Flow sensor arrangement and its use

Abstract

Flow sensor arrangement (100), comprising an optomechanical system (200), comprising - an upper cover layer (210), - a lower top layer (220), - at least one optical layer (410) designed to conduct light and optically coupled to a light source (120, 441) and arranged between the upper and lower cover layers (210, 220), - an arrangement of at least one optomechanical unit cell (400) comprising an optical volume (433) optically coupled to the at least one optical layer (410), and a transmission element (320) associated with this optical volume (433), which can be acted upon from above with a force (F) and is designed and arranged to act on the optical volume (433) depending on the force (F), wherein the optical volume (433) is formed or arranged at least sectionally in the at least one optical layer (410) and is further configured to receive a source light beam (Q) from the at least one optical layer (410) so that it penetrates the entire optical volume (433) or only a part of the optical volume (433) which forms an active optical volume (434), and to modify the source light beam (Q) depending on the force (F) currently acting on the transmission element (320) and to direct the modified source light beam out of the optical volume (433) as a signal light beam (S), and further comprising the flow sensor arrangement: at least one sensing element (300) arranged on the upper cover layer (210) of the optomechanical system (200), to which the optomechanical unit cell (400) or one of the optomechanical unit cells (400) is assigned, or to which several of the optomechanical unit cells (400) are assigned, wherein the sensing element (300) is configured to apply a respective flow-dependent external force (F) to the transmission element (320) of each assigned optomechanical unit cell (400), wherein the sensing element (300) and the assigned optomechanical unit cell (400) or the assigned optomechanical unit cells (400) together form a flow sensor element (500), wherein the sensing element (300) comprises an upwardly open cavity (361) in the upper cover layer (210) of the optomechanical system (200).

Description

[0001] The present invention relates to a flow sensor arrangement based on an optomechanical system with one or more optomechanical unit cells and to the use of the flow sensor arrangement.

[0002] In gas or liquid flows that propagate over extended areas, different flow conditions can prevail at different locations within the area and at different times. Key parameters of fluid flow can include, for example: the flow velocity and its distribution or profile, the flow direction and the resulting pressure, as well as the degree of laminarity or turbulence, and, if applicable, vibration frequencies.

[0003] Understanding variable parameters is crucial in numerous technical fields to ensure desired functionality and energy optimization. Examples of such fields include all types of fixed-wing aircraft, drones, conventional and flying vehicles, sailing ships and transport vessels with auxiliary sails, stationary and airborne wind turbines, and much more. A failure of the intended function in these technical fields can lead to fatal situations. For example, a stall on the wing can result in an aircraft crash.

[0004] The measurement of different flow conditions or parameters across the entire surface exposed to the flow remains fundamental for assessing factors such as flow resistance and energy expenditure, turbulence, migrating flow separation, local flow velocity and direction, noise generation and vibration states, to name just a few.

[0005] To visualize flow processes on surfaces such as aircraft wings, wind turbine rotor blades, ship sails, or vehicle surfaces, wool threads are still sometimes used today. This method is very cost-effective. However, the local flow direction can only be determined visually. Analysis options for flow information captured using this technique, such as camera recordings, are very limited.

[0006] More advanced techniques for capturing local flow conditions, such as laser Doppler anemometry, are very bulky and therefore either unusable or only usable with considerable effort for the objects being measured. If several measurement points are to be recorded simultaneously, such an apparatus must be set up for each one.

[0007] Other techniques are already attempting to capture the planar or spatially distributed nature of flows. These include, for example, hot-film arrays, which are difficult to attach to the surfaces subjected to the flow, and whose production and calibration are very complex.

[0008] To determine pressures in the flow, piezoelectric films, planar condenser microphones or silicon pressure sensors based on piezoresistive or capacitive principles are used, among others, all of which, in addition to the disadvantages of expensive and complex manufacturing and sometimes difficult installation, have in particular the disadvantage of sensitivity to electrostatic, magnetic or electromagnetic interference.

[0009] Document US 8749766 B1 describes hair-like sensors based on light-conducting fibers, whose deformation in a flow-through state is optically detected based on the distribution of the light emitted by the fiber. A disadvantage of this design is that the light signal escapes from the sensor into the surrounding environment, meaning that it can no longer be guaranteed that the signal will not be disrupted by contamination.

[0010] In practice, sensors used to assess flow separation, for example, must be integrated into the structure of the object being measured. This generally has negative effects on structural stability, and at the same time, the sensors can influence the flow through their volume and / or mass.

[0011] One example of a commonly used stall warning system is based on a flap mechanism at the leading edge of a wing or rotor blade. Disadvantages include the risk of icing and contamination, the impact on the object structure due to deep installation, and especially the fact that a single sensor cannot represent the distributed airflow.

[0012] Another example of commercially available flow monitoring sensors are multi-hole probes. These can be used to determine flow velocity and / or angle of attack, which serves as an indicator of flow separation and for stall warnings. When assessing distributed flow conditions, such systems only provide a single value and are unable to depict the flow patterns in detail. The risk of icing and contamination is also a disadvantage.

[0013] In German patent application DE 4443665 C2, the applicant presents a miniaturized sensor for monitoring flow separation. When these sensors are used in an array, it is already possible to make statements about the dynamics of flow fields, for example on wings or rotor blades. However, this solution is purely electrical and therefore not protected against the aforementioned external influences, in particular electric, magnetic, and electromagnetic fields.

[0014] US Patent 5,004,913 A discloses various techniques for the local determination of different physical quantities, in particular temperature, pressure, and flow rate, using an optomechanical or optothermic system, according to the following principle: Source light from an optical fiber is first split into a measurement path and a control path. The measurement path is passed through a sensor element, where the light is modified by the quantity to be measured. The wavelength of the light in one of the two paths is converted to a different wavelength in a converter. Then the two paths are combined again into one path, and finally, the signals are separated again according to wavelength by suitable devices. The intensity ratio of the signals with the different wavelengths provides a measure of the physical quantity. The light is guided in optical fibers, each of which is enclosed in a sheath.

[0015] US 2012 / 0186337A1 describes a system for determining the flow distribution along a predefined line on a surface, in particular an aircraft wing, using a series of sensor elements connected in series along an optical fiber, each of which may include a Bragg grating. The flow is determined indirectly via its cooling effect, as the light transported along the optical fiber heats the sensor elements, and the flow cools them. The resulting temperature influences the grating constant of the Bragg grating, whereby the light reflected from the Bragg grating is detected and evaluated.

[0016] GB 2 570 332 A describes a flow sensor for determining flow in a physiological environment, particularly in a patient's blood vessel. A Fabry-Perot interferometer-type structure is formed at the distal end of an optical fiber and is influenced by the flow, allowing conclusions to be drawn about flow parameters from the interference pattern of the light directed into the fiber.

[0017] US 2010 / 0253650A1 describes an optomechanical sensor arrangement for measuring force distribution across a surface, with a substantially two-layer structure. A lower substrate layer contains an arrangement of light sources and detector elements. A source light beam is coupled from below by the light sources into an elastically deformable optomechanical layer applied to the substrate layer. The source light beam is modified depending on a force acting on the optomechanical layer from above and is coupled out downwards as a signal light beam, where it is detected.The optomechanical layer contains an arrangement of closed cavities whose walls are wholly or partially mirrored, so that the source light beam is reflected differently depending on a momentary deformation of the cavity. This allows the magnitude and direction of the force deforming the cavities to be determined. To improve the sensitivity of the sensor, some embodiments employ tactile elements projecting outwards from the optomechanical layer.

[0018] DE 31 43 475 C2 finally discloses a flow sensor arrangement in which a light-conducting fiber is clamped at one end and exposed to a flow at its free end. Light emerging from the fiber is projected onto a photosensor, so that the displacement of the projected light spot represents a measure of the deflection of the free fiber end.

[0019] Against this background, the object of the present invention, according to a first aspect, is to provide an improved sensor arrangement, which can avoid or reduce the disadvantages of conventional systems described above.

[0020] This problem is solved according to one aspect of the invention by a flow sensor arrangement having the features of claim 1 and according to another aspect of the invention by a flow sensor arrangement having the features of claim 4.

[0021] The optomechanical system (OMS) of the flow sensor arrangement proposed according to the invention comprises an upper cover layer, preferably opaque, a lower cover layer, preferably opaque, at least one optical layer designed to guide light and optically coupled to a light source and arranged between the upper and lower cover layers, and an arrangement of at least one optomechanical unit cell, preferably several optomechanical unit cells.

[0022] According to the invention, the optomechanical unit cell (unit cell or OMEZ for short) comprises an optical volume optically coupled to the at least one optical layer, and a transmission element associated with this optical volume, which can be subjected to a force from above and is designed and arranged to act on the optical volume depending on the force, for example by penetrating the optical volume or elastically compressing it.

[0023] The optical volume is formed or arranged at least sectionally, preferably completely, in the optical layer and is further configured to receive a source light beam from the at least one optical layer, so that it penetrates the entire optical volume or only a part of the optical volume, which forms an active optical volume, and to modify the source light beam depending on the force currently acting on the transmission element and to direct the modified source light beam out of the optical volume as a signal light beam.

[0024] Since light is used as the signal carrier, interference from electric, magnetic and electromagnetic fields can be reduced or minimized.

[0025] Sensors based on the aforementioned optomechanical system can also be easily miniaturized to such an extent that effects due to inertia are largely negligible.

[0026] Light should be understood in particular as light in the narrower sense, i.e. in the wavelength range of visible light, but also light in the wavelength range of the infrared and / or ultraviolet range.

[0027] As described in more detail below, the signal light beam can then be transmitted in a suitable manner to a processing unit, received there, and, if necessary, converted into electrical signals and processed. Purely optical processing of the signal light beam or optical preprocessing prior to conversion into electrical signals is also possible.

[0028] The optomechanical unit cell can be integrated into the optomechanical system of a flow sensor arrangement according to the invention in such a way that the force acting on the transmission element depends on a fluid flow along a surface to be investigated. In this way, information about the flow at a specific location on the surface can be obtained by modifying the source light beam.

[0029] The force acting on the transmission element can be an external force, such as that caused by a fluid flow, but it can also be an inertial force acting on the mass of the transmission element or on a test mass mechanically coupled to the transmission element, which enables the local measurement of accelerations and vibrations, for example in the context of flutter analysis of an aircraft wing.

[0030] In the simplest case, the optical volume can be empty (unfilled and, for example, open at the top) in the sense that the transmission element, when subjected to force, can penetrate the optical volume and partially block or reduce its size, thus reducing the total amount of light exiting the optical volume per unit of time. Alternatively, the optical volume can be filled, preferably with an elastic, translucent material.

[0031] Preferably, the filling material of the optical volume is selected such that the transparency of the optical volume or the active optical volume for a given light wavelength or for a given light wavelength range depends on the force currently acting on the transmission element, in the case of an elastically stretchable or compressible optical volume, for example, on a momentary stretching or compression of the optical volume caused by the transmission element.

[0032] The active optical volume can be designed to contain a Bragg grating. When the volume is stretched or compressed, the wavelength for which the Bragg condition is satisfied shifts, thus changing the spectral composition of the signal light beam depending on the force applied.

[0033] For the targeted coupling of the source light beam into the optical volume or the active optical volume and / or for the coupling of the signal light beam out of the optical volume or the active optical volume, at least one optical component can be provided at a suitable location.

[0034] For this, as for coupling light in or out of planar systems in general, there are several possibilities: for example, micromirrors, optical gratings, planar microstructures with pyramidal, conical, cylindrical, or any other shape and arrangement, thin films, photonic crystals, prisms, lenses, and more. Manufacturing methods include, for example, embossing, lithography, 3D printing, inkjet printing, screen printing, laser ablation, and others.

[0035] The optomechanical system is a layered system and can, for example, serve as an intermediate product or semi-finished product for the manufacture of a flow sensor arrangement or an acceleration sensor arrangement according to the invention.

[0036] The terms "top" and "bottom" are to be understood here as meaning that, in the intended use of the optomechanical system, the lower cover layer is attached to the object under investigation (aircraft wing, etc.), while, for example, the fluid flow under investigation flows along the upper cover layer.

[0037] The fact that the force acts on the transmission element "from above" means that the force has a non-zero component perpendicular to the upper layer. Preferably, the force component perpendicular to the upper layer is greater than any force component parallel to the upper layer, and particularly preferably, the force is directed perpendicular to the upper layer.

[0038] Thin, transparent films can be used as optical layers and thus as carriers for the light signals. These films can be made of, for example, a polymer (e.g., PMMA, PDMS, etc.), glass, or a combination of the aforementioned materials. These materials are available in film form or can be manufactured using roll-to-roll or sheet-to-sheet processes. The entire system can also be manufactured in this way. As described in more detail below, optical waveguides can be embedded in the optical layers.

[0039] Polymer solutions are generally more cost-effective than glass solutions. Glass solutions can be chosen when, for example, higher optical quality is required. Longer light paths can be traversed with less loss in glass solutions. Further advantages of using glass for light transmission include high stability against temperature changes and lower sensitivity to moisture.

[0040] In order to guide the movement of the transmission element of the at least one optomechanical unit cell, the optomechanical system may further comprise an adapter layer arranged between the upper cover layer and the at least one optical layer, in which the transmission element of the at least one optomechanical unit cell is formed or provided and guided.

[0041] To minimize the influence of external disturbances, contamination, moisture, aggressive substances, UV radiation, light, etc. on the system, the optical volume(s), preferably also the optical layer(s), can be enclosed between the upper and lower cover layers in a gas-tight, liquid-tight, opaque, and / or UV-blocking manner. In particular, all optically active components of the system can be enclosed between the upper and lower cover layers in a gas-tight, liquid-tight, opaque, and UV-blocking manner, most preferably in a gas-tight, liquid-tight, opaque, and UV-blocking manner.

[0042] For this purpose and / or to adjust a desired restoring force, the optomechanical system can further comprise at least one elastic layer arranged between the optical layer and at least one of the cover layers. For example, an elastic layer can be provided between the adapter layer, in which the transmission element is guided, and the upper cover layer. Alternatively or additionally, an elastic layer can be provided between the lower cover layer and the optical layer. Suitable materials for the elastic layer include, for example, polymers, elastomers, silicones, PDMS, spring steel, glass, and others.

[0043] There are several possibilities for guiding the source light beam and / or the signal light beam in the optical layer.

[0044] Thus, at least one optical waveguide can be arranged in the at least one optical layer to guide the source light beam to the optical volume of the at least one optomechanical unit cell or to guide the signal light beam away from it. This allows defined light paths to be created within the optical layer. Optical waveguides can be manufactured, for example, by a hot stamping process in plastic layers, particularly in PMMA layers. However, conventional glass or polymer fibers can also be used, arranged or embedded in the optical layer.

[0045] In the case of multiple optomechanical unit cells in a system, several separate optical waveguides can be provided in the optical layer, which preferably define light paths that do not cross each other.

[0046] Alternatively, at least one optical layer can be designed to be partially or completely flooded with the source light beam.

[0047] The choice of light guidance technology allows for design flexibility in terms of cost and accuracy requirements, as well as for the specific application. For example, the use of optical fibers is suitable for products with particularly high demands on the accuracy of measurement results, while flooded light guidance in the optical layers enables particularly cost-effective production.

[0048] It is also possible to connect several optomechanical unit cells in series in such a way that the signal light beam emitted by one unit cell is used as the source light beam of another unit cell, regardless of whether the light is guided in an optical waveguide or whether the optical layer is flooded with light completely or section by section.

[0049] To separate different light beams, especially when the system comprises several optomechanical unit cells, the optomechanical system can include at least one further optical layer configured to guide light along this additional optical layer, as well as a coupling structure to guide light from one of the two optical layers to the other. Any desired number of optical layers can be provided. Furthermore, any combination of light-guiding methods within the individual optical layers is possible.

[0050] For example, the source light beam for a unit cell can be transported in one optical layer and supplied to the unit cell, while the signal light beam of the unit cell can be transferred to the other optical layer via a suitable coupling structure and discharged there.

[0051] Numerous methods exist for directing light from one plane to another. Two of these offer particular advantages in manufacturing: (a) optical structures (such as planar structures, prisms, etc.) positioned perpendicular to the light path, and (b) mirrors within the light path for deflection. Methods (a) and (b) can also be combined.

[0052] Finally, the optomechanical system can further comprise at least one light source optically coupled to the at least one optical layer, and / or at least one processing device designed to receive and process the signal light beam or beams.

[0053] In particular, the processing device can first convert the signal light beam(s) from various optomechanical unit cells into electrical signals and then process the electrical signals in a known manner. It may be advantageous to provide additional layers for EMC protection.

[0054] Various components can be used to provide light: LEDs, OLEDs, LDs, VCSELs, etc. Such components are available in discrete form as micro-components or can be printed, as in the case of OLEDs.

[0055] Photodetectors can be used to convert light signals into electrical signals. Such components are available in discrete form as micro-devices or can also be 3D printed.

[0056] However, direct optical processing or preprocessing of the optical signals is also possible, for example in an optical neural network.

[0057] For control purposes, the optomechanical system may include at least one control light path that directly connects the light source and the processing unit optically, without an intermediate optomechanical unit cell. This ensures that the source light beam on this control light path is not modified by the flow conditions. This can be used to verify the system's functionality and, for example, to readjust the luminance of the emitted source light beam, thus calibrating the system. It is also possible to use a pulsed light signal for monitoring or general measurement purposes.

[0058] Protection is also claimed for the use of the flow sensor arrangement according to the invention, the optomechanical system described above comprising an arrangement of several optomechanical unit cells distributed over an area, for determining a distribution of at least one characteristic parameter of a fluid flow propagating over the area.

[0059] The force acting on the transmission element(s) is an external force caused by the fluid flow.

[0060] Furthermore, protection is claimed for the use of the flow sensor arrangement according to the invention, whose optomechanical system described above comprises an arrangement of several optomechanical unit cells distributed over an area, for determining a distribution of a local acceleration over the area, in particular in the context of a flutter analysis, preferably for an aircraft wing.

[0061] The force acting on the respective transmission element is an inertial force caused by the local acceleration of, for example, an object under investigation that is set into vibration, which acts directly on the respective transmission element or on a test mass (inertial mass) mechanically coupled to it.

[0062] The flow sensor arrangement proposed according to the invention comprises an optomechanical system as described above and at least one sensing element provided on the upper cover layer of the optomechanical system, to which the optomechanical unit cell or one of the optomechanical unit cells is assigned, or to which several of the optomechanical unit cells are assigned, wherein the sensing element is further configured to apply a respective flow-dependent external force to the transmission element of each assigned optomechanical unit cell. The sensing element and the assigned optomechanical unit cell or the assigned optomechanical unit cells together form a flow sensor element.

[0063] By appropriately selecting the shape and coupling the sensing element to the transmission element of each associated optomechanical unit cell, different types of flow sensor elements can be formed that are adapted to the requirements of the respective individual case.

[0064] The principle for converting the signal into a photonic signal can be chosen to be the same for all specific types of flow sensor elements, which is advantageous for manufacturing and material logistics.

[0065] Several types of measurements can be acquired with a single optical base system, such as flow velocity, flow profile, flow direction, flow type (laminar, turbulent, degree of turbulence), flow separation, and pressure in the flow. In the worst case, only the sensing element (the external mechanical sensor component) needs to be adapted.

[0066] According to one aspect of the invention, the sensing element comprises an upwardly open cavity in the upper cover layer of the optomechanical system, which enables a targeted transmission of the external force to the transmission element.

[0067] In particular, it can be provided that a cavity in an adapter layer of the optomechanical system is formed below the cavity in the upper cover layer and overlapping it in a top view of the upper cover layer. The transmission element is arranged in this cavity, wherein the cavity in the adapter layer is separated from the cavity in the upper cover layer by a membrane, which is formed, for example, by an elastic layer and / or a preferably elastic membrane formed separately from the elastic layer. A predetermined pressure is set within the cavity in the adapter layer, for example, a defined vacuum or another suitable predetermined pressure. The cavity in the adapter layer is preferably hermetically sealed.

[0068] In this way, a simple membrane sensor can be provided. A fluid flow along the upper cover layer generates or transmits a specific pressure in the cavity in the upper cover layer, and the pressure difference between this pressure and the preset pressure in the cavity in the adapter layer moves the membrane and thus the transmission element, which acts on the optical volume with a corresponding force. Therefore, from the modification of the source light beam coupled into the optical volume, conclusions can ultimately be drawn about the pressure in the cavity of the upper cover layer and thus about the pressure in the fluid flow at the location of the cavity. In this sensor, the sensing element, as defined in the claims, thus comprises the cavity in the upper cover layer and the membrane.

[0069] According to a further aspect of the invention, the preferably flow-dependent deformable stylus element comprises a flow body anchored to the upper cover layer or one of the layers arranged below it of the optomechanical system above the upper cover layer.

[0070] The sensing element preferably further comprises a connecting element that anchors the flow body to the upper cover layer or one of the underlying layers of the optomechanical system. The connecting element preferably comprises a tongue, a rod, and / or a thread.

[0071] Depending on the selected connecting element and its attachment, this results in, for example, a tongue, rod, or thread sensor. However, the flow body can also be anchored directly to the upper cover layer or one of the underlying layers of the optomechanical system, i.e., without a connecting element.

[0072] By adjusting the method of fastening the flow body, for example by choosing the length of the connecting element, the flow velocity profile at a defined height above the upper surface layer can be determined.

[0073] By using a suitable shape for the flow body and structuring its surface, the disruptive effect of the sensor on the flow can be minimized.

[0074] A sensor type that also allows the determination of the flow direction at a specific point can be provided, for example, in the case of a rod or thread sensor, by the fact that the sensing element further comprises a pendulum disk to which the connecting element is attached, wherein the sensing element is assigned several optomechanical unit cells which interact with the pendulum disk at different positions, wherein the several optomechanical unit cells are preferably distributed over a circumferential edge region of the pendulum disk, particularly preferably with substantially the same angular spacing.

[0075] In a simple design, the pendulum disc can be round and flat, but other shapes and / or curvatures are also possible. The pendulum disc can be supported in the center by a centering pin, for example, against the optical layer. It should also not be ruled out that the pendulum disc is at least partially elastic.

[0076] The technique according to the invention makes it possible in particular to determine the flow distribution over the upper cover layer by comprising several sensing elements distributed on the upper cover layer, preferably differently designed sensing elements, wherein each sensing element forms a flow sensor element with the associated optomechanical unit cell or the associated optomechanical unit cells.

[0077] The flow sensor arrangement thus comprises various types of flow sensor elements, which are appropriately distributed over the area under investigation in order to determine the desired parameters of a fluid flow along this area. The underlying measurement principle is based on a single fundamental technique that enables the investigation of flows in both gases and liquids.

[0078] An accelerometer arrangement can comprise a previously described optomechanical system, wherein a test mass is assigned to the at least one optomechanical unit cell or to each of the optomechanical unit cells.

[0079] The test mass can be formed by the transmission element of the respective unit cell or be formed separately from the transmission element and mechanically coupled to it (e.g., firmly connected).

[0080] Preferably, the test mass is arranged above the transmission element and the latter is arranged overlapping in a top view, for example on an elastic membrane arranged between the test mass and the transmission element.

[0081] To protect against other influences, the test mass can be arranged in a cavity, preferably enclosed, below the upper cover layer, which is formed, for example, in a further adapter layer.

[0082] The optomechanical unit cell, including the associated test mass, forms an acceleration sensor element that enables the measurement of an inertial force acting locally on the test mass and thus of a local acceleration.

[0083] The advantages regarding material and manufacturing explained for the flow sensor arrangement also apply accordingly to the acceleration sensor arrangement.

[0084] A combination of acceleration sensor elements and flow sensor elements based on the aforementioned optomechanical system is also possible, in particular the integration of acceleration and flow sensor elements into a single optomechanical system.

[0085] The invention can be manufactured using mass-production-ready and cost-effective processes (RollToRoll R2R, SheetToSheet S2S, inkjet printing, 3D printing, embossing processes, etc.). Furthermore, the presented invention enables a simple and arbitrarily combinable arrangement of the different sensor types, e.g., on a belt or on an extended surface.

[0086] The external mechanical sensor components (flow bodies, rods, threads, tongues, cavities, test masses) of the invention can be flexibly adapted and positioned for the respective flow situation (medium, flow velocity, flow profile, pressure, frequency of pressure fluctuations or changes in flow direction, vibrations, accelerations, etc.) without having to modify the design of the underlying optical structures. This results in significant cost advantages due to the standardized production technology, and furthermore, a large number of product variants can be offered on the same basic optical technology with minimal development effort.

[0087] Temperature measurement is also frequently relevant. For this purpose, known technologies can be implemented cost-effectively on the same substrate, together with the solutions from the invention.

[0088] The invention thus enables the real-time acquisition of relevant flow parameters and / or accelerations distributed over a surface and their digital representation. This real-time digital acquisition allows the flow data to be linked with measurement data otherwise acquired from the object under consideration (e.g., a missile), for example, for analysis related to so-called "condition-based maintenance." Due to the large number of sensors that can be simultaneously acquired, AI methods such as neural networks can also be applied.

[0089] There is a strong trend away from expensive materials and manufacturing technologies, such as silicon, towards inexpensive materials like plastics. This invention addresses this trend. For the optical part of the invention, the use of polymers and glass films, for example, is suitable. Most of the films used are available in roll form, which significantly reduces material and processing costs.

[0090] The various sensor variants covered by the invention can largely be based on the same fundamental technology (same structure and functionality of the optical layers (planes) for the different sensor types). This allows for a high degree of flexibility in the design of the final product according to customer requirements without significant additional costs.

[0091] The process and material chain are essentially the same on the optical (photonic) side for a wide variety of sensor types. This also results in a significant reduction in manufacturing and material costs. All sensor types can be manufactured together on a single product strip.

[0092] The manufacturing of the external versions of the stylus elements can be separated from the manufacturing of the planar optomechanical system. This allows for a free choice of materials and shapes for the stylus elements.

[0093] Miniaturization in height is made possible by building the components from very thin layers. Semi-finished products such as polymer films, glass films, metal films, ceramic films, or other films can also be used for this purpose.

[0094] Lamination or adhesive bonding processes can be used to join the layers. Transparent adhesives can act as connectors and simultaneously perform optical functions, for example, by imprinting optical structures. Non-transparent adhesives can be used for bonding and, if necessary, also for encapsulation (e.g., preventing light transmission from layer to layer). Coating processes, such as inkjet printing, plasma deposition, and others, can also be used to build up layers or sub-layers. Different layers can fulfill different functions.

[0095] For example, conductive traces are needed for the power supply of light sources (LEDs, LDs, VCSELs, etc.), for signal taps at photodetectors (photodiodes, phototransistors, etc.), for photovoltaic cells for energy supply, for energy storage (rechargeable batteries, batteries, supercapacitors, etc.) and for contacts for signal processing.

[0096] There are various methods for equipping optical layers with the necessary electrical contacts and conductive traces. For example, prefabricated films coated with electrically conductive material (IoT, metals such as silver, etc.) made of optical polymer or optical glass can be used, with the excess conductive material being removed. This removal can be achieved, for example, through lithographic processes or laser ablation. Another method for applying electrical contacts and conductive traces is printing, for example, using inkjet technology.

[0097] The layered, and therefore planar, structure of the invention offers the use of the surface for applying further functionalities above and below the optical layers.

[0098] There are methods for the large-area fabrication of photovoltaic cells. These are intended to enable energy generation. To store the energy, printable batteries, accumulators, or capacitors can also be integrated into the flow sensor array in layers. Using the same technique, photodetectors can be integrated to capture the light signals and convert them into electrical signals.

[0099] Analog-to-digital converters and microcontrollers can now also be manufactured as thin films on foil, making such components particularly suitable for integration with the thin structure of the invention, thus keeping the overall solution thin.

[0100] Fiber-reinforced or metallic materials can be used to increase mechanical strength.

[0101] It is also possible to integrate temperature sensors and heating elements into the flat structure as needed, for example to prevent ice formation. Inkjet and / or screen printing methods can also be used for these functions.

[0102] Depending on the application, the upper cover layer of the optomechanical system or any other outer surface of a flow sensor arrangement according to the invention can be provided with a suitable coating, such as an anti-stick coating, a dirt-repellent coating, a UV-protective coating, an anti-icing coating, a (super-)hydrophobic coating, a sliding coating, etc. With regard to the material used, for example a metallic or ceramic coating or a plastic coating, such as a polyimide, can be employed.

[0103] The proposed technique, through the appropriate selection and distribution of the individual sensor elements and their evaluation, allows, for example, the detection of gusts that may occur locally on the surfaces exposed to the airflow. When vibrations (e.g., fluttering) occur, their causes can be identified, provided they are fluid-related. The invention can be used to determine sound emissions caused by airflow.

[0104] Another particular advantage is that, due to the thin, flat structure of the invention, a user system can be retrofitted with it at any time.

[0105] The present invention will now be explained in more detail with reference to some selected embodiments and the accompanying figures. These figures represent: Fig. 1-6 perspective views of different embodiments of an optomechanical unit cell, Fig. Figures 7-14 in sub-figures a) and b) show a cross-sectional view and a perspective view of different embodiments of an optomechanical system, Fig. 15 in the partial figures a), b) and c) a perspective view, a top view and a sectional view of an essential section of an embodiment of a flow sensor arrangement according to the invention with a membrane sensor as a flow sensor element, Fig. 16 in the partial figures a) and b) various sectional views of an essential section of an embodiment of a flow sensor arrangement according to the invention with a tongue sensor as a flow sensor element, Fig. 17 in the partial figures a), b) and c) a perspective view, a top view and a sectional view of an essential section of an embodiment of a flow sensor arrangement according to the invention with a rod sensor as a flow sensor element, Fig. 18 a perspective view of an essential section of an embodiment of a flow sensor arrangement according to the invention with a thread sensor as a flow sensor element, Fig. 19-21 Perspective views of various embodiments of flow sensor arrangements, and Fig. 22 a sectional view of a significant section of an embodiment of an unclaimed acceleration sensor arrangement.

[0106] All figures are highly simplified and schematic representations that essentially serve to illustrate the principle of the invention. Identical or corresponding features of different embodiments are identified by the same reference numeral.

[0107] It should be noted that not all features in every figure are labelled with reference symbols, but essentially only those needed to explain the respective figure.

[0108] To allow a view of all essential components, the various parts are shown partially transparent in the perspective drawings. Electrical conductors are not shown in the figures. Furthermore, embodiments are conceivable that largely or completely do without electrical conductors, for example, if the processing is optical rather than electrical.

[0109] In the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. Figure 6 illustrates various examples of optomechanical unit cells 400, which represent a basic building block of the present invention and are hereinafter also referred to as OMEZ.

[0110] The optomechanical unit cells 400 each comprise a preferably elastically expandable and / or elastically compressible optical volume 433, which is supplied with light by a source light beam Q, and a transmission element 320, here by way of example designed as a cone-shaped component, which can be subjected to a force F and is designed to influence the optical volume 433 depending on the force F, for example to compress or expand it. This modifies the source light beam that has entered the optical volume 433, and the resulting signal light beam is emitted from the optical volume 433 and subsequently preferably processed optically and / or electronically.

[0111] As explained in more detail below, the optical volume 433 is in each case contained in a Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. 6 only indicated optical layer 410 formed or arranged, which is designed to guide the source light beam Q and / or the signal light beam S.

[0112] This is described in the various versions of the Fig. 1, Fig. 2 to Fig. 3. Each optical waveguide 431 is embedded in the optical layer 410, which can be produced, for example, in a hot stamping process in the optical layer 410 or formed by an optical fiber made of a glass or polymer material. In the embodiment variants of the Fig. 4, Fig. 5 to Fig. 6 The optical layer 410 is flooded with the source light beam Q and / or the signal light beam S.

[0113] In the exemplary embodiments of the Fig. 1 and Fig. 2. The source light beam penetrates only a part of the optical volume 433, which is subsequently referred to as the active optical volume 434. In contrast, the source light beam propagates in the embodiment variants of the Fig. 3, Fig. 4, Fig. 5 to Fig. 6 in the entire optical volume 433, so that the optical volume 433 and the active optical volume 434 coincide in these examples.

[0114] The optical volume 433 is shown as a cuboid in each of the figures, but it can also have any other desired shape. In the embodiment of Fig. 1. The optical volume 433 can be empty (unfilled) or filled with an elastic material. In particular, it can consist of the same material as the rest of the optical layer 410. In this case, it is possible, but not absolutely necessary, for the optical volume 433 to have structures for demarcation from the rest of the optical layer 410.

[0115] The force exerted on the optical volume 433 or 434 by means of the transmission element 320 changes its optical properties, which in turn modify the incoming source light beam Q.

[0116] For example, the transparency of the (active) optical volume 433 (434) can depend on its instantaneous expansion or compression. In the simplest case of an empty optical volume 433, the aforementioned change can simply consist of an instantaneous shading or narrowing of the light path, which reduces the amount of light transmitted per unit time through the optomechanical unit cell 400 as a function of the force F.

[0117] However, more elaborate versions are also conceivable. In the cases described in the Fig. 2 and Fig. In the 5 illustrated embodiment variants, for example, a Bragg grating 438 is provided in the active optical volume 434, which can be used as a strain sensor in a known manner.

[0118] To couple the source light beam Q into the (active) optical volume 433 (434) and / or to couple the signal light beam S out of the (active) optical volume 433 (434), it can each contain a suitable optical component 435, such as a lens, as in the embodiments of the Fig. 3 and Fig. 6, in which the component 435 can be used, for example, to focus the respective light beam on a desired area, or to illuminate the entire optical volume 433 evenly, which then coincides with the active optical volume 434.

[0119] Based on the optomechanical unit cells, as described above using some selected examples, optomechanical systems 200 (or systems or OMS for short) can be constructed by adding further components, some of which are implemented in the Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. 14 are illustrated.

[0120] In all depicted OMS variants, an upper cover layer 210 and a lower cover layer 220 are provided, between which the optical layer 410 is arranged. This optical layer guides the source light beam to the at least one unit cell 400. The cover layers 210 serve as substrate layers, controlling the required strength and resistance to environmental influences, and accommodating further components such as photovoltaic layers, accumulator layers as energy carriers, and other potentially required systems. It is possible to provide multiple optical layers. The layers can be bonded, for example, by adhesive layers, which themselves may be equipped with structures.

[0121] In the illustrated embodiments, an adapter layer 330 is provided between the upper cover layer 210 and the optical layer 410 to guide the transmission element 320. To effect a return movement of the transmission element 320, one or more elastic layers 310 can be used, preferably above or below the optical layer 410, or in both positions.

[0122] In the various versions of the Fig. 7 and Fig. 8 is provided only with a single optical layer 410 with embedded optical waveguides 431, which serve to direct the source light beam Q to the OMEZ 400 and to direct the signal light beam S from the OMEZ 400 and to supply it for further processing.

[0123] In the cross-sectional view of the partial illustrations a) the Fig. 7 and Fig. Figure 8 shows further optical waveguides 431 which can lead to further unit cells not shown in the figures.

[0124] In Fig. 7. The optical volume 433 or the active optical volume 434 consists of the same material as the rest of the optical layer or the optical waveguide, while in Fig. 8 the active optical volume 434 is structured differently and is thus visibly represented as an independent component.

[0125] In the variants of Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. 14 each provide two optical layers 410, 420, which for the sake of simplicity are referred to below as upper optical layer 410 and lower optical layer 420.

[0126] During the construction after Fig. 9 The source light beam (not shown) is initially located (flooded) in the upper optical layer 410. The signal light beam exiting the active optical volume 434 in the upper optical layer 410 is guided downwards to the lower optical layer 420 by means of a coupling structure 436. A photodetector 442, for example, can be provided on the level of the lower optical layer 420 to detect and convert the signal light beam into an electrical signal.

[0127] Even during the construction after Fig. 10. The source light beam (not shown) is directed into the optical volume 433 in the upper optical layer 410, flooding the upper optical layer 410 with the source light beam. The signal light beam exiting the active optical volume 434 in the upper optical layer 410 is guided downwards to the lower optical layer 420 by means of a coupling structure 436. In this setup, the lower optical layer 420 preferably contains another coupling structure 436 for transmitting the signal light beam into an optical waveguide 431 embedded in the lower optical layer 420 for further transmission.

[0128] During the construction after Fig. In the lower optical layer 420, the source light beam Q is located and is supplied by an electronic light source 441, which feeds the source light beam into a coupling structure 436 leading to the upper optical layer 410. From there, the light enters the active optical volume 434 in the upper optical layer 410. The exiting signal light is guided back down to the lower optical layer 420 by means of another coupling structure 436. The lower optical layer 420 contains... Fig. 11 a photodetector 442 for recording and converting the signal light beam into an electrical signal.

[0129] During the construction after Fig. In the lower optical layer 420, the source light beam (not shown) is located and supplied by an electronic light source 441. This source light beam is fed into a coupling structure 436 leading to the upper optical layer 410. From there, the light enters the active optical volume 434 in the upper optical layer 410. The exiting signal light beam is guided downwards again towards the lower optical layer 420 by means of another coupling structure 436. In this setup, the lower optical layer 420 contains another coupling structure 436 for transmitting the signal light into an optical waveguide 431 embedded in the lower optical layer for further transmission.

[0130] During the construction after Fig. In step 13, the lower optical layer 420 is flooded with the source light beam. This beam is then guided out via an optical microstructure 437 and fed into a coupling structure 436 in the upper optical layer 410. From there, the light enters the active optical volume 434 in the upper optical layer (410). The exiting signal light beam is guided downwards towards the lower optical layer 420 by means of another coupling structure 436. In this setup, a photodetector 442 is located in the lower optical layer 420 for capturing and converting the signal light beam into an electrical signal.

[0131] During the construction after Fig. 14 The source light beam is guided by an optical waveguide 431 embedded in the lower optical layer 420. From the optical waveguide 431, the source light beam enters a coupling structure 436 in the lower optical layer 420. The lower coupling structure 436 transfers the source light beam to another coupling structure 436 in the upper optical layer 410. From there, the light enters the active optical volume 434 in the upper optical layer 410. The exiting signal light beam is guided downwards again towards the lower optical layer 420 by means of another coupling structure 436. In this setup, the lower optical layer 420 contains another coupling structure 436 for transferring the signal light beam into an optical waveguide 431 embedded in the lower optical layer 420 for further transmission.

[0132] The OMS of Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. 14 can be used, when integrated into a suitable sensor arrangement, to measure local flow properties or to measure local accelerations or vibrations, for example as the basis for a flutter analysis for an aircraft wing.

[0133] Fig. Figure 15 illustrates an embodiment of a flow sensor arrangement 100 with a membrane sensor 360 as the flow sensor element 500. In this arrangement, an upwardly open cavity 361 is provided in the upper cover layer 210 of the OMS 200, which is located directly above a cavity 363 in the adapter layer 330, in which a transmission element 320 is arranged (see Figure 15). Fig. 15c), which is a sectional view of the object of the top view of Fig. 15b) along the section plane designated CC therein).

[0134] The pressure acting in the fluid flow along the upper cover layer 210 acts through the passage opening 358 into the cavity 361 within the upper cover layer 210, via an elastic layer 310 onto a sensor membrane 362.

[0135] During manufacturing, a desired counter-pressure, such as a vacuum or another predetermined pressure, is set in the hermetically sealed cavity 363 in the adapter layer 330. The force resulting from the differential pressure between the cavities 361 and 363 moves the transmission element 320. The upwardly open cavity 361 is thus a component of a sensing element 300 according to claim 11.

[0136] Fig. Figure 16 illustrates an embodiment of a flow sensor arrangement 100 with a tongue sensor 350 as a flow sensor element 500.

[0137] In this arrangement, a connecting tongue 351, acting as a connecting element 345, is elastically connected to the layer system of the OMS about an axis of rotation D or a pivot point from a rest position and carries a tongue body 353 as a flow body 340 at its free end. By means of a pressure body 352 provided at a suitable location, the force introduced from the flow acts via the elastic layer 310 on the transmission element 320, which has already been described as a component of the OMEZ and OMS variants.

[0138] The pressure body 352 can be located at the connecting tongue 351 or at the elastic layer 310, or it can be designed in two parts and located at both points. The tongue body 353 can be designed according to the flow requirements. For example, the surface of the tongue body 353 can be adapted to reduce flow disturbances, perhaps with a variant of a sharkskin structure.

[0139] Fig. Figure 17 illustrates an embodiment of a flow sensor arrangement 100 with a rod sensor 370 as a flow sensor element 500.

[0140] In this case, the touch element 300 comprises a flow body 340, which is exemplified here as a sphere 374, as well as a rigid or elastic rod 373 as a connecting element 345, a pendulum disc 371, an elastic layer 310 and several transmission elements 320, each belonging to an OMEZ 400.

[0141] Depending on the amount and direction of the deflection of the flow body 340 from the equilibrium position shown in partial figure a), the pendulum disk 371 is tilted and thus acts to varying degrees on the different transmission elements 320, which are distributed over the circumference of the pendulum disk 371.

[0142] From a comparative analysis of the signal light beams from the various OMEZ 400 units assigned to the touch element 300, conclusions can therefore be drawn about the amount and direction of the fluid flow at the location of the touch element 300.

[0143] For the purpose of returning to a rest position and as a counterforce, the pendulum disc 371 is connected to the elastic layer 310. An elastic layer 310 can be located above or below the pendulum disc 371, or at both locations. A centering pin 372 may also be present. The pendulum disc 371 can be guided through a suitably adapted opening 363 in the adapter layer 330, preferably in a manner that prevents displacement and / or rotation.

[0144] The transmission elements 320 are distributed around the circumference of the pendulum disk 371 and interact with it. They can have any shape. The length of the rod 373 can also be adapted to the requirements of the flow situation.

[0145] The simplest form of the pendulum disk 371 is round and flat. However, any other shape can be used. The pendulum disk 371 can also be curved and / or at least partially elastic. In this case, an elastic layer is not strictly necessary.

[0146] The shape of the flow body 340 can be adapted to the requirements of the flow. As explained for the tongue sensor, the surface of the flow body 340 can be adapted to reduce disturbances to the flow.

[0147] The thread sensor 380 of the flow sensor arrangement 100 according to Fig. 18 is constructed similarly to the rod sensor 370, except that the flow body 340 is not directly mounted on the rod 373 but is connected to it via a thread 381. Here, the connecting element 345, as defined in claim 14, comprises the rod 373 and the thread 381. For further details, please refer to the preceding description of the rod sensor.

[0148] In the Fig. 19, Fig. 20 to Fig. Figure 21 shows three embodiments of a flow sensor arrangement 100 according to the invention, each comprising an optomechanical system 200 with several different sensing elements 300 distributed on its upper cover layer, wherein each sensing element 300 forms a flow sensor element 500 with the associated OMEZ 400.

[0149] The flow sensor arrangement 100 thus comprises a variety of different flow sensor elements 500, for example the tongue sensors 350, membrane sensors 360, rod sensors 370 and / or thread sensors 380 described above. The selection and distribution of the sensors in the figures is purely exemplary and can be adapted to the specific case.

[0150] The flow sensor arrangement 100 according to Fig. 19 further comprises a light source 120, for example a light source array, preferably made of LEDs, for generating the source light beam or beams, and a processing device 130 for receiving and processing the signal light beam or beams.

[0151] To convert the light signals into electronic signals, at least one suitable photodetector can be used, and the processing of electronic signals can take place in a conventional microcontroller unit 150, which may also include an interface for connection to desired electronics or similar. Purely optical signal processing of the light signals is also possible.

[0152] The energy required for operation can be taken, for example, from a battery 140 integrated in the sensor arrangement 100 or from a photovoltaic cell, or obtained via a suitable interface.

[0153] The examples of implementation of Fig. 20 and Fig. 21 differ from the embodiment of the Fig. 19 essentially by the arrangement of the light source(s) 120 and the processing device 130 relative to each other and to the individual flow sensor elements 500.

[0154] While in the example according to Fig. 19 where the light source 120 and the processing device 130 are arranged at opposite longitudinal ends of an approximately rectangular sensor section 110 of the OMS 200, in which the individual flow sensor elements 500 are located, the devices 120 and 130 are shown in the examples of Fig. 20 and Fig. 21 integrated or combined training.

[0155] For example, the light may be guided in suitable optical waveguides, although this is not explicitly shown here ( Fig. 20), and / or the light can be guided in an optical layer (not explicitly shown here) from the light source 120 to the individual flow sensor elements 500, deflected in a deflection device 170 (deflection or coupling line) into another optical layer and from there directed back to the processing device 130 ( Fig. 21).

[0156] The planar design of the sensor arrangement 100 makes it particularly suitable for use on surfaces whose flow conditions are to be investigated, such as airfoils, aerodynamic vehicle surfaces, rotor blades, turbine blades and the like.

[0157] Fig. Figure 22 shows a sectional view of an essential section of an embodiment of an acceleration sensor arrangement 190 not claimed here.

[0158] In this case, no external, flow-dependent force acts on the transmission element 320, but it is mechanically coupled to a test mass 180, on which an inertial force acts as force F in the event of acceleration (for example, in the case of vibrations of the object under investigation).

[0159] The test mass 180 and the optomechanical unit cell 400 together form an accelerometer element 550.

[0160] In the illustrated embodiment, the test mass 180 is arranged above the transmission element 320 and the latter is arranged overlapping in a top view, for example on an elastic membrane 362 or / or elastic layer 310 arranged between the test mass 180 and the transmission element 320.

[0161] To protect against external influences, the test mass 180 is preferably arranged in a cavity 364 below the upper cover layer 210, which may, for example, be formed in a further (upper) adapter layer 331. The cavity 364 may be closed, but an opening for gas exchange with the cavity 363, in which the transmission element 320 is arranged, is also conceivable.

[0162] In an alternative embodiment, the test mass can also be formed by the transmission element, contrary to the illustration shown. The accelerometer arrangement 190 can have several accelerometer elements 550 distributed over a surface to be examined, which can be integrated in a layered system.

[0163] The technique described also makes it possible to integrate flow sensors and acceleration sensors onto a substrate or in a layered system, for example by integrating them into the Fig. 19, Fig. 20 to Fig. 21 some of the flow sensor elements, such as the membrane sensors 360, by acceleration sensor elements 550 according to Fig. 22 will be replaced. Reference sign 100 flow sensor arrangement 110 Sensor section 120 light sources 130 processing facilities 140 battery 150 MCU 170 Deflection device 180 test mass 190 Accelerometer array 200 optomechanical system 210 upper cover layer 220 lower top layer 300 key element 310 elastic layer 320 transmission element 330 adapter layer 331 additional (upper) adapter layer 340 flow bodies 345 Connecting element 350 tongue sensor 351 Connecting tongue 352 pressure bodies 353 tongue bodies 358 Passage opening 360 membrane sensor 361 Cavity in the upper cover layer 362 Sensor Membrane 363 Cavity in the adapter layer 364 Cavity in the further adapter layer 370 rod sensor 371 Pendulum disc 372 centering pins 373 Staff 374 balls 380 thread sensor 381 threads 400 optomechanical unit cells 410 (upper) optical layer 420 (lower) optical layer 431 Optical fibers 433 optical volume 434 active optical volume 435 optical component 436 Coupling structure 437 optical microstructure 438 Bragg grid 441 Light source 442 Photodetector 500 flow sensor elements 550 Accelerometer element Q Source light beam S signal light beam F force D axis of rotation

Claims

[1] Flow sensor arrangement (100) comprising an optomechanical system (200) comprising - an upper cover layer (210), - a lower top layer (220), - at least one optical layer (410) designed to conduct light and optically coupled to a light source (120, 441) and arranged between the upper and lower cover layers (210, 220), - an arrangement of at least one optomechanical unit cell (400) comprising an optical volume (433) optically coupled to the at least one optical layer (410), and a transmission element (320) associated with this optical volume (433), which can be acted upon from above with a force (F) and is designed and arranged to act on the optical volume (433) depending on the force (F), wherein the optical volume (433) is formed or arranged at least sectionally in the at least one optical layer (410) and is further configured to receive a source light beam (Q) from the at least one optical layer (410) so that it penetrates the entire optical volume (433) or only a part of the optical volume (433) which forms an active optical volume (434), and to modify the source light beam (Q) depending on the force (F) currently acting on the transmission element (320) and to direct the modified source light beam out of the optical volume (433) as a signal light beam (S), and further comprising the flow sensor arrangement: at least one sensing element (300) arranged on the upper cover layer (210) of the optomechanical system (200), to which the optomechanical unit cell (400) or one of the optomechanical unit cells (400) is assigned, or to which several of the optomechanical unit cells (400) are assigned, wherein the sensing element (300) is configured to apply a respective flow-dependent external force (F) to the transmission element (320) of each assigned optomechanical unit cell (400), wherein the sensing element (300) and the assigned optomechanical unit cell (400) or the assigned optomechanical unit cells (400) together form a flow sensor element (500), wherein the sensing element (300) comprises an upwardly open cavity (361) in the upper cover layer (210) of the optomechanical system (200). [2] Flow sensor arrangement (100) according to claim 1, wherein the optomechanical system further comprises an adapter layer (330) arranged between the upper cover layer (210) and the at least one optical layer (410), in which the transmission element (320) of the at least one optomechanical unit cell (400) is formed or arranged. [3] Flow sensor arrangement (100) according to claim 2, wherein a cavity (363) is formed in the adapter layer (330) below the cavity (361) in the upper cover layer (210) and overlapping it in a top view of the upper cover layer (210), in which the transmission element (320) is arranged, wherein the cavity (363) in the adapter layer (330) is separated from the cavity (361) in the upper cover layer (210) by an elastic layer (310) and / or an elastic membrane (362), and wherein a predetermined pressure is set within the cavity (363) in the adapter layer (330). [4] Flow sensor arrangement (100) comprising an optomechanical system (200) comprising - an upper cover layer (210), - a lower top layer (220), - at least one optical layer (410) designed to conduct light and optically coupled to a light source (120, 441) and arranged between the upper and lower cover layers (210, 220), - an arrangement of at least one optomechanical unit cell (400) comprising an optical volume (433) optically coupled to the at least one optical layer (410), and a transmission element (320) associated with this optical volume (433), which can be acted upon from above with a force (F) and is designed and arranged to act on the optical volume (433) depending on the force (F), wherein the optical volume (433) is formed or arranged at least sectionally in the optical layer (410) and is further configured to receive a source light beam (Q) from the at least one optical layer (410) such that it penetrates the entire optical volume (433) or only a part of the optical volume (433) which forms an active optical volume (434), and to modify the source light beam (Q) depending on the force (F) currently acting on the transmission element (320) and to direct the modified source light beam out of the optical volume (433) as a signal light beam (S), and wherein the flow sensor arrangement further comprises: at least one sensing element (300) arranged on the upper cover layer (210) of the optomechanical system (200), to which the optomechanical unit cell (400) or one of the optomechanical unit cells (400) is assigned, or to which several of the optomechanical unit cells (400) are assigned, wherein the sensing element (300) is configured to apply a respective flow-dependent external force (F) to the transmission element (320) of each assigned optomechanical unit cell (400), wherein the sensing element (300) and the assigned optomechanical unit cell (400) or the assigned optomechanical unit cells (400) together form a flow sensor element (500), wherein the optomechanical system (200) further comprises an adapter layer (330) arranged between the upper cover layer (210) and the at least one optical layer (410), in which the transmission element (320) of the at least one optomechanical unit cell (400) is formed or arranged, and wherein the key element (300) comprises a flow body (340) anchored to the upper cover layer (210) or to one of the layers of the optomechanical system (200) arranged below it above the upper cover layer (210). [5] Flow sensor arrangement according to claim 4, further comprising a connecting element (345) which anchors the flow body (340) to the upper cover layer (210) or one of the layers arranged below it of the optomechanical system (200) and preferably has a connecting tongue (351), a rod (373) and / or a thread (381). [6] Flow sensor arrangement (100) according to claim 5, characterized by, that the stylus element (300) further comprises a pendulum disk (371) to which the connecting element (345) is attached, wherein several optomechanical unit cells (400) are assigned to the stylus element (300) which interact with the pendulum disk (371) at different positions, wherein the several optomechanical unit cells (400) are preferably distributed over a circumferential edge region of the pendulum disk (371), particularly preferably with substantially the same angular distance to each other. [7] Flow sensor arrangement (100) according to one of claims 4 to 6, wherein the sensing element (300) is deformable depending on the flow. [8] Flow sensor arrangement (100) according to one of the preceding claims, wherein the transparency of the optical volume (433) or the active optical volume (434) of the at least one optomechanical unit cell (400) depends on the force (F) currently acting on the transmission element (320) at least for a given wavelength or a given wavelength range. [9] Flow sensor arrangement (100) according to any one of claims 1 to 7, wherein the optical volume (433) of the at least one optomechanical unit cell (400) is empty or filled with an elastic material or contains a Bragg grating (438). [10] Flow sensor arrangement (100) according to one of the preceding claims, further comprising at least one optical component (435) which preferably includes at least one lens or prism to couple the source light beam (Q) into the optical volume (433) or the active optical volume (434) and / or to couple the signal light beam (S) out of the optical volume (433) or the active optical volume (434). [11] Flow sensor arrangement (100) according to one of the preceding claims, further comprising at least one elastic layer (310) formed between the at least one optical layer (410) and one of the cover layers (210, 220). [12] Flow sensor arrangement (100) according to one of the preceding claims, wherein at least one optical waveguide (431) is arranged in the at least one optical layer (410) to guide the source light beam (Q) to the optical volume (433) of the at least one optomechanical unit cell (400) or to guide the signal light beam (S) away from it. [13] Flow sensor arrangement (100) according to one of the preceding claims, wherein the at least one optical layer (410) is configured to be partially or completely flooded with the source light beam (Q) and / or the signal light beam (S). [14] Flow sensor arrangement (100) according to one of the preceding claims, further comprising at least one further optical layer (420) configured to guide light along the further optical layer (420), and a coupling structure (436) to guide light from one to the other of the two optical layers (410, 420). [15] Flow sensor arrangement (100) according to one of the preceding claims, further comprising at least one light source (120) optically coupled to the at least one optical layer (410), and / or at least one processing device (130) designed to receive and process the signal light beam (S) or signal light beams (S). [16] Flow sensor arrangement (100) according to claim 15 with a light source (120) and a processing device (130), wherein at least one control light path is provided which optically connects the light source (120) and the processing device (130) without an intermediate optomechanical unit cell (400). [17] Flow sensor arrangement (100) according to one of the preceding claims, comprising several sensing elements (300) distributed on the upper cover layer, preferably differently designed sensing elements (300), wherein each sensing element (300) with the associated optomechanical unit cell (400) or the associated optomechanical unit cells (400) forms a flow sensor element (500). [18] Use of a flow sensor arrangement (100) according to one of the preceding claims comprising an arrangement of several optomechanical unit cells (400) distributed over an area, for determining a distribution of at least one characteristic parameter of a fluid flow propagating over the area. [19] Use of a flow sensor arrangement (100) according to one of claims 1 to 17 comprising an arrangement of several optomechanical unit cells (400) distributed over an area, for determining a distribution of a local acceleration over the area, in particular in the context of a flutter analysis, preferably for an aircraft wing.

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