Optical detection device for a fluid in a line section of a medical device

Abstract

The invention relates to an optical detection device and to an assembly comprising such an optical detection device and a light-transmissive line section (1) in which a fluid (2) is guided. The invention relates to a method for detecting a measuring light sensor (10), comprising exactly one measuring light source (6) and exactly one measuring light sensor (10), a measuring light region (18) extending along a measuring light axis (16) from the measuring light source (6) to the measuring light sensor (10). For self-testing or functional testing, a test light sensor (8) is arranged adjacent to the measurement light source (6), which test light sensor can be optically operatively connected to the measurement light source (6), and a test light source (12) is arranged adjacent to the measurement light sensor (10), which test light source can be optically operatively connected to the measurement light sensor (10).

Description

Technical Field

[0001] The present disclosure relates to a preferably automatic self-test or functional test of an optical detection device for a fluid in a line section of a medical device and in particular to a corresponding optical detection device. Background Art

[0002] In medical devices, such as dialysis devices, of particular interest are optical sensor methods that can analyze blood, for example, of a circuit system, contactlessly and non-destructively. Contactless in this context means that the blood does not come into contact with materials other than the standard materials of the circuit system. Non-destructive in this context means that the measuring method does not have any negative effects on the cellular or molecular components of the blood, does not weaken or even destroy them. This is particularly important, for example, in dialysis, because in dialysis patients the formation of red blood cells is affected and any loss of red blood cells can permanently affect the health and well-being of the patient.

[0003] In the case of patients with limited or absent renal function, waste products of natural metabolism are removed by renal replacement or dialysis methods. Here, substances are removed from the blood by contacting it with a dialysate, which is taken from the patient and conducted outside the body, wherein the blood and the dialysate are in contact with each other not directly but via a membrane arranged outside the body. The dialysate is doped with various salts and thus produces diffusion and convection effects, which are responsible for transferring substances of the blood through the membrane into the dialysate. After the removal of some of the waste products has been completed, the blood treated in this way is again delivered to the patient.

[0004] Known optical sensors in medical devices such as dialysis devices are, for example, hematocrit sensors (based on red and infrared light), blood leak detectors (measuring the red color in the dialysate in the dialysate circuit) and red sensors (indicating the presence of blood in the blood hose).

[0005] The present disclosure now relates to an optical detection device (especially a red sensor) for a fluid (especially blood) in a line section (especially a hose section) of a medical device, such as a dialysis device. The optical detection device is constructed or prepared and designed to perform a preferably automatic self-test.

[0006] Prior art

[0007] EP 2767821 A1 discloses an optical detection device having a light source, the light of which is directed along a measuring section through a fluid, wherein the light is detected by a light detector. In order to perform a self-test, a reference light detector is provided, which is arranged on the same side of the fluid to be analyzed as the light source. In this case, the reference light detector is arranged directly adjacent to the light source and optically coupled thereto.

[0008] EP 2605810 B1, EP 2579910 B1 and EP 2579911 B1 respectively disclose an optical detection device having a reference light detector, which is arranged on the same side of the fluid to be analyzed as the light source. Here, the reference light detector is arranged spaced apart from the light source and the measuring section on the side of the measuring section or in the direction of the light. The reference light detector receives light from the light source, which is split via a beam splitter.

[0009] In addition, optical detection devices for fluids (blood or saline solution or air) in blood hose sections of dialysis devices with two redundant channels are known from the internal prior art. Each channel has an LED on a first side of the hose and a photodiode on a second side of the blood hose opposite the first side. The two measuring sections are parallel to each other and oriented perpendicular to the hose section. The two measuring sections are spaced apart from each other along the line section or the flow direction of the fluid. The two LEDs can emit corresponding transmission signals in the form of light and corresponding test signals along the corresponding measuring sections through the hose section. This results in operational safety, because by comparison it is possible to identify when a channel fails. Summary of the invention

[0010] The object of the present disclosure is to provide an optical detection device for a fluid contained in a light-transmissive line section, in particular for blood guided in a hose section, and an assembly having such an optical detection device, which is designed, prepared and arranged for carrying out a self-test or a functional test. In this case, the space requirement and the expenditure in terms of device technology as well as the computing power required for operation and during the self-test or the functional test should be reduced.

[0011] This object is achieved with the optical detection means according to the invention and the assembly according to the invention.

[0012] According to the present disclosure, the optical detection device has exactly one measuring light source and exactly one measuring light sensor, wherein a measuring light area extends from the measuring light source along a measuring light axis to the measuring light sensor. The detection device is arranged and designed for optical detection of a fluid guided in a light-transmitting line section (preferably a hose section). The term "measuring light area" is to be understood as a preferably rotationally symmetrical, elongated, preferably very narrow space, which is defined or filled by the measuring light radiated from the measuring light source to the measuring light sensor. In other words, the "measuring light area" is a partial spatial area of ​​a space filled with fluid (light-transmitting line section), wherein the measuring light is transmitted only through this partial spatial area in a manner intended in terms of measurement technology. The measuring light area defined in this way passes through the space / line section filled with fluid and thus passes through the fluid to be detected. The measuring light axis is preferably the center axis of the measuring light area and is further preferably perpendicular to the space / line section filled with fluid. On the first side (radially viewed) of the line section (that is, in the region of the first circumferential area of ​​the light-transmitting line section, for example according to Figure 1 At 9:00 o'clock), a test light sensor is arranged adjacent to the measuring light source (preferably on a side of the measuring light source that is substantially facing away from the line section), which test light sensor can be optically (optically) operatively connected to the measuring light source.

[0013] The measuring light sensor is placed on a second side (circumferential region) of the line section which is opposite the first side (viewed radially or along the diameter) defined in this way (for example according to Figure 1 3:00 of the embodiment of the present invention), wherein the test light source is arranged adjacent to the measuring light sensor (preferably on a side of the measuring light sensor that is substantially facing away from the line section), and the test light source can be placed in an optical (optical) effective connection with the measuring light sensor. "Effectively connected" means that light can be transmitted from the light source to the light sensor for functional testing and / or self-testing.

[0014] Thus, an optical detection device is achieved which, on the one hand, can test its measuring light source on a first side of the line section by means of a test light sensor, without having to guide the test light required for this purpose from one side of the line section to the other side and, in particular, without having to guide it through the line section and the fluid and not being absorbed by it. The latter can therefore be referred to as a single-channel principle, according to which only the measuring light (in a single channel) is guided from the light source side to the measuring light sensor side, while the light for the functional test / self-test is always generated and measured on the side on which the measuring light source or the measuring light sensor, respectively, is located.

[0015] In principle, on the other hand, the measuring light sensor can be tested on the second side of the line section by means of a test light source, without the test light required for this having to be guided from one side of the line section to the other side and in particular without having to pass through (or bypass) the line section and the fluid and either be absorbed by them or deflected multiple times.

[0016] With the optical single-channel detection device according to the present disclosure, a reduced structural space and a smaller required computing power for self-testing or functional testing are obtained compared to detection devices with reflectors and compared to dual-channel detection devices of the prior art. Since only one measuring light axis is required instead of two measuring light axes spaced apart from each other along the line section, the structural space of the detection device is reduced along the line section in the flow direction of the fluid, and due to the simple design, components and costs can be saved. In addition, since the single-channel principle is adopted, clear measurement results can be obtained. In contrast, a dual-channel detection device has two measuring light sensors, which will obtain different measurement values, so the measurement results are not clear. Therefore, the single-channel optical detection device of the present disclosure simplifies signal evaluation. In addition, due to the simplified structure, it is also easier to shield external light.

[0017] In other words, the test light sensor is set and / or designed and / or arranged to test / check the measuring light source (its functionality) or to test / check the measuring light source (its functionality) with the test light sensor. In other words, the test light sensor is set and / or designed and / or arranged to perform a functional test and / or a self-test of the measuring light source or to perform a functional test and / or a self-test of the measuring light source with the test light sensor.

[0018] In other words, the test light source is set and / or designed and / or arranged to test / check the measuring light sensor (its functionality) or to test / check the measuring light sensor (its functionality) with the test light sensor. In other words, the test light source is set and / or designed and / or arranged to perform a functional test and / or a self-test of the measuring light sensor or to perform a functional test and / or a self-test of the measuring light sensor with the test light source.

[0019] Since the functional test of the measuring light source can be carried out completely on the first side of the line section without having to guide the test light through the line section or around the line section via a semi-transparent reflector, the test light sensor can have a lower sensitivity than the measuring light sensor. The detection means is thus simplified in terms of device technology and is cost-effective.

[0020] Since the test of the measuring light sensor can be carried out completely on the second side of the conducting section without having to irradiate the test light through the line section and be absorbed by it, the test light source can have a lower light intensity than the measuring light source. The detection device is thus simplified in terms of device technology and is cost-effective.

[0021] The two light sources are preferably LEDs and / or the two light sensors are preferably photodiodes or phototransistors.

[0022] For example, when a commercially available LED is used as a measuring light source, the measuring light region incident on the measuring light sensor is usually only a (e.g., concentric) partial region of the main light region defined or illuminated by the measuring light source. In a preferred design of the detection device, the test light sensor is arranged outside the measuring light region and at least in sections within the main light region. Then, during a self-test or functional test, the relatively strong main light of the measuring light source can be detected by the test light sensor without having to irradiate the main light through a line section or guide it through a semi-transparent reflector.

[0023] For example, when a commercially available LED is used as a measuring light source, the LED can define or illuminate a scattered light area, in which the measuring light area and, if necessary, the main light area are arranged. In another preferred embodiment of the detection device, the test light sensor is arranged outside the measuring light area and in the scattered light area. Then, during the self-test, the relatively weak scattered light of the measuring light source can be detected by the test light sensor. This provides advantages in a space-saving arrangement and when the measuring light source and the test light sensor are installed on the first side of the line section.

[0024] If the center axis of the test light sensor is arranged perpendicularly to the measuring light axis, advantages result in a space-saving arrangement and when the measuring light source and the test light sensor are mounted on a first side of the line section.

[0025] Preferably, a first circuit board is arranged on a first side of the line section, and a measuring light source and a test light sensor are fastened on the first circuit board.

[0026] In a particularly preferred embodiment of the detection means, the test light source is arranged on the second side outside the measuring light range, so that the test light source does not cause a shadowing of the measuring light incident on the measuring light sensor.

[0027] In a preferred embodiment of the detection device, the measuring light sensor is arranged in the scattered light area of ​​the test light source. During a self-test or functional test, the (relatively weak) scattered light of the test light source can then be detected by the measuring light sensor. This results in advantages in a space-saving arrangement and when the test light source and the measuring light sensor are mounted on the second side of the line section.

[0028] If the radiation direction of the test light source is arranged perpendicularly to the measuring light axis, advantages result in a space-saving arrangement and in the installation of the test light source and the measuring light sensor on the second side of the line section.

[0029] Preferably, a second circuit board is arranged on the second side of the line section, on which the measuring light sensor and the test light source are fastened.

[0030] In a preferred embodiment of the detection means, the two printed circuit boards are arranged parallel to one another and perpendicular to the measuring light axis.

[0031] The measuring light source or the measuring light sensor may have a cuboid housing or a cuboid body, which is abutted or soldered on a circuit board with a large side or with a bottom. Preferably, the measuring light source and the measuring light sensor each have a cuboid housing or a cuboid body, which is abutted or soldered on a corresponding circuit board with a corresponding large side or with a bottom. Therefore, in the case of flat-designed LED functional blocks (such as SMD components), these LED functional blocks are flatly mounted on the corresponding circuit board.

[0032] The test light source or the test light sensor may have a cuboid housing or a cuboid body, which rests on the circuit board with its narrow side. Preferably, the test light source and the test light sensor each have a cuboid housing or a cuboid body, which rests on the corresponding circuit board with its corresponding narrow side. Therefore, in the case of flat-designed LED functional blocks (such as SMD components), these LED functional blocks are mounted vertically or perpendicularly on the corresponding circuit board.

[0033] If the measuring light source and / or the test light source radiates green light with a wavelength of 490 to 575 nm, i.e. between 490 and 575 nanometers, preferably 520 to 530 nm, it is possible to particularly well identify whether the fluid contained in the line section is a red fluid or a colorless fluid. In particular, it is possible to identify whether blood or another fluid (saline solution or air) is in the line section.

[0034] The assembly according to the present disclosure has the above-mentioned optical detection device and a light-transmissive line section through which the measuring light area and the measuring light axis extend. On the mutually opposite sides of the line section, on the one hand, a measuring light source is arranged together with a test light sensor, and on the other hand, a measuring light sensor is arranged together with a test light source.

[0035] In a particularly preferred embodiment of the assembly, the line section is a blood hose section and the measuring light sensor and the test light sensor are red sensors. The assembly can thus be installed and used on a blood hose of a dialysis apparatus, for example on a blood hose that is returned to a patient. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Preferred embodiments of the present disclosure are described below based on the accompanying drawings.

[0037] Figure 1 is a functional diagram of an embodiment of components of a detection device of the present disclosure.

[0038] Figure 2 yes Figure 1 A cross-sectional view of an embodiment of the invention; and

[0039] Figure 3 yes Figure 1 and Figure 2 A perspective view of components of a first side of an embodiment of a detection device.

[0040] Among them: 1-line section / blood hose section; 2-fluid; 3-first side; 4-second side; 6-measuring light source; 8-test light sensor; 10-measuring light sensor; 12-test light source; 14-sending signal; 15-receiving signal; 16-measuring light axis; 18-measuring light (area); 20-scattered light of measuring light source (area); 22-test sending signal; 24-test receiving signal; 26-test receiving signal; 28-test sending signal; 30-scattered light of test light source (area); 31-irradiation direction of test light source; 32-first circuit board; 34-second circuit board. DETAILED DESCRIPTION

[0041] Figure 1 is a functional diagram of an exemplary embodiment of an assembly having a detection device according to the present disclosure. The detection device has a (light-transmissive) line section 1, which is Figure 1 The line section is shown in cross section in the embodiment shown and can be formed, for example, by a blood hose section, which is arranged between an extracorporeal blood treatment machine, such as a dialysis device, and a patient and in which the blood is returned to the patient in the blood hose section after successful removal of waste. In other words, an extracorporeal blood treatment machine or dialysis machine having an extracorporeal blood circuit is provided, preferably having a (patient) blood withdrawal line section (hose), a (patient) blood return line section (hose) and a dialysis filter optionally connecting these two sections, wherein a light-transmissive line section 1 having a detection device arranged / integrated on / in the blood withdrawal line section and / or the blood return line section.

[0042] The light-transmissive line section 1 is preferably made of silicone or PVC, but can also be designed as a glass tube or a plastic glass tube. In the light-transmissive line section as part of the blood hose section 1 (not shown in detail), it is to be determined or recognized by means of a detection device (using light waves) whether the patient's blood or another (flushing) liquid, such as saline solution or (only) air, is present in the light-transmissive line section of the blood hose section.

[0043] Radially to the blood hose section 1, viewed on (preferably diametrically) opposite sides, a first side (circumferential region) 3 of the light-transmissive line section is defined on the one hand, and a second side (circumferential region) 4 is defined on the other hand. On the first side 3, a (main) measuring light source 6 and a test light sensor 8 are arranged. On the second side 4, a measuring light sensor 10 and a (side) test light source 12 are arranged.

[0044] During normal operation of the optical detection device thus formed for the fluid 2 currently located in the light-transmitting line section 1, the measuring light source 6 receives a transmission signal 14 from a control / regulatory device, not shown in further detail, which controls the measuring light source 6 so that it emits measuring light along a measuring light axis 16 oriented transversely through the blood hose 1, which passes through the light-transmitting line section 1 and is received by the measuring light sensor 10 on the other second side 4 (minus a certain absorption portion due to the fluid contained in the line section), so that it generates a corresponding reception signal 15 and outputs it to the control / regulatory device, not shown in further detail.

[0045] In this case, the light emitted by the measuring light source 6 as a whole can in principle be divided into three parts or spatial light regions:

[0046] A main light region of the light emitted by the measuring light source 6 is defined, which main light region can be intuitively described as a main light cone of the measuring light source 6 , wherein the main light has a relatively high light intensity.

[0047] Since only a portion of the main light can be precisely directed (focused) onto the measuring light sensor 10 arranged on the second side 4, this portion is referred to as the measuring light region 18. The measuring light region is preferably smaller than the diameter of the light-transmitting line section 1. The measuring light region 18 is therefore a preferably concentric partial region of the main light region (and also of the cross section of the light-transmitting line section 1) and is defined in such a way that its (entire) measuring light is directed (focused) onto the measuring light sensor 10. Figure 1 Schematically in the form of the outermost measuring light beam (upper and lower arrows) the circumferential boundaries of the measuring light region 18 are shown. In the special case where the entire main light emitted by the measuring light source 6 is (precisely) directed (focused) to the measuring light sensor 10, the measuring light region 18 corresponds to the main light region.

[0048] Furthermore, the main light region is surrounded by a scattered light region 20 (not directed onto measuring light sensor 10) which may have the same light frequency as the main light region, but of course has a reduced light intensity. Figure 1 Only the scattered light beams (curved arrows) from this scattered light region 20 are shown symbolically.

[0049] The three (or in special cases two) light regions defined in this way are the spaces which are flooded with light during normal operation of the optical detection device.

[0050] In the automatic test operation of the optical detection device or in the automatic functional test, on the one hand, the function of the measuring light source 6 is tested on the first side 3, wherein a (predetermined) electrical test transmission signal 22 (for generating light with a predetermined optical frequency and / or light intensity) is transmitted to the first side, wherein / thereby (simultaneously) an electrical test reception signal 24 is generated by the test light sensor 8. In the embodiment shown in the figures, the test reception signal 24 is related to the received scattered light 20, which the test light sensor 8 receives from the measuring light source 6.

[0051] In an alternative embodiment not shown, the test light sensor 8 can generate an electrical test reception signal which, unlike the previously described embodiment, depends on the main light received by the test light sensor 8 from the measuring light source 6. In this alternative embodiment not shown, the test light sensor 8 is therefore arranged in the main light area of ​​the measuring light source 6 instead of in the measuring light area.

[0052] exist Figure 1 During the automatic test operation of the optical detection device of the embodiment shown in , the function of the measuring light sensor 10 is also tested on the second side 4, wherein an electrical test sending signal 28 for generating predetermined test light is transmitted to a test light source 12 arranged on the second side 4, wherein an electrical test receiving signal 26 is generated by the measuring light sensor 10 (simultaneously) and preferably depends on scattered light 30 (of the test light), and the measuring light sensor 10 receives the scattered light from the test light source 12.

[0053] In an alternative embodiment not shown, measuring light sensor 10 may generate an electrical test reception signal based on the main light of the test light received by test light source 12. To this end, test light source 12 is arranged on the second side so that its main light directly irradiates measuring light sensor 10.

[0054] In principle, therefore, only the main light of the measuring light unit 6 is guided from the first side 3 in the direction of the second side 4, and not also test light (either through a light-transmissive line section or at least partially surrounding this line section) as is known in the prior art, so that the detection device can in principle also be called a (safe) single-channel (red) light sensor.

[0055] Figure 2 yes Figure 1 , comprising an (optical) detection device, whose light sources and sensors are arranged on both sides 3, 4 of a light-transmissive line section 1 of a blood hose section. On the first side 3, a first circuit board 32 is arranged perpendicular to the measuring light axis 16, and on the second side 4, a second circuit board 34 is arranged perpendicular to the measuring light axis 16. The two circuit boards 32, 34 are therefore oriented parallel to each other.

[0056] In the embodiment shown, the two light sources 6, 12 are LED functional blocks and the two light sensors 8, 10 are photodiodes or phototransistors. The LED functional blocks and the photodiodes or phototransistors are surface mounted components (SMD components) having a rectangular parallelepiped housing or body.

[0057] It is shown that measuring light source 6 and measuring light sensor 10 are soldered with their large sides or bottoms (approximately lying flat) to the corresponding circuit boards 32 , 34 , while test light sensor 8 and test light source 10 are soldered with their narrow sides or edges (approximately standing upright) to the corresponding circuit boards 32 , 34 .

[0058] A center axis (not shown) of test light sensor 8 and an emission direction 31 of test light source 12 intersect measuring light axis 16 at right angles.

[0059] The result of the detection device being arranged at a maximum of 90° is that an automatic self-test or functional test is performed using scattered light 20, 30. Furthermore, this results in a space-saving arrangement of the housing of the assembly directly adjacent to the blood hose section 1, wherein a minimum of structural space is required, viewed along the blood hose section 1 in the flow direction of the blood.

[0060] Figure 3 yes Figure 1 and Figure 2 3 is a perspective view of the components of the first side 3 of an embodiment of the detection device in FIG. The first circuit board 32 and the measuring light source 6 and the test light sensor 8 are shown.

[0061] The measuring light source 6 radiates measuring light along a measuring light region 18 in the direction of the line section 1 (see Figure 1 and Figure 2 ). In this case, scattered light 20 is generated, which can be detected directly by the test light sensor 8, that is, it is not necessary to deflect / redirect the light by means of a reflector according to the prior art, and it is not necessary for the test light to pass through the light-transmissive line section 1 and the fluid contained therein, as is necessary in a two-channel detection device of the prior art.

[0062] Different from the embodiment shown, for example, a non-parallel arrangement of the two circuit boards is also possible. Therefore, the two circuit boards can also have a right angle with each other. Then, either the measuring light source rests on the first circuit board with its large side and / or with its bottom, and the measuring light sensor rests on the second circuit board with its narrow side. Or vice versa, the measuring light source rests on the first circuit board with its narrow side, and the measuring light sensor rests on the circuit board with its large side and / or with its bottom.

Claims

1. An optical detection device, which is configured and designed for optically detecting a fluid (2) guided in a light-transmissive line section (1), wherein: The detection device has exactly one measuring light source (6) and exactly one measuring light sensor (10), wherein a measuring light region (18) extends from the measuring light source (6) to the measuring light sensor (10) along a measuring light axis (16), characterized in that a test light sensor (8) is arranged adjacent to the measuring light source (6), the test light sensor can be optically effectively connected to the measuring light source (6) and the test light sensor is configured and designed to test the measuring light source (6), and a test light source (12) is arranged adjacent to the measuring light sensor (10), the test light source can be optically effectively connected to the measuring light sensor (10) and the test light source is configured and designed to test the measuring light sensor (10).

2. The optical detection device according to claim 1, characterized in that: The test light sensor (8) has a smaller light sensitivity than the measuring light sensor (10).

3. The optical detection device according to claim 1 or 2, characterized in that: The test light source (12) has a smaller light intensity than the measuring light source (8).

4. The optical detection device according to any one of the preceding claims 1 to 3, wherein: A main light area is defined by the measuring light source (6), the measuring light area (18) is arranged in the main light area, and the test light sensor (8) is arranged outside the measuring light area (18) and at least partially in the main light area.

5. The optical detection device according to any one of the preceding claims 1 to 4, wherein: A scattered light area (20) is defined by a measuring light source (6), in which the main light area and / or the measuring light area (18) are arranged, and the test light sensor (8) is arranged outside the measuring light area and inside the scattered light area (20).

6. The optical detection device according to any one of the preceding claims 1 to 5, characterized in that: The central axis of the test light sensor (8) is arranged perpendicular to the measuring light axis (16).

7. An optical detection device according to any one of the preceding claims 1 to 6, characterized in that The optical detection device has a first circuit board (32) on which the measuring light source (6) and the testing light sensor (8) are fastened.

8. The optical detection device according to any one of the preceding claims 1 to 7, characterized in that: The measuring light sensor (10) is arranged in a scattered light region (30) of the test light source (12).

9. The optical detection device according to any one of the preceding claims 1 to 8, characterized in that: The irradiation direction (31) of the test light source (12) is arranged perpendicular to the measurement light axis (16).

10. The optical detection device according to any one of the preceding claims 1 to 9, characterized in that: The optical detection device has a second circuit board (34) on which the measuring light sensor (10) and the test light source (12) are fastened.

11. The optical detection device according to claims 7 and 10, characterized in that: The two printed circuit boards (32, 34) are arranged parallel to each other and perpendicular to the measuring light axis (16).

12. The optical detection device according to claim 7 and 10 or claim 11, characterized in that The measuring light source (6) and the measuring light sensor (10) each have a cuboid housing or a cuboid body, which rests with the respective large sides and / or with the bottom on the respective circuit boards (32, 34).

13. The optical detection device according to claims 7 and 10 or according to claim 11 or according to claim 12, characterized in that The test light source (12) and the test light sensor (8) each have a cuboid housing or a cuboid body, and the housing / body rests on a corresponding circuit board (32, 34) with a corresponding narrow side.

14. The optical detection device according to any one of the preceding claims 1 to 13, characterized in that: The measuring light source (6) and / or the testing light source (12) irradiates light having a wavelength of 490 to 575 nm.

15. The optical detection device according to claim 14, characterized in that: The wavelength is between 520 and 530 nm.

16. An extracorporeal blood treatment machine having an extracorporeal blood circuit, the extracorporeal blood circuit having an optical detection device according to any one of the preceding claims 1 to 15 and having a light-transmitting line section (1), the measuring light axis (16) and the measuring light area (18) extending through the light-transmitting line section.

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