Sensor device for optical measurement of biological properties

Abstract

A device, the substrate includes a connection port. The substrate includes traces for implementing the circuitry of the substrate. The circuitry is connected to the connection port. An optical sensor is mechanically and electrically attached to a first planar surface of the substrate and the circuitry, respectively. A light source is mechanically and electrically attached to the first planar surface and the circuitry, respectively. The light source is positioned transversely to the optical sensor at a first distance. The light signal of the light source is emitted from the light source at an angle perpendicular to the first planar surface, and a reflector is mechanically attached to the first planar surface and positioned between the optical sensor and the light source. The light signal is substantially reflected by the reflector away from the optical sensor.

Description

Technical Field

[0001] The present invention generally belongs to the field of optical measurement of biological characteristics of a subject and relates to optical measurement of blood-related parameters of a subject. In particular, the present invention relates to the structure of a device for performing reflectance blood measurement of certain characteristics of an optical measurement detected by a detector. This structure improves the signal-to-noise ratio of the optical measurement detected by the detector. Background Art

[0002] Most optical blood pulse measurements (e.g., pulse oximetry) can be performed using a transmission measurement technique that requires a sensor device that can be mounted on two opposite sides of a thin body part / organ (e.g., fingertip or earlobe). Compared with the transmission measurement technique, the reflectance measurement technique uses a light source and a light detector located on the same side of the tissue.

[0003] However, the reflectance blood measurement technique has various advantages and can be considered preferable in certain applications, especially in various types of wearable medical devices (e.g., medical watches or patches). Some of the advantages of the reflectance blood measurement technique include the ability to perform optical measurements on almost any part of the body (including thick organs), etc. Other advantages may be related to the reduced energy consumption of the reflectance measurement technique. Contrary to the transmission technique that requires light to pass through the entire width of the organ, the reduced energy consumption results from the minimum energy required to reflect light from the tissue layer.

[0004] However, there may be various limitations associated with the reflectance measurement technique, such as low signal-to-noise ratio (SNR) and low AC / DC ratio. The alternating current (AC) resulting from the optical detection of the light wave signal reflected from (capillary) blood vessels in the light detector may originate from cardiac activity. The direct current (DC) resulting from the optical detection of the light wave signal in the light detector can be a combination of the light wave signal reflected from other parts of the tissue of the subject organ and the light wave signal directly reflected from the organ surface that does not pass through the subject tissue.

[0005] Attempts to overcome the limitations of the reflectance measurement technique may include increasing the power of the radiated light by increasing the current supplied to the light source and / or by increasing the number of light sources. Increasing the power of the radiated light and / or increasing the number of light sources may also result in a corresponding increase in the noise component in the measured optical signal. The corresponding increase in the noise component in the measured optical signal may be due to the corresponding increase in the baseline DC component and may therefore not provide satisfactory results. Therefore, it is necessary to improve the quality of the optical signal measured by the reflectance blood measurement technique to provide a higher AC / DC ratio and to increase the signal-to-noise ratio of the measured optical signal. Summary of the Invention

[0006] The present invention discloses the structure of a sensor device designed for optical measurement of biological characteristics of an object using a reflection measurement technique. The reflection measurement technique can be used to measure blood characteristics (e.g., heart rate, blood parameters, and / or blood analysis concentration / level) in the living tissue of a subject under examination. The optical measurement sensor device and its structure disclosed herein overcome the deficiencies associated with conventional measurement setups by including in the structure the reflection of incident light of one or more light emitters by a reflector positioned at an appropriate angle and distance relative to the light detector unit of the sensor device. The direction and distance of one or more light sources relative to the light reflector (or one or more light reflectors relative to the light emitters) are appropriately selected to significantly improve the amplitude, SNR ratio, and AC / DC ratio of the measured optical signal.

[0007] By appropriately setting the distance between the light emitter and the light detection unit of the device and the angle between its light detector and the direction of the reflected light irradiation, the optical signal measured by the reflection measurement technique can be significantly improved. In this way, most of the light components reaching the light detector are reflected / scattered from the perfused layer of the irradiated tissue (also referred to herein as the distal tissue layer), and most of the light components reflected / scattered from the non-perfused layer of the irradiated tissue (also referred to herein as the near-surface tissue layer) do not reach the detector and are thus not measured.

[0008] Therefore, embodiments of the present invention provide that most of the light components detected by the light detection unit are scattered from the tissue layer including blood vessels and thus contain more information about the blood flowing through the tissue under examination (i.e., pulsating alternating current (AC) as a result of light detection in the light detector). On the other hand, since many light components reflected / scattered from the non-perfused tissue layer do not reach the detector and are thus not measured, the direct current (DC) as a result of light detection of the optical signal measured in the light detector is significantly reduced, which provides a significant increase in the SNR ratio and AC / DC ratio of the measured signal.

[0009] In a possible measurement setup of the measurement device, according to some possible embodiments, at least one light emitter and the structure of the device are used to emit light in one or more predetermined wavelength ranges above the tissue under examination. At least one adjacent-positioned light detector is used to detect the light radiation in one or more predetermined wavelength ranges reflected from the irradiated tissue. At least one light emitter and at least one light detector are arranged in a spaced-apart relationship to obtain a specific distance between them, thereby obtaining a specific angle between their respective irradiation and detection directions.

[0010] In some embodiments of the device configuration disclosed herein, a specific distance and a predetermined orientation between the light emitter and the light detector of the reflectance measurement device are configured such that only light components within a predetermined range of angular reflection can reach the light detector and contribute to the measured optical signal. The device configuration reduces or in some cases substantially prevents the collection of light components that are directly reflected without passing through any layer of the tissue under examination from the organ surface (e.g., the stratum corneum), such as direct surface reflection, and / or light components that are reflectively scattered from the unperfused upper layer of the tissue under examination. The above two components (direct surface reflection and unperfused upper layer reflection) are the main DC components. Therefore, the reduction of these components directly improves the AC / DC ratio. In some other exemplary embodiments of the present invention, the reflectance measurement device and its configuration can be configured to increase light emission. Such a configuration can extend the optical path of the emitted light in a given tissue layer, thereby increasing light scattering and the probability of collecting light components reflected from the perfused tissue layer.

[0011] In some possible embodiments, the reflectance measurement device may include a plurality of light emitters (e.g., 2, 3, or 4 or more) arranged around the light detector. The light emitted from each of the light emitters is reflected away from the direction of the light detector. However, note that in some embodiments, a single light emitter can be used to configure the reflectance measurement device with acceptable good results. Additionally, in possible embodiments of the present invention, when the direction and distance of the light detector relative to the light emitter of the device can be within an acceptable range of a specific distance and a predetermined measurement of the measurement device, a plurality of light detectors can be used to collect the light components reflected from the tissue under examination.

[0012] Embodiments of the present invention can be used to implement a wearable device worn on a part of an object's body part, such as but not limited to the chest, head and neck, trunk, or limbs (e.g., on the wrist, like a watch).

[0013] The biological characteristics measured by the measurement device of the present invention can include heart rate, blood flow, arterial oxygen saturation, and various blood-related parameters, such as the concentration of substances / analytes (e.g., sugar, cholesterol, hemoglobin, bilirubin) in the blood, cardiac parameters, etc. Therefore, in some possible embodiments, the light emitter is configured to irradiate the tissue under examination at a plurality of wavelengths selected for determining one or more biological characteristics of the object.

[0014] The present subject matter discloses a device having a substrate including a connection port. The substrate includes traces for implementing circuitry of the substrate. The circuitry is connected to the connection port. A light sensor is mechanically and electrically attached to a first planar surface of the substrate and the circuitry, respectively. A light emitter is mechanically and electrically attached to the first planar surface and the circuitry, respectively. The light emitter is positioned laterally to the light sensor at a first distance. The light emitter emits a light signal at an angle perpendicular to the first planar surface, and the light signal is reflected by a reflector that is mechanically attached to the first planar surface and positioned between the light sensor and the light emitter. The light signal is substantially reflected by the reflector away from the light sensor. The profile of a cross-section of the reflector is at least one of a linear profile, a concave profile, a convex profile, and a parabolic profile.

[0015] The first distance between the light emitter and the light emitter can be established in response to the profile of the reflector that reflects light emitted by the light emitter. The light emitter can include a lens configured to collimate the light signal of the light emitter at an angle perpendicular to the first planar surface. The light emitter can include an offset lens configured to collimate the light signal of the light emitter at a second angle away from the angle perpendicular to the first planar surface. The light emitter can include a lens configured to polarize the light signal of the light emitter. The light emitter can include a prism configured to reflect the light signal of the light emitter.

[0016] The device can further include a second reflector configured to reflect light emitted from a second light emitter. The second light emitter is mechanically and electrically attached to the first planar surface and the circuitry, respectively. A second light signal of the second light emitter exits the second light emitter at an angle perpendicular to the first planar surface. The second light signal is substantially reflected by the second reflector away from the light detector. A second distance between the light sensor and the second light emitter can be established in response to the profile of the second reflector.

[0017] A second planar surface of the reflector can be placed on a tissue under examination to measure a biological property of the tissue under examination. The second plane is parallel to the first planar surface. The device can further include an attachment device for implementing attachment of the device to the tissue under examination. The tissue under examination is in contact with the second planar surface of the reflector.

[0018] The device may further include a control unit operatively connected to the substrate and configured to select parameters of the optical signal and / or the second optical signal applied to the tissue under examination. The parameters may be wavelength and / or light intensity. The control unit may be configured to select the optical signal or the second optical signal and apply it to the tissue under examination. The control unit may also be configured to sense the reflected optical signal from the optical signal and / or the second optical signal applied in response to the parameters and / or the respective first distance and second distance. The control unit may also be configured to receive and process the measurement data of the reflected optical signal sensed by the optical sensor to determine the biological characteristics of the tissue under examination. The biological characteristics may include heart rate, oxygen saturation, hemoglobin level, blood pressure, cardiac output, stroke volume, sweating, glucose / sugar level, bilirubin level, or fat level. Description of the Drawings

[0019] To understand the present invention and to see how it may be carried into effect in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings. Unless otherwise explicitly stated, the features shown in the drawings are only for illustration of some embodiments of the present invention. In the drawings, the same reference numerals are used to denote corresponding parts, and in the drawings:

[0020] Figure 1 Illustrations of applying the sensor device to the tissue under examination in accordance with one or more illustrative aspects of the present disclosure are shown.

[0021] Figure 2 A plan view and a side view cross-section of the sensor device in accordance with one or more illustrative aspects of the present disclosure are shown.

[0022] Figure 3a 、 Figure 3b 、 Figure 3c 、 Figure 3d 、 Figure 3e and Figure 3f More details of regions of the sensor device in accordance with one or more illustrative aspects of the present disclosure are shown.

[0023] Figure 4 A two-dimensional view of the underside of the sensor device in accordance with one or more illustrative aspects of the present disclosure is shown.

[0024] Figure 5a A partial cross-sectional side view of the sensor device and its application to the tissue under examination in accordance with one or more illustrative aspects of the present disclosure is shown.

[0025] Figure 5b Illustrations in accordance with one or more illustrative aspects of the present disclosure of Figure 5a A simplified schematic diagram to illustrate the characteristics of the region of light interaction in the perfused tissue layer.

[0026] Figure 5c A partial cross-sectional side view of a sensor device according to one or more illustrative aspects of the present disclosure and its application to tissue is shown.

[0027] Figure 5d One or more illustrative aspects of the present disclosure are shown Figure 5c A simplified schematic diagram of to illustrate the characteristics of the region of optical interaction in the perfused tissue layer.

[0028] Figure 5e A partial cross-sectional side view of a sensor device according to one or more illustrative aspects of the present disclosure and its application to tissue is shown.

[0029] Figure 6 A plan view and a cross-sectional side view of a sensor device according to one or more illustrative aspects of the present disclosure are shown.

[0030] Figure 7 A plan view of a sensor device according to one or more illustrative aspects of the present disclosure is shown.

[0031] Figure 8 A plan view of a sensor device according to one or more illustrative aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0032] One or more specific embodiments of the present disclosure will be described below with reference to the accompanying drawings, which should be considered illustrative in all respects and not restrictive in any way. To provide a concise description of these embodiments, not all features of the actual implementation are described in the specification. The elements shown in the drawings are not necessarily drawn to scale, but rather emphasize clearly illustrating the principles of the invention. The invention may be provided in other specific forms and embodiments without departing from the basic features described herein.

[0033] As an introduction, the present invention discloses an optical sensor device, whereby the structure of the optical sensor device utilizes an optical signal traveling laterally away from a photodetector included in the optical sensor device to provide illumination of the tissue under examination. The characteristics of this structure enable the measurement of the amplitude of the reflected optical signal from the tissue under examination with a significantly improved SNR ratio and AC / DC ratio of the reflected optical signal.

[0034] It should be noted that the reflective measurement techniques and the structure of the sensor device disclosed herein are also used to mitigate optical signal distortion that may be caused in the measurement signal of the photodetector due to the movement of the body part / organ to which the sensor device is attached.

[0035] The techniques disclosed herein can be applied to almost any type of optical measurement of blood properties, parameters, and / or analytes, utilizing the optical absorption and scattering effects of electromagnetic radiation in living tissue. In particular, the techniques disclosed herein can be used to measure pulsatile signals such as those typically obtained in various types of non-invasive blood measurements such as, but not limited to, pulse oximetry, photoplethysmography (PPG) measurements, etc. For example, and without limitation, the optical measurement techniques disclosed herein can be used to measure blood pulse, oxygen (O 2 ) saturation, hemoglobin level, glucose / sugar level, bilirubin level, etc.

[0036] Now referring to Figure 1 , Figure 1 FIG. shows an illustration of the application of a sensor device 10 in accordance with one or more illustrative aspects of the present disclosure. The sensor device 10 is an example of a reflective optical measurement device described in further detail below. The sensor device 10 (shown in dashed lines) is positioned on the bottom side of the housing 12 such that the reflector 24 of the sensor device 10 (shown in dashed lines) is in contact with the skin of the user's wrist. Also positioned on the bottom side of the housing 12 is a light detector 26 (shown in dashed lines). The housing 12 includes a display 13 on its upper surface. The housing 12 is shown as a watch device in which an adjustable band 15 is used to attach the watch to the user's wrist. A handle (not shown) may be attached to the housing 12 to provide a means for pressing the sensor device 10 against a part of the user's body.

[0037] FIG. 100 shows a side view of the bottom side of the housing 12, where the adjustable band 15 is attached to the housing 12, and a base 20 is mechanically and electrically operatively attached within the housing 12 and may protrude from the housing 12 and includes a connection to a battery 17. The base 20 includes electrical interconnections for providing the components of the sensor device 10 and traces (not shown) for connections such as to the display 13, the battery 17, and a microcontroller (not shown). The sensor device 10 is mechanically and electrically connected to the housing 12, the base 20, and the battery 17.

[0038] The adjustable band 15 can be tightened around the wrist to firmly press the sensor device 10 against a part of a person's body. The body part can be the ankle or around the torso of a person. Thus, the adjustable band 15 can enable the biological characteristics of a person who is currently exercising or a subject tissue of a patient to be monitored over a long period of time. The biological characteristics can include, for example, heart rate, oxygen saturation, hemoglobin level, blood pressure, cardiac output, stroke volume, sweating, glucose / sugar level, bilirubin level, and fat level. The biological characteristics can be displayed to the user on the display 13.

[0039] Now referring to Figure 2 , Figure 2A top view and a side view cross-section AA of a sensor device 10 in accordance with one or more illustrative aspects of the present disclosure are shown. The top view shows a reflector 24 mounted on a substrate 20, and the substrate 20 is partially shown in the side view cross-section AA. A photodetector 26 is positioned in the center of the reflector 24. Regions 30 (shown by dashed ellipses) in the side view cross-section and the top view show how the reflector 24 covers a light emitter 22. The light emitter 22 is shown by a dashed box in the top view. In the side view cross-section AA, the light emitter 22 is mechanically and electrically attached to a planar surface of the substrate 20, and both light emitters 22 are laterally positioned at a distance d1 from the center of the photodetector 26. The dashed line 28 shows how the planar surface of the substrate 20 is parallel to a second planar surface of the reflector 24. To measure a biological property of a tissue under examination, the second planar surface of the reflector 24 of the sensor device 10 is pressed against the tissue under examination. The reflector 24 is made of a material rigid enough not to deform due to the sensor device 10 being pressed against the tissue under examination.

[0040] Now refer to Figure 3a , Figure 3a which shows more details of the region 30 in accordance with one or more illustrative aspects of the present disclosure. The region 30 shows reflective surfaces 32a and 32b of the reflector 24. In the cross-section AA, the reflective surfaces 32a and 32b of the reflector 24 are examples of linear shapes. An optical signal 34a is emitted from the light emitter 22 at an angle perpendicular to the first planar surface of the substrate 20. The optical signal 34a is reflected from the reflective surface 32a as a reflected light 34b at an angle α with respect to the dashed line 28. The optical signal 34a is reflected away from the photodetector 26 (not shown).

[0041] Now refer to Figure 3b , Figure 3b which shows a region 30b of the sensor device 10 in accordance with one or more illustrative aspects of the present disclosure. Figure 3b In relation to Figure 3aThe same, except that the lens 36 is shown as being placed on the distal end of the light source 22. The optical signal 34a still emanates from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20. However, the lens 36 collimates the optical signal 34a into a collimated beam 34c. The collimated beam 34c minimizes the divergence of the rays of the optical signal 34a. The collimated beam 34c still emanates from the lens 36 at an angle perpendicular to the first planar surface of the substrate 20. The collimated beam 32c is reflected from the reflective surface 32a of the reflector 24 at an angle α with respect to the dashed line 28 as a reflected optical signal 34b. The collimated beam 32c is reflected away from the photodetector 26 (not shown) as the reflected optical signal 34b. The lens 36 may also include a polarization filter (not shown) that polarizes the collimated beam 34c. The reflector 24 also includes a reflective surface 32b. In some cases, instead of the lens 36, the device may include a prism for reflecting the collimated beam 32c away from the photodetector 26.

[0042] Now refer to Figure 3c , Figure 3c which shows the region 30c of the sensor device 10 according to one or more illustrative aspects of the present disclosure. Figure 3c Same as Figure 3b except that the lens 36 is placed on the distal end of the light source 22 and is laterally offset towards the reflective surface 32a. The lens 36 may also be laterally offset further away from the reflective surface 32a. The optical signal 34a still emanates from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20. However, different from Figure 3b the lens 36 collimates the optical signal 34a into a collimated beam 34d. The lens 36 minimizes the divergence and / or scattering of the rays of the optical signal 34a. However, different from Figure 3b the collimated beam 34d is not at a perpendicular angle to the first planar surface of the substrate 20. The collimated beam 34d is reflected from the reflective surface 32a of the reflector 24 at an angle α' with respect to the dashed line 28 as a reflected optical signal 34b. The optical signal 34a is reflected away from the photodetector 26 (not shown). Since the lens 36 is laterally offset towards the reflective surface 32a, the angle α' may not be reflected as sharply as the angle α. The lens 36 may also include a polarization filter (not shown) that polarizes the collimated beam 34d. The reflector 24 also includes a reflective surface 32b.

[0043] Now refer to Figure 3d , Figure 3d which shows the region 30d of the sensor device 10 according to one or more illustrative aspects of the present disclosure. Figure 3d Same as Figure 3cThe same, except that the lens 36 is placed on the distal end of the light source 22 and is laterally offset away from the light detector 26. The optical signal 34a still emits from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20. The lens 36 collimates the optical signal 34a into a collimated beam 34d. The lens 36 minimizes the divergence and / or scattering of the light rays of the optical signal 34a. The collimated beam 34d is not at an angle perpendicular to the first planar surface of the substrate 20. The collimated beam 34d is skewed away from the light detector 26 (not shown) due to the lateral offset of the lens 36 away from the light detector 26. Due to the lateral offset of the lens 36 away from the light detector 26, the angle α' may not be as sharp as the angle α upon reflection. The lens 36 may also include a polarization filter (not shown) that polarizes the collimated beam 34d. The region 30d of the sensor device 10 is an example where the use of the lens 36 does not require the reflector 24. Thus, the sensor device 10 may include a plurality of light sources 22 and corresponding lenses 36 without any reflectors 24. Another possibility is that the sensor device 10 may include a combination of the light source 22 and the reflector 24, the light source 22 / lens 36a and the reflector 24, or the light source 22 / lens 36 without the reflector 24.

[0044] Now refer to Figure 3e , Figure 3e which shows the region 30e of the sensor device 10 according to one or more illustrative aspects of the present disclosure. Figure 3e Same as Figure 3a , Figure 3b and Figure 3c except that the reflector 24 is an example that is concave or parabolic in shape in cross-section AA. The optical signal 34a still emits from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20. The reflector 24 that is concave or parabolic in shape reflects the optical signal 34a from the reflective surface 32a at an angle β with respect to the dashed line 28 as the reflected light 34b. The angle β may be sharper compared to the angle α shown in Figure 3a due to the reflector 24 being concave or parabolic in shape in cross-section AA. The reflector 24 also includes a reflective surface 32b.

[0045] Now refer to Figure 3f , Figure 3f which shows the region 30f of the sensor device 10 according to one or more illustrative aspects of the present disclosure. The reflector 24 is an example that is convex in shape in cross-section AA. The optical signal 34a still emits from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20. The reflector 24 that is convex in shape at cross-section AA reflects the optical signal 34a from the reflective surface 32a at an angle β' with respect to the dashed line 28 as the reflected light 34b. The angle β' is compared with Figure 3eThe angle β shown is potentially sharper than would be the case if the reflector 24 were convex in shape in cross-section AA. The reflector 24 also includes a surface 32b.

[0046] Now refer to Figure 4 , Figure 4 FIG. shows a two-dimensional view of the underside of a sensor device 10 in accordance with one or more illustrative aspects of the present disclosure. The underside of the sensor device 10 shows a substrate 20. The substrate 20 may form a housing for the sensor device 10 or may be included and operatively attached to a separate housing for the sensor device 10. The housing or separate housing may additionally provide a handle or an adjustable strap as described above to enable the sensor device 10 to be pressed against tissue. The substrate 20 also provides mechanical attachments for a plurality of reflectors 24, a light source 22, and a light detector 26 to the substrate 20. The plurality of reflectors 24 are shown concentric with each other about the center of a first planar surface of the substrate 20 where the light detector 26 is located.

[0047] The substrate 20 also provides electrical attachments (not shown) to the light source 22 and the light detector 26. The electrical attachments may include traces providing electrical interconnections of the light sources 22 to each other, connections to the light detector 26, and additional components that may be connected to the electrical interconnections. The light source 22 and the light detector 26 are shown attached to a surface of the substrate 20, but may be positioned and attached below the surface. The additional components may include driver circuitry that may be used to set the current level, light intensity, and wavelength of the optical signals that may be emitted from the light source 22. The additional components may also include a microcontroller or microprocessor (not shown) that may be connected to the additional components and the traces. The microcontroller may be used to select which light source 22 and / or plurality of light sources 22 will be activated and applied in response to which biological characteristic of the body and which light source 22 and / or plurality of light sources 22 will be monitored by the light detector 26. Further, an analysis of the biological characteristic monitored by the light detector 26 is performed to store and display the data of the analysis in a corresponding memory or display, such as a display 13 that may be operatively attached to the microcontroller. The additional components may also include a connector for the microcontroller. The connector may be provided on the housing of the sensor device 10, or the sensor device 10 may provide a wireless connection to another computing device (cloud or server) to enable remote analysis, storage, and display of data.

[0048] As a non-limiting example, light source 22 can be a multi-color light-emitting diode (LED). Multi-color LEDs typically have three selectable wavelengths: red (wavelength [λ] ≈ 670 nanometers [nm]), blue (λ ≈ 460 nm), and green (λ ≈ 550 nm). White light can be selected by a microcontroller through additional control of the LED driver circuit to select the red, blue, and green wavelengths / color temperatures. The selection by the microcontroller of which wavelength, color temperature, and / or combination of wavelength and color temperature can be responsive to different tissues in the human body having different absorption and reflectance levels.

[0049] The absorption and reflectance levels may also be wavelength-dependent. The selection by the microcontroller of which light source 22, wavelength, color temperature, and / or combination of wavelength and color temperature can also be responsive to the distance of light source 22 to light detector 26 as further discussed in detail below.

[0050] Now referring to Figure 5a , Figure 5a FIG. 10 shows a partial cross-sectional side view of a sensor device 10 and its application to tissue 50 in accordance with one or more illustrative aspects of the present disclosure. Tissue 50 includes, for example, unperfused near-surface tissue layers S1 and S2 that form the epidermis of the skin. Tissue 50 also includes distally perfused tissue layers S3, S4, and S5 that may include blood vessels 16. Sensor device 10 is shown pressing against tissue layer S1 such that the second planar surface of reflector 24 contacts tissue layer S1. Reflector 24 contacts tissue layer S1 to enable measurement of the biological properties of tissue 50. The second planar surface of reflector 24 is parallel to the first planar surface of substrate 20 and is represented by dashed line 28. Four light sources 22 are shown.

[0051] For ease of illustration, one light source 22 is shown having a light signal 34a emitted therefrom. This one light source is laterally positioned at a shorter distance d2 to the right of light detector 26 compared to another light source 22 that is laterally positioned at a greater distance d1 to the right of light detector 26. Similarly, the other two light sources 22 are also shown to be laterally positioned to the left of light detector 26. One of the other two light sources 22 that are laterally positioned to the left of light detector 26 is positioned at a shorter distance d2 compared to the other light source 22 at the greater distance d1 among the two light sources 22. The light signal 34a from light source 22 is emitted perpendicular to both the first planar surface and the second planar surface. The light signal 34a is reflected by the reflective surface 32a of reflector 24 at an angle α with respect to dashed line 28 as reflected light 34b'.

[0052] The angle α of the orientation of the reflected light 34b' allows the light source 22 to be positioned at a relatively short distance d2 near the light detector 26. The relatively short distance d2 near the light detector 26 can ensure that the light components L0', L1', and L2' of the reflected light 34b' are never reflected from the unperfused tissue layers S1 and S2. The light direction towards the light detector 26 can be perpendicular to both the first planar surface and the second planar surface. Therefore, the number of light components L0', L1', and L2' reflected from the unperfused near-surface tissue layers S1 and S2 towards the light detector 26 is reduced to provide an improved SNR and AC / DC ratio. Among them, the alternating current (AC) in the light detector 26 can be the result of the optical detection of the light wave signal of the light 34b' reflected from the (capillary) blood vessel 16, and this alternating current (AC) may originate from cardiac activity. Among them, the direct current (DC) in the light detector 26 can be the result of the optical detection of the light wave signal of the light 34b' reflected from other parts of the tissue 50 and the light wave signal directly reflected without passing through the surface layers S1 and S2 of the tissue 50.

[0053] The direct current (DC) that is the result of the optical detection of the light wave signal in the light detector can be a combination of the reflected light wave signals.

[0054] On the other hand, the light components L3', L4', and L5' respectively reflected from the perfused tissue layers S3, S4, and S5 are made to travel a greater distance into the tissue 50 until they are reflected towards the light detector 26. The greater distances traveled by the light components L3', L4', and L5' are compared with respect to the light signal entering perpendicularly to the surface of the tissue 50. Therefore, the light components L3', L4', and L5' can interact with a larger amount of the corresponding perfused tissue layers S3, S4, and S5, such that the amount of pulsatile AC information contained in the light components L3', L4', and L5' is significantly increased.

[0055] Now refer to Figure 5b , Figure 5b which shows a simplified schematic diagram of Figure 5a according to one or more illustrative aspects of the present disclosure to illustrate the characteristics of the region of light interaction in the perfused tissue layers S1 to S5. The region 58a (shown shaded) includes the intersection of the illumination sector 56a with the perfused layers S3 to S5 that coincide within a part of the sector 54. The illumination sector 56a is formed by the light signal 34a (not shown) reflected from the reflective surface 32a as the reflected light 34b'. The light signals L3', L4', and L5' are reflected from the perfused tissue layers S3, S4, and S5 towards the light detector 26. The receiving field of view of the light signals received by the light detector 26 is indicated by the sector 54. The light intersection region 58a in the perfused tissue layers S3, S4, and S5 thus depends on the angle α with respect to the dashed line 28, such that the light components L3', L4', and L5' are reflected from the perfused tissue layers S3, S4, and S5 towards the light detector 26.

[0056] Thus, by reducing (or completely eliminating) the amount of the light components L0’, L1’, and L2’ reflected from the non-perfused tissue layers by the lights S1 and S2 (as Figure 5a shown), the baseline DC component in the optical signal measured by the photodetector 26 in the reflectance measurement is significantly reduced. On the other hand, since the optical paths of the light components L3’, L4’, and L5’ reflected from the perfused tissue layers towards the photodetector 26 are increased due to the angle α. The light components L3’, L4’, and L5’ indicate a stronger interaction with the perfused tissue layers S3, S4, and S5. Therefore, the light components L3’, L4’, and L5’ may contain significantly more blood-related information and contribute a larger pulsatile AC component to the optical signal measured by the photodetector 26.

[0057] Now referring to Figure 5c , Figure 5c FIG. 10 shows a partial cross-sectional side view of a sensor device 10 and its application to a tissue 50 in accordance with one or more illustrative aspects of the present disclosure. Figure 5c Similar to Figure 5a , one light source is laterally positioned at a shorter distance d2 to the right of the photodetector 26 when compared with another light source 22 that is laterally positioned at a larger distance d1 to the right of the photodetector 26. In the following description, attention is focused on the light source 22 that is laterally positioned at a larger distance d1 to the right of the photodetector 26 from the photodetector 26. The light source 22 includes a lens 36 that is laterally offset to the left towards the photodetector 26. The optical signal 34a still emits from the light source 22 at an angle perpendicular to the first planar surface of the substrate 20.

[0058] However, different from Figure 5a , the lens 36 collimates the optical signal 34a into a collimated beam 34d. The lens 36 minimizes the divergence and / or scattering of the light rays of the optical signal 34a. However, different from Figure 5a , the collimated beam 34d is not at a perpendicular angle to the first planar surface of the substrate 20. The collimated beam 34d is reflected as a reflected light 34b” from the surface 32b of the reflector 24 at an angle β laterally to the right of the light source 22 with respect to the dashed line 28. The angle β may not be as sharp as the angle α because the lens 36 is laterally offset to the left of the light source 22 towards the reflective surface 32a. The lens 36 may also include a polarization filter (not shown) that polarizes the collimated beam 34d. The reflector 24 that is laterally positioned to the right of the light source may also include a reflective surface 32a.

[0059] Now referring to Figure 5d , Figure 5d FIG. 11 shows one or more illustrative aspects of the present disclosure Figure 5cA simplified schematic diagram to illustrate the characteristics of the region of light interaction in the perfused tissue layers S1 to S5. Region 58b (shown shaded) includes the interaction of the illumination sector 56b with the perfused layers S3 to S5 that overlap within a portion of sector 54. The illumination sector 56b is formed by an optical signal 34b (not shown) that is reflected from the reflective surface 32b as the reflected light 34b”. Optical signals L3”, L4” and L5” are reflected from the perfused tissue layers S3, S4 and S5 towards the optical detector 26. The optical signals L3”, L4” and L5” are reflected towards the optical detector 26. The receiving field of view of the optical signals received by the optical detector 26 is indicated by sector 54.

[0060] The alternating current (AC) in the optical detector 26 can be the result of the optical detection of the light wave signal of the light 34b” reflected from the (capillary) blood vessel 16, and this alternating current (AC) may originate from cardiac activity. Among them, the direct current (DC) in the optical detector 26 can be the result of the optical detection of the light wave signal of the light 34b” reflected from other parts of the tissue 50 and the light wave signal directly reflected without passing through the surface layers S1 and S2 of the tissue 50. Therefore, the light intersection region 58a in the perfused tissue layers S3, S4 and S5 depends on the angle β with respect to the dashed line 28, such that the light components L3”, L4” and L5” are reflected from the perfused tissue layers S3, S4 and S5 towards the optical detector 26. In addition, the baseline DC component in the optical signals L0”, L1” and L2” measured by the optical detector 26 in the light intersection region 58b is reduced significantly more than the DC component measured by the optical detector 26 shown by the light intersection region 58a. Therefore, the light components L3”, L4” and L5” reflected towards the optical detector 26 may contain significantly more blood-related information and contribute a larger pulsating AC component to the optical signals measured by the optical detector 26.

[0061] Now refer to Figure 5e , Figure 5e A partial cross-sectional side view of the sensor device 10 and its application to the tissue 50 is shown in accordance with one or more illustrative aspects of the present disclosure. Figure 5e Similar to Figure 5a , except that a light source 22 is shown as having an optical signal 34a emitted from the light source 22. The light source 22 is laterally located at a longer distance d1 to the right of the optical detector 26 compared to another light source 22 that is laterally located at a shorter distance d2 to the right of the optical detector 26. The optical signal 34a from the light source 22 is emitted perpendicular to both the first planar surface and the second planar surface. The optical signal 34a is reflected as the reflected light 34b”’ by the reflective surface 32a of the reflector 24 at an angle α’ with respect to the dashed line 28.

[0062] The angle α' of the orientation of the reflected light 34b''' allows the light source 22 to be positioned at a relatively long distance d1 near the light detector 26. The relatively long distance d1 near the light detector 26 can ensure that the light components L0''', L1''', and L2''' of the reflected light 34b''' are reflected from the unperfused tissue layers S1 and S2 at significantly smaller acute angles with respect to the light direction towards the light detector 26 compared to the light components L0', L1', and L2' of Figure 5a . The light direction towards the light detector 26 can be perpendicular to both the first planar surface and the second planar surface. Therefore, the number of light components L0''', L1''', and L2''' reflected from the unperfused near-surface tissue layers S1 and S2 towards the light detector 26 is reduced, providing an improved SNR and AC / DC ratio.

[0063] Wherein, the alternating current (AC) in the light detector 26 can be the result of the optical detection of the light wave signal of the light 34b'' reflected from the (capillary) blood vessel 16, and this alternating current (AC) may originate from cardiac activity. Wherein, the direct current (DC) in the light detector 26 can be the result of the optical detection of the light wave signal of the light 34b'' reflected from other parts of the tissue 50 and the light wave signal directly reflected without passing through the surface layers S1 and S2 of the tissue 50. On the other hand, compared with positioning the light source 22 at a shorter distance d2, since the light source 22 is positioned at the distance d1, the light components L3''', L4''', and L5''' reflected from the distal perfused tissue layers S3, S4, and S5 towards the light detector 26 travel a greater distance. The greater distance traveled by the light components L3''', L4''', and L5''' interacts with a larger amount of the corresponding perfused tissue layers S3, S4, and S5, such that the amount of pulsatile AC information contained in the light components L3''', L4''', and L5''' is significantly increased.

[0064] Now referring to Figure 6 , Figure 6 shows a plan view and a side view cross-section BB of the sensor device 10 according to one or more illustrative aspects of the present disclosure. The plan view shows a plurality of light apertures 60 placed in concentric circles (shown by dashed lines) positioned in the substrate 20 around the light detector 26. The side view cross-section BB shows a plurality of light sources 22 mechanically and electrically attached in the substrate 20. The substrate 20 can also provide electrical attachments (not shown) to the light sources 22 and the light detector 26. The electrical attachments can include traces providing electrical interconnections between the light sources 22 with each other, connections to the light detector 26, and additional components. The microcontroller can be connected, for example, to the electrical interconnections as described above with respect to Figure 4 . The light sources 22 and the light detector 26 are shown as being embedded in the surface of the substrate 20.

[0065] Positioned and operatively attached between the light source 22 and the aperture 60 is a reflector 24, which may be implemented as an optical fiber cable. Light emitted from the light source 22 may be transmitted from the light source 22 to the aperture 60 through the optical fiber cable according to the total internal reflection (TIR) characteristics of the optical fiber cable. The substrate 20 may be an opaque material and may also be made of a material rigid enough not to deform when the sensor device 10 is pressed against the tissue under examination. For two light sources 22 laterally positioned to the left and right of the light detector 26, a possible light emission at an angle α at a distance d2 controlled by a microcontroller is shown. The operation of the two light sources 22 laterally positioned to the left and right of the light detector 26 is described in detail above with respect to Figure 5a and Figure 5b For one light source 22 laterally positioned to the right of the light detector 26, a possible light emission at an angle α' at a distance d1 controlled by a microcontroller is shown. The operation of one light source 22 laterally positioned to the right of the light detector 26 is described in detail above with respect to Figure 5a 、 Figure 5b and Figure 5e For one light source 22 laterally positioned to the left of the light detector 26, a possible light emission at an angle β at a distance d1 controlled by a microcontroller is shown. The operation of one light source 22 laterally positioned to the left of the light detector 26 is described in detail above with respect to Figure 5c and Figure 5d Additional light sources 22 are shown with possible light emissions at angles δ' and δ respectively to the left and right of the light detector 26.

[0066] The light source 22 may also include or may not include a lens 36 (not shown) for collimating the optical signal emitted from the light source 22 into the optical fiber cable. The lens 36 may be positioned at the end of the optical fiber cable and attached to the first planar surface of the substrate 20 shown by the dashed line 28. The light source 22 may also include or may not include a polarization filter (not shown) for polarizing the collimated optical signal and / or the optical signal from the light source 22. The polarization filter (not shown) may be mounted on the first planar surface of the substrate 20 shown by the dashed line 28.

[0067] Now referring to Figure 7 , Figure 7 A plan view of the sensor device 10 according to one or more illustrative aspects of the present disclosure is shown. The plan view shows the four-leaf clover shape of the reflector 24. With Figure 4Similarly, multiple four-leaf clover-shaped reflectors 24 can be positioned concentric to each other with respect to the center of the first planar surface where the light detector 26 of the substrate 20 is located. Two light sources 22 are shown at respective distances d3 and d4. However, multiple light sources can be positioned at other parts of the four-leaf clover shape of the reflector 24 and, similarly, there can be multiple four-leaf clover-shaped reflectors 24. The side cross-section of the four-leaf clover shape of the reflective surface of the reflector 24 is, for example, linear, convex, concave, or parabolic, as Figures 3a to 3c and Figure 3f shown.

[0068] Now referring to Figure 8 , Figure 8 a two-dimensional view of the underside of the sensor device 10 in accordance with one or more illustrative aspects of the present disclosure is shown. The substrate 20 is shown as having two reflectors 24 mechanically attached to the substrate 20. The two reflectors 24 are concentric to each other. The light detector 26 is positioned in the center of the smaller reflector 24 and is mechanically and electrically attached to the trace 80. Similarly, the light source 22 is mechanically and electrically attached to the trace 80. The trace 80 provides the interconnection between the light source 22 and the control line to the driver circuit associated with each light source 22. The ribbon cable 80 is mechanically and electrically attached to the substrate 20 and provides the connection port 82a. The connection port 82a provides the connection to the trace 80. This connection can allow further electrical connection to the microprocessor and / or the display 13 as described above. The sensor device 10 can be housed in a housing 12 as Figure 1 shown.

[0069] Note that the reflective measurement techniques disclosed herein are also very useful for portable devices because the improved SNR ratio and AC / DC ratio provided by the reflective measurement techniques reduce the signal distortion caused in the measurement signal due to the movement of the body part / organ to which the device is attached.

[0070] The structure of the present invention enables the emission of various wavelengths and the measurement of various characteristics. Certain wavelengths are reflected differently from the same tissue under examination. Therefore, the present invention also discloses the selection of the optimal combination of the angle between the light emitter and the light detector and the distance between them.

[0071] As described above and shown in the related figures, the present invention provides a structure for implementing a reflective measurement configuration with a significantly improved SNR ratio and AC / DC ratio to measure the biological characteristics of a tissue / object under examination. Although specific embodiments of the present invention have been described, it should be understood that the present invention is not limited thereto, as those skilled in the art can make modifications, particularly in accordance with the foregoing teachings. As will be understood by those skilled in the art, the present invention can be implemented in multiple ways using one or more of the above techniques, all of which are within the scope of the present invention.

Claims

1. A device, the device comprises: a substrate including a connection port, wherein the substrate includes traces for implementing a circuit of the substrate, and wherein the circuit is connected to the connection port; an optical sensor mechanically attached to a first planar surface of the substrate and electrically attached to the circuit; a light source, wherein the light source is mechanically attached to the first planar surface and electrically attached to the circuit, wherein the light source is positioned transversely to the optical sensor at a first distance, and wherein an optical signal of the light source is emitted from the light source at an angle perpendicular to the first planar surface; and a reflector mechanically attached to the first planar surface and positioned between the optical sensor and the light source, wherein the reflector covers the light source and the optical signal is substantially reflected by the reflector to laterally exit the optical sensor at an acute angle with respect to a line parallel to the first planar surface.

2. The device according to claim 1, wherein, a profile of a cross-section of a surface of the reflector perpendicular to the first planar surface is at least one of a linear profile, a concave profile, a convex profile, and a parabolic profile.

3. The device according to claim 1, wherein, the first distance between the optical sensor and the light source is established in response to a profile of the reflector around the optical sensor.

4. The device according to claim 1, wherein, the light source includes a lens configured to collimate the optical signal of the light source at an angle perpendicular to the first planar surface.

5. The device according to claim 1, wherein, the light source includes an offset lens configured to collimate the optical signal of the light source at a second angle laterally away from an angle perpendicular to the first planar surface.

6. The device according to claim 5, wherein, the light source includes a lens configured to polarize the optical signal of the light source at a third angle perpendicular to the first planar surface.

7. The device according to claim 3, further comprises: a second reflector, wherein the second reflector surrounds the reflector; a second light source, wherein the second light source is mechanically and electrically attached to the first planar surface and the circuit, respectively, wherein a second optical signal of the second light source is emitted from the second light source at an angle perpendicular to the first planar surface, and wherein the second optical signal is substantially reflected by the second reflector to laterally exit the optical sensor at an acute angle with respect to a line parallel to the first planar surface, and wherein a second distance between the optical sensor and the second light source is established in response to a profile of the second reflector.

8. The device according to claim 7, wherein, a profile of a cross-section of a surface of the second reflector perpendicular to the first planar surface is at least one of a linear profile, a concave profile, a convex profile, and a parabolic profile.

9. The device according to claim 1, wherein, The profile of a cross-section of the reflector perpendicular to the first planar surface is at least one of a linear profile, a concave profile, a convex profile, and a parabolic profile.

10. The apparatus according to claim 1, wherein, the second planar surface of the reflector can be placed on the tissue under examination to measure biological characteristics of the tissue under examination, wherein the second planar surface is parallel to the first planar surface.

11. The apparatus according to claim 10, further comprising an attachment device for attaching the apparatus to the tissue under examination, wherein, the tissue under examination is in contact with the second planar surface of the reflector.

12. The apparatus according to claim 7, further comprising a control unit operably connected to the substrate and configured to select at least one of the parameters of the optical signal or the second optical signal applied to the tissue under examination, wherein, the parameter is at least one of wavelength and light intensity.

13. The apparatus according to claim 12, wherein, the control unit is configured to: select at least one of the optical signal or the second optical signal and apply it to the tissue under examination; sense from the tissue under examination a reflected optical signal from at least one of the optical signal and the second optical signal applied in response to at least one of the parameter and the corresponding first distance and second distance; and receive and process measurement data of the reflected optical signal sensed by the optical sensor to determine biological characteristics of the tissue under examination, wherein the biological characteristics include at least one of heart rate, oxygen saturation, hemoglobin level, blood pressure, cardiac output, stroke volume, sweating, glucose level, bilirubin level, and fat level.

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