Optoelectronic device and method for measuring an organic tissue

Abstract

An optoelectronic device and method for measuring organic tissue is provided that can improve optically performed biological and / or biosignal measurements. An optoelectronic device for measuring the organic tissue is attached to the organic tissue. A semiconductor optical emitter repeatedly outputs infrared pulses towards the tissue. An array of single photon avalanche diodes is aimed at the organic tissue to detect photons of the optical pulse that have interacted with the organic tissue. After output of each optical pulse, a timing unit determines the time of flight of the photons of each optical pulse within a time measurement range. A data processing unit estimates a physiological state of the tissue within at least one time window shorter than the time measurement range based on at least one of the number of detections within the time window and the distribution of detections within the at least one time window.

Description

Technical Field

[0001] The present invention relates to a optoelectronic device and method for measuring organic tissues.

Background Art

[0002] Variations in the oxygen content of blood and the pulsation of the heart can be optically measured in a non-invasive manner using a transmissive oximeter. An oximeter attached to a fingertip or earlobe typically has an LED (light emitting diode) that continuously lights up, but a laser that outputs infrared light can also be used, and the oximeter measures the absorbance that depends on the oxygenation of hemoglobin. A reflectance oximeter measures the light scattered and / or reflected back from a body part, rather than the light traveling from one side to the other of a body part such as the chest or arm, and basically performs measurements in the same manner as transmissive measurements, except for this point. However, these measurements do not function well for, for example, skin, muscle, and venous blood.

[0003] Time-domain near infrared spectroscopy based on the transmission and reception of short light pulses and the determination of the time duration between them is also used to provide concentration values of the oxygenation level of hemoglobin. However, the development of these devices is not complete. Therefore, improvement of optically performed biological measurements and / or biosignal measurements is desired.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention aims to improve measurements.

Means for Solving the Problems

[0005] The present invention is defined by the independent claims. Embodiments are defined by the dependent claims.

[0006] Hereinafter, an example of an embodiment of the present invention will be described as just one example with reference to the accompanying drawings.

Brief Description of the Drawings

[0007]

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Modes for Carrying Out the Invention

[0008] The following embodiments are merely examples. In this specification, reference may be made to "an" embodiment in several places, but such an expression does not necessarily mean that each such reference is to the same (singular or plural) embodiment, or that its features apply only to a single embodiment. It is also possible to combine the single features of different embodiments to provide other embodiments. Furthermore, the words "comprising" and "including" should not be understood as limiting the described embodiments to consisting only of the recited features, and such embodiments may also include features / structures not specifically mentioned. All such combinations are considered possible as long as they do not result in a structural or logical contradiction.

[0009] Note that although the figures show various embodiments, these are simplified diagrams showing only some of the structural and / or functional entities. The connections shown in the figures can mean logical or physical connections. It will be apparent to those skilled in the art that the devices described may also include functions and structures other than those described in the figures and the text. Some of the details of the functions, structures, and signaling used for measurement and / or control are understood to be irrelevant to the actual invention. Therefore, there is no need to explain these in further detail here.

[0010] FIG. 1 shows an example of an optoelectronic device 100 that utilizes the flight time of photons of an optical pulse. A semiconductor optic radiation source 102 repeatedly outputs infrared pulses. In one embodiment, the semiconductor optic radiation source 102 can include a CMOS (complementary metal oxide semiconductor) source. The optic radiation source 102 can include one or more optically radiating semiconductor lasers. The plurality of semiconductor lasers can be in the form of an array.

[0011] In certain embodiments, the duration of the optical pulse can be, for example, less than about 1 ns. In certain embodiments, the duration of the optical pulse can be, for example, less than about 500 ps.

[0012] The repetition of the optical pulses can be regular or irregular. The repetition can have, for example, a specific frequency. The repetition rate can be adjustable.

[0013] The optical pulses are directed towards the organic tissue, which is shown in more detail in FIGS. 2, 3 and 4. In certain embodiments, for example, the organic tissue can be a piece of meat. The organic tissue can be a biological tissue. In certain embodiments, for example, the organic tissue can be an animal tissue. In certain embodiments, for example, the organic tissue can be a mammalian tissue such as that of a human. The organic tissue of a living animal can be considered to have three basic layers, namely the skin, fat and muscle, from the surface towards the interior, as shown in FIGS. 2 and 3. In certain embodiments, an animal such as a human can wear the optoelectronic device 100.

[0014] In certain embodiments, for example, the organic tissue can be a plant tissue such as wood, grass or moss. The organic tissue of a plant can be considered to have three basic layers, namely the epidermal tissue, the ground tissue and the vascular tissue, from the surface towards the interior, as shown in FIGS. 2, 3 and 4. However, the number of layers may vary, or these layers may not be important for the measurements shown in this document.

[0015] An organic tissue can include one or more organs. A tissue of a single organ is an aggregate of similar cells that function similarly. Blood is both a tissue of cells and a fluid substance. The physiological state of blood can mean hemoglobin level, the trend of hemoglobin level, and / or the difference between oxygenated hemoglobin and deoxygenated hemoglobin. In addition to or instead of this, the physiological state of blood can also mean the variation of blood volume as a function of time within the tissue, i.e., the heartbeat of the heart. Correspondingly, the physiological state of a plant tissue can depend on at least one fluid substance within the tissue.

[0016] An array 106 of single - photon avalanche diodes 400 of a photoreceptor 104, an example of which is shown in FIG. 4, is also directed towards the tissue. The fact that the single - photon avalanche diodes 400 are directed towards the organic tissue means that the fields - of - views 402 of the single - photon avalanche diodes 400 are directed towards the organic tissue. The single - photon avalanche diodes 400 are configured to detect photons of the light pulse that interacted with the organic tissue.

[0017] The single - photon avalanche diodes (SPADs) 400 of the photoreceptor 104 operate in Geiger mode rather than in linear mode. Therefore, the output of the single - photon avalanche diodes 400 is binary, indicating only detection or non - detection triggered by a single photon.

[0018] FIG. 2 shows an example of a measurement in which a radiation source 102 and a photoreceptor 104 are attached to the skin or the epidermal layer.

[0019] FIG. 3 shows an example of using an optical transmission cable 300 and an optical reception cable 302. The optical cables 300 and 302 can include one or two or more optical fibers. In FIG. 3, the optical cables 300 and 302 are adjacent to each other, but they can also be coaxial. Only the radiation source 102 has the optical transmission cable 300, and it is also possible for the light receiver 104 that does not include the optical reception cable 302 to contact the skin or the epidermal layer. Alternatively, only the light receiver 104 has the optical reception cable 302, and it is also possible for the radiation source 102 that does not include the optical transmission cable 300 to contact the skin or the epidermal layer.

[0020] A timing unit 108 including an electric circuit determines the time interval between the output of an optical pulse and the reception of each photon of the optical pulse from the tissue. The term "determine" in the present application can also mean, in its various grammatical forms, calculation, operation, data processing for deriving a result, or search in a database, etc. As a result, "determine" can also mean selecting or sorting, etc.

[0021] The optical pulse transmitted from the radiation source 102 can travel along various paths through the tissue, indicated by dashed lines in FIGS. 1 to 4. The radiation source 102 and the light receiver 104 can be connected such that when the optical pulse is transmitted toward the tissue, a reference signal 114 is transmitted to the light receiver 104 at the same time to determine the output moment of the optical pulse. A part of the optical pulse can be transmitted to the light receiver 104 via a partial reflection mirror or a prism, etc. as the reference signal 114 for determining the output moment of the optical pulse, while most of the optical pulse is transmitted toward the tissue. Alternatively, the radiation source 102 can also directly transmit another electric pulse or optical pulse as the reference signal 114 to the light receiver 104 for determining the output moment. Generally, the reference signal 114 has a predetermined time dependence with respect to the optical pulse transmitted toward the tissue for determining the time of flight.

[0022] A portion of the photons of the output optical pulse 500 is reflected and / or scattered from the tissue and hits the array 106 of single photon detectors 400. In any of these single photon detectors 400, photons can be detected as a result of high-speed breakdown in the detector 400. In a CMOS single photon detector, the detection timing jitter can be at a level of about 10 ps to 50 ps. Further, since a logic level signal (e.g., 3 V) can be immediately generated by this breakdown, an analog amplifier can be unnecessary. The light receiver 104 can include a timing unit 108 that can have a plurality of time-digital converters (TDCs) in addition to the 2D array 106 of SPAD detectors 400. Generally, the timing unit 108 can be part of the light receiver 104 or can exist outside the light receiver 104.

[0023] In one embodiment, the semiconductor light source 102 can enable the array 106 of single photon avalanche diodes 400 for detection, but the array 106 of single photon avalanche diodes 400 can control the time-digital converter. That is, the time-digital converter consumes electrical energy only in conjunction with the detection of photons in the single photon avalanche diode 400, and thus energy is generally conserved. The length of the time measurement range 510 can be determined using the delay from the transmission of the optical pulse. Detection is stopped after this predetermined delay. The time measurement range 510 can be based on the time range of the time-digital converter.

[0024] Therefore, time-digital conversion can be realized with a resolution of, for example, about 10 ps to 50 ps, and the arrival time of the detected photons can be measured to reconstruct the distribution of the flight time of the photons.

[0025] Accordingly, the function of the time-to-digital converter is to measure the interval between the emitted laser pulse 500 and the breakdown that occurred in all SPAD detectors 400 that detected photons. These intervals are the transit times of photons from the radiation source 102 through the organic tissue to the photoreceiver 104.

[0026] FIG. 5 shows an example of the output optical pulse 500 and the received optical pulse 502 that interacted with the organic tissue. The x-axis is time T on an arbitrary scale, and the y-axis is the detection intensity and the number of detections on an arbitrary scale. The timing unit 108 determines the flight time of the photons of each optical pulse within the time measurement range 510 after the output of each optical pulse. The time range 510, which is the allowable range for measuring the flight time of photons, can start after a certain dead time from the output of the optical pulse so that, for example, reflections from the optical components of the device, the hair(s), other extensions, and / or the layer(s) of liquid or droplets on the outer surface of the tissue and / or the outer surface of the tissue itself are excluded from the measurement. Each flight time is based on the output time of the optical pulse from the semiconductor light radiation source 102 and the detection time of the photons of the optical pulse 502 by the single-photon avalanche diodes 400 of the array 106.

[0027] Due to scattering within the tissue, the received optical pulse 502 is much wider than the output optical pulse 500. The data processing unit 110 estimates or determines the physiological state of the tissue within at least one time window 504, 506, 508 that is shorter than the time measurement range 510, based on at least one of the number of detections within each time window 504, 506, 508 and the distribution of detections within at least one time window 504, 506, 508. In this way, the organic tissue can be hierarchically measured regardless of the layered or non-layered structure of the organic tissue. Here, the term "estimate" can mean, in its various grammatical forms, calculations, operations, data processing, or searches in a database for at least approximate results.

[0028] A physiological state can define or estimate the function of at least one organ of an organic tissue or at least a part of at least one organ. Various changes in the organic tissue can cause a change in the transit time of photons, thereby making the shape of the optical pulse 502 interacting with the organic tissue depend on the change in the tissue. That is, the transit time of photons is a function of the state of the organic tissue. Shape means the distribution of detections over a certain period. Instead of or in addition to this, the number of detections at a specific point in time or within a time window can also vary as a function of the state of the organic tissue.

[0029] In one embodiment, each of the single photon avalanche diodes 400 can detect a single photon of each optical pulse scattered from the tissue towards the array 106.

[0030] In one embodiment, the array 106 of single photon avalanche diodes 400 can detect at least one of the number of detections of at least one wavelength mainly absorbed by blood containing deoxygenated hemoglobin and the number of detections of at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin. Deoxygenated hemoglobin mainly exists in veins. Deoxygenated hemoglobin exists in blood that is not saturated with oxygen. Oxygenated hemoglobin mainly exists in arteries. Oxygenated hemoglobin exists in blood that is saturated with oxygen.

[0031] Figure 6 shows an example of how deoxygenated hemoglobin and oxygenated hemoglobin affect the shape and / or the number of detected light pulses. The y-axis shows the intensity of the light pulse 500 and the number of detected received light pulses 502 on an arbitrary scale, and the x-axis shows the time T on an arbitrary scale. In a sense, Figure 6 is a histogram showing the received pulse 502 as bars. On the time scale, the width of each bar represents the integration period for counting detections for one light pulse. For more reliable measurements, the total number of detections of multiple light pulses can also be counted for each bar (this is done in the example of Figure 6). The integration period of one bar can be determined, for example, by the time resolution of time-to-digital conversion. Thus, for example, the integration period can be from about 10 ps to 50 ps, i.e., it can be the time width of each bar. However, any other integration period can also be used. Any bar can be used alone as a time window for performing measurements. However, measurements can also be performed over multiple bars, such as within time windows 504, 506, and 508.

[0032] Time window 504 can be related to skin or epidermal tissue. Time window 506 can be related to fat or basic tissue. Time window 508, which has a longer flight time than time windows 504 and 506, can be considered to be related to the muscle of an animal. The higher the degree of oxygenation of hemoglobin in the blood in the muscle, the fewer the number of detections within the time window 508 related to the muscle. The difference between oxygenated hemoglobin and deoxygenated hemoglobin in the blood in the muscle can also be seen from the shape of the received light pulse 502. That is, the shorter the received light pulse 502 (refer to the solid line), the more oxygenated hemoglobin is present in the muscle. Corresponding changes can also be observed in plants.

[0033] To detect fluctuations in blood volume within tissue based on changes in light absorption, optical photoplethysmogram (PPG) measurement can be used. In the embodiments of this document, the fluctuations in blood volume can be detected by utilizing the flight time of photons of each light pulse such that the number of detected photons in at least one time window is determined. The number of detections is related to the absorption of the photoplethysmogram measurement. In certain embodiments, the measurement rate of the fluctuations in blood volume can be about 10 measurements per second. In certain embodiments, the measurement rate of the fluctuations in blood volume can be about 5 measurements per second.

[0034] The optical signal X received as a function of time t from a certain depth dk of the tissue dk (t) can be expressed in mathematical form as follows: X dk (t)=H dk (t)+D dk (t) Here, H dk (t) is the time variation of the intensity, that is, the number of detections due to the fluctuations in blood volume at depth dk, namely the pulsation of the heart, and D dk (t) includes the light loss as a function of time and other time variations such as the movement of the tissue that can be regarded as disturbances. The movement of the tissue can be caused by, for example, the movement of the body or limbs.

[0035] The received optical signal X dn (t) can be expressed in the form of a group of equations in mathematical form as a function of time from depth d1 to dn of the tissue: X d1 (t)=H d1 (t)+D d1 (t) X d2 (t)=H d2 (t)+D d2 (t) : X dn (t)=H dn (t)+D dn (t) These can be represented as matrices: X d (t)=Hd (t) + D d (t) Here, X d (t), H d (t) and D d (t) is a time-dependent matrix.

[0036] There is a one-to-one correspondence between the depths d1 to dn and the time windows w1 to w of the measured flight times. The time windows w1 to w n can also be regarded as a range of flight times. That is, the data processing unit 110 can execute the estimation of the physiological state of the tissue as a function of time inside each of the plurality of time windows. Since different levels of tissue respond differently to movements and contact variations, the disturbance D n (t) varies as a function of depth and thus as a function of the time window, but the variations in blood volume, i.e., each phase of the heartbeat, occur synchronously at all depths and time windows. For this reason, as shown in FIG. 7, the data processing unit 110 can cancel or reduce the disturbance and reliably separate and determine the variations in blood volume, i.e., the heartbeat, based on the estimation even under the disturbance. The heartbeat of the heart, which can also be called the heart rate, can be separated from the received signal using, for example, principal component analysis (PCA), independent component analysis (ICA), Kalman filter, digital filter, neural network, artificial intelligence, machine learning, etc. Those skilled in the art are proficient in the cancellation, reduction, and / or separation of the disturbance itself and the useful signal. dk (t)

[0037] As described, data processing unit 110 estimates the physiological state in at least one specific depth range 504, 506, 508, w1 - wn within the tissue using detected photons that are organized and interacted within at least one time window 504, 506, 508, w1 - wn that is shorter than the time measurement range 510. Each of the at least one time window 504, 506, 508, w1 - wn corresponds to a specific depth range d1 - dn within the tissue. Thereafter, data processing unit 110 can estimate the physiological state in at least one specific depth range 504, 506, 508, w1 - wn based on the number of detections within each of the at least one time window 504, 506, 508, w1 - wn. Alternatively, data processing unit 110 can also estimate the physiological state based on the detection distribution of a plurality of time windows 504, 506, 508, w1 - wn. Of course, combinations of these are also possible.

[0038] FIG. 8 shows an example in which a part of the SPADs 400 of the array 106 is covered by a polarizing plate 800. Using the polarizing plate 800, more information about the tissue can be provided.

[0039] As a result, data processing unit 110 can estimate or determine the physiological state related to lactate. In one embodiment, data processing unit 110 can estimate or determine, for example, the accumulation of lactate within the tissue.

[0040] In one embodiment, the data processing unit 110 can perform an estimation based on the number of detections of at least one wavelength absorbed by blood mainly containing oxygenated hemoglobin. In one embodiment, the data processing unit 110 can perform an estimation based on the difference between the number of detections of at least one wavelength absorbed by blood mainly containing deoxygenated hemoglobin and the number of detections of at least one wavelength absorbed by blood mainly containing oxygenated hemoglobin. In one embodiment, the data processing unit 110 can perform an estimation based on the number of detections of at least one wavelength absorbed by blood mainly containing oxygenated hemoglobin, and the difference between the number of detections of at least one wavelength absorbed by blood mainly containing deoxygenated hemoglobin and the number of detections of at least one wavelength absorbed by blood mainly containing oxygenated hemoglobin. In one embodiment, at least one of these measurements can be performed from muscle.

[0041] FIG. 9 shows an example trend of how the lactic acid concentration, oxygenated hemoglobin concentration, and deoxygenated hemoglobin concentration change in muscle tissue during incremental exercise from rest to maximum load. The vertical axis indicates the lactic acid concentration and hemoglobin concentration on an arbitrary scale. The horizontal axis indicates time on an arbitrary scale.

[0042] During high-intensity activities, an athlete's respiratory rate increases to deliver sufficient oxygen to the working muscles to produce adenosine triphosphate (ATP) molecules through aerobic respiration. When the training load is high, oxygen delivery to the muscles is too slow to produce sufficient energy for the muscles. In this case, the body's energy production transitions to anaerobic conditions at a certain threshold (see FIG. 9). Under this condition, energy production is replaced by lactic acid fermentation. Therefore, by measuring the oxygenation of hemoglobin (oxygenated hemoglobin HbO2 and / or deoxygenated hemoglobin Hb) as described above, the transition point to anaerobic conditions and the lactic acid threshold of a specific muscle can be determined.

[0043] During incremental exercise, oxygenated hemoglobin HbO2 gradually decreases until the blood lactate threshold and then decreases. This decrease is abrupt and may be linear. Blood lactate gradually increases until it reaches the lactate threshold and then increases. This increase is abrupt and may be linear. Therefore, there is a correlation between the measured oxygenated hemoglobin HbO2 and the lactate threshold.

[0044] In one embodiment, by evaluating the gradient change of oxygenated hemoglobin HbO2 and / or deoxygenated hemoglobin Hb in the blood, the conversion point of lactate production, i.e., the approach to the lactate threshold, can be determined. When the decrease in oxygenated hemoglobin HbO2 and / or the increase in deoxygenated hemoglobin Hb in the blood continue over a predetermined time T0, and / or the change in oxygenated hemoglobin HbO2 and / or deoxygenated hemoglobin Hb relative to the initial level LO is greater than a predetermined change PT. In this way, physical exercise can be reduced or stopped before it is detected that lactate production is at the lactate threshold. The predetermined time T0 and the predetermined change PT can be adaptable. The predetermined time T0 and the predetermined change PT can vary depending on, for example, gender, type of exercise, length of exercise, age, physical condition, amount of previous physical training, etc.

[0045] In one embodiment, the conversion point of lactate production, i.e., the lactate threshold, can be determined by evaluating how abrupt the change in the gradient of oxygenated hemoglobin HbO2 and / or deoxygenated hemoglobin Hb in the blood is. In one embodiment, when the gradients are different at different time points, the lactate threshold exists between these time points. In one embodiment, when the difference in gradients at different time points is greater than a predetermined value PV, it can be considered that the lactate threshold exists between these time points. In this way, physical exercise can be reduced or stopped when it is detected that lactate production has reached the lactate threshold. The predetermined value PV can vary depending on, for example, gender, type of exercise, length of exercise, age, physical condition, amount of previous physical training (e.g., professional, advanced amateur, regular amateur / exerciser, occasional exerciser, non-exerciser).

[0046] The difference ΔHb between oxygenated hemoglobin HbO2 and deoxygenated hemoglobin Hb also shows a conversion point and a variation trend similar to those of lactic acid in the blood. According to physiological theory, the curve of the difference ΔHb shows a variation period around the analyzed oxygen dissociation point. It is exactly this variation period during which the metabolic state of the body changes. The difference ΔHb can be a function of oxygenated hemoglobin HbO2 and deoxygenated hemoglobin Hb, such as the difference between them. Alternatively or in addition, the difference ΔHb can also be a function of the change in oxygenated hemoglobin HbO2 and the change in deoxygenated hemoglobin Hb.

[0047] In one embodiment, the data processing unit 110 can determine the temporal variation in the detection of a plurality of output light pulses 500 within a window 506 of an intermediate portion of the optical pulse 502 received after interaction with a tissue assumed to be adipose tissue during examination of an animal. Next, the data processing unit 110 can correct the temporal variation in the detection in a time window 508 having a flight time longer than the detection in the window 506 of the intermediate portion of the optical pulse 502 based on the temporal variation in the detection within the window 506 of the intermediate portion of the optical pulse 502 received after interaction with the tissue assumed to be adipose tissue. Since adipose tissue has less blood circulation than other tissues and is less susceptible to interference from tissues related to the deeper time window 508 than the skin, the data processing unit 110 can determine and reduce the effects of noise and tissue interference.

[0048] Correspondingly, the basic tissue of a plant can also be used to determine the temporal variation in the detection of a plurality of output light pulses 500. And since the basic tissue of a plant is also less susceptible to interference from tissues related to the deeper time window 508 than the epidermis, the data processing unit 110 can determine and reduce the effects of noise and tissue interference.

[0049] Noise and tissue interference may be caused by the movement of an animal or a plant.

[0050] In one embodiment, at least one of the timing unit 108 and the data processing unit 110 can be programmed such that at least one of the time measurement range 510 and at least one of the at least one time windows 504, 506, 508 can be repeatedly adjusted. At least one of the at least one time windows 504, 506, 508 can be adjusted manually or automatically. Manual adjustment can be performed through the user interface 112. In this way, for example, an organic tissue can be scanned in the depth direction.

[0051] In one embodiment, the semiconductor light source 102 and the array 106 of single photon avalanche diodes 400 can be separated by a non-zero distance on the skin, and an example of this is shown in FIG. 2.

[0052] In the embodiment shown by way of example in FIG. 4, the output portion 310 of the semiconductor light source 102 and the input portion 310 of the array 104 of single photon avalanche diodes 400 can be optically coaxial on the skin. In this embodiment, the light radiation strikes the same area of the skin or epidermis both when entering and when exiting an animal or plant.

[0053] In the embodiment illustrated in FIGS. 10 and 11, the optoelectronic device 100 can include alone a wearable muscle measurement device 600 that is attached to a muscle area of the body 12 of an animal such as a human. The muscle area can be, for example, the thigh or upper arm, calf, or neck. The muscle measurement device 600 can include a wireless transmitter 610, a semiconductor light source 102, an array 106 of single photon avalanche diodes 400, and a timing unit 108. The optoelectronic device can also include a single wearable device 602 that includes a wireless receiver 612 and a data processing unit 110. The single wearable device 602 can be attached, for example, to the wrist. The wireless transmitter 610 can transmit information regarding the detection to the wireless receiver 612, and the wireless receiver 612 can supply this information to the data processing unit 110 to determine the physiological state of the tissue in the muscle area of the body 12. The user interface 112 can present the results to a user or individual or staff performing the examination. The wireless transmitter 610 and the wireless receiver 612 can perform the transmission using electromagnetic radiation such as radio frequency, Bluetooth® or WLAN (Wireless Local Area Network).

[0054] In one embodiment, the single wearable device 602 can further include a further semiconductor light source 102' and a further array 106' of single photon avalanche diodes 400 to determine the physiological state of the tissue of the wrist. The further semiconductor light source 102' and the further array 106' of single photon avalanche diodes 400 are each similar to the semiconductor light source 102 and the array 106, respectively.

[0055] In the embodiment illustrated in FIG. 12, the data processing unit 110 can include one or more processors 900 and one or more memories 902 that include computer program code. The one or more memories 902 and the computer program code, together with the one or more processors 900, can cause the data processing unit 110 to estimate at least the physiological state of the tissue.

[0056] FIG. 13 shows an example of a single circuit board 1000 of a optoelectronic device for measuring organic tissue. The circuit board 1000 can include a semiconductor light emitter 102, an array 106 of single photon avalanche diodes 400, and a data processing unit 110. By integrating electronic circuits on a single circuit board, the optoelectronic device can be made wearable. In certain embodiments, the weight of the optoelectronic device can be kept below 100 g by correctly selecting the packaging and case materials. In certain embodiments, the weight of the optoelectronic device can be kept below 50 g by correctly selecting the packaging and case materials. In certain embodiments, the weight of the optoelectronic device can be kept below 10 g.

[0057] In the method described, a histogram can be formed based on the detection timing of photons scattered from various and / or determined depths of the tissue. That is, the depth can be determined by selecting or setting a suitable time window. From these histograms, i.e., digital time-of-flight, multiple biological signals and / or unintended tissue movements (disturbances) that appear in different forms at different depths while being mixed can be separated. Separation is possible due to differences in depth. FIG. 14 is a flowchart of the measurement method. In step 1200, the semiconductor light emitter 102 repeatedly outputs infrared pulses towards the tissue.

[0058] In step 1202, an array 106 of single photon avalanche diodes 400 directed towards the tissue detects photons of the light pulse that interacted with the tissue.

[0059] In step 1204, the timing unit 108 determines the time-of-flight of the photons of each light pulse within the time measurement range 510 after the output of each light pulse.

[0060] In step 1206, the data processing unit 110 estimates the physiological state in at least one specific depth range within the tissue using detected photons that interacted with the tissue within at least one time window 504, 506, 508, w1 to wn that is shorter than the time measurement range 510. Each of the at least one time window (504, 506, 508, w1 to wn) corresponds to a specific depth range (d1 to dn) within the tissue, and the estimation is based on at least one of the number of detections within at least one time window 504, 506, 508, w1 to wn and the distribution of detections within at least one time window 504, 506, 508, w1 to wn.

[0061] The method for estimating the physiological state of the tissue in FIG. 13 can be implemented as a logic circuit solution or a computer program. The computer program can be arranged on a computer program distribution means for its distribution. The computer program distribution means is readable by a data processing device, and the data processing device encodes computer program commands, executes measurements, and optionally controls a process based on the measurements.

[0062] The computer program can be distributed using a distribution medium that can be any medium readable by a controller. The distribution medium can be a program storage medium, a memory, a software distribution package, or a compressed software package. In some cases, distribution can be performed using at least one of a short-range wireless communication signal, a short-distance signal, and a remote communication signal.

[0063] It will be apparent to those skilled in the art that the concept of the present invention can be implemented in various ways as technology advances. The present invention and its embodiments are not limited to the above-described example embodiments and can vary within the scope of the claims.

Description of Reference Numerals

[0064] 100 Optoelectronic device 102 Semiconductor light source 104 Light receiver 106 Array of single photon avalanche diodes 108 Timing unit 110 Data processing unit 112 User interface 114 Reference signal

Claims

1. A optoelectronic device for measuring an organic tissue, attached to the organic tissue, comprising: A semiconductor light source configured to repeatedly output infrared pulses towards the tissue; An array of single-photon avalanche diodes configured to be directed towards the tissue and detect photons of the light pulses that have interacted with the tissue; A timing unit configured to determine the flight time of each photon of the light pulses within a time measurement range after each output of the light pulses; A data processing unit configured to estimate the physiological state in at least one specific depth range within the tissue using detected photons that have interacted with the tissue within at least one time window shorter than the time measurement range; Wherein each of the at least one time window is configured to correspond to a specific depth range within the tissue, and the estimation is based on at least one of the number of detections within each of the at least one time window and the distribution of the detections in a plurality of time windows; An optoelectronic device characterized by the above.

2. Each of the single-photon avalanche diodes is configured to detect each single photon of the light pulses scattered from the tissue towards the array. The device according to claim 1.

3. The array of single-photon avalanche diodes is configured to detect at least one of the number of detections at at least one wavelength mainly absorbed by blood containing deoxygenated hemoglobin and the number of detections at at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin. The data processing unit is configured to estimate the physiological state related to lactate based on at least one of: The number of detections at at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin; and The difference between the number of detections at at least one wavelength mainly absorbed by blood containing deoxygenated hemoglobin and the number of detections at at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin. The device according to claim 1.

4. The data processing unit is configured to perform the estimation of the physiological state of the tissue within each of a plurality of the time windows as a function of time, and separate and determine the heartbeat of the heart based on the estimation. The device according to claim 1 or 3.

5. ​ ​ ​ At least one of the timing unit and the data processing unit is programmable such that at least one of the time measurement range and the at least one time window is repeatedly adjustable. The apparatus according to claim 1.

6. The array of the semiconductor light source and the single photon avalanche diodes are separated by a non-zero distance. The apparatus according to claim 1.

7. The output portion of the semiconductor light source and the input portion of the array of single photon avalanche diodes are optically coaxial. The apparatus according to claim 1.

8. The optoelectronic device is attached to a muscular area of the body and includes a muscular measurement device including a wireless transmitter, the semiconductor light source, the array of single photon avalanche diodes, and the timing unit, and a separate wearable device including a wireless receiver and the data processing unit. The wireless transmitter is configured to transmit information regarding detection to the wireless receiver, and the wireless receiver is configured to supply the information to the data processing unit to determine the physiological state of the tissue in the muscular area of the body. The apparatus according to claim 1.

9. The separate wearable device includes an additional semiconductor light source and an additional array of single photon avalanche diodes to determine the physiological state of the tissue. The apparatus according to claim 8.

10. The data processing unit includes one or more processors and one or more memories including computer program code. The one or more memories and the computer program code are configured, together with the one or more processors, to cause the data processing unit to estimate at least the physiological state of the tissue. The apparatus according to claim 1.

11. A method for measuring organic tissue, comprising: repeatedly outputting infrared pulses toward the tissue by a semiconductor light source; detecting photons of the light pulses that interacted with the tissue by an array of single photon avalanche diodes directed toward the tissue; determining, by a timing unit, the flight time of each photon of the light pulses within a time measurement range after each output of the light pulses; The data processing unit uses detected photons that interacted with the tissue within at least one time window shorter than the time measurement range to estimate the physiological state in at least one specific depth range within the tissue; including, each of the at least one time window corresponds to a specific depth range within the tissue, and the estimation is based on at least one of the number of detections within the at least one time window and the distribution of the detections within the at least one time window; A method characterized by this.

12. The method is detecting at least one of the number of detections of at least one wavelength mainly absorbed by blood containing deoxygenated hemoglobin and the number of detections of at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin by the array of single photon avalanche diodes; The data processing unit the number of detections of at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin, and the difference between the number of detections of at least one wavelength mainly absorbed by blood containing deoxygenated hemoglobin and the number of detections of at least one wavelength mainly absorbed by blood containing oxygenated hemoglobin, estimating the physiological state related to lactic acid based on at least one of them; The method according to claim 11, further including this.

13. The data processing unit executes the estimation of the physiological state of the tissue within each of the plurality of time windows as a function of time; separating and determining the heartbeat based on the estimation; The method according to claim 11 or 12, characterized by including this.

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