WO2024114217A1

WO2024114217A1 - Physiological parameter sensor and wearable device

Info

Publication number: WO2024114217A1
Application number: PCT/CN2023/127616
Authority: WO
Inventors: 杨素林
Original assignee: 华为技术有限公司
Priority date: 2022-11-30
Filing date: 2023-10-30
Publication date: 2024-06-06
Also published as: CN118105048A

Abstract

A physiological parameter sensor and a wearable device. The physiological parameter sensor comprises: a substrate (10), at least one light source (11), at least one optical detector (12), a polarizer (15), and a phase retarder (16). Each light source (11) and each optical detector (12) are located on the surface of the same side of the substrate (10). The physiological parameter sensor further comprises: at least one optical signal transmitting region (P) and at least one optical signal receiving region (Q); each optical signal transmitting region (P) corresponds to at least one light source (11), and each optical signal receiving region (Q) corresponds to at least one optical detector (12). The polarizer (15) is located in a region corresponding to at least one optical signal receiving region (Q), and the phase retarder (16) is located in a region corresponding to at least one optical signal receiving region (Q). The phase retarder (16) is located on the side of the polarizer (15) facing away from the substrate (10). By means of the arrangement of the polarizer (15) and the phase retarder (16), the exercise noise can be reduced or filtered out, thus improving the detection performance of the physiological parameter sensor.

Description

A physiological parameter sensor and wearable device

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to a Chinese patent application filed with the Chinese Patent Office on November 30, 2022, with application number 202211529424.8 and application name “A Physiological Parameter Sensor and Wearable Device”, the entire contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the technical field of wearable devices, and in particular to a physiological parameter sensor and a wearable device.

Background technique

Photoplethysmograph (PPG) sensors are important sensors in wearable devices. PPG sensors are basic sensors for sports and health characteristics in wearable devices. They can be used to continuously and non-sensitively measure the human body, continuously collect sports and health data such as heart rate and blood oxygen, and provide a basis for sports and health analysis.

The working principle of the PPG sensor is: the amount of blood in the microvessels of the measured tissue changes with the beating of the heart, that is, the blood volume will change with the beating of the heart. The PPG sensor irradiates the measured tissue with a light signal, and the transmitted or reflected light signal changes with the blood volume. The PPG sensor detects human physiological parameters such as heart rate, blood oxygen, and carbon oxygen by detecting the light signal that reflects the change in blood volume. When the user wears the wearable device and remains static, the relative position of the user's skin and the PPG sensor remains basically unchanged, and the PPG sensor can provide better detection of physiological parameters such as heart rate. However, when the user wears the wearable device and exercises, the phase position between the user's skin and the PPG sensor changes greatly, which introduces motion noise or interference, making detection difficult, resulting in poor detection performance of the PPG sensor.

Summary of the invention

The embodiments of the present application provide a physiological parameter sensor and a wearable device to solve the problem of poor detection performance of the PPG sensor in sports scenarios.

In the first aspect, an embodiment of the present application provides a physiological parameter sensor, which may include: a substrate, at least one light source, at least one light detector, a polarizer and a phase delay plate, and each light source and each light detector are located on the surface of the same side of the substrate. The physiological parameter sensor may also include: at least one light signal emitting area and at least one light signal receiving area. Each light signal emitting area corresponds to at least one light source, that is, the light signal emitted by at least one light source can be emitted in the light signal emitting area. Each light signal receiving area corresponds to at least one light detector, that is, the light signal incident in the light signal receiving area can be emitted to at least one light detector. In specific implementation, the position and number of the light signal emitting area and the light signal receiving area can be set according to the actual needs of the optical path. The polarizer is located in the area corresponding to the light signal receiving area, the phase delay plate is located in the area corresponding to the light signal receiving area, the polarizer is located on the side of each light detector away from the substrate, and the phase delay plate is located on the side of the polarizer away from the substrate.

Each light source can emit a first light signal for detecting physiological parameters, and the phase delay plate can be used to phase delay the received second light signal. The polarizer can allow light signals that are consistent with the polarization direction of the polarizer to pass through. In other words, the polarizer can select the polarization state of the light signal according to its own polarization direction, and determine which polarization state of the light signal can pass through the polarizer. The photodetector is used to receive the second light signal that passes through the polarizer, and the physiological parameter sensor can determine human physiological parameters such as heart rate, blood oxygen and carbon oxygen based on the light signal detected by the photodetector.

In the physiological parameter sensor provided in the embodiment of the present application, by setting a polarizer and a phase delay plate, the crosstalk and reflection of other components inside the physiological parameter sensor, the skin surface reflection, the shallow skin reflection and/or the shallow skin internal scattering can be reduced or prevented, that is, the DC signal of the physiological parameter sensor can be reduced. Because when the user wears the wearable device and exercises, the motion noise is mainly related to the DC signal change caused by the deflection and movement of the wearable device, therefore, the physiological parameter sensor in the embodiment of the present application can reduce or filter out the motion noise. The perfusion rate of the physiological parameter sensor is inversely proportional to the DC signal, and the DC signal accounts for a high proportion of the electrical signal of the physiological parameter sensor. Therefore, the embodiment of the present application can improve the perfusion rate of the physiological parameter sensor by reducing the DC signal, thereby improving the detection performance of the physiological parameter sensor.

In the embodiments of the present application, the polarizer and the phase retarder may be implemented in a variety of ways, and the implementation methods of the polarizer and the phase retarder are described in detail below.

Implementation method 1:

The polarizer can also be located in the area corresponding to each light signal emission area, that is, the polarizer can be located in the area corresponding to the light signal emission area and the light signal receiving area. The phase delay plate can also be located in the area corresponding to each light signal emission area, that is, the phase delay plate can be located in the area corresponding to the light signal emission area and the light signal receiving area. The polarizer is located on the side of each light source away from the substrate, and the phase delay plate is located on the side of the polarizer away from the substrate.

At least one light source can be used to emit the first light signal to the polarizer, and the polarizer can allow light with the same polarization direction as the polarizer to pass through. In other words, the polarizer can select the polarization state of the first light signal according to its own polarization direction, and determine which polarization state of the first light signal can pass through the polarizer and continue to be transmitted toward the skin.

The first light signal passing through the polarizer is delayed in phase after passing through the phase delay plate, and the first light signal after the phase delay is emitted toward the skin.

In a possible implementation, the substrate may be a supporting substrate such as a ceramic substrate or a printed circuit board (PCB). Each light source may include a light emitting diode (LED) or a laser. Exemplarily, the laser may be a vertical cavity surface emitting laser (VCSEL). In the embodiment of the present application, the first light signal emitted by the light source may be a light signal of various polarization states such as natural light, linearly polarized light (the polarization direction of the linearly polarized light is not perpendicular to the polarization direction of the polarizer), circularly polarized light or elliptically polarized light, as long as the first light signal emitted by the light source has at least a component consistent with the polarization direction of the polarizer, so that at least part of the light signal in the first light signal can pass through the polarizer. Preferably, the light source may be a linearly polarized light source or a nearly linearly polarized light source, and the polarization state of the light signal emitted by the light source is substantially consistent with the polarization direction of the polarizer. Each light detector may include a photodiode (PD). Exemplarily, the photodiode can be a PIN photodiode (PIN PD) or an avalanche photon diode (APD). The light detector can receive the light signal transmitted through the skin, and the physiological parameter sensor can determine the human physiological parameters such as heart rate, blood oxygen and carbon oxygen according to the light signal detected by the light detector.

In some embodiments of the present application, the polarizer may be a linear polarizer, which allows polarized light that is consistent with the polarization direction of the linear polarizer to pass through. The phase retarder may be a quarter wave plate, which can cause the optical signal to produce a phase delay of an odd multiple of π/2. In this way, the crosstalk and reflection of other components inside the physiological parameter sensor, the skin surface reflection, the shallow skin reflection and/or the shallow skin internal scattering can be prevented, thereby greatly reducing the DC signal of the physiological parameter sensor, effectively filtering out motion noise, and improving the detection performance of the physiological parameter sensor. In other embodiments of the present application, the phase retarder may also be other optical elements with a phase delay function. Based on similar principles, the crosstalk and reflection of other components inside the physiological parameter sensor, the skin surface reflection, the shallow skin reflection and/or the shallow skin internal scattering can also be reduced, that is, the DC signal of the physiological parameter sensor can be reduced, and the detection performance of the physiological parameter sensor can also be improved.

In one possible implementation, the polarizer located in each optical signal transmission area and the polarizer located in each optical signal receiving area are the same polarizer, that is, the polarizer is an integrated structure. The phase delay plate located in each optical signal transmission area and the phase delay plate located in each optical signal receiving area are the same phase delay plate, that is, the phase delay plate is an integrated structure. In another possible implementation, the polarizer may include: a plurality of discretely arranged polarizing parts, each polarizing part corresponds to an optical signal transmission area or an optical signal receiving area. The phase delay plate may include: a plurality of discretely arranged phase delay parts, each phase delay part corresponds to an optical signal transmission area or an optical signal receiving area.

Implementation method 2:

Different from the above-mentioned implementation method 1, in implementation method 2, the first light signal emitted by each light source is linearly polarized light. For example, the light source may include a distributed feedback laser (DFB). A polarizer may be arranged in an area corresponding to each light signal receiving area. A phase delay plate is also arranged in an area corresponding to each light signal transmitting area, that is, the phase delay plate is arranged in an area corresponding to the light signal transmitting area and the light signal receiving area. After the first light signal emitted by the light source passes through the phase delay plate, the phase is delayed, and the first light signal after the phase delay is emitted to the skin.

In a possible implementation, the optical axis direction of the phase retarder at the corresponding position of the optical signal transmitting area can be ±45 degrees with the polarization direction of the first optical signal emitted by the light source, so that the first optical signal after passing through the phase retarder is circularly polarized light. The polarization direction of the polarizer at the corresponding position of the optical signal receiving area can be parallel to the polarization direction of the first optical signal emitted by the light source, and the optical axis of the phase retarder at the corresponding position of the optical signal receiving area can be ±45 degrees with the polarization direction of the first optical signal emitted by the light source.

In a specific implementation, the polarizer may include: at least one polarizing portion, each polarizing portion corresponds to an optical signal receiving area. The phase delay plate may include: a plurality of discretely arranged phase delay portions, each phase delay portion corresponds to an optical signal transmitting area or an optical signal receiving area. In some cases, the phase delay plate located in each optical signal transmitting area and the phase delay plate located in each optical signal receiving area may also be the same phase delay plate.

Compared with the solution of implementation method 1, the first optical signal emitted by the light source in implementation method 2 is linearly polarized light, so the polarizer at the corresponding position of the optical signal emission area can be omitted. Other specific implementation methods in implementation method 2 are similar to implementation method 1, and can be implemented with reference to the implementation method of implementation method 1 above, and the repeated parts will not be repeated.

Implementation method three:

Different from the above-mentioned implementation method 1, in implementation method 3, the polarizer may include: at least one polarizing portion, each polarizing portion corresponds to an optical signal receiving area, that is, the polarizer may be arranged in an area corresponding to each optical signal receiving area. The phase delay plate may include: at least one phase delay portion, each phase delay portion corresponds to an optical signal receiving area, that is, the phase delay plate may be arranged in an area corresponding to each optical signal receiving area.

In a possible implementation, the first light signal emitted by each light source may be circularly polarized light, and the circularly polarized light may be left-handed or right-handed circularly polarized light. The optical axis direction of the phase retarder may be ±45 degrees to the polarization direction of the polarizer. When the first light signal emitted by the light source is right-handed circularly polarized light, the optical axis direction of the phase retarder may be +45 degrees to the polarization direction of the polarizer. When the first light signal emitted by the light source is left-handed circularly polarized light, the optical axis direction of the phase retarder may be -45 degrees to the polarization direction of the polarizer.

Compared with the solution of implementation method 1, the polarizer and phase delay plate at the corresponding position of the optical signal transmitting area can be omitted in implementation method 3, and the polarizer and phase delay plate are only set at the corresponding position of the optical signal receiving area. The first optical signal emitted by the light source can be circularly polarized light, which can also filter out the crosstalk and reflection of other components inside the physiological parameter sensor, skin surface reflection, shallow skin reflection and/or shallow skin internal scattering. Other specific implementation methods in implementation method 3 are similar to implementation method 1, and can be implemented with reference to the implementation method of the above-mentioned implementation method 3, and the repeated parts will not be repeated.

In summary, in the above-mentioned implementation methods one to three, according to the different polarization states of the optical signals emitted by the light sources, the specific settings of the polarizers and phase delay plates arranged in the corresponding areas of each optical signal transmitting area are different, while the specific settings of the polarizers and phase delay plates arranged in the corresponding areas of each optical signal receiving area are the same.

In scenarios where users wear wearable devices, the perfusion rate of the physiological parameter sensor may be different due to the influence of the user's own physiological factors or environmental factors. For example, due to the influence of their own physiological factors, the perfusion rate corresponding to the skin of some users is inherently low. For example, in a low temperature environment, the capillaries on the surface of the skin are blocked, resulting in the perfusion rate of the physiological parameter sensor being much lower than that at normal temperature. In these cases, since the AC signal detected by the physiological parameter sensor is relatively weak, the physiological parameters of the human body are not easy to detect. In an embodiment of the present application, by providing a polarizer and a phase delay plate, the DC signal of the physiological parameter sensor can be reduced, and the perfusion rate of the physiological parameter sensor can be increased, thereby improving the detection performance of the physiological parameter sensor in static scenarios. For example, the detection performance of low perfusion rate scenarios caused by physiological factors or environmental factors can be improved.

In a possible implementation, the physiological parameter sensor in the embodiment of the present application may also include: a bracket located on the surface of the substrate, the bracket and the multiple light sources are located on the surface of the same side of the substrate, the light source and the light detector can be separated by the bracket, and the bracket can isolate the light source and the light detector to prevent or reduce the light signal emitted by the light source from being directly emitted to the light detector without being transmitted through the skin, and reduce the crosstalk (or crosstalk) of the light signal emitted by the light source to the light signal received by the light detector. The polarizer and the phase delay plate are located on the side of the bracket away from the substrate, and the bracket can support the polarizer and the phase delay plate. In a specific implementation, the shape of the bracket can constitute multiple areas, and any light source and any light detector are located in different areas, thereby achieving isolation between the light source and the light detector.

When the structure of the bracket is specifically set, the surface of the bracket away from the substrate can have a depression concave toward the substrate, and the polarizer and phase retarder are embedded in the depression. In this way, the polarizer and phase retarder will not increase the thickness of the physiological parameter sensor, making the structure of the physiological parameter sensor more compact and easier to miniaturize. In addition, the bracket can limit the position of the polarizer and phase retarder, so that the reliability of the physiological parameter sensor is better. Of course, in some cases, the bracket can also be provided with no depression, and the polarizer and phase retarder can be directly attached to the surface of the bracket away from the substrate.

In a possible implementation, when the polarizer in the area corresponding to each optical signal transmitting area is the same polarizer as the polarizer in the area corresponding to the optical signal receiving area, and the phase delay film in the area corresponding to each optical signal transmitting area is the same phase delay film as the phase delay film in the area corresponding to the optical signal receiving area, a depression can be set on the surface of the bracket away from the substrate, and the polarizer and the phase delay film are embedded in the same depression. Alternatively, no depression may be set, and the polarizer and the phase delay film are directly attached to the surface of the bracket away from the substrate. In another possible implementation, when the polarizer includes a plurality of discretely arranged polarizers, and the phase delay film includes a plurality of discretely arranged phase delay parts, multiple depressions can be set on the surface of the bracket away from the substrate, different polarizers can be embedded in different depressions, and different phase delay parts can be embedded in different depressions, and the polarizer and the phase delay part at the corresponding position of the same optical signal transmitting area (or the same optical signal receiving area) can be embedded in the same depression. Alternatively, no depression may be set, and each polarizer and each phase delay part are directly attached to the surface of the bracket away from the substrate.

In a possible implementation, the bracket and the substrate may be an integrated structure, and the substrate with the bracket may be directly manufactured by an integrated molding process. For example, a hole may be dug on one side of the substrate to achieve the bearing function of the light source and the light detector, and the light isolation function between the light source and the light detector (i.e., the function of the bracket). Alternatively, the bracket and the substrate may be separately provided, and the bracket may be attached to a surface using a sticky material such as glue or double-sided tape.

In some embodiments of the present application, the bracket may include: a first bracket and a second bracket, the first bracket may be annular, each light source is located in the area surrounded by the first bracket, the second bracket may be annular, the second bracket surrounds the first bracket, and each light detector may be located in the area surrounded by the first bracket and the second bracket. By setting the first bracket, the light source and the light detector can be separated to prevent the light signal emitted by the light source from crosstalking the light signal received by the light detector. In addition, by setting the second bracket, external light can be prevented from being directed to each light detector to avoid interference of external light on the light detector. The first bracket and the second bracket may also support the polarizer and the phase delay plate. In addition, each light source is arranged inside the area surrounded by the first bracket, the area surrounded by the first bracket can be used as a light signal emitting area, each light detector is arranged between the first bracket and the second bracket, and the area between the first bracket and the second bracket can be used as a light signal receiving area. Such a structural arrangement is more in line with the transmission path of the light signal, so that the light signal emitted from the light signal emitting area can be directed to the light signal receiving area after being transmitted through the skin, so that the intensity of the returned light signal received by the physiological parameter sensor is larger, thereby improving the detection accuracy of the physiological parameter sensor.

In some other embodiments of the present application, in addition to the first bracket and the second bracket, the bracket may also include: a plurality of isolation parts connected between the first bracket and the second bracket, and two adjacent photodetectors are separated by the isolation parts. In this way, each photodetector can be isolated, thereby reducing the crosstalk between the optical signals received by each photodetector.

In specific implementation, the physiological parameter sensor in the embodiment of the present application may also include: a light-transmitting portion located on the side of the phase delay plate away from the substrate. In a possible implementation, a through hole may be provided on the bottom shell of the wearable device, and the light-transmitting portion may be provided at the position of the through hole or embedded inside the through hole, so that the light-transmitting portion can be used as a detection window for contact between the wearable device and the skin, and the light signal emitted by the light source can pass through the light-transmitting portion and then be emitted to the skin, and the light signal returned by the skin can also pass through the light-transmitting portion and then be emitted to the light detector.

In a specific implementation, the shape of the physiological parameter sensor can be circular, square, rectangular, elliptical or polygonal, etc., which is not limited here.

In the second aspect, the embodiment of the present application further provides a wearable device, which may include: any of the above-mentioned physiological parameter sensors, and a shell, wherein the physiological parameter sensor is located inside the shell. The wearable device may be a smart watch, a smart bracelet, a virtual reality (VR) glasses, and other devices. Of course, the wearable device may also be other devices with physiological parameter detection functions, which are not limited here. Since the detection performance of the physiological parameter sensor in the embodiment of the present application is good, the detection performance of the wearable device including the physiological parameter sensor is also good.

In a third aspect, an embodiment of the present application further provides a wearable device, which may include: a physiological parameter sensor, a phase delay plate, and a shell, wherein the physiological parameter sensor is located inside the shell.

The physiological parameter sensor may include: a substrate, at least one light source, at least one light detector, and a polarizer. Each light source and each light detector are located on the surface of the same side of the substrate, the polarizer is located on the side of each light source and each light detector away from the substrate, and the polarizer allows light signals emitted by at least one light source that are consistent with the polarization direction of the polarizer to pass through, and allows light signals emitted to at least one light detector that are consistent with the polarization direction of the polarizer to pass through.

The above-mentioned shell may include a bottom shell, and the phase delay plate may be arranged on a side of the bottom shell close to the physiological parameter sensor, that is, the phase delay plate may be mounted on the inner surface of the bottom shell. Alternatively, the phase delay plate may also be arranged on a side of the bottom shell away from the physiological parameter sensor, that is, the phase delay plate may also be mounted on the outer surface of the bottom shell. The phase delay plate may phase-delay the optical signal emitted from the polarizer to the bottom shell, and phase-delay the optical signal emitted from the outside of the wearable device to the bottom shell.

In the embodiment of the present application, by setting a polarizer and a phase delay plate in the wearable device, the crosstalk and reflection of other components inside the physiological parameter sensor, the skin surface reflection, the shallow skin reflection and/or the shallow skin internal scattering can be reduced or prevented, that is, the DC signal of the physiological parameter sensor can be reduced. When the user wears the wearable device and exercises, the motion noise is mainly related to the DC signal change caused by the deflection and movement of the wearable device. Therefore, the physiological parameter sensor in the embodiment of the present application can reduce or filter out the motion noise, thereby improving the detection performance of the physiological parameter sensor.

The specific implementation of the wearable device in the third aspect can be implemented with reference to the specific implementation of the wearable device in the second aspect, and the repeated parts will not be repeated.

In a fourth aspect, an embodiment of the present application further provides a wearable device, which may include: a physiological parameter sensor, a polarizer, a phase delay plate, and a shell, wherein the physiological parameter sensor is located inside the shell. The physiological parameter sensor may include: a substrate, at least one light source, and at least one light detector. Each light source and each light detector are located on the surface of the same side of the substrate. The above-mentioned shell may include a bottom shell, and the polarizer and the phase delay plate are arranged on the bottom shell. Among them, the polarizer is located on the side of each light source and each light detector away from the substrate, and the phase delay plate is located on the side of the polarizer away from the substrate.

In one possible implementation, the polarizer and the phase retarder can be stacked on the side of the bottom shell close to the physiological sensor, that is, the polarizer and the phase retarder can be arranged on the inner surface of the bottom shell, wherein the phase retarder is located on the side of the bottom shell close to the physiological parameter sensor, and the polarizer is located on the side of the phase retarder close to the physiological parameter sensor.

In another possible implementation, the polarizer may be located on a side of the bottom shell close to the physiological parameter sensor, that is, the polarizer may be mounted on the inner surface of the bottom shell. The phase delay plate may be located on a side of the bottom shell away from the physiological parameter sensor, that is, the phase delay plate may be mounted on the outer surface of the bottom shell.

In another possible implementation, the polarizer and the phase retarder can be stacked on the side of the bottom shell away from the physiological sensor, that is, the polarizer and the phase retarder can be arranged on the outer surface of the bottom shell. The polarizer can be located on the side of the bottom shell away from the physiological parameter sensor, and the phase retarder can be located on the side of the polarizer away from the physiological parameter sensor.

The specific implementation of the wearable device in the fourth aspect can be implemented with reference to the specific implementation of the wearable device in the second aspect, and the repeated parts will not be repeated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a functional block diagram of a PPG sensor;

FIG2 is a schematic diagram of the basic principle of a PPG sensor;

FIG3 is a schematic diagram of the waveform of the electrical signal in the PPG sensor;

FIG4 is a schematic diagram of the structure of a physiological parameter sensor provided in an embodiment of the present application;

FIG5 is a schematic diagram of optical signal transmission during operation of the physiological parameter sensor in an embodiment of the present application;

FIG6 is a schematic diagram of the three-dimensional structure of a physiological parameter sensor provided in an embodiment of the present application;

FIG7 is a schematic diagram of the three-dimensional structure of a physiological parameter sensor provided in an embodiment of the present application;

FIG8 is a schematic cross-sectional view of FIG7 taken along the dashed line AA′;

FIG9 is another schematic diagram of the structure of the physiological parameter sensor provided in an embodiment of the present application;

FIG10 is another schematic diagram of the structure of the physiological parameter sensor provided in an embodiment of the present application;

FIG11 is a bottom view of the physiological parameter sensor in an embodiment of the present application;

FIG12 is another bottom view of the physiological parameter sensor in the embodiment of the present application;

FIG13 is another bottom view of the physiological parameter sensor in the embodiment of the present application;

FIG14 is a schematic diagram of the structure of a wearable device provided in an embodiment of the present application;

FIG15 is another schematic diagram of the structure of a wearable device provided in an embodiment of the present application;

FIG16 is another schematic diagram of the structure of a wearable device provided in an embodiment of the present application;

FIG17 is another schematic diagram of the structure of a wearable device provided in an embodiment of the present application;

FIG18 is another schematic diagram of the structure of a wearable device provided in an embodiment of the present application;

FIG. 19 is another schematic diagram of the structure of the wearable device provided in an embodiment of the present application.

Figure numerals: 10-substrate; 11-light source; 12-photodetector; 13-analog front-end chip; 131-driver; 132-gain controller; 133-signal converter; 14-processor; 15-polarizer; 151-polarizer; 16-phase delay plate; 161-phase delay unit; 17-bracket; 171-first bracket; 172-second bracket; 173-isolation unit; 200-skin; 201-superficial skin; 202-deep skin; 300-shell; 301-bottom shell; U-recess; P-optical signal transmitting area; Q-optical signal receiving area; W-area.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present application more clear, the present application will be further described in detail below in conjunction with the accompanying drawings.

It should be noted that the same reference numerals in the drawings of this application represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing positions and directions described in this application are all explained using the drawings as examples, but can be changed as needed, and all changes are included in the scope of protection of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportion.

In order to better understand the technical solution of the embodiments of the present application, the working principle of the PPG sensor is described in detail below with reference to the accompanying drawings.

The PPG sensor is a basic sensor for wearable devices. It can be used to continuously and non-inductively measure the human body, continuously collect sports health data such as heart rate and blood oxygen, and provide a basis for sports and health analysis. Figure 1 is a functional block diagram of a PPG sensor. As shown in Figure 1, the PPG sensor may include: a light source 11, a light detector 12, an analog front end (Analog Front End, AFE) chip 13 and a processor 14. Among them, the analog front end chip 13 has the functions of driving the light source 11 to emit light, receiving and processing the electrical signal output by the light detector 12 and other control functions. The analog front end chip 13 may include: a driver 131, a gain controller 132 and a signal converter 133. During the operation of the PPG sensor, the light source 11 can emit a light signal driven by the driver 131. The light signal passes through the skin 200 and then is emitted to the light detector 12. The light detector 12 converts the received light signal into an electrical signal, and transmits the converted electrical signal to the gain controller 132. The gain controller 132 can perform gain processing on the received electrical signal, and transmit the processed electrical signal to the signal converter 133. The signal converter 133 can convert the electrical signal into a digital signal, and transmit the converted digital signal to the processor 14 through the interface. The processor 14 can determine human physiological parameters such as heart rate, blood oxygen and carbon oxygen based on the digital signal.

FIG2 is a schematic diagram of the basic principle of the PPG sensor. As shown in FIG2 , the test light signal emitted by the light source 11 is directed toward the skin 200. Part of the light signal directed toward the skin 200 will be reflected at the interface or inside the skin 200, and part of the reflected light signal will return to the PPG sensor and be received by the light detector 12 in the PPG sensor. Part of the light signal that enters the skin 200 will be scattered, and part of the scattered light signal will return to the PPG sensor and be received by the light detector 12 in the PPG sensor. This part of the scattered light signal can be called a backscattered signal. In other words, the light detector 12 can receive part of the reflected light signal after being directed toward the skin 200, and can also receive part of the scattered light signal after passing through the skin 200.

FIG3 is a schematic diagram of the waveform law of the electrical signal in the PPG sensor. As shown in FIG3, after the PPG sensor receives the optical signal returned through the skin, it converts the received optical signal into an electrical signal. The obtained electrical signal may have the waveform law shown in FIG3. The electrical signal of the PPG sensor may include an alternating current signal (AC signal) and a direct current signal (DC signal). The optical signal has a certain degree of attenuation when it is transmitted in the skin. The amount of absorption of the optical signal by the muscles, bones, veins and connecting tissues in the shallow skin is basically unchanged. This part of the optical signal is converted into an electrical signal and is expressed as a DC signal. The blood in the deep skin is flowing, so the amount of absorption of the optical signal by the blood in the deep skin changes. This part of the optical signal is converted into an electrical signal and is expressed as an AC signal. Therefore, the AC signal in the PPG sensor can reflect the change in blood volume. The larger the AC signal, the greater the change in blood volume. By extracting the AC signal in the PPG sensor, the change in blood volume can be reflected, thereby obtaining human physiological parameters such as heart rate, blood oxygen and carbon oxygen.

The signal characteristics of the PPG sensor can be described by the perfusion index (PI). The perfusion index is proportional to the AC signal. The calculation formula of the perfusion index can be: PI = AC signal / DC signal, that is, the larger the AC signal, the larger the PI, and the easier it is to detect the physiological parameters of the human body. Therefore, the detection performance of the PPG sensor can also be reflected by the perfusion index, that is, the higher the perfusion index, the better the detection performance of the PPG sensor.

When the user wears the wearable device and remains static, the relative position between the user's skin and the PPG sensor remains basically unchanged, so the PPG sensor can provide better detection of physiological parameters such as heart rate, and the detection performance of the PPG sensor is good. However, when the user wears the wearable device and exercises, the phase position between the user's skin and the PPG sensor changes greatly, which introduces motion noise or interference, making detection difficult, resulting in poor detection performance of the PPG sensor in sports scenes.

When users wear wearable devices and exercise, the main reasons that affect the signal changes of PPG sensors are: (1) the changes in blood flow velocity and direction caused by exercise lead to changes in blood volume; (2) the movement of the wearable device in parallel, vertical, rotational and other directions, causing changes in the reflection intensity at the interface of each layer; (3) the refractive index of each layer of the skin is different, and light signal reflection will occur at the interface; (4) other unknown reasons. Since the intensity of the reflected light signal at the skin interface is much higher than the intensity of the scattered light signal inside the skin, the motion noise is mainly related to the DC signal changes caused by the deflection and movement of the wearable device. Therefore, in order to improve the detection performance of the PPG sensor in sports scenes, it is necessary to eliminate the noise introduced by the deflection and movement of the wearable device.

Based on this, in order to solve the problem of poor detection performance of PPG sensors in sports scenes, the embodiment of the present application provides a physiological parameter sensor and a wearable device. The physiological parameter sensor can be a PPG sensor. Of course, the physiological parameter sensor can also be other types of sensors, which are not limited here. The physiological parameter sensor can be applied to various wearable devices, for example, it can be applied to wearable devices such as smart watches, smart bracelets, and virtual reality (VR) glasses.

FIG4 is a schematic diagram of the structure of the physiological parameter sensor provided in the embodiment of the present application, and FIG5 is a schematic diagram of the transmission of optical signals during the operation of the physiological parameter sensor in the embodiment of the present application. In combination with FIG4 and FIG5, the physiological parameter sensor provided in the embodiment of the present application may include: a substrate 10, at least one light source 11, at least one light detector 12, a polarizer 15, and a phase delay plate 16. Each light source 11 and each light detector 12 are located on the surface of the same side of the substrate 10. The physiological parameter sensor may also include: at least one optical signal emitting area P and at least one optical signal receiving area Q. Each optical signal emitting area P corresponds to at least one light source 11, that is, the optical signal emitted by at least one light source 11 can be emitted in the optical signal emitting area P. Each optical signal receiving area Q corresponds to at least one optical detector 12, that is, the optical signal incident in the optical signal receiving area Q can be emitted to at least one optical detector 12. In the specific implementation, the position and number of the optical signal emitting area P and the optical signal receiving area Q can be set according to the actual requirements of the optical path. The polarizer 15 is located in the area corresponding to the optical signal receiving area Q, and the phase delay plate 16 is located in the area corresponding to the optical signal receiving area Q. The polarizer 15 is located on a side of each photodetector 12 away from the substrate 10 , and the phase delay plate 16 is located on a side of the polarizer 15 away from the substrate 10 .

Each light source 11 can emit a light signal a1 for detecting physiological parameters, so that the light signal a1 is emitted to the skin 200 to be detected. The phase delay plate 16 can phase-delay the received light signal. For example, the phase delay plate 16 can phase-delay the light signal b1 that is returned in the light signal receiving area Q after passing through the skin 200, and emit the light signal b2 obtained after the phase delay to the polarizer 15.

The polarizer 15 allows the optical signal with the same polarization direction as the polarizer 15 to pass through, and the optical signal b2 passes through the polarizer 15 to obtain the optical signal b3, and the optical signal b3 is emitted to at least one optical detector 12. In other words, the polarizer 15 can select the polarization state of the optical signal according to the polarization direction of the polarizer 15, and determine which polarization state of the optical signal b2 can pass through the polarizer 15 and continue to be transmitted in the direction of the optical detector 12.

After the light signal emitted by the light source 11 is emitted to the skin 200, a part of the light signal a31 will pass through the crosstalk and reflection of other components inside the physiological parameter sensor (for example, the other component can be the light-transmitting portion of the phase delay plate 16 on the side away from the substrate 10), the surface reflection of the skin 200, the reflection of the shallow skin 201 and/or the internal scattering of the shallow skin 201, and then return to the physiological parameter sensor to obtain the light signal b11. Another part of the light signal a32 will pass through the reflection of the deep skin (vascular layer) 202 and/or the internal scattering of the deep skin 202, and then return to the physiological parameter sensor to obtain the light signal b12.

For the optical signal b11 obtained after transmission through the superficial skin 201, the crosstalk and reflection of other components inside the physiological parameter sensor and the reflection on the surface of the skin 200 will not change the polarization state of the optical signal, and the reflection of the superficial skin 201 and/or the scattering inside the superficial skin 201 will basically not change the polarization state of the optical signal, or the degree of changing the polarization state of the optical signal is small (the phase delay amount is small or the polarization rotation angle is small). Therefore, the polarization state of the optical signal b11 obtained after transmission through the superficial skin 201 is basically consistent with the polarization state of the optical signal a31 incident at the skin 200. After the optical signal b11 passes through the phase delay plate 16, the phase is delayed to obtain the optical signal b21, and the optical signal b21 is emitted to the polarizer 15. The phase delay effect of the phase delay plate 16 on the optical signal b11 makes the polarization direction of the optical signal b21 obtained after the phase delay perpendicular to or nearly perpendicular to the polarization direction of the polarizer 15, so that the optical signal b21 cannot pass through the polarizer 15, or only a small part of the optical signal b21 can pass through the polarizer 15.

For the optical signal b12 obtained after being transmitted through the deep skin 202, the birefringent tissue structure in the deep skin (depth ≥ 300um) 202 will depolarize the optical signal, making the polarization state of the optical signal b12 obtained after being transmitted through the deep skin 202 random. After the optical signal b12 passes through the phase delay plate 16, the optical signal b22 obtained is still an optical signal with a random polarization state. The portion of the optical signal b22 whose polarization state is consistent with the polarization direction of the polarizer 15 can pass through the polarizer 15 to obtain the optical signal b3. The optical signal b3 continues to be transmitted to the photodetector 12, while the portion of the optical signal b22 that is perpendicular to the polarization direction of the polarizer 15 is blocked from passing through the polarizer 15.

In the physiological parameter sensor provided in the embodiment of the present application, by setting the polarizer 15 and the phase delay plate 16, the crosstalk and reflection of other components inside the physiological parameter sensor, the surface reflection of the skin 200, the reflection of the shallow skin 201 and/or the internal scattering of the shallow skin 201 can be reduced or prevented, that is, the DC signal of the physiological parameter sensor can be reduced. Because when the user wears the wearable device and exercises, the motion noise is mainly related to the change of the DC signal caused by the deflection and movement of the wearable device, therefore, the physiological parameter sensor in the embodiment of the present application can reduce or filter out the motion noise. The perfusion rate of the physiological parameter sensor is inversely proportional to the DC signal, and the proportion of the DC signal in the electrical signal of the physiological parameter sensor is relatively high. Therefore, the embodiment of the present application can improve the perfusion rate of the physiological parameter sensor by reducing the DC signal, thereby improving the detection performance of the physiological parameter sensor.

In the embodiments of the present application, the polarizer and the phase retarder may be implemented in a variety of ways. The implementation methods of the polarizer and the phase retarder are described in detail below in conjunction with the accompanying drawings.

Implementation method 1:

Continuing to refer to FIG. 4 and FIG. 5 , the polarizer 15 may also be located in the area corresponding to each optical signal transmitting area P, that is, the polarizer 15 may be located in the area corresponding to the optical signal transmitting area P and the optical signal receiving area Q. The phase retarder 16 may also be located in the area corresponding to each optical signal transmitting area P, that is, the phase retarder 16 may be located in the area corresponding to the optical signal transmitting area P and the optical signal receiving area Q. The polarizer 15 is located on the side of each light source 11 away from the substrate 10, and the phase retarder 16 is located on the side of the polarizer 15 away from the substrate 10.

At least one light source 11 is used to emit the light signal a1 to the polarizer 15. The polarizer 15 can be used to allow the light signal with the same polarization direction as the polarizer 15 to pass through and be emitted to the phase delay plate 16. The light signal a1 passes through the polarizer 15 to obtain the light signal a2. In other words, the polarizer 15 can select the polarization state of the light signal a1 according to its own polarization direction, and determine which polarization state of the light signal a1 can pass through the polarizer 15 and continue to be transmitted toward the skin 200.

The light signal a2 passing through the polarizer 15 is delayed in phase after passing through the phase retarder 16 , and the light signal a3 obtained after the phase delay is emitted to the skin 200 .

In a possible implementation, the substrate 10 may be a substrate with a supporting function such as a ceramic substrate or a printed circuit board (PCB). Each light source 11 may include a light emitting diode (LED) or a laser. Exemplarily, the laser may be a vertical cavity surface emitting laser (VCSEL). In the embodiment of the present application, the light signal a1 emitted by the light source 11 may be a light signal of various polarization states such as natural light, linear polarized light (the polarization direction of the linear polarized light is not perpendicular to the polarization direction of the polarizer 15), circular polarized light or elliptically polarized light, as long as the light signal a1 emitted by the light source 11 has at least a component consistent with the polarization direction of the polarizer 15, so that at least part of the light signal a1 can pass through the polarizer 15. Preferably, the light source 11 may be a light source of linear polarized light or a light source of approximately linear polarized light, and the polarization state of the light signal emitted by the light source 11 is substantially consistent with the polarization direction of the polarizer 15. Each photodetector 12 may include a photodiode (PD). Exemplarily, the photodiode may be a PIN photodiode (PIN PD) or an avalanche photodiode (APD). The photodetector 12 may receive light signals transmitted through the skin, and the physiological parameter sensor may determine human physiological parameters such as heart rate, blood oxygen, and carbon oxygen based on the light signals detected by the photodetector 12.

In some embodiments of the present application, the polarizer 15 may be a linear polarizer, which allows polarized light with the same polarization direction as the linear polarizer to pass through. The phase retarder 16 may be a quarter-wave plate, which can cause the optical signal to produce a phase delay of an odd number of π/2. In conjunction with FIG5, the specific process of optical signal transmission is described in detail by taking the polarization direction of the polarizer 15 as the horizontal direction in the figure and the phase retarder 16 as a quarter-wave plate as an example. As shown in FIG5, after the optical signal a1 emitted by the light source 11 passes through the polarizer 15, a linear polarized light with a horizontal polarization direction (i.e., optical signal a2) is obtained. After the linear polarized light passes through the phase retarder 16, the phase is delayed by an odd number of π/2 or rotated by 45° to obtain an optical signal a3. When the polarization direction of the polarizer 15 and the optical axis direction of the phase retarder 16 are ±45°, the obtained optical signal a,3 is circularly polarized light (taking right-handed circularly polarized light as an example in the figure). After the light signal a3 is emitted to the skin 200, a part of it (the light signal a31) returns to the physiological parameter sensor after being reflected by other components inside the physiological parameter sensor, reflected by the surface of the skin 200, reflected by the shallow skin 201 and/or scattered inside the shallow skin 201. The obtained light signal b11 is still circularly polarized light (the rotation direction changes, for example, the rotation direction of the light signal b11 returned by the shallow skin 201 in the figure is left-handed). After the light signal b11 is transmitted through the shallow skin 201, it is phase-delayed by an odd number of π/2 or rotated by 45° after passing through the phase delay plate 16 to obtain the light signal b21. After the light signal of this transmission path is superimposed by the two phase delay effects of the phase delay plate 16, the obtained light signal b21 is linearly polarized light with a vertical polarization direction. Since the polarization direction of the light signal b21 is perpendicular to the polarization direction of the polarizer 15, it cannot pass through the polarizer 15. After the light signal a32 directed to the skin 200 is reflected by the deep skin 202 and/or scattered inside the deep skin 202, it is depolarized by the deep skin 202 to obtain a light signal b12 with a random polarization state. After the light signal b12 with a random polarization state passes through the phase retarder 16, the light signal b22 obtained is still a light signal with a random polarization state. The part of the light signal b22 whose polarization state is consistent with the polarization direction of the polarizer 15 can pass through the polarizer 15 to obtain a light signal b3, and the light signal b3 can continue to be transmitted to the light detector 12. Therefore, when the phase retarder 16 is a quarter-wave plate, it can prevent the crosstalk and reflection of other components inside the physiological parameter sensor, the surface reflection of the skin 200, the reflection of the shallow skin 201 and/or the scattering inside the shallow skin 201, thereby greatly reducing the DC signal of the physiological parameter sensor, effectively filtering out motion noise, and improving the detection performance of the physiological parameter sensor.

In other embodiments of the present application, the phase delay plate 16 may also be other optical elements with a phase delay function. Based on similar principles, it can also reduce the crosstalk and reflection of other components inside the physiological parameter sensor, the surface reflection of the skin 200, the reflection of the shallow skin 201 and/or the scattering inside the shallow skin 201, that is, it can reduce the DC signal of the physiological parameter sensor and improve the detection performance of the physiological parameter sensor.

As shown in Fig. 4, in a possible implementation, the polarizer 15 located in each optical signal transmitting area P is the same polarizer as the polarizer 15 located in each optical signal receiving area Q, that is, the polarizer 15 is an integrated structure. The phase delay plate 16 located in each optical signal transmitting area P is the same phase delay plate as the phase delay plate 16 located in each optical signal receiving area Q, that is, the phase delay plate 16 is an integrated structure.

FIG6 is a schematic diagram of the three-dimensional structure of the physiological parameter sensor provided in the embodiment of the present application. In order to facilitate the internal structure of the physiological parameter sensor, FIG6 does not show the polarizer and the phase delay plate. The shape of the physiological parameter sensor in FIG6 can be rectangular. Of course, in the specific implementation, the physiological parameter can also be circular, elliptical, polygonal, etc. The shape of the physiological parameter sensor can be set according to actual needs, which is not limited here. FIG7 is a top view corresponding to the structure shown in FIG6 after the polarizer and the phase delay plate are set. Since the polarizer is blocked by the phase delay plate, the polarizer is not shown in FIG7. FIG8 is a cross-sectional schematic diagram of FIG7 at the dotted line AA′. In combination with FIG6 to FIG8, in another possible implementation, the polarizer 15 may include: a plurality of discretely arranged polarizers 151, each polarizer 151 corresponds to an optical signal transmitting area P or an optical signal receiving area Q. The phase delay plate 16 may include: a plurality of discretely arranged phase delay portions 161, each phase delay portion 161 corresponds to an optical signal transmitting area P or an optical signal receiving area Q.

Implementation method 2:

FIG9 is another schematic diagram of the structure of the physiological parameter sensor provided in an embodiment of the present application. As shown in FIG9 , the difference from the above-mentioned implementation method 1 is that in implementation method 2, the optical signal emitted by each light source 11 is linearly polarized light. For example, the light source 11 may include: a distributed feedback laser (DFB). The polarizer 15 may be arranged in the area corresponding to each optical signal receiving area Q. The phase delay plate 16 is also arranged in the area corresponding to each optical signal emitting area P, that is, the phase delay plate 16 is arranged in the area corresponding to the optical signal emitting area P and the optical signal receiving area Q. After the optical signal emitted by the light source 11 passes through the phase delay plate 16, the phase is delayed, and the optical signal after the phase delay is emitted to the skin.

In a possible implementation, the optical axis direction of the phase retarder 16 at the corresponding position of the optical signal transmitting area P may be ±45 degrees to the polarization direction of the optical signal emitted by the light source 11, so that the optical signal after passing through the phase retarder 16 is circularly polarized light. The polarization direction of the polarizer 15 at the corresponding position of the optical signal receiving area Q may be parallel to the polarization direction of the optical signal emitted by the light source 11, and the optical axis of the phase retarder 16 at the corresponding position of the optical signal receiving area Q may be ±45 degrees to the polarization direction of the optical signal emitted by the light source 11.

In a specific implementation, the polarizer 15 may include: at least one polarizer 151, each polarizer 151 corresponds to an optical signal receiving area Q. The phase delay plate 16 may include: a plurality of discretely arranged phase delay sections 161, each phase delay section 161 corresponds to an optical signal transmitting area P or an optical signal receiving area Q. In some cases, the phase delay plate 16 located in each optical signal transmitting area P and the phase delay plate 16 located in each optical signal receiving area Q may also be the same phase delay plate.

Compared with the solution of implementation mode 1, the optical signal emitted by the light source 11 in implementation mode 2 is linearly polarized light, so the polarizer at the corresponding position of the optical signal emission area P can be omitted. Other specific implementation methods in implementation mode 2 are similar to implementation mode 1, and can be implemented with reference to the implementation method of implementation mode 1 above, and the repeated parts will not be repeated.

Implementation method three:

FIG10 is another schematic diagram of the structure of the physiological parameter sensor provided in an embodiment of the present application. As shown in FIG10 , the difference from the above-mentioned implementation mode 1 is that in implementation mode 3, the polarizer 15 may include: at least one polarizer 151, each polarizer 151 corresponds to an optical signal receiving area Q, that is, the polarizer 15 may be arranged in an area corresponding to each optical signal receiving area Q. The phase delay plate 16 may include: at least one phase delay portion 161, each phase delay portion 161 corresponds to an optical signal receiving area Q, that is, the phase delay plate 16 may be arranged in an area corresponding to each optical signal receiving area Q.

In a possible implementation, the optical signal emitted by each light source 11 may be circularly polarized light, and the circularly polarized light may be left-handed or right-handed circularly polarized light. The optical axis direction of the phase retarder 16 may be ±45 degrees with the polarization direction of the polarizer 15. When the optical signal emitted by the light source 11 is right-handed circularly polarized light, the optical axis direction of the phase retarder 16 may be +45 degrees with the polarization direction of the polarizer 15. When the optical signal emitted by the light source 11 is left-handed circularly polarized light, the optical axis direction of the phase retarder 16 may be -45 degrees with the polarization direction of the polarizer 15.

Compared with the solution of implementation method 1, the polarizer and phase delay plate at the corresponding position of the optical signal transmitting area P can be omitted in implementation method 3, and the polarizer and phase delay plate are only set at the corresponding position of the optical signal receiving area Q. The optical signal emitted by the light source 11 can be circularly polarized light, which can also filter out the crosstalk and reflection of other components inside the physiological parameter sensor, skin surface reflection, shallow skin reflection and/or shallow skin internal scattering. Other specific implementation methods in implementation method 3 are similar to implementation method 1, and can be implemented with reference to the implementation method of the above-mentioned implementation method 3, and the repeated parts will not be repeated.

In the scenario where the user wears the wearable device, the perfusion rate of the physiological parameter sensor may be different due to the influence of the user's own physiological factors or environmental factors. For example, due to the influence of their own physiological factors, the perfusion rate corresponding to the skin of some users is relatively low. For example, in a low temperature environment, the capillaries on the surface of the skin are blocked, resulting in the perfusion rate of the physiological parameter sensor being much lower than that at normal temperature. In these cases, since the AC signal detected by the physiological parameter sensor is relatively weak, the physiological parameters of the human body are not easy to be detected. In the embodiment of the present application, by setting a polarizer and a phase delay plate, the DC signal of the physiological parameter sensor can be reduced, the perfusion rate of the physiological parameter sensor can be increased, and the detection performance of the physiological parameter sensor in a static scene can be improved. For example, the detection performance of the low perfusion rate scene caused by physiological factors or environmental factors can be improved. Table 1 shows the composition of the received signal of the physiological parameter sensor in a static scene and the corresponding signal ratio. In Table 1, the structure of the physiological parameter sensor having the above-mentioned implementation method 1 is taken as an example. The following is a detailed description of the scheme of the embodiment of the present application in combination with the data in Table 1, which can improve the detection performance of the physiological parameter sensor in a static scene.

Assuming that the perfusion rate PI of the physiological parameter sensor without polarizer and phase delay plate is 1%, the path loss of the optical signal is exp(IL1), and the unit of loss is dB, that is, the energy of the optical signal emitted by the light source is P0, then the optical signal received by the optical detector is P0*exp(IL1), and the AC signal in the physiological parameter sensor is P0*exp(IL1)*PI.

As shown in Table 1, the received signal of the physiological parameter sensor in a static scene includes: the signal obtained by the crosstalk and reflection of other components inside the physiological parameter sensor, the signal obtained by the reflection of the skin surface, and the signal obtained by the reflection and/or scattering of each layer inside the skin. In the embodiment of the present application, by setting a polarizer and a phase delay plate, the light signals reflected by the crosstalk and reflection of other components inside the physiological parameter sensor, the skin surface reflection, and the light signals reflected and/or scattered back by the shallow skin such as the stratum corneum, epithelium and papillary layer can be filtered out or eliminated. It can be seen from Table 1 that this part of the signal accounts for about 59.18%. Taking the following two cases as an example, the perfusion rate of the physiological parameter sensor is analyzed when a polarizer and a phase delay plate are provided in the physiological parameter sensor (taking the phase delay plate as a quarter-wave plate as an example). In the following two cases, the energy of the light signal emitted by the light source is still taken as P0, and the path loss of the light signal is taken as exp(IL1) as an example.

The first case: Take the case where the light signal emitted by the light source is linearly polarized light, and the polarization state of the linearly polarized light is consistent with the polarization direction of the polarizer. In the light signal transmission channel, the intensity of the light signal emitted by the light source is basically not attenuated after passing through the polarizer and phase retarder. In the light signal receiving channel, the light signal returned by the skin passes through the phase retarder and polarizer. Compared with not setting the polarizer and phase retarder, the loss will be doubled (causing the AC signal in the physiological parameter sensor to attenuate by about 3dB), that is, the intensity of the AC signal received by the light detector is about P0*exp(IL1)*PI/2. The DC signal corresponding to the light signal returned by the deep skin will also be attenuated by about 3dB. About 59.18% of the DC signals transmitted through the shallow skin will be blocked by the polarizer and phase retarder. Therefore, the intensity of the DC signal received by the physiological parameter sensor is approximately: 0*P0*exp(IL1)*59.18%+P0*exp(IL1)*40.82%*1/2=P0*exp(IL1)*40.82%*1/2. The perfusion rate is AC signal/DC signal=[P0*exp(IL1)*PI/2]/[P0*exp(IL1)*40.82%*1/2]=2.45%. In other words, in the present application, by setting a polarizer and a phase delay plate, the perfusion rate of the physiological parameter sensor in a static scene can be increased by about 2.45 times, which can improve the measurement performance of the physiological parameter sensor in a static scene. For example, the detection performance in scenes such as low temperature and low perfusion rate can be improved.

The second case: Take the case where the light signal emitted by the light source is circularly polarized light or randomly polarized light. In the transmission channel of the light signal, after the light signal emitted by the light source passes through the polarizer and phase retarder, the loss will double compared to when no polarizer and phase retarder are set (causing the AC signal in the physiological parameter sensor to attenuate by about 3dB). In the receiving channel of the light signal, the light signal returned by the skin passes through the phase retarder and polarizer, and the loss will also double compared to when no polarizer and phase retarder are set (causing the AC signal in the physiological parameter sensor to attenuate by about 3dB), that is, the intensity of the AC signal received by the light detector is about P0/2*exp(IL1)*PI/2. The DC signal corresponding to the light signal returned by the deep skin will also be attenuated by about 3dB. About 59.18% of the DC signal transmitted through the shallow skin will be blocked by the polarizer and phase retarder. Therefore, after adding the polarizer and phase retarder, the intensity of the DC signal received by the physiological parameter sensor is approximately: 0*P0/2*exp(IL1)*59.18%+P0/2*exp(IL1)*40.82%*1/2=P0/2*exp(IL1)*40.82%*1/2. The perfusion rate is AC signal/DC signal=[P0/2*exp(IL1)*PI/2]/[P0/2*exp(IL1)*40.82%*1/2]=2.45%. In other words, by setting the polarizer and phase retarder in the present application, the perfusion rate of the physiological parameter sensor in a static scene can be increased by about 2.45 times, and the measurement performance of the physiological parameter sensor in a static scene can be improved. For example, the detection performance in scenes such as low temperature and low perfusion rate can be improved.

Table 1 Composition of signals received by physiological parameter sensors in static scenes and corresponding signal proportions

In summary, the physiological parameter sensor in the embodiment of the present application can reduce or prevent the crosstalk and reflection of other components inside the physiological parameter sensor, skin surface reflection, shallow skin reflection and/or shallow skin internal scattering by setting a polarizer and a phase delay plate, that is, the DC signal of the physiological parameter sensor can be reduced. Since the motion noise is mainly related to the DC signal change caused by the deflection and movement of the wearable device when the user wears the wearable device for exercise, the physiological parameter sensor in the embodiment of the present application can reduce or filter out the motion noise. Therefore, the physiological parameter sensor in the embodiment of the present application can be applied to measurement scenarios in motion, for example, it can measure physiological parameters such as the user's exercise heart rate and exercise blood oxygen in the exercise state, which is less affected by motion noise or interference, and the detection results of the physiological parameters are more accurate. In addition, the physiological parameter sensor in the embodiment of the present application can also be applied to measurement scenarios where the wear is relatively loose and the physiological parameter sensor is not in good contact with the skin, which can reduce the impact of noise or interference caused by the movement of the wearable device. In addition, in the embodiment of the present application, by setting a polarizer and a phase delay film, the DC signal of the physiological parameter sensor can be reduced, thereby improving the detection performance of the physiological parameter sensor in static scenes. Therefore, the physiological parameter sensor in the embodiment of the present application can also be used in low perfusion rate scenes caused by physiological factors or environmental factors, such as low temperature scenes or people with low perfusion.

In a possible implementation, as shown in FIG4 , the physiological parameter sensor in the embodiment of the present application may further include: a bracket 17 located on the surface of the substrate 10, the bracket 17 and each light source 11 are located on the surface of the same side of the substrate 10, and the one or more light sources 11 are separated from the one or more light detectors 12 by the bracket 17. The bracket 17 can isolate the light source 11 and the light detector 12, prevent or reduce the light signal emitted by the light source 11 from being directly emitted to the light detector 12 without being transmitted through the skin, and reduce the crosstalk (or crosstalk) of the light signal emitted by the light source 11 to the light signal received by the light detector 12. The polarizer 15 and the phase delay plate 16 are located on the side of the bracket 17 away from the substrate 10, and the bracket 17 can support the polarizer 15 and the phase delay plate 16. In a specific implementation, the shape of the bracket 17 can constitute multiple areas W, and any light source 11 and any light detector 12 are located in different areas W, thereby achieving isolation between the light source 11 and the light detector 12.

Continuing to refer to FIG. 4 , when the structure of the bracket 17 is specifically set, the surface of the bracket 17 away from the substrate 10 may have a depression U concave toward the substrate 10, and the polarizer 15 and the phase delay plate 16 are embedded in the depression U. In the specific implementation, the polarizer 15 and the phase delay plate 16 may be mounted in the depression U using a sticky material such as glue or double-sided tape. In this way, the polarizer 15 and the phase delay plate 16 will not increase the thickness of the physiological parameter sensor, making the structure of the physiological parameter sensor more compact and easier to miniaturize. In addition, the bracket 17 can limit the position of the polarizer 15 and the phase delay plate 16, so that the reliability of the physiological parameter sensor is better. Of course, in some cases, the bracket 17 may not be provided with a depression U, and the polarizer 15 and the phase delay plate 16 may be directly attached to the surface of the bracket 17 away from the substrate 10.

As shown in FIG4 , in a possible implementation, when the polarizer 15 in the area corresponding to each optical signal transmitting area P and the polarizer 15 in the area corresponding to the optical signal receiving area Q are the same polarizer, and the phase delay plate 16 in the area corresponding to each optical signal transmitting area P and the phase delay plate 16 in the area corresponding to the optical signal receiving area Q are the same phase delay plate, a recess U can be provided on the surface of the bracket 17 away from the substrate 10, and the polarizer 15 and the phase delay plate 16 are embedded in the same recess U. Alternatively, the recess U may not be provided, and the polarizer 15 and the phase delay plate 16 may be directly attached to the surface of the bracket 17 away from the substrate 10.

[Corrected 03.01.2024 in accordance with Article 91]
As shown in FIGS. 8 to 10 , when the polarizer 15 includes a plurality of discretely arranged polarizers 151 and the phase delay plate 16 includes a plurality of discretely arranged phase delay units 161, a plurality of recesses U may be provided on the surface of the bracket 17 away from the substrate 10, different polarizers 151 may be embedded in different recesses U, different phase delay units 161 may be embedded in different recesses U, and the polarizers 151 and phase delay units 161 at corresponding positions of the same optical signal transmitting area P (or the same optical signal receiving area Q) may be embedded in the same recess U. Alternatively, the recess U may not be provided, and each polarizer 151 and each phase delay unit 161 may be directly attached to the surface of the bracket 17 away from the substrate 10.

In the embodiment of the present application, the bracket 17 and the substrate 10 can be separately provided, and the bracket 17 can be attached to the surface of 10 by using a sticky material such as glue or double-sided tape. Alternatively, the bracket 17 and the substrate 10 can be an integral structure, and the substrate 10 with the bracket 17 can be directly manufactured by an integral molding process. For example, a hole can be dug on one side of the substrate 10 to achieve the bearing function of the light source 11 and the light detector 12, as well as the light isolation function between the light source 11 and the light detector 12 (i.e., the function of the bracket 17).

FIG11 is a bottom view of the physiological parameter sensor in an embodiment of the present application, that is, a view obtained by viewing the physiological parameter sensor from the skin side. As shown in FIG11, in some embodiments of the present application, the bracket 17 may include: a first bracket 171 and a second bracket 172. The first bracket 171 may be annular, and each light source 11 is located in the area W surrounded by the first bracket 171. The second bracket 172 may be annular, and the second bracket 172 surrounds the first bracket 171. Each light detector 12 is located in the area W surrounded by the first bracket 171 and the second bracket 172. By setting the first bracket 171, the light source 11 and the light detector 12 can be separated to prevent the light signal emitted by the light source 11 from crosstalking the light signal received by the light detector 12. In addition, by setting the second bracket 172, external light can be prevented from being emitted to each light detector 12, avoiding interference of external light on the light detector 12. In combination with FIG4 and FIG11, the first bracket 171 and the second bracket 172 can also support the polarizer and the phase delay plate. In addition, each light source 11 is arranged inside the area surrounded by the first bracket 171, and the area surrounded by the first bracket 171 can be used as a light signal emitting area. Each light detector 12 is arranged between the first bracket 171 and the second bracket 172, and the area between the first bracket 171 and the second bracket 172 can be used as a light signal receiving area. Such a structural setting is more in line with the transmission path of the light signal, so that the light signal emitted from the light signal emitting area can be emitted to the light signal receiving area after being transmitted through the skin, so that the intensity of the return light signal received by the physiological parameter sensor is greater, thereby improving the detection accuracy of the physiological parameter sensor.

In the physiological parameter sensor shown in FIG11 , the bracket 17 and the substrate 10 can be set to be discrete. During the manufacturing process, the pre-made annular first bracket 171 and the second bracket 172 can be mounted on the surface of one side of the substrate 10, and then the light sources 11 can be mounted in the area surrounded by the first bracket 171, and the light detectors 12 can be mounted in the area between the first bracket 171 and the second bracket 172, thereby reducing the complexity of the processing technology and the processing cost. Alternatively, during the manufacturing process, the light sources 11 and the detectors 12 can be installed first, and then the pre-made annular first bracket 171 and the second bracket 172 can be mounted on the surface of one side of the substrate 10.

FIG12 is another bottom view of the physiological parameter sensor in the embodiment of the present application. As shown in FIG12 , in other embodiments of the present application, in addition to the first bracket 171 and the second bracket 172, the bracket 17 may also include: a plurality of isolation parts 173 connected between the first bracket 171 and the second bracket 172, and two adjacent light detectors 12 may be separated by the isolation parts 173. In this way, each light detector 12 can be isolated, thereby reducing the crosstalk between the optical signals received by each light detector 12. In the physiological parameter sensor shown in FIG12 , the bracket 17 and the substrate 10 can be set as an integral structure, and the substrate 10 with the bracket 17 can be directly manufactured by an integral molding process, which can reduce the manufacturing process steps and reduce the processing complexity and processing cost. For example, a plurality of grooves can be formed on the surface of the substrate 10 by digging holes on one side of the substrate 10. For example, a circular groove and a plurality of quadrilateral grooves surrounding the circular groove can be made according to the structure shown in FIG. 12. Each light source 11 can be mounted in the circular groove, and each light detector 12 can be mounted in the corresponding quadrilateral groove, so as to realize the bearing function of the light source 11 and the light detector 12, and the optical isolation function between the light source 11 and the light detector 12 (that is, the function of the bracket 17).

FIG13 is another bottom view of the physiological parameter sensor in the embodiment of the present application. FIG13 is a schematic diagram of the mounted polarizer and phase retarder 16. The polarizer is located on the side of the phase retarder 16 close to the substrate 10, so the polarizer is blocked by the phase retarder 16 and is not shown in FIG13.

In FIG. 11 to FIG. 13 , the shape of the physiological parameter sensor is circular as an example. In a specific implementation, the shape of the physiological parameter sensor may also be square, rectangular, elliptical or polygonal, etc., which is not limited here.

In a specific implementation, the physiological parameter sensor in the embodiment of the present application may further include: a light-transmitting portion located on the side of the phase delay plate away from the substrate. In a possible implementation, a through hole may be provided in the bottom shell of the wearable device, and the light-transmitting portion may be provided at the position of the through hole or embedded inside the through hole, so that the light-transmitting portion can be used as a detection window for contact between the wearable device and the skin, and the light signal emitted by the light source can pass through the light-transmitting portion and then be emitted to the skin, and the light signal returned by the skin can also pass through the light-transmitting portion and then be emitted to the light detector. In a specific implementation, the light-transmitting portion may be combined with other structures in the physiological parameter sensor through materials such as double-sided tape or foam. Of course, in some cases, the light-transmitting portion may also be provided on the outside of the physiological parameter sensor, or at other positions of the wearable device, and the physiological parameter sensor may be mounted on the inner surface of the light-transmitting portion through materials such as double-sided tape or foam.

In the embodiment of the present application, the polarizer and the phase retarder can be mounted on the surface of the bracket away from the substrate. In some embodiments of the present application, the polarizer and the phase retarder can also be mounted on the surface of the light-transmitting portion. For example, the polarizer and the phase retarder can be mounted on the inner surface of the light-transmitting portion, or the polarizer and the phase retarder can be mounted on the outer surface of the light-transmitting portion, or the polarizer is mounted on the inner surface of the light-transmitting portion, and the phase retarder is mounted on the outer surface of the light-transmitting portion. Among them, the inner surface of the light-transmitting portion refers to the surface of the light-transmitting portion close to the substrate, and the outer surface of the light-transmitting portion refers to the surface of the light-transmitting portion away from the substrate (i.e., the surface close to the skin side). Alternatively, the polarizer can also be mounted on the surface of the bracket away from the substrate, and the phase retarder can be mounted on the inner surface (or outer surface) of the light-transmitting portion. In addition, the polarizer can also be set inside the physiological parameter sensor or mounted on the outer surface close to the bottom shell, and the phase retarder can be mounted on the inner surface of the bottom shell. In the specific implementation, the specific positions of the polarizer and the phase retarder can be set according to the internal space of the wearable device.

Based on the same technical concept, the embodiment of the present application also provides a wearable device. FIG14 is a schematic diagram of the structure of the wearable device provided in the embodiment of the present application. As shown in FIG14, the wearable device may include: any of the above-mentioned physiological parameter sensors 100, and a housing 300, and the physiological parameter sensor is located inside the housing 300. The wearable device may be a smart watch, a smart bracelet, a virtual reality (VR) glasses, and other devices. Of course, the wearable device may also be other devices with physiological parameter detection functions, which are not limited here. Since the detection performance of the physiological parameter sensor in the embodiment of the present application is good, the detection performance of the wearable device including the physiological parameter sensor is also good.

Based on the same technical concept, an embodiment of the present application also provides a wearable device. Figure 15 is another structural schematic diagram of the wearable device provided by the embodiment of the present application, and Figure 16 is another structural schematic diagram of the wearable device provided by the embodiment of the present application. As shown in Figures 15 and 16, the wearable device may include: a physiological parameter sensor 100, a phase delay plate 16, and a shell 300, and the physiological parameter sensor 100 is located inside the shell 300.

The physiological parameter sensor 100 may include: a substrate 10, at least one light source 11, at least one light detector 12, and a polarizer 15. Each light source 11 and each light detector 12 are located on the surface of the same side of the substrate 10, and the polarizer 15 is located on the side of each light source 11 and each light detector 12 away from the substrate 10. The polarizer 15 allows the light signal consistent with the polarization direction of the polarizer 15 in the light signal emitted by at least one light source 11 to pass through, and allows the light signal consistent with the polarization direction of the polarizer 15 in the light signal emitted to at least one light detector 12 to pass through.

The above-mentioned shell 300 may include a bottom shell 301. For example, the lower side of the shell 300 in Figures 15 and 16 can serve as the bottom shell 301. As shown in Figure 15, the phase delay plate 16 can be arranged on the side of the bottom shell 301 close to the physiological parameter sensor 100, that is, the phase delay plate 16 can be mounted on the inner surface of the bottom shell 301. Alternatively, as shown in Figure 16, the phase delay plate 16 can also be arranged on the side of the bottom shell 301 away from the physiological parameter sensor 100, that is, the phase delay plate 16 can also be mounted on the outer surface of the bottom shell 301. The phase delay plate 16 can phase-delay the optical signal emitted from the polarizer 15 to the bottom shell 301, and phase-delay the optical signal emitted from the outside of the wearable device to the bottom shell 301.

The specific implementation of the wearable device shown in Figures 15 and 16 can be implemented with reference to the specific implementation of the wearable device shown in Figure 14, and the repeated parts are not repeated here.

Based on the same technical concept, the embodiment of the present application also provides a wearable device. Figures 17 to 19 are schematic diagrams of the structure of the wearable device provided by the embodiment of the present application. As shown in Figures 17 to 19, the wearable device may include: a physiological parameter sensor 100, a polarizer 15, a phase delay plate 16, and a housing 300. The physiological parameter sensor 100 is located inside the housing 300. The physiological parameter sensor 100 may include: a substrate 10, at least one light source 11 and at least one light detector 12. Each light source 11 and each light detector 12 are located on the surface of the same side of the substrate 10. The housing 300 may include a bottom shell 301. For example, the lower side of the housing 300 in Figures 17 to 19 can be used as the bottom shell 301. The polarizer 15 and the phase delay plate 16 are arranged on the bottom shell 301. Among them, the polarizer 15 is located on the side of each light source 11 and each light detector 12 away from the substrate 10, and the phase delay plate 16 is located on the side of the polarizer 15 away from the substrate 10.

As shown in Figure 17, in a possible implementation, the polarizer 15 and the phase retarder 16 can be stacked on the side of the bottom shell 301 close to the physiological sensor 100, that is, the polarizer 15 and the phase retarder 16 can be arranged on the inner surface of the bottom shell 301, wherein the phase retarder 16 is located on the side of the bottom shell 301 close to the physiological parameter sensor 100, and the polarizer 15 is located on the side of the phase retarder 16 close to the physiological parameter sensor 100.

As shown in FIG. 18 , in another possible implementation, the polarizer 15 may be located on a side of the bottom shell 301 close to the physiological parameter sensor 100, that is, the polarizer 15 may be mounted on the inner surface of the bottom shell 301. The phase delay plate 16 may be located on a side of the bottom shell 301 away from the physiological parameter sensor 100, that is, the phase delay plate 16 may be mounted on the outer surface of the bottom shell 301.

As shown in FIG19 , in another possible implementation, the polarizer 15 and the phase retarder 16 may be stacked on the side of the bottom shell 301 away from the physiological sensor 100, that is, the polarizer 15 and the phase retarder 16 may be arranged on the outer surface of the bottom shell 301. The polarizer 15 may be located on the side of the bottom shell 301 away from the physiological parameter sensor 100, and the phase retarder 16 may be located on the side of the polarizer 15 away from the physiological parameter sensor 100.

The specific implementation of the wearable device shown in Figures 17 to 19 can be implemented with reference to the specific implementation of the wearable device shown in Figure 14, and the repeated parts are not repeated here.

Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present application without departing from the spirit and scope of the embodiments of the present application. Thus, if these modifications and variations of the embodiments of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

A physiological parameter sensor, characterized in that it comprises: a substrate, at least one light source, at least one light detector, a polarizer and a phase delay plate;

The at least one light source and the at least one light detector are located on a surface on the same side of the substrate;

The physiological parameter sensor further comprises: at least one light signal emitting area and at least one light signal receiving area; each of the at least one light signal emitting area corresponds to at least one light source, and each of the at least one light signal receiving area corresponds to at least one light detector;

The polarizer is located in the area corresponding to the at least one optical signal receiving area, the phase delay plate is located in the area corresponding to the at least one optical signal receiving area, the polarizer is located on the side of the at least one optical detector away from the substrate, and the phase delay plate is located on the side of the polarizer away from the substrate.
The physiological parameter sensor according to claim 1, characterized in that

The at least one light source is used to emit a first light signal;

The phase delay plate is used to phase delay the received second optical signal;

The polarizer is used to allow light signals having a polarization direction consistent with that of the polarizer to pass through.
The physiological parameter sensor according to claim 1 or 2, characterized in that the polarizer is also located in an area corresponding to the at least one light signal emission area;

The phase retarder is also located in the area corresponding to the at least one optical signal emission area, the polarizer is located on the side of the at least one light source away from the substrate, and the phase retarder is located on the side of the polarizer away from the substrate.
The physiological parameter sensor according to claim 2 or 3, characterized in that the first light signal emitted by the at least one light source is natural light, linearly polarized light, circularly polarized light or elliptically polarized light; wherein the polarization direction of the linear polarized light is not perpendicular to the polarization direction of the polarizer.
The physiological parameter sensor according to claim 3, characterized in that the polarizer located in the at least one optical signal emitting area and the polarizer located in the at least one optical signal receiving area are the same polarizer, and the phase delay plate located in the at least one optical signal emitting area and the phase delay plate located in the at least one optical signal receiving area are the same phase delay plate;

Alternatively, the polarizer includes: a plurality of discretely arranged polarization units, each of which corresponds to one of the optical signal emitting areas or one of the optical signal receiving areas; the phase delay plate includes: a plurality of discretely arranged phase delay units, each of which corresponds to one of the optical signal emitting areas or one of the optical signal receiving areas.
The physiological parameter sensor according to claim 1 or 2, characterized in that the first light signal emitted by the at least one light source is linearly polarized light;

The phase delay plate is also arranged in a region corresponding to the at least one optical signal transmitting region.
The physiological parameter sensor according to claim 6, characterized in that the polarizer comprises: at least one polarizing portion, each of the polarizing portions corresponding to one of the light signal receiving areas;

The phase delay plate located in the at least one optical signal transmitting area and the phase delay plate located in the at least one optical signal receiving area are the same phase delay plate; or, the phase delay plate includes: a plurality of discretely arranged phase delay units, each of the phase delay units corresponds to one of the optical signal transmitting areas or one of the optical signal receiving areas.
The physiological parameter sensor according to claim 1, characterized in that the polarizer comprises: at least one polarizing portion, each of the polarizing portions corresponding to one of the light signal receiving areas;

The phase delay plate includes: at least one phase delay unit, each of which corresponds to one of the optical signal receiving areas.
The physiological parameter sensor according to any one of claims 1 to 8, characterized in that the polarizer is a linear polarizer, and the phase delay plate is a quarter wave plate.
The physiological parameter sensor according to any one of claims 1 to 9, characterized in that each of the at least one light source comprises a light emitting diode or a laser; and each of the at least one light detector comprises a photodiode.
The physiological parameter sensor according to any one of claims 1 to 10, characterized in that it further comprises: a bracket located on the surface of the substrate;

The bracket and the at least one light source are located on a surface on the same side of the substrate;

The at least one light source is separated from the at least one light detector by the bracket;

The polarizer and the phase delay plate are located on a side of the bracket away from the substrate.
The physiological parameter sensor according to claim 11, characterized in that the bracket comprises: a first bracket and a second bracket;

The first bracket is ring-shaped, and the at least one light source is located in the area surrounded by the first bracket;

The second bracket is ring-shaped and surrounds the first bracket. The at least one light detector is located in a region enclosed by the first bracket and the second bracket.
The physiological parameter sensor according to claim 12, characterized in that the bracket further comprises: a plurality of isolation portions connected between the first bracket and the second bracket;

Two adjacent photodetectors are separated by the isolation portion.
The physiological parameter sensor according to claim 11, characterized in that a surface of the bracket away from the substrate has a depression concave toward the substrate;

The polarizer and the phase delay plate are embedded in the recess.
The physiological parameter sensor according to any one of claims 11 to 14, characterized in that the bracket and the substrate are an integrated structure; or the bracket and the substrate are arranged separately.
A wearable device, characterized in that it comprises: a physiological parameter sensor according to any one of claims 1 to 15, and a shell, wherein the physiological parameter sensor is located inside the shell.
A wearable device, characterized in that it comprises: a physiological parameter sensor, a phase delay plate, and a shell, wherein the physiological parameter sensor is located inside the shell;

The physiological parameter sensor comprises: a substrate, at least one light source, at least one light detector and a polarizer;

The at least one light source and the at least one light detector are located on the same side of the substrate, the polarizer is located on a side of the at least one light source and the at least one light detector away from the substrate, and the polarizer allows light signals consistent with the polarization direction of the polarizer among the light signals emitted by the at least one light source to pass through, and allows light signals consistent with the polarization direction of the polarizer among the light signals emitted to the at least one light detector to pass through;

The shell includes a bottom shell, and the phase delay plate is arranged on a side of the bottom shell close to the physiological parameter sensor or a side of the bottom shell away from the physiological parameter sensor. The phase delay plate is used to phase delay the light signal emitted from the polarizer to the bottom shell, and to phase delay the light signal emitted from the outside of the wearable device to the bottom shell.
A wearable device, characterized in that it comprises: a physiological parameter sensor, a polarizer, a phase delay plate, and a housing;

The physiological parameter sensor is located inside the housing and includes: a substrate, at least one light source and at least one light detector;

The at least one light source and the at least one light detector are located on a surface on the same side of the substrate;

The housing comprises a bottom shell, and the polarizer and the phase delay plate are arranged on the bottom shell;

Wherein, the polarizer is located on a side of the at least one light source and the at least one light detector away from the substrate, and the phase delay plate is located on a side of the polarizer away from the substrate.
The wearable device according to claim 18, characterized in that the polarizer is located on a side of the at least one light source and the at least one light detector away from the substrate, and the phase delay plate is located on a side of the polarizer away from the substrate, comprising:

The polarizer and the phase delay plate are stacked on a side of the bottom shell close to the physiological sensor, wherein the phase delay plate is located on a side of the bottom shell close to the physiological parameter sensor, and the polarizer is located on a side of the phase delay plate close to the physiological parameter sensor.
The wearable device according to claim 18, characterized in that the polarizer is located on a side of the at least one light source and the at least one light detector away from the substrate, and the phase delay plate is located on a side of the polarizer away from the substrate, comprising:

The polarizer is located on a side of the bottom shell close to the physiological parameter sensor, and the phase delay plate is located on a side of the bottom shell away from the physiological parameter sensor.
The wearable device according to claim 18, characterized in that the polarizer is located on a side of the at least one light source and the at least one light detector away from the substrate, and the phase delay plate is located on a side of the polarizer away from the substrate, comprising:

The polarizer and the phase delay plate are stacked on a side of the bottom shell away from the physiological parameter sensor, wherein the polarizer is located on a side of the bottom shell away from the physiological parameter sensor, and the phase delay plate is located on a side of the polarizer away from the physiological parameter sensor.