DEVICE FOR TEMPERATURE-COMPENSATED OPTICAL DETECTION OF THE OXYGEN CONTENT OF A FLUID

Description

[0001] The present invention relates to a planar layered component arrangement for temperature-compensated optical detection of an oxygen content of a fluid according to the appended claims.

[0002] A generic layered component arrangement is known from US 2013 / 0023782 A1. The layered component arrangement known from US 2013 / 0023782 A1 comprises a flat window body coated on one side with a luminophore. This document describes a sensor arrangement with such a layered component arrangement for measuring the oxygen concentration of a respiratory gas based on the known measuring principle of oxygen-induced luminescence quenching of luminophors. Luminophores present in the reaction layer body are excited by irradiation with the first electromagnetic radiation to emit a second electromagnetic radiation different from the first. The second electromagnetic radiation is generally longer-wavelength than the first electromagnetic radiation.

[0003] In simplified terms, the underlying measurement principle can be described as follows: Irradiation with the first electromagnetic radiation causes energy to be introduced into the luminophore. The luminophore releases the excitation energy imparted to the luminophore by irradiation with a certain time delay in the form of the second electromagnetic radiation. However, if the luminophore excited by irradiation with the first electromagnetic radiation comes into contact with oxygen, a radiation-free de-excitation of the luminophore occurs through energy transfer to the contacting oxygen. In this way, the oxygen present at the luminophore influences its radiation behavior in response to the excitation received by irradiation.

[0004] The oxygen contacting the luminophore influences its radiation behavior under otherwise identical excitation with respect to the intensity of the second electromagnetic radiation and the duration of the radiation of the second electromagnetic radiation. The evaluation of the radiation behavior of the luminophore, influenced by the presence of oxygen, in response to irradiation with the first electromagnetic radiation based on the temporal characteristics of the radiation behavior is considered more accurate than the evaluation based on the influenced intensity, since the evaluation based on the temporal characteristics of the radiation of the second electromagnetic radiation, in contrast to the evaluation based on its intensity, is unaffected or at least less strongly affected by age-related fading of the luminophore.

[0005] The emission behavior of luminophores is also influenced by the temperature of the luminophore, all other conditions being equal. This makes the evaluation of the emission behavior, which is usually observed sensorically, difficult in temperature-varying environments. A temperature-varying environment exists, for example, when measuring the oxygen concentration in a respiratory gas, which is usually delivered to the patient at a different temperature than the temperature at which it is exhaled after a certain amount of metabolism. The temperature of the expiratory respiratory gas can also change depending on the patient's state of health.

[0006] To solve this problem, US 2013 / 0023782 A1 proposes, according to one embodiment, forming the window body from a material permeable to infrared radiation and measuring the temperature of the luminophore-containing reaction layer body through the window body in a contactless manner using an infrared detector. This is intended to simultaneously detect the luminophore's temperature and its radiation behavior, so that the radiation behavior can be accurately evaluated with knowledge of the temperature.

[0007] According to a further embodiment of US 2013 / 0023782 A1, infrared radiation is detected by the window body in a contactless manner, wherein the window body is then to be made so thin that the temperature of its surface facing away from the surface coated with luminophore is approximately equal to the temperature of the luminophore.

[0008] A planar layered component arrangement for a sensor arrangement for measuring the oxygen content of respiratory gas is also known from US Pat. No. 7,833,480 B2. This document also teaches how to eliminate the inherent uncertainty in the evaluation of the detected radiation behavior due to the temperature dependence of the radiation behavior of luminophores by heating the reaction layer body to a constant, known temperature and maintaining it there. Thus, the temperature of the luminophores does not change during detection, and the resulting radiation signal can be evaluated.

[0009] The disadvantage of the latter solution is the high equipment complexity, since a heating device must be provided on the layered component arrangement, which must be supplied with energy. Furthermore, the additional heating device can distort the measurement result or not suppress the temperature dependence to the desired extent, since the measurement principle requires that the excited luminophore comes into contact with oxygen. Thus, a certain degree of convective heat transfer between the reaction layer body and the target fluid, whose oxygen content is to be measured, is unavoidable. Despite the provision of a heating device, the temperature of the luminophore during the measurement of its emission is not necessarily known precisely.

[0010] The solution proposed by the generic document US 2013 / 0023782 A1 for detecting the temperature of the reaction layer body and for data-based temperature compensation of the detected radiation behavior is also not without disadvantages.

[0011] Firstly, the generic solution involves two radiation sources and two radiation detectors in the same measurement chamber. The first radiation source is intended to excite the luminophore in the reaction layer body by emitting the first electromagnetic radiation. While this excitation typically does not occur in the infrared wavelength range of electromagnetic radiation, it cannot be ruled out that this first radiation source, in addition to the desired first electromagnetic radiation, also emits other wavelengths that extend into the infrared range and could thus constitute a source of interference.

[0012] The second radiation source is the luminophore of the reaction layer body, which emits both the second electromagnetic radiation in response to its excitation and infrared radiation corresponding to its temperature.

[0013] On the one hand, the wavelengths of both radiations: second electromagnetic radiation and temperature infrared radiation, can be close to each other and thus difficult to distinguish, which in turn forms a mutual source of interference between the respective signals.

[0014] Secondly, the known reaction layer body is wetted on one side with the target fluid, whose oxygen content is to be measured, and is detected on its opposite side with regard to the radiation emitted by it. Therefore, the known reaction layer body must be shielded from the first radiation source and the radiation detectors to prevent oxygen-containing fluid from reaching the luminophore of the reaction layer body from the detection side and distorting the detection of the radiation behavior.

[0015] The at least oxygen-tight shielding of the reaction layer body towards the first radiation source and the detector array must transmit both the second electromagnetic radiation and the temperature-infrared radiation as unaffected as possible in order to be able to record the radiation behavior of the reaction layer body as accurately as possible. This leads to a significant limitation of the materials that can be used for shielding. For some wavelength ranges of second electromagnetic radiation and temperature-infrared radiation, it may not be possible to find a material that transmits both electromagnetic radiations sufficiently unadulterated.

[0016] It is therefore an object of the present invention to further develop a generic planar layered component arrangement in such a way that the disadvantages mentioned above in connection with the known generic layered component arrangement are reduced or completely eliminated. The aim is therefore to provide a layered component arrangement that enables highly precise optical detection of the oxygen content of a fluid by temperature compensation of the detected radiation behavior of the reaction layer body, while simultaneously maintaining the simplest possible structural design.

[0017] This object is achieved according to the invention by a layered component arrangement having all the features of claim 1.

[0018] By separately forming the reaction layer and the temperature-sensing layer, the two layers are spatially separated and arranged on a fluid-carrying line or on a fluid-receiving vessel, so that the devices required for measuring the radiation emitted by both layers can be spatially separated from each other. This allows the radiation source of the first electromagnetic radiation to be arranged spatially separated and thus shielded from an infrared detector, since the radiation source only needs to irradiate the reaction layer, and the infrared detector only needs to detect the temperature-sensing layer. Thus, the radiation source of the first electromagnetic radiation is no longer a source of interference for the contactless temperature detection of the temperature-sensing layer.

[0019] Furthermore, the reaction viewing body and the temperature detection layer body can be arranged in measuring environments that are optimally adapted to their respective requirements, so that the detection of the second electromagnetic radiation from the reaction layer body can be carried out just as optimally as the detection of the infrared radiation from the temperature detection layer body.

[0020] When the present application refers to a laminated body, this means that this body, as a flat body, has significantly larger dimensions in two mutually orthogonal spatial directions than in its thickness direction, which is orthogonal to both of these spatial directions. The thickness direction is therefore always the shortest dimension of the laminated body.

[0021] In principle, it may be sufficient for the reaction layer and / or the temperature sensing layer to have only a single layer. However, each of the layers may have multiple layers if this is necessary or beneficial for its function or intended use.

[0022] One problem with the separate design of the reaction layer and the temperature-sensing layer lies in assessing the significance of the temperature measured on the temperature-sensing layer for the actual temperature of the reaction layer. The fundamentally possible use of an identical copy of the reaction layer as a temperature-sensing layer to detect only the second electromagnetic radiation on one of the two layers and only the infrared radiation on the other layer is, on the one hand, expensive and therefore economically questionable.Secondly, without guaranteeing a truly identical design of the two reaction layers and their arrangement under as identical operating conditions as possible during the detection of the radiation emitted by them, calibration is still necessary in order to be able to determine the actual temperature of the reaction layer with sufficient accuracy from the infrared radiation detected by the temperature detection layer. Finally, the second electromagnetic radiation that can be excited by the luminophore can interfere with the infrared radiation of the temperature detection layer.

[0023] Therefore, in order to ensure the simplest and most cost-effective construction of the planar layered component arrangement according to the invention, the temperature detection layer body is free of luminophore.

[0024] This ensures that a luminophore on the temperature-detecting visible body is not inadvertently stimulated to emit electromagnetic radiation, which could interfere with the detection of the temperature-related infrared radiation emanating from it. Since the most reliable possible transfer of the temperature of the temperature-detecting laminated body determined by infrared radiation detection to a temperature of the reaction laminated body assumed or determined on this basis can or should be achieved using a data processing device based on a previously performed calibration, the structural design of the temperature-detecting laminated body can be significantly simplified compared to that of the reaction laminated body.Therefore, it can generally be provided that the reaction layer body has a different layer structure than the temperature detection layer body, at least in sections, with regard to layer material and / or layer sequence and / or layer thickness.

[0025] For example, it can be provided that both layer bodies: reaction layer body and temperature detection layer body have a uniform substrate layer on which different functional layers are applied, for example at least one layer containing luminophore and another layer intended for temperature detection by detecting infrared radiation.

[0026] However, for reasons of the best possible functional fulfilment of the two layered bodies, it can also be considered that they are constructed completely differently and have a completely different layer structure with regard to at least one of the layer parameters mentioned above.

[0027] For the most meaningful and accurate detection result of the oxygen content in the fluid to be detected (measurement object fluid), it is advantageous if the detection of the radiation emanating from the layered component arrangement does not interfere with the fluid to be detected, and vice versa. For this purpose, according to an advantageous development of the present invention, the reaction layered body and the temperature detection layered body each have a fluid contact side, on which the respective layered body is designed for contact with the measurement object fluid, and a detection side opposite the fluid contact side, which is designed to interact with radiation detectors.

[0028] Non-contact optical sensing of the layered component arrangement discussed here is preferred not only because of the reduced risk of interference with the processes being recorded by the measurement technology itself. Contact temperature detection of the temperature of the reaction layer body using sensors and the like is also difficult or even impossible because most sensors that are sufficiently stable and robust detect temperatures and temperature changes too slowly and would therefore indicate a temperature that is not the actual temperature of the reaction layer body at the time of a detected radiation emission.

[0029] Temperature sensors that can detect temperature changes quickly enough, however, have proven to be too error-prone and not robust enough to be used in a safety-critical application, such as the detection of oxygen concentrations of a ventilation gas during artificial respiration.

[0030] Since it is therefore important that the temperature sensing layer, when it has the aforementioned sensing side and fluid contact side, transmits a temperature change on the fluid contact side to the sensing side as quickly as possible, it is advantageous if the temperature sensing layer comprises a layer of material with the best possible thermal conductivity, which can also be thin. For this purpose, the temperature sensing layer can be specifically provided with a metal foil.

[0031] The metal foil can in principle be any metal foil, for example a copper foil, which is, however, particularly susceptible to oxidation in an oxygen-containing environment and changes its properties with increasing oxidation. Therefore, an aluminum foil is preferably proposed as the metal foil, which is self-passivating and can therefore provide the same material properties over a long period of time. Furthermore, an aluminum foil, like other metal foils, can be formed with sufficient strength even with a thin foil thickness of less than 15 µm. Preferably, a metal foil, in particular the aforementioned aluminum foil, as part of the temperature-sensing laminate or as this laminate has a thickness in the range of 6 to 12 µm, preferably in the range of 8 to 11 µm. Due to the high thermal conductivity provided by metal, in particular aluminum, heat is quickly conducted through the material.Due to the low material thickness of less than 15 µm, the heat conduction path is also short, so that a temperature change on the fluid contact side can be detected on the detection side within a range of a few milliseconds.

[0032] The reaction layered body, on the other hand, can be constructed as a known reaction layered body and, for example, comprise a porous, oxygen-permeable substrate layer made of polyvinylidene fluoride. However, any known reaction layered body can be used in the layered component arrangement discussed here.

[0033] In order to further ensure that a temperature changing on the fluid side can be detected as quickly as possible on the detection side of the temperature detection layer body, according to a further development of the invention it is provided that an outer surface of the metal foil forms the fluid contact side of the temperature detection layer body.

[0034] Preferably, at least one layered body comprising the reaction layered body and the temperature-detecting layered body is flat. Particularly preferably, both layered bodies are flat in order to minimize any disruption to any flow of the fluid whose oxygen content is to be detected. If the at least one layered body comprising the reaction layered body and the temperature-detecting layered body is used to detect the oxygen content of a flowing fluid, then the at least one layered body, preferably both layered bodies, can be curved about an axis of curvature parallel to the flow direction of the fluid at the location where the at least one layered body is attached, in order to minimize disruption to the fluid flow of the measurement object. Preferably, the at least one layered body is curved only about this axis of curvature.

[0035] The laminated bodies can be adhesively bonded to the housing, for example, by a trace of adhesive applied to the detection side of the layered component arrangement, which leaves out a region of the detection side of the respective laminated body intended for radiation detection. This ensures that the radiation emission of the at least one laminated body and its detection by the adhesive are not disrupted.

[0036] Alternatively or additionally, one or both laminated bodies can be connected to the housing via an adhesive tape, wherein the adhesive tape is adhesively bonded partially to the fluid contact side and partially to the housing, leaving a region of the respective fluid contact sides unaffected. Thus, the contact of the at least one laminated body with the fluid is not disrupted by the adhesive tape.

[0037] In principle, the temperature-sensing layer body can comprise a substrate layer supporting a functional layer. This was already mentioned above. The substrate layer can, for example, be the aforementioned metal foil, which can be provided with sufficient stability at a low thickness. On the sensing side, the temperature-sensing layer body can comprise an emission layer with an emissivity of no less than 0.75, either indirectly (i.e., with the interposition of additional layers) or directly supported by the substrate layer.

[0038] Even better, the emissivity layer should have an emissivity of no less than 0.9. The higher the emissivity, the better the prevention of disturbing reflections on the sensing side of the temperature sensing layer. This ensures that the temperature sensing layer is indeed the source of the infrared radiation detected near its sensing side, and not merely reflected from the surface of the sensing side toward the corresponding detector.

[0039] In principle, it should not be ruled out that the emission layer and the substrate layer are of identical material, and that the emission layer on the detection side is formed by mechanical and / or chemical roughening of the surface of the substrate layer on the detection side. This is particularly relevant for substrate layers with an inherently high emissivity of more than 0.75.

[0040] Since the metal foil preferred as a substrate layer often has undesirably highly reflective surfaces, a separate emission layer on the substrate layer can be advantageous. To achieve the most favorable emission behavior in the infrared wavelength range, it is advantageous for the emission layer to contain color pigments. The color of the pigments plays only a minor role, since many color pigments are "black" in the infrared wavelength range and thus provide a sufficiently high emissivity. Nevertheless, the use of anthracite to black color pigments is preferred.

[0041] In tests, a carbon-based coating has proven effective as an emissive layer. For example, the emissive layer can be applied as a carbon-based paint. A carbon-based conductive paint from Peters GmbH & Co. KG in Kempen (Germany) with the designation "SD 2843 HAL" has proven suitable.

[0042] An epoxy can also form the emissive layer. Epoxies can also be applied to a substrate in thin layers, for example, by printing or spraying. After curing, they form a beneficially solid, robust surface. Potentially advantageous epoxies for forming an emissive layer are available under the product names EP 601 or EP 653 with USP Class VI from Polytec PT GmbH in Waldbronn, Germany. These epoxies should preferably be used filled with color pigments, preferably with black pigments for the reasons mentioned above.

[0043] Since the layered component arrangement discussed here is suitable and intended for directly detecting an oxygen partial pressure of a fluid and, derived therefrom, the oxygen content of the fluid, the present invention also relates to a reaction assembly comprising a housing and a layered component arrangement provided in the housing, as described and further developed above, wherein the housing has an opening through which a fluid can be introduced into the housing, wherein the housing has a reaction window through which the reaction layer body can be reached by the first electromagnetic radiation and which can be penetrated by the second electromagnetic radiation, and wherein the housing has a temperature detection window which is arranged spatially remote from the reaction window and which can be penetrated by the infrared radiation emitted by the temperature detection layer body.

[0044] The measuring fluid, whose oxygen partial pressure is to be measured, can be introduced into the housing for detection. With the separately designed and spatially separated windows (reaction window and temperature detection window), the electromagnetic radiation emanating from the respective layered bodies (reaction layered body and temperature detection layered body) can be detected at spatially separated locations, so that the electromagnetic radiation involved cannot interfere with each other.

[0045] In order to equip the housing as optimally as possible for detecting the electromagnetic radiation emanating once from the reaction layer body and again from the temperature detection layer body, the reaction window can be designed differently from the temperature detection window.

[0046] The structurally different design can be expressed, on the one hand, by a different choice of material. Alternatively or additionally, the reaction window can be thicker than the temperature detection window. A thickness of zero for the temperature detection window should be explicitly included. A sufficiently thick reaction window is also advantageous because the reaction window must not only allow the first and second electromagnetic radiation to pass through, but also shield the reaction layer body from the detection side against contact with oxygen that does not originate from the measurement object fluid.

[0047] By making the temperature detection window thinner, if no material that is optimally permeable to infrared radiation is available, the less optimal material can at least be made thin enough to have as little interference as possible.

[0048] However, the choice of an infrared-transmissive material can be omitted if the above-mentioned solution of a temperature detection window with a thickness of zero is used. Accordingly, according to a particularly preferred embodiment of the present invention, the reaction window comprises a material transparent to light in the optically perceptible wavelength range, and the temperature detection window comprises a hole extending through the housing in the direction of its thickness, which hole is covered by the temperature detection laminate.

[0049] Particularly when the temperature sensing laminate comprises the above-mentioned preferred metal foil, the hole penetrating a housing wall as a temperature sensing window can be securely and permanently covered with the temperature sensing laminate. The sensing side of the temperature sensing laminate is then preferably exposed for any infrared detector arrangement provided in the hole.

[0050] The hole penetrating the housing as a temperature detection window preferably has an increasing hole cross-sectional area as the housing side facing away from the temperature detection layer body approaches the housing side closest to the temperature detection layer body. The hole is preferably negatively conical, opening toward the temperature detection layer body, so that it can at least approximately correspond to a detection cone of an infrared detector for detecting infrared radiation emanating from the temperature detection layer body.

[0051] To prevent external interference, the housing surface bordering the hole between the housing's exterior and interior can be coated, particularly with a mirror finish. This prevents a housing made of transparent material from acting as an optical conductor and conducting electromagnetic radiation to the temperature sensing window that does not emanate as infrared radiation from the temperature sensing layer.

[0052] In principle, the housing can be cup-shaped, i.e., with only one opening through which the measurement object fluid can be introduced and discharged again. Such a housing can be used, for example, to determine the partial pressure of oxygen dissolved in liquid. However, for use in a ventilation device, a housing through which the measurement object fluid can flow is advantageous. Therefore, it is preferred that the housing have a further opening that is different from and located remote from the opening, such that fluid can flow through the housing between the opening and the further opening.

[0053] Thus, it is fundamentally possible to advantageously arrange the reaction assembly in a ventilation device in the main ventilation gas flow. A preferably compact reaction assembly can be achieved by providing the layered component arrangement between the opening and the further opening.

[0054] Preferably, the housing can be flowed through in a straight line in order to avoid turbulence of the fluid to be detected as it passes through the housing and thus as it passes the layered component arrangement.

[0055] In order to realize the particularly advantageous application of the reaction assembly discussed above in a ventilation device, according to an advantageous development of the present invention, the reaction assembly is designed for arrangement in a ventilation line arrangement of a ventilation device, wherein the reaction assembly is designed in the region of both the opening and the further opening with a connection formation for connection to a respective section of the ventilation line arrangement.

[0056] Advantageously, the reaction assembly is designed as an oxygen measuring cuvette. Such a measuring cuvette typically has at least one housing section configured as a parallelepiped. Preferably, the reaction assembly is arranged in such a parallelepiped section of the housing, with one surface of the parallelepiped section of the housing, preferably flat or curved around only one axis of curvature, preferably containing both the reaction window and the temperature detection window.

[0057] Since the described reaction assembly serves for the sensory detection of the oxygen partial pressure and the oxygen content of a fluid derived therefrom, the present application further relates to a sensor arrangement comprising a reaction assembly as described and further developed above, and further comprising a detector assembly, with a radiation source configured to emit the first electromagnetic radiation through the reaction window, a radiation detector configured to detect the second electromagnetic radiation through the reaction window, and an infrared detector configured to detect the infrared radiation emitted by the temperature detection layer body through the temperature detection window.

[0058] Preferably, the infrared detector and the radiation source are arranged in measuring rooms that are shielded from each other with respect to the first electromagnetic radiation and the infrared radiation in order to avoid mutual radiation-related interference as far as possible.

[0059] Although the sensor arrangement is preferably intended for use in a ventilation device or in conjunction with such a device, it should be noted that the sensor arrangement is fundamentally designed to detect any oxygen partial pressure of oxygen dissolved in a fluid. However, the fluid is preferably a ventilation gas.

[0060] To ensure a high degree of component hygiene for the reaction assembly that comes into direct contact with the fluid, it is advantageous, as already mentioned above, if the detector assembly can be detachably connected to the reaction assembly. The significantly more expensive detector assembly can thus be used sequentially with multiple reaction assemblies to detect oxygen levels in fluids.

[0061] Therefore, the aforementioned reaction assembly is preferably a single-use or disposable reaction assembly, which can be disposed of, for example, in clinical operation after a single use on a patient. In order to detachably connect a reusable detector assembly to the reaction assembly, in particular to the reaction assembly designed as an oxygen measuring cuvette, as simply and reliably as possible, and in particular with a degree of certainty regarding the possibility of confusion, the parallelepiped section is preferably designed as a cuboid section. Advantageously, the cuboid section can have pairs of shell side surfaces of different widths to prevent incorrect attachment of the detector assembly to the housing, in particular to the measuring cuvette.

[0062] As explained initially in connection with the layered component arrangement, calibration of the contactless, infrared-based temperature detection of the temperature-detection layered body with the actual temperature of interest of the reaction layered body may be necessary or at least advantageous in order to obtain the most accurate luminophore-based detection result of the oxygen content in the measurement object fluid. For this purpose, the sensor arrangement can be connected for signal transmission to an electronic evaluation device, which has at least one data storage device and a data processing processor in data exchange communication with the data storage device, wherein calibration information for correlating the detected infrared radiation of the temperature-detection layered body and the temperature of the luminophore is stored in the data storage device.

[0063] The temperature of the luminophore is equal to the temperature of the reaction layer, whereby the temperature of the detection side of the reaction layer is of particular interest.

[0064] Calibration can be performed in advance in the laboratory for the specific layered component arrangement or reaction assembly, or for a class of layered assemblies or reaction assemblies. For this purpose, the two layered assemblies can be successively brought to thermal equilibrium states of different, yet uniform and known temperatures. Then, for each equilibrium state, the measured value of the infrared radiation emitted by the temperature-sensing layered assembly can be linked to the respective known equilibrium temperature of the reaction layered assembly.

[0065] In order to check that the temperature sensing layer follows a temperature change of the reaction layer sufficiently quickly, the two fluid contact sides can be brought into contact with a temperature source of known temperature that changes in a known manner over time, and the temperatures of the sensing sides of both layers can be recorded contactlessly as a function of time.

[0066] From the data thus obtained, a highly accurate calibration relationship can be obtained between a temperature measured non-contact on the sensing side of the temperature sensing layer and the temperature of the sensing side of the reaction layer and thus the temperature of the luminophore present therein.

[0067] Furthermore, the electronic evaluation device can contain calibration information for correlating the second electromagnetic radiation detected by the radiation detector with an oxygen concentration value or oxygen content value of the measured fluid. As described above, the second electromagnetic radiation detected by the radiation detector and its temporal and / or intensity relationship to the exciting first electromagnetic radiation are directly related to the partial pressure of oxygen in the measured fluid. However, the oxygen concentration or oxygen content of the fluid can easily be determined or calculated from the detected partial pressure.

[0068] Since the preferred application of the sensor arrangement described above is its interaction with a ventilator for artificial respiration, a ventilator for artificial respiration is disclosed with a ventilation gas source, a ventilation line arrangement running between the ventilation gas source and a patient-side, proximal end, a valve arrangement comprising an inspiration valve and an expiration valve, a flow sensor arrangement for quantitatively detecting a gas flow in the ventilation line arrangement, a pressure change arrangement for changing the gas pressure of the gas flowing in the ventilation line arrangement, and with a control device which is at least designed to control the operation of the pressure change arrangement on the basis of measurement signals from the proximal flow sensor, and a sensor arrangement, as presented above and advantageously further developed, for determining an oxygen content of gas flowing in the ventilation line arrangement.

[0069] "Ventilation gas source" generally refers to any type of ventilation gas source used to introduce ventilation gas into the ventilation line assembly. This can be a connection formation of the ventilation device designed for connection to a replaceable or permanently installed ventilation gas supply within the building. This can also be a pump that draws ventilation gas from a supply in the ventilation gas device, which can also be the outside environment, and introduces it into the ventilation line assembly. Such a pump can also be designed as a blower.

[0070] A "pressure-variation device" is any device suitable and intended to change the pressure of the ventilation gas flowing in the ventilation line arrangement. If the ventilation gas source is merely a connection for connecting to a gas supply installed in the building, this can be a valve arrangement for pressure reduction. If the ventilation gas source includes the aforementioned pump or blower, the pressure-variation device can include or even be parts or the entirety of the ventilation gas source, such as the pump or blower, whose output can be varied by the control device.Even if the ventilation gas source is formed by the above-mentioned pump or blower, the pressure variation arrangement may comprise a pressure reducing valve in addition to the ventilation gas source itself or may be formed exclusively by a pressure reducing valve, for example when the pump or blower runs at a constant load.

[0071] The control device preferably comprises or is the above-mentioned electronic evaluation device of the sensor arrangement.

[0072] The sensor arrangement is preferably arranged in the main ventilation gas flow so that it can directly detect at least one of the expiratory and inspiratory ventilation gas flows. The sensor arrangement is preferably provided in the ventilation line arrangement such that it can detect both the expiratory and inspiratory ventilation gas flows. For this purpose, the sensor arrangement can be arranged close to the patient, i.e., proximally, preferably between a Y-connection, with which separate expiratory and inspiratory ventilation line sections are joined toward the patient, and an endotracheal tube on the patient.

[0073] More preferably, the sensor arrangement is arranged between the point where separate expiratory and inspiratory ventilation line sections meet toward the patient and the flow sensor. The present invention will be explained in more detail below with reference to the accompanying drawings. It shows: Fig. 1 shows a preferred and yet only exemplary application of the layered component arrangement, reaction assembly and sensor arrangement according to the present invention in a ventilator, Fig. 2A shows a roughly schematic plan view of a planar layered component arrangement according to the present invention, Fig. 2B shows a sectional view through the layered component arrangement of Fig. 2A along the section plane IIB-IIB of Fig. 2A , Fig. 3A a plan view of an assembly comprising the layer component arrangement of the Fig. 2A und 2B and a window component of a housing of a reaction assembly accommodating the layered component arrangement, Fig. 3B a sectional view through the assembly of Fig. 3A along the section plane IIIB-IIIB of Fig. 3A , Fig. 4 a reaction assembly according to the invention of the present invention and Fig. 5 a roughly schematic cross-sectional view through a sensor arrangement according to the invention with the reaction assembly of Fig. 4 , as used as a sensor arrangement on the ventilator device of Fig. 1 is applied.

[0074] To explain the preferred field of application of the objects discussed in the present application: layered component arrangement, reaction assembly, sensor arrangement and ventilation device, a ventilation device using the said components will first be described in connection with Fig. 1 explained: In Figur 1 An embodiment of a ventilation device is generally designated 10. In the example shown, the ventilation device 10 serves for the artificial ventilation of a human patient 12.

[0075] The ventilation device 10 can be accommodated as a mobile ventilation device 10 on a rollable frame 13.

[0076] The ventilation device 10 has a housing 14 in which a pressure change arrangement 16 and a control device 18 can be accommodated - not visible from the outside due to the opaque housing material.

[0077] The pressure-variation arrangement 16 is constructed in a manner known per se and comprises a ventilation gas source 15 in the form of a pump, a compressor, or a blower, each of which can be controlled with variable load and therefore serves not only to introduce ventilation gas into the ventilation device, but also to change the pressure of the introduced ventilation gas. The ventilation gas source 15 can alternatively be formed by a pressure vessel that can be connected to the housing 14 of the ventilation device 10. The pressure-variation arrangement 16 can comprise the ventilation gas source 15 and, if appropriate, additionally—or alternatively, in the case of a pressurized gas supply as the ventilation gas source—a reducing valve and the like. Furthermore, the ventilation device 10 comprises, in a manner known per se, an inspiration valve 20 and an expiration valve 22.

[0078] The control device 18 is usually implemented as a computer or microprocessor. It comprises a Figur 1 A data storage device (not shown) is provided for storing data necessary for operating the ventilator 10 and retrieving it if necessary. In network operation, the storage device can also be located outside the housing 14 and connected to the control device 18 via a data transmission link. The data transmission link can be formed by a cable or a radio link. However, to prevent disruptions in the data transmission link from affecting the operation of the ventilator 10, the storage device is preferably integrated into the control device 18 or at least accommodated in the same housing 14 as the control device.

[0079] For inputting data into the ventilator 10 or more precisely into the control device 18, the ventilator 10 has a data input 24, which is arranged in the Figur 1 In the example shown, this is represented by a keyboard. Alternatively or in addition to the keyboard shown, the control device 18 can receive data via various data inputs, such as a network cable, a radio link, or sensor connections 26, which will be discussed in detail below.

[0080] To output data to the treating therapist, the ventilator 10 can have an output device 28, in the example shown a screen.

[0081] For artificial ventilation, the patient 12 is connected to the ventilation device 10, more precisely to the pressure-variation arrangement 16 in the housing 14, via a ventilation line arrangement 30. For this purpose, the patient 12 is intubated with an endotracheal tube 58.

[0082] The ventilation line arrangement 30, via which fresh ventilation gas can be supplied from the ventilation gas source 15 and the pressure-variation arrangement 16 into the lungs of the patient 12, has an inspiration tube 32 outside the housing 14. The inspiration tube 32 can be interrupted and comprise a first inspiration tube section 34 and a second inspiration tube section 36, between which a conditioning device 38 can be provided for the targeted humidification and, if necessary, also temperature control of the fresh ventilation gas supplied to the patient 12. The conditioning device 38 can be connected to an external liquid supply 40, via which water for humidification or a medication, for example for anti-inflammatory purposes or to dilate the airways, can be supplied to the ventilation gas.When the present ventilator 10 is used as an anesthesia ventilator, volatile anesthetics can be delivered to the patient 12 in a controlled manner via the ventilator 10. The conditioning device 38 ensures that the fresh ventilation gas is delivered to the patient 12 with a predetermined humidity content, optionally with the addition of a medication aerosol, and at a predetermined temperature.

[0083] In addition to the already mentioned inspiration valve 20, the ventilation line arrangement 30 has the expiration valve 22 and further an expiration tube 42, via which metabolized ventilation gas is released from the lungs of the patient 12 into the atmosphere.

[0084] The inspiratory tube 32 is coupled to the inspiratory valve 20, and the expiratory tube 42 is coupled to the expiratory valve 22. Only one of the two valves is open at a time to allow the passage of a gas flow. The actuation of the valves 20 and 22 is also controlled by the control device 18.

[0085] During a ventilation cycle, the expiration valve 22 is initially closed and the inspiration valve 20 is opened for the duration of the inspiration phase, allowing fresh ventilation gas to be directed from the housing 14 to the patient 12. A flow of fresh ventilation gas is achieved by a targeted increase in the pressure of the ventilation gas by the pressure-variation arrangement 16. Due to the pressure increase, the fresh ventilation gas flows into the lungs of the patient 12 and expands the body area near the lungs, particularly the rib cage, against the individual elasticity of the body parts near the lungs. This also increases the gas pressure inside the lungs of the patient 12.

[0086] At the end of the inspiration phase, the inspiration valve 20 is closed and the expiration valve 22 is opened. The expiration phase begins. Due to the increased gas pressure of the ventilation gas in the lungs of the patient 12 until the end of the inspiration phase, this gas flows into the atmosphere after the expiration valve 22 opens, with the gas pressure in the lungs of the patient 12 decreasing as the flow duration progresses. If the gas pressure in the lungs 12 reaches a positive end-expiratory pressure set on the ventilation device 10, i.e., a pressure slightly higher than atmospheric pressure, the expiration phase is ended with the closing of the expiration valve 22, and another ventilation cycle follows.

[0087] During the inspiration phase, the patient 12 is supplied with the so-called ventilation tidal volume, i.e., the volume of ventilation gas per breath. The ventilation tidal volume multiplied by the number of ventilation cycles per minute, i.e., multiplied by the ventilation rate, results in the minute volume of the artificial ventilation being performed.

[0088] The ventilation device 10, in particular the control device 18, is preferably designed to repeatedly update or determine ventilation operating parameters that characterize the ventilation operation of the ventilation device 10 during ventilation operation, in order to ensure that the ventilation operation is optimally tailored to the respective patient 12 to be ventilated at all times. Particularly advantageously, one or more ventilation operating parameters are determined using the ventilation frequency, so that current ventilation operating parameters that are thus optimally adapted to the patient 12 can be provided for each ventilation cycle.

[0089] For this purpose, the ventilator 10 is connected to one or more sensors for data transmission, which monitor the condition of the patient and / or the operation of the ventilator.

[0090] One of these sensors is a proximal flow sensor 44, which is arranged on the side of a Y-connector 45 closer to the patient 12 and there detects the ventilation gas flow prevailing in the ventilation line arrangement 30. The flow sensor 44 can be coupled to the data inputs 26 of the control device 18 by means of a sensor line arrangement 46. The sensor line arrangement 46 can, but does not have to, include electrical signal transmission lines. It can also have hose lines that transmit the gas pressure prevailing in the flow direction on both sides of the flow sensor 44 to the data inputs 26, where this pressure is quantified by pressure sensors 27. Although the flow sensor 44 is preferably a flow sensor operating according to the differential pressure principle, it can also be a flow sensor operating according to a different physical principle.

[0091] A further flow sensor 48 is provided in the housing 14, which is referred to as distal flow sensor 48 due to its greater distance from the patient 12 - compared to the proximal flow sensor 44.

[0092] In the ventilation line arrangement 30 between the Y-connector 45 and the flow sensor 44, a sensor arrangement 50 comprising a reaction assembly 72 with a housing 52 designed as a measuring cuvette 52 and a detector assembly 54 is arranged to detect the oxygen content of the ventilation gas in both the expiratory and inspiratory ventilation gas main stream. The sensor arrangement 50, which will be described further below in connection with Fig. 5 will be explained in more detail, is coupled to the control device 18 via a signal line 56 and transmits to it the detection results of its detector assembly 54 for further evaluation.

[0093] Calibration information is stored in the data storage device of the control device 18 in order to evaluate the detection results of the sensor arrangement 50 with high precision.

[0094] The sensor arrangement 50 is designed for temperature-compensated, luminophore-based detection of the partial pressure of the oxygen contained in the ventilation gas flowing through the housing 52. Both the temperature compensation and the conversion of the detection values ​​obtained directly in relation to the oxygen partial pressure into an oxygen concentration or oxygen content of the ventilation gas are performed by the control device 18 based on the stored calibration information.

[0095] The luminophore-based detection of oxygen content in a fluid is known per se. In the present embodiment, it is carried out with the participation of a Fig. 2A und 2B shown and generally designated 60. It comprises a reaction layer body 62 (see also Fig. 2B ), which is shown here as a two-layer reaction layer body 62. In fact, the reaction layer body 62 can have only one or more than two layers. In the example shown - also visible in the cross-sectional view of Fig. 2B - the reaction layer body 62 has a substrate layer 62a and a luminophore-containing reaction layer 62b applied thereon.

[0096] The ratios of length and width of the reaction layer body 62 to its thickness are not to scale in the figures. Fig. 2A und 2B The reaction layer body 62 shown as square can have an edge length of approximately 7 to 10 mm, wherein its thickness measured over both layers 62a and 62b can be approximately 300 µm.

[0097] The substrate layer 62a can be formed from a material sufficiently porous for oxygen molecules, such as polyvinylidene fluoride. The substrate layer 62a can be cut from a suitable film and have a thickness of between 100 and 150 µm. Under certain circumstances, the thickness of the substrate layer can also be less.

[0098] The luminophore-containing reaction layer 62b may also contain polyvinylidene fluoride as a matrix material in which luminophores are embedded.

[0099] The reaction layer body 62 has a fluid contact side 62c and a detection side 62d.

[0100] The luminophore-containing reaction layer 62b may be somewhat smaller than the substrate layer 62a supporting it in order to facilitate the adhesive attachment of the reaction layer body 62 with the detection side to a window component or generally to a housing, without having to coat the detection side of the luminophore-containing reaction layer 62b with adhesive.

[0101] As explained below in connection with Fig. 5 As will be explained below, and as is generally known, the reaction layer 62b is irradiated with a first electromagnetic radiation of a first wavelength and thereby excited to emit a second electromagnetic radiation of a second, generally longer, wavelength. The intensity and duration of the excited second electromagnetic radiation depend on the presence of oxygen, more precisely on the contacting of the luminophores embedded in the reaction layer 62b by oxygen. Furthermore, the radiation behavior of the reaction layer 62b is temperature-dependent.

[0102] For temperature compensation of the detection of the radiation behavior of the reaction layer body 62, the layer component arrangement 60 has a temperature detection layer body 64, which in the example shown occupies an area identical in size to the reaction layer body 62, although this is not absolutely necessary.

[0103] The representation of the temperature-sensing layer body 64 is also not to scale with regard to its dimensions. In the example shown, it has an edge length in the same range as the reaction layer body 62, but is preferably thinner than the reaction layer body 62 due to its different structure.

[0104] Again, the temperature detection layer body 64 has a substrate layer 64a, for example formed from an aluminum foil with a thickness of approximately 10 µm or even less, for reasons of the best possible heat conduction.

[0105] In the illustrated embodiment, a detection layer 64b, for example, made of a carbon-containing lacquer, is applied to the substrate layer 64a. The carbon-containing lacquer, as exemplified in the introduction to the description, comprises carbon as black color pigments and therefore has a very high emissivity of more than 0.9.

[0106] Since, as explained below in connection with the Fig. 3A und 3B will be explained, the infrared radiation emanating from the detection layer 64b is detected by an exemplary circular hole 68, which always has a circular cross-section along its hole axis, along which the hole 68 extends, the detection layer 64b is also formed as a circular area on the exemplary square-shaped substrate layer 64a.

[0107] The surface of the substrate layer 64a facing away from the sensing layer 64b is exposed as the fluid contact side 64c. It is formed by the metallic surface of the aluminum foil forming the substrate layer 64a of the temperature-sensing laminate 64. The sensing side 64d of the temperature-sensing laminate 64 forms the free surface of the sensing layer 64b. Fluid can therefore flow past the layered component arrangement 60 on its fluid contact side 62c or 64c, with oxygen passing through the substrate layer 62a to the luminophore-containing reaction layer 62b, where it quenches an excitation generated by the first electromagnetic radiation, while the fluid contact on the fluid contact side 64c of the temperature-sensing laminate 64 serves solely to transfer heat from the fluid to the temperature-sensing laminate 64.

[0108] Due to the selected material (aluminum) for the substrate layer 64a and due to its small thickness, the substrate layer 64a takes on the temperature of the fluid flowing past its fluid contact side 64c in the millisecond range and ensures a temperature equalization of the detection layer 64b as well, so that with an infrared detector on the detection side 64d of the temperature detection layer body 64, a temperature value related at least to the temperature of the measurement object fluid can be detected.Since the reaction layer body 62 comes into contact with the same fluid in approximately the same way, the detection of the temperature of the detection side 64d of the temperature detection layer body 64 allows conclusions to be drawn about the temperature of the detection side 62d of the reaction layer 62b based on the calibration information stored in the data storage device of the control device 18, which is a prerequisite for temperature compensation of the measurement results obtained on the reaction layer body 62 regarding the oxygen content of the measurement object fluid.

[0109] The temperature compensation is necessary because the fluid to be measured can change its temperature as it flows past the layered component arrangement 60, for example because a patient in the ventilator is exposed to Fig. 1 Ventilation air is supplied at a lower temperature than that returned after exhalation.

[0110] The layered component arrangement 60 is therefore usually arranged in the housing 52, which guides the flow of the measuring object fluid during the detection of its oxygen content and temperature.

[0111] The detection sides 62d and 64d of the two layered bodies 62 and 64 are advantageously directed outwards, i.e. away from the measurement object fluid, while the fluid contact side 62c or 64c of the two layered bodies comes into contact with the fluid over as large an area as possible.

[0112] To ensure that the reaction layer 62b is only reached by oxygen dissolved in the measuring object fluid, the reaction layer body is covered by a window on its detection side. Fig. 3A shows the layer component arrangement 60 of the Fig. 2A und 2B in the top view of Fig. 2A with a window component 66 arranged above it. The window component 66 is part of the Fig. 1 The window component 66 can be made of a transparent polyamide or another plastic permeable to the first and second electromagnetic radiation. For example, the window component 66 can be made of amorphous polyamide, such as that offered under the name "Grilamid TR" by EMS-Chemie AG in Domat, Switzerland.

[0113] In its region located directly above the reaction layer 62b, the window component 66 thus forms a reaction window 66a through which the reaction layer 62b is reached by first electromagnetic radiation and the thereby excited emitted second electromagnetic radiation is transmitted.

[0114] In order to be able to detect the infrared radiation emitted by the detection layer 64b of the temperature detection layer body 64 as unadulterated as possible, a detection window 66b is formed in the window component 66 directly above the location of the temperature detection layer body, which detection window is formed as a hole 68 widening negatively conically from the side facing away from the layer component arrangement 60 towards the detection layer 64b and penetrating the window component 66 in its entire thickness.

[0115] The circular hole edge 68a on the side of the window component 66 facing the detection layer 64b is larger in diameter than the concentric hole edge 68b of the hole 68 on the side of the window component 66 facing away from the detection layer 64b. The negatively conical hole wall 68c extending between the two hole edges 68a and 68b is preferably coated, particularly preferably mirrored, in order to minimize or exclude interference from radiation components that could be guided through the window component 66.

[0116] In Fig. 4 the housing 52 of the sensor arrangement 50 is shown in a kind of exploded view.

[0117] The housing 52 comprises a base housing 53 and the window component 66 with the arranged thereon, in Fig. 4 however, not recognizable layered component arrangement 60. With the window component 66, an opening 70 in the base housing 53 can be closed, so that the housing 52 is then closed and forms the reaction assembly 72 due to the arrangement of the layered component arrangement 60 therein.

[0118] The housing 52 has connecting pieces 76a and 76b on both sides of the parallelepiped-shaped section 74 formed with the participation of the window component 66 for connecting ventilation line sections thereto.

[0119] The housing 52 can be flowed through bidirectionally along the flow axis S.

[0120] In Fig. 5 the sensor arrangement 50 is shown roughly schematically in cross section.

[0121] The housing 52 can be bidirectionally flowed through by ventilation gas between its two openings 78a and 78b along the flow axis S. The ventilation gas flows past the layered bodies 62 and 64, making contact with the fluid contact sides 62c and 64c. The flow axis S lies in the plane of the drawing of Fig. 5 .

[0122] The sensor arrangement 54, which can be detachably arranged on the housing 52 and for this purpose surrounds the parallelepiped-shaped section 74 on three sides in a U-shape, with the base of the "U" opposite the window component 66, comprises two measuring chambers 80 and 82, which are structurally separated from one another.

[0123] A radiation source 82, for example in the form of an LED, is provided in the measuring chamber 80, which emits electromagnetic radiation E1 of a first wavelength. In order to keep the wavelength band of the first electromagnetic radiation emanating from the radiation source 82 as narrow as possible and to avoid interference, the radiation source 82 can advantageously be surrounded by a filter body 84, which transmits the first electromagnetic radiation E1 of the specified wavelength with the smallest possible tolerance.

[0124] Furthermore, a radiation detector 86 is arranged in the first measuring chamber 80, which detects a second electromagnetic radiation E2 emanating from the reaction layer 62b after its excitation by the first electromagnetic radiation E1. A radiation filter 88 can also be arranged upstream of the radiation detector 86 to allow only the second electromagnetic radiation E2, which has a second wavelength different from the first wavelength, to pass through. The filter arrangements 84 and 88 ensure that no radiation passes directly from the radiation source 82 to the radiation detector 86, thereby "confounding" the signal detected there.

[0125] The signal emitted by the radiation detector 86 due to its detection of the second electromagnetic radiation E2 is transmitted via the Fig. 1The signal is transmitted to the control device 18 via the data line 56 shown. It is indicative, in a manner known per se, of the oxygen partial pressure in the fluid flowing through the housing 52.

[0126] An infrared detector 90 is arranged in the second measuring chamber 82, which detects infrared radiation I emitted by the detection layer 64b. The signal output by the infrared detector 90 based on its detection of the infrared radiation I is also transmitted to the control device 18 via the data line 56. This signal is indicative of a temperature of the detection layer 64b.

[0127] Based on the calibration information stored in the data storage device of the control device 18, which was determined remotely in the laboratory prior to use of the layered component arrangement 60, the control device 18 can determine the temperature of the reaction layer 62b from the detection signal of the infrared detector 90 for each detection time of a signal from the radiation detector 86 and thus compensate the detection signal of the radiation detector 86 with respect to the temperature of the radiating reaction body 62 or the reaction layer 62b thereof. The result is a highly accurate determination of the oxygen partial pressure in the fluid flowing through the housing 52 as a time-variable variable.

[0128] The highly accurate temperature compensation is achieved using extremely simple means, such as the metal foil 64a as a substrate and the detection layer 64b applied thereon. The use of the metal foil 64a (aluminum foil) allows the window component 66 or, more generally, the housing 52 to be completely penetrated to form a detection window 68, so that the temperature information emitted by the detection layer 64b as infrared radiation reaches the infrared detector 90 with the least possible distortion.

[0129] The control device 18 can contain further calibration information in a data memory which enables the usual conversion of the oxygen partial pressure of the fluid, which is directly related to the detection of the second electromagnetic radiation, into an oxygen content of the fluid.

Claims

1. A flat layer component arrangement (60) for temperature-compensated optical detection of an oxygen content of a fluid, the flat layer component arrangement (60) comprising: - a luminophore-containing reaction layer body (62) comprising one or more layers (62a, 62b), the luminophore of which can be excited by irradiation with a first electromagnetic radiation (E1) of a first wavelength to radiate a second electromagnetic radiation (E2) of a second wavelength different from the first wavelength, the excited emission behaviour of the luminophore is dependent on an oxygen partial pressure in a fluid contacting the luminophore, and - a temperature-detecting layer body (64) comprising one or more layers (64a, 64b) and emitting infrared radiation (I), characterised in that the reaction layer body (62) and the temperature-detecting layer body (64) are formed separately from each other and are arranged spatially separated from each other, the temperature-detecting layer body (64) being free of luminophore.

2. The layer component arrangement (60) according to claim 1, characterised in that the reaction layer body (62) has a different layer structure, at least in some sections, with respect to layer material and / or layer sequence and / or layer thickness than the temperature-detecting layer body (64).

3. The layer component arrangement (60) according to claim 1, characterised in that the reaction layer body (62) and the temperature-detecting layer body (64) are arranged spatially separated in such a way that only the reaction layer body (62) can be irradiated with the first electromagnetic radiation (E1) and that only infrared radiation (I) emanating from the temperature-detecting layer body (64) can be detected.

4. The layer component arrangement (60) according to one of the preceding claims, characterised in that the reaction layer body (62) and the temperature detection layer body (64) each have a fluid contact side (62c, 64c) on which the respective layer body (62, 64) is designed to come into contact with the fluid, and a detection side (62c, 64c) opposite the fluid contact side (62c, 64c) 4d) which is designed to interact with radiation detectors (86, 90).

5. The layer component arrangement (60) according to one of the preceding claims, characterised in that the temperature-detecting layer body has a substrate layer with an emission layer of identical material, wherein the emission layer is formed on a detection side by mechanical and / or chemical roughening of the surface of the substrate layer on the detection side.

6. A reaction assembly (72) comprising a housing (52) and a layer component arrangement (60) provided in the housing (52) according to any one of the preceding claims, the housing (52) having an opening (78a, 78b) through which a fluid can be introduced into the housing (52), the housing (52) has a reaction window (66a) through which the reaction layer body (62) can be reached by the first electromagnetic radiation (E1) and which can be penetrated by the second electromagnetic radiation (E2), and the housing (52) has a temperature-detecting window (66b) arranged at a distance from the reaction window (66a) 6b) which can be penetrated by the infrared radiation (I) radiated by the temperature-detecting layer body (64).

7. The reaction assembly (72) according to claim 6, characterised in that the reaction window (66a) is designed to be structurally different from the temperature-detecting window (66b).

8. The reaction assembly (72) according to claim 7, characterised in that the reaction window (66a) is thicker than the temperature detection window (66b).

9. The reaction assembly (72) according to claim 8, characterised in that the reaction window (66a) comprises a material transparent to light in the optically perceptible wavelength range and in that the temperature detection window (66b) comprises a hole (68) passing through the housing (52) and covered by the temperature detection layer body (64).

10. The reaction assembly (72) according to any one of claims 6 to 9, characterised in that the housing (52) has a further opening (78b) distinct from and remote from the opening (78a) such that fluid can flow through the housing (52) between the opening (78a) and the further opening (78b).

11. The reaction assembly (72) according to claim 10, characterised in that the laminar component assembly (60) is provided between the opening (78a) and the further opening (78b).

12. The reaction assembly (72) according to claim 10 or 11, characterised in that it is adapted for disposition in a breathing conduit assembly (30) of a breathing apparatus (10), the reaction assembly (72) being formed with a respective attachment formation (76a, 76b) in the region of each of the opening (78a) and the further opening (78b) for connection to a respective portion of the breathing conduit assembly (30).

13. A sensor assembly (50) comprising a reaction assembly (72) according to any one of claims 7 to 13 and further comprising a detector assembly (54) comprising - a radiation source (82) configured to radiate the first electromagnetic radiation (E1) through the reaction window (66a), - a radiation detector (86) which is designed to detect the second electromagnetic radiation (E2) through the reaction window (66a), and - an infrared detector (90) which is designed to detect the infrared radiation (I) radiated from the temperature detection layer body (64) through the temperature detection window (66b).

14. The sensor arrangement (50) according to claim 13, characterised in that the detector assembly (54) is removably connected or connectable to the reaction assembly (72).