "bottom", "upper", "lower", "above", "below", "beneath", "front", "back", "over", "under", "lift", "right", etc. are used with reference to the orientation of some components in some of the specification drawings described below. Because components in various embodiments can be positioned in many different orientations, the directional terms are used for illustrative purposes only and are not limiting in any way. Directional terms are intended to be interpreted broadly, and therefore should not be interpreted to exclude components oriented in different ways.

[0057] Figure 1A An example of a wearable device 100 is shown. In some examples, the wearable device 100 can be configured to take a number of biometric or physiological measurements of a user or person who may wear the wearable device 100. Figure 1A In an example, the wearable device 100 may include a reflectance sensing device configured to perform pulse oximetry on a user wearing the wearable device 100.

[0058] Figure 1A An example of a wearable device 100 having a front side 105 and a back side 110 is depicted, which can be worn on a user's wrist and can be any type of watch (e.g., a smart watch or a sports watch), or any type of biometric device, such as a heart rate monitor. The back side 110 of the wearable device 100 will be discussed in further detail herein. In alternative embodiments, the wearable device can be configured to be worn on an arm, head, neck, thigh, torso, or other body part.

[0059] A user of the wearable device 100 can view a display of the wearable device 100 through the front side 105 of the wearable device 100. The display can be configured to display information, such as time, date, weather, etc. The display can also be configured to display biometric measurements or data (e.g., a user's heart rate or blood oxygenation level) obtained by a reflective sensing device, which can be at least partially visible on the back side 110 of the wearable device 100. The back side 110 of the wearable device 100 can be a skin-facing side that can be adjacent to the skin of a user wearing the wearable device 100. In some examples, the back side 110 of the wearable device may or may not be in direct contact with the skin of the user wearing the wearable device 100. The back side 110 will be discussed in further detail herein.

[0060] In some examples, the wearable device 100 may be a watch and a biometric measurement device. The wearable device 100 may be configured to measure various biometric user data of the user wearing the wearable device 100, such as heart rate and blood oxygenation level. Because the wearable device 100 may be worn on the user's wrist, different factors than other types of biometric sensors or detectors may be taken into account.

[0061] Biometric sensor design may take into account various factors, such as whether to use optical or electrical sensors, ease of use, the likely use environment of the sensor, battery and / or power consumption, accuracy of measurement, wavelength of the emitter, size and form factor of the detector or sensor, any combination thereof, etc. The terms detector and sensor are used interchangeably herein. Some biometric sensors may measure heart rate via a chest strap that may include two electrodes. The electrodes on the chest strap may contact the skin to measure the user's heart rate. Electrical sensors may be used for chest straps due to the user's dynamic movement and the various environments and physical conditions in which the chest strap may be used, such as extremely cold weather, very hot weather, sweat, salt water, chlorinated water, etc. Although chest straps may be bulky, may be additional components that the user must wear, and may have limited battery life, the ability to accurately measure in multiple environments while performing dynamic movement may outweigh the inconvenience of wearing a chest strap.

[0062] Other biometric sensors used by medical professionals may be used and / or worn on a user's finger, or in some cases, on a user's ear or earlobe. Biometric sensors, such as thermometers and pulse oximeters, may be configured to be used in small body areas (such as on the index finger or in or on the ear) of a body part having blood vessels (such as veins, arteries, and capillaries close to the skin surface). The proximity of the blood vessels in the finger to the skin surface may facilitate accurate measurements when detecting heart rate or blood oxygen levels. Additionally, because the small tissue area used is on the fingertip or in the ear, these biometric sensors may be useful for controlled environments, but not so useful when conducting daily activities. Further, the small area of ​​the fingertip or earlobe may provide homogenous tissue for the sensor, allowing accurate data to be measured when measurements are taken in a small area.

[0063] A pulse oximeter may be able to measure the color of a person's blood, and generally provides a quick and accurate way to monitor a person's heart and / or lung function. The color of a person's blood may change as the oxygen concentration in the person's blood changes. When the color of a person's blood changes, the pulse oximeter may detect or sense the change. Because a pulse oximeter used on a fingertip or ear measures a small area, the sensing device may use a single light source or emitter and a single detector for each corresponding wavelength. For example, these pulse oximeters may use a light source that emits red light and a light source that emits infrared light, and may sense the emitted light using a single detector that is capable of sensing both red and infrared light.

[0064] exist Figure 1AIn the embodiment of the present invention, the wearable device 100 can be worn on the wrist of the user, and because the pulse oximetry is performed by the wearable device 100 having the transmitter and detector on the wrist, the measurement may become more complex. Typically, the wrist tissue in the area of ​​the wrist where a watch is typically worn is heterogeneous and may have a different vascular density than the fingertips or earlobes or ears. The wrist may have bones, tendons, veins, and arteries that light from the sensor may reflect off of, which may provide unpredictable results and, in some cases, may provide erroneous measurements. Additionally, the area of ​​the wrist that can be measured is a larger area than the fingertips or earlobes, and therefore may provide more data, some of which may not be accurate data.

[0065] Figure 1B An example of a wearable device 100 is shown. Figure 1A , the wearable device 100 may include a reflective sensing device configured to perform pulse oximetry on a user wearing the wearable device 100 . Figure 1B Depict shown on Figure 1A An example of a back side 110 of a wearable device 100 in FIG. Figure 1B having a front side 105 (such as Figure 1A The wearable device 100 having a front side 110 and a back side 110 shown can be worn on the wrist of a user and can be any type of watch (e.g., a smart watch or a sports watch), or any type of biometric measurement device, such as a heart rate monitor.

[0066] exist Figure 1B In the embodiment, the wearable device 100 includes a back cover 107 or skin-side cover that forms part of the housing of the wearable device 100. The wearable device 100 also includes a window 120 in the back cover 107, which in some examples may be visible on the outer surface of the skin-facing side of the wearable device 100. The back cover 107 and / or the window 120 may be formed of sapphire, glass, plastic, or other materials. In some embodiments, some or all of the windows 120 may be sapphire windows mounted (i.e., inserted) within openings in the sapphire back cover 107. Some or all of the windows may also be integrated with the back cover 107 and defined by other portions of the back cover 107 that do not have an optical shield (e.g., ink (optically opaque ink), film, coating, or surface treatment) thereon. For example, the optical shield may be on a first portion (e.g., a non-window portion) of the back cover 107 and not present on a second portion of the back cover 107. Some windows 120 may provide apertures to allow emitters of a reflective sensor system (not shown) to be visible. Figure 1B The emitted light may be transmitted into the user's tissue and then scattered, absorbed, or reflected away by the user's tendons, bones, and blood vessels. Light reflected from arterial blood may be detected by a reflective sensor system (not shown) incorporated into the wearable device 100. Figure 1B Some windows 120 may provide an aperture through which a detector (i.e., a light detector or a photodetector) may detect light reflected from the tissue. The window 120 may provide good coupling between the window 120 and the skin, which may ensure acceptable measurement accuracy. Further, the window 120 may provide optical isolation of the reflected light, and methods of providing such optical isolation are discussed in further detail herein. In some embodiments, the window 120 above the emitter may be integrated with the back cover 107, and the window 120 above the detector may be inserted into the back cover 107.

[0067] In some examples, the outer surface of the back side 110 of the wearable device 100 may be in close contact with the user's wrist, which may reduce the air gap between the window 120 and the user's tissue. The air gap may reduce the accuracy of the detector because the tilt of the wearable device 100 makes contact with the skin in some places but not in other places, so some light reflected from the tissue may pass through the air while some reflected light may not pass through the air, thereby changing the optical path to the detector and possibly affecting the detector reading. Alternatively, the wearable device 100 may be in close contact with the user's tissue and may be too tight, thereby restricting the user's blood flow and affecting the detector reading. As discussed herein, multiple emitters and multiple detectors can be used to provide blood oxygenation measurements. When more than one emitter and detector are used, there may be multiple different optical path lengths and optical path directions between the emitter and the detector. These multiple optical path lengths and optical path directions can be used to compensate for air gaps, etc. by selecting (multiple) appropriate paths that can provide meaningful information used in determining the degree of blood oxygenation.

[0068] Figure 2 An example layout 200 of a transmitter and a detector is shown. In some examples, the layout 200 of a transmitter and a detector can be incorporated into some aspects of the wearable device 100, such as reference Figure 1A and Figure 1B Described. Figure 2 In the example of FIG. 1 , the arrangement 200 of the emitter and the detector can be included in a wearable device to provide a wearable Figure 1A and Figure 1B Physiological measurements and / or biometric measurements of a user of the wearable device 100.

[0069] By way of example and for purposes of description, the emitter and detector arrangement 200 may be positioned on the skin-facing side of the wearable device 100, as shown in FIG. Figure 1A and Figure 1B The emitter and detector arrangement 200 may be provided by a back cover or skin side cover (not shown) having windows or apertures. Figure 2), which is discussed in further detail herein.

[0070] like Figure 2 As shown, layout 200 may include emitters positioned within various emitter windows 205 , 210 , 215 , and 220 (eg, emitters 205 a - c positioned within emitter window 205 ). Figure 2 Also shown are detectors 225a, 235a, 240a, and 250a. Emitters 205a-205c may include a green light emitter 205a, an infrared light emitter 205b, and a red light emitter 205c. Similarly, groups of emitters positioned within other emitter windows 210, 215, and 220 may include a green light emitter, an infrared light emitter, and a red light emitter. Although green light, infrared light, and red light may be described herein as being emitted by emitters, green light may be understood as electromagnetic radiation in the approximate range of green light wavelengths, infrared light may be electromagnetic radiation in the approximate range of infrared light wavelengths, and red light may be electromagnetic radiation in the approximate range of red light wavelengths. In some examples, the emitters may be coherent light sources (such as lasers and / or laser diodes), semi-coherent light sources (such as light emitting diodes or superluminescent diodes), incoherent light sources, or any other suitable light emitting source. Additionally depicted in Figure 2 In an embodiment, each of the individual emitters and detectors (or photodetectors) may receive power and / or communication via bonding wires.

[0071] Figure 2 The detectors 225a, 235a, 240a, and 250a of the windows 225, 235, 240, and 250 may be electromagnetic radiation detectors. The terms detector and sensor are used interchangeably herein. Figure 2 Each of the detectors in the emitter windows 205, 210, 215, and / or 220 may be configured to receive any light emitted from any of the emitters in the emitter windows 205, 210, 215, and / or 220. Detectors 225a, 235a, 240a, and 250a may be configured to detect or receive light or photons and convert the detected light / photons into an electrical current and / or electrical signal. Depending on the location of the emitter from which the detector receives light, the detected light may have varying magnitudes due to various light scattering, absorption, and / or reflections caused by wrist tissue and may be more or less easily detected by the detector.

[0072] Detectors 225a, 235a, 240a, and 250a can detect Figure 2, any of the emitted green light, infrared light, and / or red light emitted by the emitter in. Although detectors 225a, 235a, 240a, and 250a may be described as detecting green light, infrared light, and red light, detecting green light may be understood as detecting electromagnetic radiation in the approximate range of green light wavelengths, detecting infrared light may be understood as detecting electromagnetic radiation in the approximate range of infrared light wavelengths, and detecting red light may be understood as detecting electromagnetic radiation in the approximate range of red light wavelengths. In some examples, as described herein, Figure 2 The detector 225a can be a photodiode, a photoconductor, or any other suitable detector capable of sensing light of appropriate wavelength and magnitude. As discussed herein, the detector is described as receiving or detecting light emitted from the emitter, but it is understood that the received light or detected light is light reflected from the tissue and / or backscattered from the tissue. Further, the reflected light and / or backscattered light may include emitted light that has passed through the tissue, light that has been reflected off the surface of the tissue, or both. In some examples, the detector can be at least partially optically isolated so that detection of light directly from the emitter is at least partially reduced or minimized and in some examples prevented. Optically isolating the detector is discussed in further detail herein.

[0073] Can Figure 2 The emitters 205a to 205c and the detectors 225a, 235a, 240a, and 250a of the emitter windows 205, 210, 215, and 220 in the layout 200 are arranged in a ring around the central portion of the back cover or skin side cover of the wearable device or watch. Figure 2 As shown in the example of , the emitters 205a to 205c of the emitter windows 205, 210, 215, and 220 may be configured to alternate with the detectors 225a, 235a, 240a, and 250a. That is, emitter window 205 may be adjacent to detector window 225 and detector window 250, emitter window 210 may be adjacent to detector window 235 and detector window 250, and so on. In some examples, due to the heterogeneous nature of the tissue in the wrist, the distance between the emitters and detectors may be maximized by configuring the emitters and detectors in a ring or a ring-like configuration to image and / or cover as much wrist tissue as possible for any given watch size. In some examples, the configuration of the emitters and detectors may be any other shape. The windows in the skin side cover disposed above the emitters and detectors may also be configured in a ring, and in some cases, the windows integrated with the skin side cover may be interspersed with windows inserted in the skin side cover (i.e., different types of windows may be interspersed around the ring). Figure 2In the example of FIG, by making the emitters and detectors in a ring around a central area, the coverage area can be increased with fewer components. Due to the complexity of imaging and / or optically probing heterogeneous tissue, in addition to maximizing the distance between the emitters and detectors, the emitter and detector layout may consider other factors such as false readings, emitter light clipping, path or channel length, battery life, power consumption, any combination thereof, etc. These factors are discussed in further detail herein.

[0074] like Figure 2 As shown, layout 200 can be configured to accommodate eight windows, which may include four emitters and four detectors for measuring pulse oximetry. Although four emitters and four detectors may be discussed herein, in some examples, six windows (which may include three emitters and three detectors) may be used to accommodate the size of the watch. As long as the configuration and number of emitters and detectors can be integrated into the wearable device, any appropriate number of multiple emitters and multiple detectors can be used for pulse oximetry. In some examples, the use of four emitters and four detectors can establish sixteen channels or paths between the emitters and detectors, or up to sixteen different paths can be established between the emitters and detectors. Further, as the number of emitters and detectors increases, the pulse oximeter measurement may be less sensitive to erroneous and / or useless readings. Although equal numbers of emitters and detectors are described herein, any number of emitters and detectors may be used, including unequal numbers of emitters and detectors.

[0075] Figure 2 Each window of may include a green light emitter, an infrared light emitter, and a red light emitter. For example, the emitter may include a green light emitter 205a, an infrared light emitter 205b, and a red light emitter 205c. Figure 2 Other green, infrared, and red light emitters of may be similarly numbered. In some examples, the green light emitter may be used to measure or monitor the heart rate of the user. Additionally, the green light emitter may be located on the outer diameter and farthest from the central portion (or center) of the wearable device. The green light emitter may be positioned on the outer diameter because the green light may be detected by one or both of the two closest or adjacent detectors. Because of this local sensing of green light in this example, for example, when detectors 225a and 250a are two detectors that can sense green light emitted from green light emitter 205a, the distance between green light emitter 205a and detectors 235a and 240a may not be relevant. In some examples, it may be possible that detectors 235a and 240a can detect green light emitted by green light emitter 205a.

[0076] Infrared light emitters and red light emitters can be detected by any or all of the detectors 225a, 235a, 240a, and 250a, regardless of how close or far away the detectors may be from the emitters. In some examples, the red light emitter may be positioned closer to the center portion (or center) of the wearable device than the infrared light emitter. The red light emitter may be positioned closer to the middle of the wearable device because red light is generally absorbed more than infrared light, and therefore red light is more sensitive to clipping than infrared light.

[0077] exist Figure 2 In FIG. 1 , the emission areas of the emitters 205a-205c of the emitter windows 205, 210, 215, and 225 are depicted as squares, but may be any suitable shape that allows the emitters to emit a suitable amount of light. Similarly, the detection areas of the detectors 225a, 235a, 240a, and / or 250a are depicted as squares, but may be another shape or configuration that allows the detectors to detect a suitable amount of light. Further, the detection areas of the emitters 205a-205c of the emitter windows 205, 210, 215, and 225 may be squares, but may be any suitable shape that allows the detectors to detect a suitable amount of light. Figure 2 Individual emitters (e.g., light emitting diodes (LEDs)) depicted as squares in the diagram are positioned within a circular aperture, and individual detectors shown as squares may also be positioned within a circular aperture. The emitters and detectors are also depicted as being approximately equidistant from one another, but may be positioned at these distances, or may be positioned at various distances from one another as desired. Additionally, if the distance between the emitter and detector changes, the detection angle between the emitter and detector may also vary from that depicted in FIG. Figure 2 200 in FIG. 1 . The distance between the emitters and detectors may be selected to optimize battery life and power conservation. In some examples, some emitters and detectors may be positioned closer together, depending on the absorption and reflection properties of the wavelength of light. The shapes and layout configurations of the emitters and detectors are discussed in further detail herein.

[0078] exist Figure 2 In some examples, the wearable device may include windows 205, 210, 215, and 220 or apertures through which light emitted from the emitter can pass. Similarly, windows 225, 235, 240, and 250 may also serve as apertures through which light reflected and / or backscattered from wrist tissue can pass back to the wearable device and be detected by the detector. Windows 205, 210, 215, and 220 may be disposed in a back cover of the wearable device. The back cover or skin side cover may be a portion of the outer surface of the wearable device facing the skin side, such as with respect to Figure 1A and Figure 1B In some examples, the window can provide optical isolation for the detector so that the detector does not directly receive light from the emitter. Optical isolation via windows and back covers is discussed in further detail herein.

[0079] Although windows 205, 210, 215, 220, 225, 235, 240, and 250 are Figure 2 Circular in the illustration, but this is for purposes of explanation, and such windows may be of any suitable shape, as discussed in further detail herein. Additionally, for purposes of explanation, the windows are Figure 2 The centres are of approximately the same size, but the windows can be of the same size or can vary in size as required.

[0080] Figure 3 An example layout 300 of a transmitter and a detector is shown. In some examples, the layout 300 of a transmitter and a detector can be incorporated into some aspects of the wearable device 100, such as reference Figure 1A to Figure 2 Described. Figure 3 In the example of FIG. 1 , the arrangement 300 of the emitter and the detector can be included in a wearable device to provide a wearable Figure 1A and Figure 1B Physiological measurements and / or biometric measurements of a user of the wearable device 100.

[0081] By way of example and for purposes of description, the emitter and detector arrangement 300 may be positioned on the back side or skin-facing side of the wearable device 100, as shown in FIG. Figure 1A and Figure 1B The emitter and detector arrangement 300 may be provided by a back cover or skin side cover (not shown) having windows or apertures. Figure 3 ), which is discussed in further detail herein.

[0082] like Figure 3 As shown, window 345 may include emitters 305a, 305b, and 305c. Figure 2 , the emitter windows may each include a green light emitter, an infrared light emitter, and a red light emitter. For example, emitter 305 may include a green light emitter 305a, an infrared light emitter 305b, and a red light emitter 305c. Figure 3 , window 350 may include detectors 325, 330, 335, and 340. Window 363 may be a window in the center portion of the back cover. The windows, emitters, and detectors may each incorporate features of similar components described in other embodiments.

[0083] The system between each of the emitter window 345 and the detector window 350 includes multiple paths of short paths 355 and long paths 360 (i.e., for each emitter (or each detector), there are at least first and second optical paths (or light detection paths) having respective first and second lengths). Further, the method of mounting or inserting the detector window 350 into the back cover can provide optical isolation so that stray light from the emitter is not detected by the detector. In some examples, the window alone may not provide sufficient light blocking for internal crosstalk of the reflective sensing device.

[0084] Each of the emitters 305, 310, 315, and 320 includes a respective short path 355 and a long path 360 to the other detectors 325, 330, 335, and 340. For example, the emitter 320 has a short path 355 to the detector 325, a short path to the detector 340, a long path to the detector 330, and a long path to the detector 335. The long path and the short path may provide a mapping of arterial or venous blood flow for pulse oximetry. Further, the long path and the short path may provide an array of arterial or venous blood flow signals of potentially different perspectives for pulse oximetry. Each of the detectors may be capable of receiving or detecting respective light from the emitters 305, 310, 315, and 320 and respective wavelengths of the emitters. For example, the detectors 325, 330, 335, and 340 may each be capable of sensing green light, infrared light, and red light.

[0085] Figure 3 Four emitters and four detectors are depicted, which can provide sixteen different optical paths between the emitters and detectors. Figure 3 Other examples discussed herein may use four emitters and four detectors, but any number of emitters and detectors may be used as desired. For example, as shown in other embodiments herein, three emitters and three detectors may be used in a reflective sensing device, and nine optical paths or up to nine optical paths may be provided between the emitters and detectors. In some examples, the higher the number of paths, the less sensitive the measurement may be to erroneous data. With more measurements, it may be easier to verify data using redundant measurements or consistent measurements, and it may also be easier to identify erroneous data by comparing outlying measurements or inconsistent data.

[0086] Additionally, the greater the distance between the emitter and the detector, the greater the amount of wrist tissue that can be imaged and / or optically detected using the measurement. One or more of the path signals can be used to image and / or optically detect wrist tissue, so the number of emitters and detectors and the distance between the emitters and detectors can be appropriately selected to image and / or detect as much wrist tissue as possible for the corresponding size of the wearable device. In some examples, the higher the number of emitters and detectors, the greater the number of optical paths over which wrist tissue is detected and / or measurements are taken for imaging wrist tissue. However, the number of emitters and detectors may also be considered when optimizing the appearance of the wearable device and considering the battery life of the wearable device.

[0087] Although the reflective sensing device may have multiple emitters and detectors, there may be a predetermined order for turning the emitters and detectors on and off. In some examples, emitter 305 may be turned on, but emitter 305 may turn on a single green light emitter 305a. Continuing this example, adjacent detectors (detector 325 and detector 330) may be turned on to detect the return amount of green emitted light. In other examples, emitter 305 may be turned on and infrared light emitter 305b and red light emitter 305c may be turned on to emit light, and detectors 325, 330, 335, and 340 may all be turned on to detect the return amount of infrared light and red light. Some embodiments may turn on emitters 305 and 315, or may turn on emitters 315 and 320, or may turn on all emitters at once. The order in which the emitters may be turned on sequentially may be predetermined or may be random. In some examples, all emitters and detectors may be turned on at the same time.

[0088] As discussed above, detectors 325, 330, 335, and 340 can sense the amount of returning light (e.g., reflected light and / or backscattered light) that has passed through the user's arterial blood. The detectors may include additional associated circuitry that may be configured to process detected light measurements into signals and may provide these electrical signals to a processor. In some examples, the detected light measurements may come from each detector individually, or may be aggregated measurements derived from two or more detectors. The processor may be configured to receive signals (or indicators, or outputs) from one or more of the detectors. In some examples, the processor may be configured to receive signals from one or more of the transmitters. Additionally, the processor may be further configured to use at least a subset of the received signals (or indicators or outputs) and in some cases, the received light or the detected light to determine the degree of blood oxygenation. In some examples, the processor may be configured to receive signals (or indicators or outputs) representing wavelengths in the detected red and infrared ranges from at least a first detector and a second detector (e.g., detectors 325 and 330). The processor may then use the subset of signals (or indicators or outputs) representing the received red range wavelengths and the received infrared range wavelengths to determine the level of blood oxygenation.

[0089] In some examples, the processor may be configured to select which detector measurements to use and may select a subset of the received detector measurements. Additionally or alternatively, the program may be configured to select signals and / or measurements associated with one or more of the emitters for use. The processor may be configured to select a subset of measurements using various factors, such as determining erroneous outlying measurements or being able to detect erroneous reading measurements that may appear to be useful but may not conform to the assumptions made for making the measurements. The processor may utilize data received from multiple optical paths or channels and weight various features to identify useful data, for example, by analyzing multiple views and / or regions of wrist tissue obtained by taking measurements through multiple optical paths. In other examples, the processor may use all of the data received from the detector. Further, in some cases, the measurements and / or signals received from the detector may be weak signals. By selecting which detector measurements to use, the processor may select sufficiently strong signals, or in some examples, may select multiple signals (e.g., the amount of detected light) to be summed together. Additionally, the emitters and detectors may be located far from each other because the detector signals may be summed together.

[0090] exist Figure 3 In the example of , the amount of green light emitted by emitter 305a can be detected by the closest detectors (detector 325 and detector 330). Figure 3As shown, green light emitters 305a, 310a, 315a, and 320a can be positioned farthest from the center portion of the back cover of the wearable device. The green light emitter can be less sensitive to position because the green light can be detected by the closest detector. Additionally, by positioning the green light emitter close to the detector, the battery life and power saving of the wearable device can benefit. Typically, when green light is incorporated into a wearable device, the green light can be used for heart rate detection and monitoring. In some embodiments, the detected green light can also be used to distinguish between good detector readings and erroneous detector readings (i.e., the amount of detected green light can be used to determine a subset of red light and infrared light measurements (or indicators) for determining the degree of blood oxygenation).

[0091] Figure 4 An example layout 400 of a transmitter and a detector is shown. In some examples, the layout 400 of the transmitter and the detector can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 3 Described. Figure 4 In the example of FIG. 4 , the arrangement 400 of the emitter and the detector can be included in a wearable device to provide a wearable device such as a wearable device. Figures 1A to 3 Physiological measurements and / or biometric measurements of a user of a wearable device are discussed.

[0092] By way of example and for purposes of description, the emitter and detector arrangement 400 may be positioned on the back side or skin-facing side of the wearable device 100, as shown in FIG. Figure 1A and Figure 1B The emitter and detector arrangement 400 may be protected by a back cover or skin side cover having windows or apertures, which are discussed in further detail herein.

[0093] like Figure 4As shown, the layout 400 may include a window 445 for the emitter 405 and a window 450 for the near detector 430 and the far detector 435. The optional window 463 may be a window above the central portion of the back cover 407 of the wearable device. The window may be disposed in an opening 475 in the back cover 407 and may be located on the protrusion 470 or adjacent to such a protrusion. Alternatively, some or all of the windows may be integrated with the back cover 407 and defined by other portions of the back cover 407 on which there is no optical shield (e.g., ink (optically opaque ink), film, coating, or surface treatment). For example, the optical shield may be on a first portion (e.g., a non-window portion) of the back cover 407 and not present on a second portion of the back cover 407. In some cases, and by way of example, the window 445 for the emitter 405 may be defined by an optical shield (e.g., ink, film, coating, or surface treatment) without surrounding the window 445, and the window 450 for the near detector 430 and the far detector 435 may be seated on or adjacent to the protrusion 470. Openings and protrusions in the back cover are discussed in further detail herein. The back cover 407 and / or windows 445, 450, 463 may be formed of sapphire, glass, plastic, or other materials.

[0094] In some cases, the emitter 405, the near detector 430, and the far detector 435 may be mounted to a printed circuit board (PCB), and the PCB may be attached to the back cover 407 by one or more components that form a set of optical barriers (or walls) between the PCB and the back cover 407. In these cases, the back cover 507 in combination with the PCB and the one or more components that form the set of optical barriers (or walls) may define different chambers that separately house the emitter 405, the near detector 430, and the far detector 435 therein.

[0095] Figure 4 The window may form a surface with the back cover, and the back cover 407 may be adjacent to the wrist tissue 465. The emitter 405 may include an infrared light emitter 405b and a red light emitter 405c. Light from the infrared light emitter 405b and the red light emitter 405c may be transmitted to the tissue 465. Light reflected from the arterial blood flow and / or having passed through the user's arterial blood and / or tissue 465 may pass through the window 450 to the near detector 430 and the far detector 435. As previously discussed, the near detector 430 and the far detector 435 may be configured to receive or detect light from any of the emitters and receive or detect reflected green light, infrared light, and / or red light. The protrusion 470 may be at least partially used as an optical isolator between the (multiple) emitter windows and the detector window, which will be discussed in further detail herein.

[0096] As in Figure 4, emitter 405c can emit red light through window 445. The red light can pass through window 445 to tissue 465. The red light can reflect off a first region of tissue and return through window 450 to be received or detected by near detector 430. Additionally, the red light can reflect off a second region of tissue and return through window 450 to be received or detected by far detector 435. Further shown in Figure 4 In the example of FIG. 4 , red light reflected off a first region of tissue may not penetrate as deeply into the tissue as red light reflected off a second region of tissue. By positioning the emitter and detector away from each other, light may penetrate to different depths in the tissue, thereby enabling more thorough imaging and / or detection of wrist tissue. Red light from emitter 405b may also enter window 445 at an angle such that it may not pass through the window due to total internal reflection (TIR). Figure 4 As shown, red light may reflect off the outer surface of the window toward the skin and reflect back into the window. Because the reflected red light may be absorbed by the barrier or protrusion 470 that separates the window 445 from the window 450, the reflected red light may not be detected by the detector 430. The barrier or protrusion 470 may isolate the light emitted directly from the emitter from being detected by the detector, thereby preventing undesirable internal crosstalk.

[0097] Light emitted from infrared light emitter 405b may pass through window 445 and enter skin 465. The infrared light may reflect off of an arterial blood vessel in skin 465 and may pass through window 450. The infrared light may then be sensed by remote detector 435. Figure 4 In the example of , infrared light may not be received by the near detector 430. As shown, due to the angle at which the infrared light is emitted, some of the emitted infrared light may not pass through the window 445, and instead may reflect off the window due to TIR. This infrared light may reflect off the window and return into the window. Because the emitted infrared light that reflects off the window but not off the tissue may be blocked by the optical barrier or protrusion 470, it may not be detected by the detector 430. The optical barrier or protrusion 470 may isolate light that may be emitted within the window 445 at certain angles and at least partially reduce or prevent internal crosstalk, and may block light that is emitted by the emitter and does not first pass through the user's tissue from being directly sensed by the sensor. In Figure 4 In some examples, infrared light may be reflected, scattered, and / or backscattered away from the tissue and toward near detector 430. Although not depicted in Figure 44, red light emitted by red light emitter 405c may be reflected, scattered, and / or backscattered away from the tissue and into one of detectors 430 and 435. Similarly, infrared light emitted by infrared light emitter 405b may be reflected, scattered, and / or backscattered away from the tissue and into one of detectors 430 and 435. Methods of forming these windows with optical barriers via protrusions 470 and other methods of providing optical isolation within the windows are discussed in further detail herein.

[0098] FIG. 5A to FIG. 5D The respective displays are as shown in reference Figures 1A to 4 Different views of the back cover and / or back side of the wearable device previously described. Figure 5A An example 500 of a back side 510 of a wearable device is shown. In some examples, the back side 510 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 4 In the example of FIG. 5 , the back side 510 may be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 4 As discussed. Figure 5A As shown, the back side 510 of the wearable device may include a back cover 507. The back cover 507 may have six insert windows disposed around a central portion (or central window 563) of the back cover 507. Window 545 may provide an aperture through which an emitter may emit light, and window 550 may provide an aperture through which a detector may detect light reflected off the user's arterial blood flow and / or may detect backscattered light that has passed through the user's arterial blood. The window may be inserted into an opening extending through the back cover 507. Although the back cover 507 may include an insert window, such a window may form a smooth surface with the back cover 507.

[0099] Figure 5B An example elevation view of a back cover 507 of a wearable device is shown. In some examples, the back cover 507 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 5A Described. Figure 5B In an example, the back cover 507 can be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of the user wearing the wearable device, such as those related to Figures 1A to 5A discussed.

[0100] like Figure 5B As shown, the side view may be oriented as shown. Figure 5AA cross-section of the middle of the back side of the wearable device depicted. Back cover 507 may include six peripheral windows disposed around a central portion of back cover 507. In some embodiments, the central portion may include an optional central window. As previously mentioned, any suitable number of windows may be used, and the six windows are used for purposes of illustration and discussion only. Window 545 may provide an aperture through which an emitter may emit light, and window 550 may provide an aperture through which a detector may detect light reflected off and / or backscattered from the user's tissue. Window 563 (eg, Figure 5A , Figure 5B ,and Figure 5C Window 563 may be in the center portion (or center) of the wearable device and is optional. In some examples, window 563 may be used to enable an optical sensor to detect whether the wearable device is in contact with the user's skin, or to monitor the user's heart rate, or for other purposes. For example, an IR LED or other emitter may emit IR light through the center window in some cases, and an IR detector may detect a portion of the emitted IR light that returns through the center window after reflecting or scattering away from the user. The returned portion of the emitted IR light can be used to determine whether the back cover is adjacent or not adjacent to the user's wrist (or no longer adjacent to the user's wrist), or the returned portion of the emitted IR light can be analyzed to determine the user's heart rate. In some cases, the center window and / or optical sensing through the center window may be incorporated into any of the device embodiments described herein.

[0101] exist Figure 5B In the embodiment of the present invention, the back cover 507 may have an inner surface 504 that may be inside the wearable device and an outer surface 506 that may be outside the wearable device. Further, the back cover 507 may include a substrate that may define at least a portion of the inner surface 504 and the outer surface 506 of the wearable device. The outer surface 506 may be a surface that may contact the skin of a user wearing the wearable device. The back cover 507 or the skin side cover may have an opening that may extend through the back cover, for example, such an opening may extend through the inner surface and the outer surface of the back cover 507. The back cover 507 may also include a set of protrusions 570 that may be adjacent to the opening, such as Figure 5B In some examples, the protrusion 570 can be a stepped protrusion, such a protrusion can extend completely around the opening, such as with respect to FIG. 5A to FIG. 5DAs shown and discussed, or such protrusions can be positioned around the opening at a selected angle, or other suitable shape or gradient, as discussed herein. A window can be disposed in the opening and can be adjacent to the protrusion 570. The window can be joined to the back cover 507 at an appropriate location and also joined to the protrusion, which can fix the window in position so that the window does not move away or become tilted in the opening of the back cover 507. The window can be joined using any suitable method (such as adhesive, melting, etc.). In some examples, the entire back cover 507 may be optically opaque or the entire back cover 507 may be optically transparent. The back cover 507 may be optically opaque or optically transparent to light emitted and / or detected or received by the wearable device.

[0102] exist Figure 5B In some examples, the protrusion 570 may extend into the opening of the back cover 507. The protrusion may extend into the opening to provide an edge on which the window can rest. The protrusion may provide a protruding edge on which the window can sit. The protrusions can ensure that the window does not fall through the back cover and into the interior portion of the wearable device. These protrusions can be positioned adjacent to or near the inner surface of the back cover. Alternatively, the protrusions can be adjacent to or near the outer surface of the back cover so that the window can be inserted from the outside or outer surface of the back cover.

[0103] In some examples, the back cover 507 with the convex portion may be an optically opaque material, and the window may be optically transparent. As used herein, optical opacity may not block 100% of all light across all wavelengths, and instead may block light of a target wavelength that may be appropriately attenuated. In this example, the convex portion may provide at least some optical isolation for the detector so that stray light from the emitter is not received at the detector. Within a certain angle range, light leaving the emitter may be reflected off the window and returned toward the detector instead of passing through the window and entering the tissue. Without optical isolation, this light reflected off the window may be received by the detector and may provide an erroneous measurement value. With optical isolation, the light reflected off the window and returned toward the detector may be prevented from reaching the detector by optically isolating the optically opaque convex portion of the detector. In some examples, the window above the detector may have an optical barrier, while in other examples, the window above the emitter may have an optical barrier, and in further examples, the window above both the emitter and the detector may have an optical barrier. In some examples, an optical barrier may be formed by coating such sides of the opening and / or such sides of the window (e.g., around the opening or window) with an optically opaque ink or other material that is optically opaque to the emitted and detected light. Additionally or alternatively, an optical barrier may be formed by one or more of an ink, film, coating, or surface treatment disposed between the window and its corresponding opening (or protrusion). The ink, film, coating, or surface treatment may be formed on or applied to the window or opening (or protrusion) before the window is adjacent to and attached to the opening (or protrusion).

[0104] In some examples, the detector may detect a specific range of wavelengths, such as IR wavelengths. In this example, the optical barrier or optically opaque material may block the specific range of wavelengths detected by the detector (so that the emitted wavelengths are not detected by the detector without first passing through the back cover 507); or the optical barrier may block all wavelengths of light; or the optical barrier may block at least the IR range of wavelengths and a range on both sides of the IR wavelengths.

[0105] In some embodiments, the back cover 507 and / or windows 545, 550, 563 may be formed of sapphire, glass, plastic, or other materials. Although the window may be optically transparent, in some examples, the distance between the protrusions may at least partially determine the size of the aperture through which light can pass. As previously discussed, the window may be adjacent to the protrusion, and the protrusion may be an optical barrier between the emitter and the detector. The protrusion may have a protruding edge for the window to sit on it, so the distance between the inner sides of the protrusion may be less than the opening and / or window. Therefore, the area through which light can pass may be smaller than the opening in the back cover, and instead may be the internal distance between the protrusions.

[0106] Figure 5C An example of a back cover 507 of a wearable device is shown. In some examples, the back cover 507 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 5B Described. Figure 5C In an example, the back cover 507 can be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of the user wearing the wearable device, such as those related to Figures 1A to 5B discussed.

[0107] like Figure 5C As shown, the perspective view can be as follows Figure 5A and Figure 5B An example of a back cover 507 of a wearable device depicted. The back cover 507 may include six windows 545, 550 disposed around a central portion of the back cover 507 (or an optional central window 563). As previously mentioned, any suitable number of windows (such as eight windows) may be used, and six windows are used in the drawings of this specification for purposes of explanation and discussion only. Window 545 may provide an aperture through which an emitter may emit light, and window 550 may provide an aperture through which a detector may detect light reflected off and / or backscattered from the user's tissue. Window 563 may be in the central portion (or center) of the wearable device. The back cover 507 and / or windows 545, 550, 563 may be formed of sapphire, glass, plastic, or other materials.

[0108] The back cover 507 may include an opening 546 extending through the back cover. The opening 546 may include a protrusion that may be stepped, tapered, cupped, or any other suitable profile to at least partially support the window in the back cover 507. In some examples, the protrusion may be tapered, and the cone may be, for example, Figure 5D In yet other examples, the cone can extend through an opening in the back cover 507. In this example, the window can be the depth of the back cover 507.

[0109] In some examples, the protrusions 570 can determine the size of the aperture through which light can pass or be detected. The windows 545, 550 can rest on the protrusions 570 or be at least partially supported by such protrusions, and the windows 545, 550 can be optically transparent so that light can pass through the windows 545, 550 or can be detected through such windows. In some examples, the back cover 507 can be optically opaque.

[0110] In other examples, the back cover 507 may be optically translucent or transparent, and the windows 545, 550 may be optically translucent or transparent. In this example, the optically transparent back cover 507 may include a protrusion 570, but the protrusion 570 may be coated with an optically opaque material (such as ink) to provide light blocking or optical isolation between the emitter and the detector. Additionally, the protrusion 570 may be optically transparent, and the edges of the windows 545, 550 may be coated with an optically opaque ink. In yet another embodiment, both the protrusion 570 and the edges of the windows 545, 550 may be coated with an optically opaque ink to provide an optical barrier between the emitter and the detector.

[0111] Figure 5D An example side view of a back cover 507 of a wearable device is shown. In some examples, the back cover 507 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 5B Described. Figure 5D In an example, the back cover 507 can be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of the user wearing the wearable device, such as those related to Figures 1A to 5C discussed.

[0112] like Figure 5D As shown, the view can be as follows Figure 5C An example of a back cover 507 of a wearable device is depicted. Similar to Figure 5B , Figure 5D A projection 570 is shown upon which the windows 545, 550 may rest. Figure 5B The stepped convex part, Figure 5D The protrusion 570 may be tapered.

[0113] FIG. 6A to FIG. 6C The respective displays are as follows FIG. 1A to FIG. 5DDifferent views of the back cover on the back side of the wearable device described previously. Fig. 6A An example 600 of a back side 610 of a wearable device is shown. In some examples, the back side 610 can be incorporated into some aspects of the wearable device 100, such as with reference to FIG. 1A to FIG. 5D Described. Fig. 6A In an example of FIG. 1 , the back side 610 may be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to FIG. 1A to FIG. 5D discussed.

[0114] like Fig. 6A As shown, the back side 610 of the wearable device may include a back cover 607. The back cover 607 may have four to eight inserted windows that may provide sixteen optical sensing paths or channels. The window 650 may provide an aperture for the detector to detect light reflected off the user's arterial blood flow through such an aperture and / or to detect backscattered light that has passed through the user's arterial blood through such an aperture. The back cover and / or windows may be formed of sapphire, glass, plastic, or other materials. Fig. 6A The window 650 (and in some cases, the window 645) in the back cover 607 can be inserted into the opening extending through the back cover 607. Although the back cover 607 may include an insert window, such a window can form a smooth outer surface with the back cover 607. Fig. 6A As depicted, four of the eight windows (e.g., window 650) may have an optically opaque material or opaque material 687 around the perimeter of the window, which may determine the size of the aperture through which light may pass. The optically opaque material or black material around the perimeter of the window may be an optical barrier to all light or at least an optical barrier to the range of wavelengths emitted and / or received by the emitters and detectors of the wearable device. The other four windows (e.g., window 645) may be an integral part of the monolithic back cover structure (i.e., window 645 may not be an inserted window) and may be defined by an optical shield (e.g., ink, film, coating, or surface treatment) on the back cover 607. For example, an ink film, coating, or surface treatment may be on a first portion of the back cover 607 and not present on a second portion of the back cover 607.

[0115] Figure 6B An example of a back cover 607 of a wearable device is shown from a side view. In some examples, the back cover 607 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 6A Described. Figure 6B In the example of FIG. 6 , the back cover 607 may be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 6A discussed.

[0116] like Figure 6B As shown, the side view may be as follows Fig. 6AA cross-section of the dorsal side of the wearable device is depicted. Fig. 6A As depicted, back cover 607 may include eight windows. As previously mentioned, any suitable number of windows may be used, and eight windows are provided for purposes of illustration and discussion only. Each of windows 645 may provide an aperture through which an emitter may emit light, and each of windows 650 may provide an aperture through which a detector may detect light reflected off and / or backscattered from the user's tissue. By way of example, the windows shown in FIG. Figure 6B The cross section in FIG. 6 shows window 650 inserted into and extending through back cover 607. As previously discussed, window 645 may be an integral part of back cover 607 and may not be inserted. Fig. 6A and Figure 6B As shown, there may be no window in the central portion (or center) of the wearable device. However, in some embodiments, there may be Figure 5A A center window is shown.

[0117] exist Figure 6B In the embodiment of the present invention, the back cover 607 may have an inner surface 604 that may be inside the wearable device and an outer surface 606 that may be outside the wearable device. The back cover 607 may include a substrate that may at least partially define the inner surface 604 and the outer surface 606 of the wearable device. The outer surface 606 may be a surface that may contact the skin of a user wearing the wearable device. Figure 5B ,exist Figure 6B In the embodiment, the back cover 607 or the skin side cover may have an opening that can extend through the back cover. For example, the opening can extend through the inner surface 604 and the outer surface 606 of the back cover 607. Figure 6B In this non-convex example, the optically transparent frit 687 of glass or sapphire may include a central portion that is hollow (e.g., similar to a hollow tube) and may be generally cylindrical. The frit 687 may be inserted into the opening of the back cover 607, and the frit may be as Figure 6B The periphery of the adjacent opening shown is melted or bonded to the back cover 607. The window 650 can be set in the center of the frit 687, and the window can be bonded and bonded to the back cover 607 at an appropriate place. In some examples, the window 650 can provide an aperture for detecting the reflected light and / or backscattered light of the arterial blood flow through the user. By melting or bonding the frit and the window 650 to the back cover, this can fix the frit and the window to the position so that the window will not move away or become tilted in the opening of the back cover 607. In addition, the inner surface 604 and the outer surface 606 of the back cover 607 can be ground or polished to provide a back cover with a smooth surface. Further, although the frit and the window can be depicted as a circle, the frit and the window can be of any suitable shape. In some examples, as long as the frit acts as an optical barrier and blocks the light path from the emitter to the detector, the inner diameter of the frit can be of any shape.

[0118] exist Figure 6BIn some examples of the invention, the frit may be optically opaque. The frit material itself may be optically opaque, or the frit may be coated with an optically opaque material (such as an optically opaque ink or a neutral color ink that may not distinguish infrared light from red light). The frit may be inserted into the opening, and the frit may have a frit opening that is similar to a ring. Because the frit is similar to a ring with a hollow center opening, the inner diameter of the frit may provide an aperture through which light can still be detected. In some embodiments, the frit may be a glass frit (e.g., a black glass frit) that can be centered in the opening of the back cover 607. The black glass frit may form an optical bond with the sapphire opening after melting or bonding, and then both sides of the back cover may be polished to achieve a smooth surface. In this embodiment, the shielding of the emitter and / or detector may be defined by the shape of the ink or frit. The frit may be of any shape as long as the frit blocks the optical path from the emitter to the detector.

[0119] In some examples, the back cover 607 can be an optically transparent material, and the window can also be optically transparent. The optically opaque frit can provide at least some optical isolation for the detector so that stray emitter light is not received at the detector. Within a certain range of angles, light leaving the emitter can reflect off the window back toward the detector instead of passing through the window and into the tissue. Without optical isolation, this light reflected off the window can be received by the detector and may provide erroneous measurements. With optical isolation, light reflected off the window and back toward the detector can be prevented from reaching the detector by optically isolating the detector's optically opaque frit.

[0120] Similar to FIG. 5A to FIG. 5C The size of the aperture through which light can pass to reach the detector may be determined at least in part by the inner diameter of the frit and / or the ink on the periphery of the frit. Figure 6B In the embodiment of the present invention, the inner diameter of the frit and / or the ink on the inner diameter of the frit can be an optical barrier between the emitter and the detector. Therefore, the area through which light can pass can be smaller than the opening in the back cover and can instead be the inner diameter of the frit.

[0121] Figure 6C An example of a back cover 607 of a wearable device is shown. In some examples, the back cover 607 can be incorporated into some aspects of the wearable device 100, such as reference Figures 1A to 6B Described. Figure 6C In the example of FIG. 6 , the back cover 607 may be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 6B discussed.

[0122] like Figure 6C As shown, the isometric view can be as follows Fig. 6A and Figure 6BAn example of a back cover 607 for a wearable device is depicted. The back cover 607 may include four to eight windows. Window 645 may provide an aperture through which an emitter may transmit light, and in some cases, may be integrated with and defined by other portions of the back cover 607 that do not have an optical shield (e.g., ink (optically opaque ink), film, coating, or surface treatment) thereon. For example, the optical shield may be on a first portion of the back cover 607 and not present on a second portion of the back cover 607. Window 650 may provide an aperture through which a detector may detect light reflected off and / or backscattered from the user's tissue, and may be inserted into the back cover 607. In Figure 6C In the embodiment of the present invention, there may be no separately provided window in the central portion (or center) of the wearable device. However, the back cover 607 or a portion thereof may in some cases be optically transparent to the range of electromagnetic radiation wavelengths emitted and / or received through the central portion of the back cover.

[0123] exist Figure 6C In the embodiment of the present invention, the back cover 607 may include an opening extending through the window 650 of the back cover. The opening may be an annular frit having an opening in the center portion, and the frit may be inserted into the opening and act as a sleeve that fits within the opening of the back cover. The inner diameter opening of the frit or the ink applied to the frit may determine the size of the aperture through which light may pass or be detected. Although the term frit may be used herein, the frit may be understood as a hollow sleeve, ring, and / or tubular component or a hollow cylindrical component, regardless of the material composition.

[0124] Window 650 may be disposed in the center opening of the frit and may be optically transparent so that light may pass through or be detected through the window. Frit 687 may act as an optical barrier between the emitter and the detector and may minimize or prevent internal crosstalk. Using optical isolation, any emitter light that reflects off the window and back toward the detector may be prevented from reaching the detector by an optically opaque frit that optically isolates the detector.

[0125] Figure 7 An example 700 of a back cover, emitter, detector, and waveguide of a wearable device is shown from a side view. In some examples, the back cover 707 can be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 6C discussed.

[0126] like Figure 7 As shown, the side view may be as follows Figure 5A The back cover 707 may include six windows, but Figure 7 The side view shows an emitter window and two detector windows. Figure 7In the embodiment, the emitter and detector may be protected by a back cover or skin side cover having windows or apertures. Window 745 provides an aperture through which the emitter can emit light, and window 750 provides an aperture through which the detector can detect light reflected off and / or backscattered from the user's tissue. Figure 7 As shown, window 745 is used for transmitter 705, and window 750 is used for near detector 730 and far detector 735. Optional window 763 may be a window above the central portion of the back cover 707 of the wearable device. The window may be set in an opening 776 in the back cover 707, and the back cover 707 may be an optically transparent or optically opaque back cover. The opening in the back cover may extend through the inner and outer surfaces of the back cover. Alternatively, some or all of the windows may be integrated with the back cover 707 and defined by other portions of the back cover 707 that do not have an optical shield (e.g., ink (optically opaque ink), film, coating, or surface treatment) thereon. For example, the optical shield may be on a first portion (non-window portion) of the back cover 707 and not present on a second portion of the back cover 707. In some cases, and by way of example, the window 745 for the emitter 705 may be defined by an optical shield (e.g., ink, film, coating, or surface treatment) without surrounding the window 745, and the window 750 for the near detector 730 and the far detector 735 may be disposed in an opening 776 in the back cover 707. The back cover 707 and / or the windows 745, 750, 763 may be formed of sapphire, glass, plastic, or other materials.

[0127] In some cases, the emitter 705, the near detector 730, and the far detector 735 may be mounted to a PCB, and the PCB may be attached to the back cover 707 by one or more components that form a set of optical barriers (or walls) between the PCB and the back cover 707. In these cases, the back cover 707 in combination with the PCB and the one or more components that form the set of optical barriers (or walls) may define different chambers that separately house the emitter 705, the near detector 730, and the far detector 735 therein.

[0128] exist Figure 7 , the optical path for emitted light between the emitter 705 and the window 745 may be determined by the emitter waveguide 775. The emitter waveguide 775 may guide the emitted light from the emitter to the window. In some examples, light may be received in a first end of the waveguide such that the light reflects off from inside the wall of the waveguide. The light may exit from the second end of the waveguide and pass through the window and / or into the tissue of a user wearing the device. The emitter waveguide 775 may reflect internally at or around the wavelength of the light generated or emitted. Further, the emitter waveguide 775 may guide the emitted light via total internal reflection in the waveguide 775 and to the emitter window 745. Additionally, the emitter waveguide 775 may be configured to transmit light from the emitter to the wrist of a user wearing the wearable device.

[0129] like Figure 7 As depicted, emitters that can emit different wavelengths of light may each have an emitter waveguide 775, but in some embodiments, a waveguide may be configured to receive emitted light from more than one emitter. For example, the emitter waveguide 775 may be configured to receive all of the emitted green light, the emitted red light, and the emitted infrared light, and guide the light to the emitter window 745. In other examples, the emitter waveguide 775 may extend through the back cover of the wearable device, and the back cover may not include a window. In this example, the emitter may emit light through the housing of the reflective sensing device.

[0130] Also Figure 7 , the optical path for reflected exit light and / or backscattered light of arterial or venous blood flow that has passed through the wrist between the near detector 730 and the detector window 750 may be determined by the near waveguide 780. The near waveguide 780 may guide the reflected light from the window to the near detector 730. The near waveguide 780 may internally reflect at or around the wavelength of light received by the near detector 730. In some examples, the near detector 730 may internally reflect at or around the wavelength range of red light, infrared light, and / or green light. Further, the near waveguide 780 may guide the reflected light from the window via total internal reflection in the waveguide 780 and guide it to the near detector 730. In some examples, the near waveguide 780 may extend through the back cover of the wearable device, and the back cover may not include a window.

[0131] Similarly, the optical path between the remote detector 735 and the detector window 750 can be determined by the remote waveguide 785. The remote waveguide 785 can guide the reflected light from the detector window 750 to the remote detector 735. The remote waveguide 785 can internally reflect at or around the wavelength of light received by the remote detector 735. In some examples, the remote detector 735 can internally reflect at or around the red, infrared, and / or green wavelength ranges. Further, the remote waveguide 785 can guide the reflected light from the window via total internal reflection in the remote waveguide 785 and to the remote detector 735.

[0132] In some examples, the near detector 730 and the far detector 735 may include additional associated circuitry that may be configured to process the detected light measurements into signals and may provide these electrical signals to a processor. The processor may be configured to receive signals from one or more of the detectors. Additionally, the processor may be further configured to use at least a subset of the received signals and, in some cases, the received detected light to determine the level of blood oxygenation. In some examples, the processor may be configured to receive signals representing detected red and infrared range wavelengths from the far detector 735 and the near detector 730. The processor may then use a subset of the signals representing the received red range wavelengths and the received infrared range wavelengths to determine the level of blood oxygenation.

[0133] Figure 7 The waveguide may be formed of sapphire, plastic, glass, or any other suitable material. In some examples, the waveguide may be a fiber optic waveguide, which may be similar to a plastic rod having an internal reflective material that reflects light at or around wavelengths in the green range, red range, and infrared range. In other examples, the waveguide may be similar to a hollow tube and internally reflect light at or around wavelengths in the green range, red range, and infrared range. Figure 7 The waveguide may be optically coupled to the emitter and detector via butt coupling, one or more prisms, one or more lenses, and / or any other suitable method, or any combination thereof. Figure 7 The waveguide can be of any suitable shape, such as a sheet or film, a cable, a straight line, a cone, any combination thereof, etc. In some examples, the distal waveguide 785 may extend through a back cover of the wearable device, and the back cover may not include a window.

[0134] exist Figure 7 In other examples, the back cover may have an opening, but no optically transparent window. Instead, a waveguide may fill the opening in the back cover. In this example, the waveguide may directly receive reflected light and / or backscattered light that has passed through the arterial and venous blood flow of a person. The waveguide may be plastic, glass, hardened glass, a solid rod, a hollow tube, or any other suitable configuration or material, or any combination thereof. In some examples, the waveguide may be an optical fiber waveguide, which may be similar to a solid plastic rod having an internal solid reflective material that reflects light at green wavelengths, red wavelengths, and infrared wavelengths or around such wavelengths. In other examples, the optical fiber waveguide may be similar to a hollow plastic tube in which light can propagate through air, but the inner circumferential wall of the hollow plastic tube may be a reflective material that reflects light at green wavelengths, red wavelengths, and infrared wavelengths or around such wavelengths.

[0135] The emitter waveguide 775, the proximal waveguide 780, and the distal waveguide 785 may be optical waveguides, including, but not limited to, fiber optics, single mode, step index, gradient index, waveguide, planar, membrane, any combination thereof, and the like. In some examples, the emitter waveguide 775, the proximal waveguide 780, and the distal waveguide 785 may be different types of waveguides from one another. The waveguides may be inserted into holes or openings machined into the back cover 707. The emitter waveguide 775 may ensure that the emitted light is transmitted toward the tissue and not directly toward the proximal detector 730 or the distal detector 735. In some examples, the individual emitters of the emitter 705 may each have a corresponding waveguide. For example, a red light emitter may have a waveguide, an infrared light emitter may have a waveguide, and a green light emitter may have a waveguide. In additional examples, the proximal detector 730 and the distal detector 735 may not have waveguides associated with the detectors, such as with respect to FIG. 5A to FIG. 5D and FIG. 6A to FIG. 6C discussed.

[0136] In some examples, the emitter waveguide 775, the near waveguide 780, and the far waveguide 785 can have an internal core that reflects wavelengths around green, infrared, and red. Further, the core of the waveguide can be minimally absorbing around these wavelengths so that a maximum amount of emitted light can be transmitted to the wrist tissue of a user wearing the wearable device and not absorbed by the waveguide. Additionally, the waveguide internal core can be minimally absorbing around these wavelengths so that light reflected off and / or backscattered from the wrist tissue can be detected by the near detector 730 and the far detector 735.

[0137] FIG. 8A to FIG. 8D Various layouts 800, 805, 806, and 809 of the back cover of the wearable device are shown. FIG. 8A to FIG. 8D The windows of the back cover 807 in any of the layouts 800 described in any of the embodiments may be configured in some examples such that a first set of windows may be configured to transmit emitted light to the wrist of the user and a second set of windows may be configured to detect light reflected off of the user's arterial blood flow and / or backscattered light that has passed through the arterial blood. Additionally, the layout 800 may be used in conjunction with Figures 1A to 7 In any of the described examples. The back cover and / or window in each arrangement may be formed from sapphire, glass, plastic, or other materials.

[0138] Fig. 8A An example of a back cover 800 for a wearable device is shown. In some examples, a back cover 807 can be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 7 As discussed. Fig. 8AAs shown, the back cover 807 may include six windows arranged around a center portion (or center window) as described herein. Fig. 8A The window of the back cover 807 in the embodiment may be circular and may provide nine optical paths between the emitter and the detector and may be associated with FIG. 5A to FIG. 5D The convex implementation scheme discussed, related to FIG. 6A to FIG. 6C The frit implementation scheme discussed, or related to Figure 7 Any of the waveguide implementations discussed herein may be used together. Fig. 8A In , the emission area can be defined by the inner diameter of the frit, or by the distance between the inner edges of the protrusions as discussed herein. Although the window may be larger, the aperture through which light can pass can be determined by the optical barrier between the emitter and the detector. Fig. 8A In other examples, Fig. 8A The windows in the back cover 807 can provide up to nine optical paths between emitters and detectors.

[0139] Figure 8B An example of a back cover 803 of a wearable device is shown. In some examples, a back cover 807 can be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 8A As discussed. Figure 8B As shown, back cover 807 may include eight windows as described in detail herein. Figure 8B The windows of the back cover 807 in can be rectangular and triangular in shape and can provide sixteen optical paths between emitters and detectors, and in some examples, can provide up to sixteen optical paths between emitters and detectors. Figure 8B The examples can be related to FIG. 5A to FIG. 5D The convex implementation scheme discussed, related to FIG. 6A to FIG. 6C The frit implementation scheme discussed, or related to Figure 7 Any of the waveguide implementations discussed herein may be used together. Figure 8B In the embodiment, the shapes of the windows and apertures can be implemented to maximize the use of the surface area of ​​the back cover 807 as much as possible. Figure 8B In the embodiment of the present invention, the green light emitters can be positioned in the inner diameter of the triangular shape, and the red light emitters and the infrared light emitters can be positioned in the corners of the triangular shape.

[0140] Figure 8C An example of a back cover 806 of a wearable device is shown. In some examples, a back cover 807 can be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 8B As discussed. Figure 8C As shown, back cover 807 may include eight windows as described in detail herein. Figure 8CThe window of the back cover 807 in can be circular and can provide sixteen optical paths between the emitters and detectors. Figure 8C The examples can be related to FIG. 5A to FIG. 5D The convex implementation scheme discussed, related to FIG. 6A to FIG. 6C The frit implementation scheme discussed, or related to Figure 7 Any of the waveguide implementations discussed may be used together.

[0141] exist Figure 8C In the embodiment, light can be detected through window 850 after reflecting off the wrist artery, and window 850 can include an optical barrier (e.g., a projection, ink, film, coating, surface treatment, or frit) extending through back cover 807 and around the inner diameter of the window (or around the inner diameter of the window, as shown in reference Figures 1B to 7 Although all pore sizes are Figure 8C 807, but the window 845 through which the emitted light can pass may not have an optical barrier extending through the back cover 807 (but may have one). Instead, the window 845 may be integral with the back cover 807 (i.e., the window 845 may not be an inserted window) and have a diameter defined by other portions of the inner or outer surface of the back cover 807 that do not have an optical shield (e.g., ink (optically opaque ink), film, coating, or surface treatment) applied. For example, the optical shield may be on a first portion of the back cover 807 (e.g., the non-window portion) and not present on a second portion of the back cover 807. The optical shield may define the size of the aperture over each emitter, but may not block light from being redirected within the back cover 807. However, emitted light that is redirected within the back cover 807 but does not exit the back cover 807 may be blocked from reaching the detector by an optical barrier extending through the back cover 807 and extending around the detector window. The optical barrier may be formed by one or more of an ink, film, coating, surface treatment, or frit disposed between the window and its corresponding opening, which in some cases may be completely or partially surrounded by a stepped or conical protrusion. In the case of an ink, film, coating, or surface treatment, the ink, film, coating, or surface treatment may be formed on or applied to the window or opening (or protrusion) before the window is adjacent to and attached to the opening (or protrusion). Window 850 may be larger than window 845, but the aperture of window 850 and the aperture of window 850 may be the same size. In some examples, window 850 may include an optical barrier, such as a protrusion or frit, which may result in an aperture smaller than window 850.

[0142] Fig.8D An example of a back cover 809 of a wearable device is shown. In some examples, the back cover 807 can be incorporated into the wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to Figures 1A to 8C As discussed. Fig.8D As shown, back cover 807 may include eight windows as described in detail herein. Fig.8D The windows of the back cover 807 in can be rectangular and circular in shape and can provide sixteen optical paths between emitters and detectors. Fig.8D The examples can be related to FIG. 5A to FIG. 5D The convex implementation scheme discussed, related to FIG. 6A to FIG. 6C The frit implementation scheme discussed, or related to Figure 7 One of the waveguide implementations discussed above is used together with Fig.8D In the embodiment, the shapes of the windows and apertures can be implemented to maximize the use of the surface area of ​​the back cover 807 as much as possible. Fig.8D In the embodiment, the emitter can be linear in shape to use as much aperture opening as possible. Using the embodiment of the linear shaped emitter, the emitter can emit stronger or more intensive light for transmission into the wrist tissue of the user. In other examples, Fig.8D The windows in the back cover 807 can provide up to sixteen optical paths between emitters and detectors.

[0143] Fig. 9A and Fig. 9B Various layouts of back covers for wearable devices are shown. Fig.10 The windows of the back cover shown in the layouts 900 and 913 described in both examples may be configured such that the windows may be configured to transmit emitted light to the wrist of the user and may be further configured to detect light reflected off the user's arterial blood flow and / or backscattered light that has passed through the arterial blood. Additionally, the layouts may be used in conjunction with FIG. 1A to FIG. 8D in any of the described examples.

[0144] Fig. 9A Layout 900 of a back cover of a wearable device is shown. In some examples, a back cover 907 can be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to FIG. 1A to FIG. 8D As discussed. Fig. 9A As shown, the back cover 907 may include six windows disposed around a central portion (or central window) of the back cover 907, similar to Fig. 8A , and provides nine optical paths between emitters and detectors. Fig. 9A In other examples, the back cover 907 may be similar to Fig. 8A Includes six windows and can provide up to nine optical paths between emitters and detectors. Fig. 9A The windows of the back cover 907 in the embodiment may be circular in shape. The windows may alternatively have alternating shapes or sizes, and may be more or less in number.

[0145] like Fig. 9AAs shown, green light emitter 905a of emitter 905 can emit green light. Green light can be transmitted from the green light emitter and can be reflected off of arterial blood flow and can be detected by detectors 925 and 930. Fig. 9A The light reflected off the blood vessels may be stronger or of higher magnitude in some locations and weaker or of lower magnitude in other locations. Because of the circular layout and circular shape of the window and aperture, only a portion of the reflected green light may be aligned with the detector. Although the signal may provide useful information, it may be desirable to detect as much of the reflected light as possible by the detector relative to detecting only a portion of the reflected light on the periphery of the detector.

[0146] Fig. 9B Layout 913 of a back cover of a wearable device is shown. In some examples, back cover 907 can be incorporated into a wearable device to provide physiological measurements and / or biometric measurements of a user wearing the wearable device, such as those related to FIG. 1A to FIG. 8D As discussed. Fig. 9B As shown, the back cover 907 may include a Figure 8B The eight windows of the layout provide sixteen optical paths between the emitter and the detector. Fig. 9B In other examples, the back cover 907 may include eight windows and may provide up to sixteen optical paths between emitters and detectors. Fig. 9B The window of the back cover 907 can be triangular or rectangular in shape.

[0147] like Fig. 9B As shown, green light emitter 905a of emitter 905 can emit green light and, as previously discussed, can be positioned in the inner portion of the triangular window and aperture. Green light can be transmitted from the green light emitter and can be reflected off of the arterial blood flow and can be detected by detectors 925 and 930. Fig. 9B The light reflected off the blood vessels may be stronger or of higher magnitude in some locations and weaker or of lower magnitude in other locations. Because of the circular layout and rectangular shape of the windows and apertures of detectors 925 and 930, the reflected green light may "line up" or overlap with most to all of the detection area of ​​detectors 925 and 930. Fig. 9A As described above, reflected light is detected in the detector periphery, and detectors 925 and 930 may receive or detect as much reflected light as possible.

[0148] Figures 1A to 9B The described layouts and configurations of the wearable devices in have been used for purposes of explanation. In alternative embodiments, the described embodiments may include different combinations or configurations of components, or may perform additional or alternative functions. The layouts and configurations described herein may be used as part of an electronic device, such as in a watch, a biometric sensor, or in any other suitable device.

[0149] In various embodiments, a component or ink is referred to as being "opaque" or "optically opaque." A component or ink is generally optically opaque to wavelengths of electromagnetic radiation emitted or received by the component below it, or to a range of wavelengths of electromagnetic radiation emitted or received, and may therefore block (multiple) wavelengths. In some cases, a component or ink may also be optically opaque to other or all wavelengths of electromagnetic radiation, or block other or all wavelengths of electromagnetic radiation. In some cases, a component or ink may also be optically opaque to visible light for aesthetic reasons and / or other reasons.

[0150] In various embodiments, a component or ink is referred to as being "transparent" or "optically transparent." A component or ink may be optically transparent only to the wavelengths of electromagnetic radiation emitted or received by the component below it, or to a range of wavelengths of electromagnetic radiation emitted or received, and may therefore transmit the wavelength(s). In some cases, a component or ink may also be optically transparent to, or transmit, other or all wavelengths of electromagnetic radiation.

[0151] In some embodiments, the inks described herein may alternatively be or include one or more of a coating, surface treatment, etc. In some embodiments, multiple inks, coatings, or surface treatments may be combined to provide optical blocking and / or optical transparency in one or more frequency bands.

[0152] In some implementations, opaque, selectively opaque, and / or selectively transparent components, inks, coatings, surface treatments, or the like may be used to reduce undesirable optical crosstalk between transmitters and receivers, or between different optical paths.

[0153] Fig.10 A sample electrical block diagram of an electronic device 1000 is shown and the electronic device may be referred to as Figures 1A to 9B 1. The electronic device 1000 may include a display 1002 (e.g., a light-emitting display on the front side of the wearable device), a processor 1004, a power source 1006, a memory 1008 or storage device, a sensor system 1010, and an input / output (I / O) mechanism 1012 (e.g., an I / O device and / or I / O port). The processor 1004 may control some or all operations of the electronic device 1000. The processor 1004 may communicate directly or indirectly with substantially all components of the electronic device 1000. For example, a system bus or other communication mechanism 1014 may provide communication between the processor 1004, the power source 1006, the memory 1008, the sensor system 1010, and / or the I / O mechanism 1012.

[0154] The processor 1004 may be implemented as any electronic device capable of processing, receiving, or sending data or instructions. For example, the processor 1004 may be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or a combination of such devices. As described herein, the term "processor" is intended to include a single processor or processing unit, multiple processors, multiple processing units, or other appropriately configured operating components.

[0155] It should be noted that components of the electronic device 1000 may be controlled by multiple processors. For example, selected components of the electronic device 1000 may be controlled by a first processor, and other components of the electronic device 1000 may be controlled by a second processor, wherein the first and second processors may or may not communicate with each other. In some embodiments, the processor 1004 may include any of the processors described herein and / or may be capable of performing any of the processing steps described herein.

[0156] The power source 1006 may be implemented with any device capable of providing energy to the electronic device 1000. For example, the power source 1006 may be one or more batteries or rechargeable batteries. Additionally or alternatively, the power source 1006 may be a power connector or power cord that connects the electronic device 1000 to another power source, such as a wall socket.

[0157] The memory 1008 can store electronic data that can be used by the electronic device 1000. For example, the memory 1008 can store electronic data or content, such as, for example, audio and video files, documents and applications, device settings and user preferences, timing signals, control signals, data structures or databases, image data, biometric data, or focus settings. The memory 1008 can be configured as any type of memory. By way of example only, the memory 1008 can be implemented as random access memory, read-only memory, flash memory, removable memory, other types of storage components, or a combination of such devices.

[0158] The electronic device 1000 may also include a sensor system 1010, which in turn includes one or more sensors positioned substantially anywhere on the electronic device 1000 (e.g., the back side of the wearable device). The sensor(s) may be configured to sense substantially any type of characteristic, such as, but not limited to, pressure, electromagnetic radiation (light), touch, heat, movement, relative motion, biometric data, etc. For example, the sensor(s) may include thermal sensors, position sensors, light or optical sensors, accelerometers, pressure transducers, gyroscopes, magnetometers, health monitoring sensors, etc. Additionally, the one or more sensors may utilize any suitable sensing technology, including, but not limited to, capacitive, ultrasonic, resistive, optical, ultrasonic, piezoelectric, and thermal sensing technologies.

[0159] I / O mechanisms 1012 may transmit and / or receive data from a user or another electronic device. I / O devices may include a display, a touch-sensitive input surface (such as a trackpad), one or more buttons (e.g., a graphical user interface "home" button), one or more cameras, one or more emitters and / or detectors (e.g., as described herein with reference to Figures 1A to 9B The I / O devices or ports may also transmit electronic signals via a communication network, such as a wireless and / or wired network connection. Examples of wireless and wired network connections include, but are not limited to, cellular, Wi-Fi, Bluetooth, IR, and Ethernet connections.

[0160] For the purpose of explanation, the foregoing description uses specific nomenclature to provide a thorough understanding of the described implementations. However, after reading this description, it will be apparent to those skilled in the art that the specific details are not necessary to practice the described implementations. Therefore, the foregoing description of the specific implementations described herein is presented for purposes of illustration and description. The above implementations are not intended to be exhaustive or to limit the implementations to the precise form disclosed. After reading this description, it will be apparent to those skilled in the art that in view of the above teachings, many modifications and variations are possible, and that the various features of the example implementations may be combined for specific applications.

[0161] The present disclosure recognizes that personal information data (including biometric data obtained using the techniques described herein) can be used to benefit users. For example, the use of biometric authentication data can be used to conveniently access device functions without the use of passwords. In other examples, user biometric data is collected to provide users with feedback related to their health or fitness level. Further, the present disclosure also contemplates other uses of personal information data (including biometric data) that benefit users.

[0162] The present disclosure further contemplates that the physical entity responsible for the collection, analysis, disclosure, transmission, storage, or other use of such personal information data will follow a properly formulated privacy policy and / or privacy practice. Specifically, such physical entity should implement and consistently use privacy policies and privacy practices that are generally recognized as meeting or exceeding industry or government requirements for maintaining the privacy and security of personal information data, including the use of data encryption and preservation methods that meet or exceed industry or government standards. For example, personal information from users should be collected for physical legal and reasonable use and not shared or sold beyond their legal use. Further, such collection should only occur after receiving the user's informed consent. In addition, such physical entity will take any necessary steps to safeguard and protect the security of access to such personal information data, and ensure that others who have access to the personal information data comply with its privacy policies and procedures. Further, such physical entity itself may be evaluated by a third party to certify that such physical entity complies with widely accepted privacy policies and privacy practices.

[0163] Notwithstanding the foregoing context, the present disclosure also contemplates implementations in which a user selectively blocks the use or access of personal information data (including biometric data). That is, the present disclosure contemplates that hardware and / or software components may be provided to prevent or block access to such personal information data. For example, in the case of a biometric authentication method, the present technology may be configured to allow a user to optionally skip the biometric authentication step by providing security information (such as a password, personal identification number (PIN), touch gesture, or other authentication method known to those skilled in the art, either alone or in combination). In another example, a user may choose to remove, disable, or limit access to certain health-related applications that collect the user's personal health or fitness data.

Claims

1. A wearable device, comprising: A housing having a back cover; an optical shield on the first portion of the back cover; The back cover is optically transparent and includes a set of windows, wherein: A first subset of windows in the set of windows is defined by a second portion of the back cover having no optical shield thereon; and A second subset of windows in the set of windows is inserted into a set of openings in the back cover; an optical barrier surrounding each window in the second subset of windows; a set of light emitters configured to emit light through the first subset of windows; and A set of light detectors is configured to receive light passing through the second subset of windows.

2. A wearable device according to claim 1, wherein the set of light emitters is configured to emit light through the first subset of windows.

3. The wearable device of claim 1, wherein the set of light emitters comprises: A set of red light emitters; and A set of infrared light emitters.

4. The wearable device according to claim 3, further comprising: a processor configured to determine a blood oxygenation level using respective outputs of the set of light detectors indicating the following, a return amount of red light emitted by the set of red light emitters; as well as The return amount of infrared light emitted by the set of infrared light emitters.

5. The wearable device according to claim 3, wherein the set of light emitters further comprises a set of green light emitters.

6. A wearable device according to claim 3, wherein for each window in the first window subset, a red light emitter in the group of red light emitters and an infrared light emitter in the group of infrared light emitters are configured to emit light through a corresponding window in the first window subset.

7. A wearable device according to claim 1, wherein the optical barrier surrounding each window in the second window subset comprises at least one of an ink, a film, a coating, or a surface treatment disposed between a window in the second window subset and a corresponding opening in the back cover.

8. A wearable device according to claim 7, wherein: The back cover includes a stepped protrusion extending partially or completely around each opening in the back cover; and Each window of the second subset of windows is adjacent to the stepped protrusion that extends partially or completely around a corresponding opening in the back cover.

9. The wearable device according to claim 7, wherein: The back cover includes a conical protrusion extending partially or completely around each opening in the back cover; and Each window of the second subset of windows is adjacent to the tapered protrusion that extends partially or completely around a corresponding opening in the back cover.

10. The wearable device of claim 1, wherein the optical barrier surrounding each window in the second subset of windows comprises a glass frit.

11. The wearable device according to claim 1, wherein: The back cover is formed of sapphire; and Each window in the second subset of windows is formed of sapphire.

12. A wearable device according to claim 1, wherein the first window subset and the second window subset are each disposed around a central portion of the back cover.

13. The wearable device according to claim 1, wherein The set of optical transmitters comprises: a first set of emitters configured to emit a wavelength in the red range; a second set of emitters configured to emit a wavelength in the infrared range; Each photodetector in the set of photodetectors is configured to detect an amount of at least the red range wavelengths and the infrared range wavelengths; and The wearable device further includes a processor, wherein the processor is configured to: operating the first set of transmitters and the second set of transmitters; receiving an indicator of the amount of at least the red range wavelengths and the infrared range wavelengths detected by the set of light detectors; as well as A blood oxygenation level is determined using at least a subset of the indicators.

14. A wearable device according to claim 13, wherein: For each emitter in the first set of emitters and each emitter in the second set of emitters, the set of photodetectors includes at least, a first detector that detects emitted light on a first optical path having a first length; and A second detector detects emitted light on a second optical path having a second length different from the first length.

15. The wearable device according to claim 13, further comprising: a third group of emitters, the third group of emitters being configured to emit a wavelength in the green range; wherein, Each photodetector in the set of photodetectors is further configured to detect the emitted green range wavelengths; and The processor is further configured to: operating the third set of transmitters; and An indicator of an amount of the detected green-range wavelengths received by the set of light detectors is received.

16. A wearable device according to claim 15, wherein: The processor is further configured to: The indicator of the amount of the detected green range wavelengths is used to determine the at least a subset of the indicators for determining the level of blood oxygenation.

17. A wearable device comprising: a housing; a display, the display being viewable through a front side of the housing; a skin side cover, the skin side cover being on a back side of the housing and being formed of an optically transparent material, the skin side cover having: an inner surface; an outer surface; and a set of protrusions adjacent to a set of openings extending through the skin side cover from the inner surface to the outer surface; a set of windows disposed in the set of openings and adjacent to the set of protrusions; a set of optical barriers positioned between the set of windows and the set of protrusions; as well as A set of light detectors is disposed within the housing and is configured to receive light that propagates across the set of protrusions and through the set of windows.

18. A wearable device according to claim 17, wherein: The skin side cover is formed of sapphire; and Each window in the set of windows is formed from sapphire.

19. The wearable device according to claim 17, wherein: The set of protrusions are stepped protrusions; The set of optical barriers each include an ink that is opaque to at least one red range wavelength and one infrared range wavelength detectable by the set of light detectors.

20. The wearable device according to claim 19, further comprising: A set of red light emitters; A set of infrared light emitters; and A group of green light emitters; wherein, The group of windows is a first group of windows; The skin side cover further includes a second set of windows; A red light emitter in the group of red light emitters, an infrared light emitter in the group of infrared light emitters, and a green light emitter in the group of green light emitters are disposed below each window in the second group of windows; and The windows in the first group of windows and the second group of windows are annularly interspersed around a central portion of the skin side cover.

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