Compact target flowmeter

Abstract

A flow measurement apparatus is provided. The flow measurement device includes a rigid housing defining a flow channel having a channel input and a channel output, the flow channel configured to allow a fluid medium to flow from the channel input to the channel output; a moving member hingedly mounted within the flow channel and extending transversely to the flow direction of the fluid medium, the moving member comprising a moving member magnet, the moving member operably moving under the action of resistance generated by the fluid passing through the flow channel, the moving member consisting of a flexible support structure forming a living hinge, the moving member magnet is coupled to the flexible support structure; a fixed magnet disposed at least proximate a sidewall of the flow channel, the fixed magnet having the same polarity with respect to the moving member magnet and arranged to operably apply a repulsive force to the moving member magnet, thereby limiting displacement of the moving member in proportion to a magnitude of resistance applied by the fluid flow, to linearize the relationship between the flow rate of the fluid medium and the displacement of the moving member; and a sensing element positioned relative to the moving member and configured to provide an output indicative of movement of the moving member within the flow channel.

Description

Technical Field

[0001] The present invention relates to a miniaturized flow sensing method for fluid media. It relates to a sensing technology that allows real-time, accurate and stable measurement of the volume of a fluid, gas or liquid passing through a channel, and provides a wide dynamic sensing range, especially when used in a channel with a cross-sectional area of ​​square millimeters. Background Art

[0002] Many approaches have been employed in limited form factor flow sensing; primary among these are thermal methods - anemometer, calorimetry, and time of flight, to name a few. These methods work well for measuring low flow rates, but tend to saturate at higher rates, especially in media with high thermal conductivity such as water. Another drawback is that sensor placement and channel geometry are critical, and sensitivity to flow orientation and state (turbulent / laminar) is difficult to avoid.

[0003] A simple alternative to the calorimetric approach is the target flow meter (also known as a vane meter or paddle meter), in which a physical target partially blocks the channel; the displacement or stress of the target due to the force of the flow is converted into a flow measurement. Although conceptually simple, this type of meter has several limitations. The first of these comes from the fact that the force of the flow is proportional to the square of the flow rate; this inherently limits the turndown (dynamic range) since a 10-fold increase in flow will mean a 100-fold increase in the force acting on the target.

[0004] A further complication, especially in the context of flow metering in confined spaces, is the need to articulate the target in order to register the deflection. Conventional mechanical hinges have a variable frictional resistance, which can overwhelm the deflection force at low flow rates. Living hinges (which are sometimes called integral hinges and are thin, flexible hinges made of the same material as the two rigid pieces they connect) can overcome this problem, but only if the hinge material is perfectly elastic; viscoelastic materials such as plastics exhibit similar frictional effects, although these effects are internal to the material. Considering elastic materials, the most common of these are metals, which are also characterized by a higher elastic modulus. This means that even in very thin sheets, the stiffness can be too high to deflect against small flow forces. This is especially true for channels with diameters in the order of millimeters.

[0005] Related examples of target flow meters equipped with magnets for the purpose of overcoming these limitations are mentioned in the following prior art documents.

[0006] US881586A to Howe-Gould Robert is an early example of a target flow meter. It discloses a fluid velocity meter in which the flow of fluid causes a vane in a flow channel to move, the vane being connected to a spindle perpendicular to the flow channel. The moving spindle is connected to a first magnet and coupled to a second spindle, the second spindle moves in an external chamber and is connected to a second magnet of opposite polarity, the second spindle ends in a pointer to which the movement of the vane is transmitted by the magnet, and the second spindle provides a reading of the fluid velocity on a dial.

[0007] GB2499995B of Grant Needham discloses a flow meter comprising a target in a fluid flow conduit and a beam attached to the target. The beam is coupled to a sensor, which moves with the beam as the fluid passes through the channel. The displacement of the entire movable sensor generates a signal detected by a static sensor and representing the flow rate of the fluid. The movable sensor may include an inductive sensor, wherein each fixed sensor board includes a printed circuit board having at least one primary coil and at least one secondary coil.

[0008] US8783088B2 to Drew S. Weaver discloses a method and apparatus for providing a flow meter, wherein a displacement body moving within a flow tube carries a magnetic target, the movement of the magnetic target being detected by an inductive transmitter along the flow tube, and wherein a signal generated by the transmitter indicates the velocity of the displacement body, from which the fluid velocity can be inferred.

[0009] US8800473B1 to Richard DeVerse discloses a mass flow meter consisting of a valve flap structure placed transversely to the fluid flow in a channel, which allows the fluid to flow in only one direction. The valve flap is mounted to rotate around an axis whose axis is perpendicular to the flow direction, and the valve flap is balanced by a spring. A harder spring will limit the flow range to higher flow rates, while a softer spring will result in sensitivity for a lower flow range. Although the present invention solves the problem of balancing the force applied by the fluid to the hinged element in the channel, however, due to the limitations of the mechanical properties of the spring, it only allows the selection of a high or low flow rate range. Furthermore, if the size of the cross-section of the channel is reduced to the millimeter level, the nature of the mechanical components in this sensing unit makes its use tricky.

[0010] EP1376635A1 to Paul K. Edwards discloses a switch operated by fluid flow and consisting of an assembly having a paddle at a first end, an activation magnet at a second end, and a pivot shaft between the first and second ends. A bias magnet is positioned on an outer housing of a sensor unit to force the magnet on the paddle assembly to remain in an inactive, stable position under conditions of zero flow. An activation sensor interacts with the magnet on the paddle to signal the presence of flow. Although the present invention relates to a paddle equipped with a magnet, however, it is arranged outside the flow channel and is primarily used to maintain the paddle in a stable, vertical position in the absence of flow.

[0011] WO1999050621A1 by Stanley E. Hawkins discloses an online flow meter for a drip irrigation system that provides visual flow indications for high flow rates above a field-adjustable normal flow rate and low flow rates below a field-adjustable normal flow rate. The flow meter consists of a paddle with a permanent magnet attached in a flow channel. The paddle hangs down into the fluid and rotates up and down depending on whether the flow is increasing or decreasing. An indicator rod located outside the flow channel carries a second magnet that interacts with the magnet on the paddle, and its rotation mimics the angular orientation of the paddle in the flow channel, which is achieved by the interaction of two oppositely magnetized magnets. Although the present invention describes flow metering by the interaction of paddles and magnetic forces, its purpose is to indicate the flow rate relative to a field-adjustable zero position, which corresponds to a predetermined flow value.

[0012] US6681645B1 to Murray F. Feller discloses a device for measuring flow rate, wherein a target in a flow channel moves a certain amount depending on the flow rate and an external force applied to the target by an electromechanical transducer, which also senses the amount of target movement and converts it into a flow rate reading. The target can be a shaft to which a rigid blade is attached, wherein the shaft is rotated by a motor (transducer), or the target can be a blade attached to a post, wherein the transducer includes at least one electric winding connected to the post and cooperating with a permanent magnet attached to the blade.

[0013] CN111504395 discloses a rotating plate flow measurement device with magnetic linearization. The flow meter includes a rigid housing, a moving member including a rotating plate with a moving member magnet 10, a fixed magnet, and a sensing member. At low flow rates, multiple magnets provide a small repulsive force, which increases with increasing flow rates, and multiple magnets become more closely packed, thereby providing linearization.

[0014] Similar to the rotating plate flow measurement device in CN111504395, which includes a magnet attached to a moving member and a fixed magnet, JP2008089320 describes another rotating plate flow measurement device. The repulsive force increases as the distance between the magnets increases. The repulsive force causes stress, which is measured by a strain gauge to provide a flow measurement.

[0015] While these known solutions all fall into the broad category of "target flow meters" based on magnetic or inductive sensing technology, there remains a need for a system and methodology that allows for measurement of fluid volume over a wider dynamic range and linearization of the sensor response, particularly for miniaturized applications. Summary of the invention

[0016] These and other problems are solved by a flow measurement device according to the present teachings including an arrangement of multiple magnets, one magnet located in an articulated target and another magnet located downstream of the one magnet in a channel, the multiple magnets being arranged relative to each other so that their respective like polarities face each other so that a repulsive force is generated between the opposing magnets. The force versus distance relationship between the multiple magnets is complex, but can be approximately represented by a polynomial function of order n, with the order depending on the geometry of the magnets and the spacing distance between the multiple magnets. The relative geometry and displacement range can be carefully selected so that the 2nd order component dominates, thereby canceling out the secondary flow-force in the opposite direction and effectively linearizing the force versus displacement relationship of the target over a wider range than other flow sensing technologies, thereby increasing the turndown ratio, or increasing the width of the operable range of the device. Especially for, but not limited to, millimeter-sized channels, this arrangement provides reliable measurements with a wide dynamic range and fast response.

[0017] A preferred arrangement of the flow measurement device or flow sensor described herein comprises: a rigid housing defining a flow channel and sized to allow a fluid medium to flow from a channel input to a channel output; an articulated target member mounted in the flow channel and oriented transversely to the direction of fluid flow, the target member comprising a permanent magnet and the fluid flow will exert a resistance on the target member; a fixed element consisting of a permanent magnet embedded in the flow channel wall, opposite to the target member and having the same polarity, the fixed element being configured to exert a counteracting magnetic force on the target member to limit the displacement of the target member in proportion to the flow rate; a sensing element located outside the flow channel, the sensing element being close to the target member and oriented perpendicularly to the target member, the sensing element being configured to measure changes in a static magnetic field, the changes in the static magnetic field being generated by the target displacement and being proportional to the mass / volume flow rate of the fluid in the channel.

[0018] In another arrangement, the fixed permanent magnet of the flow sensor is positioned in the middle of the flow channel with the fixed permanent magnet transverse to the flow direction and parallel to the stationary position of the articulated target using adhesive or other fixing or clamping means.

[0019] In another arrangement, the sensing element operates on the principle of capacitance and consists of a pair of capacitive plates, one plate located on a moving target, transverse to the flow direction, and the other plate fixed near the channel input or channel output, transverse to the flow direction. In this arrangement, the displacement of the articulated target caused by the flow of fluid in the channel will cause a change in the electric field between the electrode pair, which has the fluid medium as the dielectric. The sensed capacitance change can then be converted into a flow reading by the connected electronics.

[0020] In another arrangement, the displacement of the articulated target is measured via an optical sensing method. One or more optical light transmitters can be positioned near the channel wall, and the displacement of the articulated target can be detected via optical time of flight, Doppler shift or interferometric methods applied to light reflected from the target and detected by receiving means on the optical transmitter. The detected signal can be converted into a flow reading by connected electronics.

[0021] In another arrangement, the articulated target is an electromagnet, for example, which can be, but is not limited to, comprised of a conductive path on a flexible substrate. In this arrangement, a current is driven into the conductor so that when the target is deflected by fluid flow, the target is subject to a repulsive magnetic force from a magnet located on the opposite side of the channel, and the repulsive magnetic force is proportional to the resistance force. The parameters of the current driven into the conductor can be adjusted depending on the desired range of flow rates to be measured in the selected application.

[0022] In another arrangement, the fixed magnet at the channel output can be replaced by an electromagnet and the sensor unit can consist of a combination of a permanent magnet and an electromagnet, depending on the chosen application.

[0023] In another arrangement, when the two magnets in the flow channel are electromagnets, the displacement of the articulated target is measured via an inductive sensing method. Current is driven into the two electromagnets so that when the target is deflected by the fluid flow, the target is subjected to a repulsive magnetic force from the fixed electromagnet, and the repulsive magnetic force is proportional to the resistance. At the same time, the mutual inductance between the multiple electromagnets will change proportionally with the change in distance between the moving electromagnet and the fixed electromagnet, and the inductance change is measured on the fixed electromagnet and converted into a flow reading by the connected electronics. The measuring electromagnet of this arrangement can also be placed at the channel input, measuring the inductance change between the electromagnet and the electromagnet located on the moving member, and a third electromagnet or permanent magnet provides the repulsive magnetic force.

[0024] In another low-friction arrangement, instead of being connected to a movable hinge, the movable target member in the flow channel is mounted transversely to the fluid flow and connected to a pin such that the permanent magnet located on the movable member moves parallel to the flow direction and towards the fixed magnet, the fixed magnet being placed at a downstream position and in the middle of the flow channel and being parallel to the movable member. A sensing device located near the flow channel detects the displacement of the movable member and sends the output of the sensing device to a processing unit and converts the output of the sensing device into a flow rate reading.

[0025] In another arrangement, the movable target member in the flow channel is mounted transversely to the fluid flow and supported by a plurality of movable hinges such that the movement of the member remains perpendicular to the flow direction. In this arrangement, the movable member is pushed by the fluid medium towards the fixed magnet placed downstream of the flow channel, and the movable member is transverse to the fluid flow. A sensing device located near the flow channel detects the displacement of the movable member and sends the output of the sensing device to a processing unit and converts the output of the sensing device into a flow rate reading.

[0026] To further understand the nature of the forces acting in the flow channel in relation to the present teachings, it is convenient to describe the nature of the forces acting in the flow channel: 1) the magnetic force between two cylindrical magnets when the distance between the two cylindrical magnets changes; 2) the drag force exerted by a fluid having a non-zero velocity on a target transverse to the fluid flow.

[0027] 1) When the magnetic dipoles of two cylindrical magnets are aligned on the z-axis, the force between the two cylindrical magnets is proportional to the following parameters:

[0028]

[0029] where M is the magnetization of the magnet, L is the length of the magnet, r is the radius of the magnet, and z is the distance between the magnets. For small values of z, when the distance approaches zero, if the force becomes large, this approximation becomes invalid. According to the following equation, when L << z, the point dipole approximation can be considered, and for large distances z, the force along the z-direction decreases proportionally to 1 / z 4 as:

[0030]

[0031] where μ 0 is the permeability of free space, m 1 , m 2 are the magnetic moments of the two dipoles, and z is the distance between the two dipoles. However, when the spacing distance z is comparable to the size of the cylindrical-shaped magnet, the accuracy of the dipole approximation decreases. Therefore, the relationship between the magnetic force and the spacing distance cannot be accurately modeled and needs to be measured experimentally one by one.

[0032] 2) The drag force applied by the fluid to the target perpendicular to the direction of flow is directly proportional to the square of the fluid velocity according to the following equation:

[0033]

[0034] Among them, c d is the drag coefficient, ρ is the fluid density, v is the fluid velocity, and A is the area of ​​the target. Clearly, as the flow rate increases, the drag on the target increases quadratically.

[0035] It will be appreciated that this makes it difficult to adjust the size of the articulated target in contact with the fluid and to select a suitable material for the articulated target in contact with the fluid, especially in those applications where the dynamic range of flow rates spans different orders of magnitude. In fact, low flow rates will result in very little deflection, while high flow rates will cause the flexible member of the target to bend irreversibly.

[0036] This interaction between the above forces is effectively exploited in the sensing techniques described herein, where the increase in repulsive magnetic force is conveniently used to counteract the effect of the drag exerted on the target by fluid flow as a magnet on the target approaches a fixed magnet on the opposite side of the channel.

[0037] By appropriately selecting the characteristics of the magnets, their spacing in the flow channel, and the flow channel geometry, the linearization effect and the range of measurable flow rates can be matched to the resistance-target displacement relationship, which is another advantage of sensing methods deployed in accordance with the present teachings.

[0038] These and other advantages of the present invention will be further understood by considering the following detailed description of the embodiments and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings provide a further understanding of the sensing arrangement described in the present invention, however, they are not intended to limit the scope of the appended claims.

[0040] Figure 1A is a schematic representation of a side cross-section of an apparatus according to the present teachings, showing the configuration under zero flow conditions, and with the sensing element being a Hall effect sensor.

[0041] Figure 1B yes Figure 1A Schematic representation of a side cross-section of a device showing exemplary conditions at maximum opening, corresponding to maximum detectable flow rate, and with the sensing element being a Hall effect sensor.

[0042] Figure 1C yes Figure 1A Schematic representation of the rear section of the device, showing the cross-sectional geometry of the flow channel and the geometry of the moving components.

[0043] Figure 2A is a simplified representation of the voltage response of a Hall effect linear sensor when a magnetic field is applied along the length of the sensor.

[0044] Figure 2B A representation of how the strength of the magnetic field produced by a permanent magnet decays with distance from the magnet.

[0045] Figure 3 yes Figure 1A Schematic representation of a side cross-section of an alternative arrangement of a device in which the moving member is constructed of a flexible structure and the permanent magnet is attached to the moving member by adhesive or other clamping means.

[0046] Figure 4 yes Figure 1A Schematic representation of a side cross-section of an alternative arrangement of a device in which a fixed magnet is placed in the middle of the flow channel, transverse to the fluid flow and parallel to the stationary position of the moving member.

[0047] Figure 5A yes Figure 1A A schematic representation of a side cross-section of an alternative arrangement of an apparatus in which the moving member comprises an electromagnet.

[0048] Figure 5B yes Figure 5A Schematic representation of a side section of an arrangement, wherein the moving member comprises an electromagnet and a fixed magnet or a second electromagnet is placed in the middle of the flow channel, transverse to the fluid flow and parallel to the stationary position of the moving member, and wherein the displacement of the moving member can be measured using an external sensing unit or by inductive sensing technology.

[0049] Fig. 6A yes Figure 1A Schematic representation of a side cross-section of an arrangement depicting the forces acting on the moving member under expected operating conditions of the flow sensor when the flow channel central axis is parallel to the horizontal.

[0050] Figure 6B yes Figure 1A A schematic representation of a side cross-section of an arrangement depicting the flow channel central axis at an angle relative to the horizontal The force acting on the moving component when .

[0051] Fig. 7A is a schematic representation of a side cross-section of a flow channel in an alternative arrangement of an apparatus of the present teachings, wherein the displacement of a moving member is measured via capacitive sensing technology by a pair of capacitor plates, one capacitor plate being located on the moving member and one capacitor plate being fixed transverse to the direction of the fluid and proximate to the channel input, and the pair of capacitor plates having the fluid medium as the dielectric.

[0052] Figure 7B is a schematic representation of a side cross-section of a flow channel in an alternative arrangement of an apparatus of the present teachings, wherein the displacement of a moving member is measured via capacitive sensing technology by a pair of capacitor plates, one capacitor plate being located on the moving member and one capacitor plate being fixed transverse to the direction of the fluid and proximate to the channel output, and the pair of capacitor plates having the fluid medium as the dielectric.

[0053] Fig. 8A is a schematic representation of a side cross-section of a flow channel in an alternative arrangement of an apparatus of the present teachings, wherein the displacement of a moving member is measured via optical sensing techniques by one or more optical transducers placed on the channel wall and within the flow channel.

[0054] Figure 8B is a schematic representation of a side cross-section of a flow channel in an alternative arrangement of an apparatus of the present teachings, wherein the displacement of a moving member is measured via optical sensing techniques by one or more optical transducers placed on the channel wall and outside the flow channel.

[0055] Fig. 9A and Fig. 9B Schematic representations of a side section and a front section, respectively, of a flow channel in an alternative arrangement of the apparatus of the present teaching under conditions of zero flow, wherein the moving member in the flow channel is a permanent magnet displaced parallel to the direction of flow, and wherein a fixed magnet is placed in a downstream position in the middle of the flow channel and parallel to the moving member.

[0056] Fig. 10A and Fig. 10B Schematic representations of side and front cross-sections, respectively, of an alternative arrangement of an apparatus of the present teachings under conditions of zero flow wherein a moving member in a flow channel is supported by a plurality of living hinges such that movement of the member remains perpendicular to the flow.

[0057] Fig.11 It is a representation of the relationship between the magnetic force on two cylindrical magnets with a radius r equal to their length L and the distance between them.

[0058] Fig.12 is a representation of a calibration function for a flow sensor of the present teachings, showing the relationship between sensor output and flow rate. DETAILED DESCRIPTION

[0059] refer to Figure 1A and Figure 1B , provides a schematic representation of a preferred arrangement of a flow sensor provided according to the present teachings in cross-section. Figure 1C , a schematic representation of a rear cross-section of this flow sensor is provided.

[0060] The sensor comprises a rigid housing 101 in which a flow channel is defined, the flow channel having a port 102 of an input and a port 103 of an output. In operation, the fluid will flow from the port of the input to the port of the output in a directional flow. A moving member 104 is mounted in the flow channel transverse to the direction of the fluid flow and near the port 102 of the channel input. The moving member 104 acts as a target and can be articulated and moved under the influence of the fluid flowing into the flow channel. The moving member has a Figure 1A The first stationary position shown in FIG. Figure 1B The second non-stationary position shown in , wherein the mobile member moves towards the port 103 of the output portion under the influence of the fluid flowing into the flow channel. This movement is facilitated by using a living hinge including a flexible structure 105 and a permanent mobile member magnet 106, and the fluid flow will apply resistance to the living hinge. A fixed member 107 consisting of a permanent magnet with the same polarity relative to the mobile member magnet 106 on the mobile member 104 is arranged or embedded in the flow channel wall, the fixed member 107 is opposite to the mobile member and close to the port 103 of the channel output portion. The fixed member 107 is oriented relative to the mobile member magnet and is arranged to apply a counteracting magnetic force to the mobile member magnet. Given that the mobile member magnet is positioned on the movable target member, this counteracting force is used to limit the displacement of the target member in proportion to the magnitude of the resistance applied by the fluid flow.

[0061] The fixing member 107 can be embedded or otherwise positioned in or on the channel wall by gluing or other clamping means, and the dipole axis of the fixing member 107 is angled relative to the channel central axis 108. The sensing device or sensing element 109 is positioned outside the flow channel and is perpendicular to the configuration of the mobile member 104. The sensing device is sufficiently close to the mobile member to be able to measure the displacement of the mobile member. The sensing device is configured to provide an output indicating the sensed displacement. These output signals can be sent to a processing unit via a flexible cable 110 and converted into flow measurements.

[0062] In a preferred arrangement, the sensing device comprises a Hall effect sensor. It will be appreciated that the Hall effect sensor monitors magnetic fields with high accuracy, consistency and reliability, and is also a cost-effective way of monitoring the displacement of an object. A Hall effect sensor comprises a Hall element, typically a thin metal strip, to which an electric current is applied. If a static magnetic field is applied perpendicular to the direction of the current, the carriers are deflected by the Lorentz force. This effect causes a potential difference (Hall voltage) between the two sides of the metal strip, which is proportional to the strength of the applied magnetic field. The ability of the Hall effect sensor to respond to a static magnetic field is a key difference from an inductive sensor, which is only sensitive to a changing magnetic field. The output voltage of the Hall element is typically very small (microvolts), so it is important to provide the Hall element with appropriate processing circuitry such as amplification and noise suppression. The Hall element is typically integrated into a Hall sensor chip including signal processing and digitization circuitry, thereby simplifying the interface task.

[0063] Hall effect sensors are widely used in industrial and consumer applications and are primarily used for proximity sensing, positioning, speed detection, and current sensing. When combined with threshold detection, Hall effect sensors can be used as switches featuring a binary response, or as linear sensors when the output voltage varies in proportion to the magnetic field the Hall effect sensor is sensing.

[0064] Figure 1A The flow channel is depicted under zero flow conditions, wherein the articulated target member 104 is in a rest position, and the rest position forms an angle 'α' = 90° with the channel central axis. In order to maximize the resolution of the Hall effect sensor, it is important that the sensing element 109 is correctly positioned relative to the magnet 106 on the articulated target 104 to generate the measured magnetic field object: the minimum-to-maximum distance value of the sensing element must fall within the region where the maximum change in the magnetic field occurs.

[0065] To address this, in a preferred arrangement, when 'α' = 90°, the sensing element is configured so that its edge on the channel input side 111 corresponds to the edge of the permanent magnet 106 on the target.

[0066] To further understand this concept, Figure 2A A simplified description of the typical voltage response of a Hall effect linear sensor to a magnetic field applied along the sensor length l is provided in Figure 2B In FIG. 1 , it is depicted how the magnetic field B generated by a permanent magnet decays with the distance d from the magnet.

[0067] In the absence of a magnetic field, the sensor output will be equal to the supply voltage V 0 As the applied magnetic field increases, the output voltage will be pulled toward the supply voltage value V corresponding to the geomagnetic south pole S.MAX , or pull towards the ground V corresponding to the magnetic north pole N MIN If the saturation point is reached, ideally the voltage output will no longer change if a stronger magnetic field is applied. In practice, near saturation, the sensor response has an inflection point that indicates the end of the linear region, and the response no longer differs from the response in the active region of the sensor.

[0068] To maximize the sensing resolution, it is important that the minimum-to-maximum distance value of the Hall effect sensing element is located at Figure 2B The linear region is marked by a horizontal dashed line in FIG. , in which the magnetic field variation is the largest.

[0069] In a preferred arrangement, for the purpose of enhancing low flow discrimination, a flexible member 105 facilitating the target is clamped in position close to the channel input 102 so that in a zero flow condition, the magnet 106 on the target is repelled by the downstream fixed magnet 107 and completely seals the channel input 102. This means that instead of resistance being the main contributor to target displacement, the pressure difference across the channel will force the target to deflect and pass open, even at very low flow rates. In this way, the target also constitutes a one-way valve that limits the presence of backflow that affects the measurement.

[0070] In a preferred arrangement, it is convenient to make the housing of the sensing unit out of a hard material so that during measurement, the sensing unit is protected from external forces and the channel geometry is maintained. The material chosen should have a low magnetic permeability so as not to interfere with the magnetic field generated by the movement of the target: examples are metals such as austenitic stainless steel or polyetheretherketone (PEEK) or It will be appreciated that Delrin is an example of a polyoxymethylene (POM), a high performance acetal resin. PEEK is a high performance semi-crystalline engineering thermoplastic.

[0071] In order to ensure the correct operation of the sensing unit and avoid any fluid leakage that may affect the sensor element, the flow channel should be completely sealed and the fluid medium in the channel must be isolated from the external environment. In order to achieve a complete seal around all parts of the flow channel, it is convenient to fix the flexible member 105 in the sensor body using a suitable adhesive or mechanical clamping device.

[0072] Figure 1B A flow channel is depicted under exemplary conditions corresponding to a maximum detectable flow rate and at maximum opening, wherein the articulated target 104 is at an angle 'α' < 90° relative to the channel central axis.

[0073] In order to maximize the sensing range of the Hall effect sensor, 'α' should correspond to the maximum deflection of the target, so that the edge of the permanent magnet 106 on the target passes through the edge of the sensing element on the channel output side 112. In fact, when the target passes around said edge 112, the signal from the Hall effect sensor is characterized by an inflection point and can no longer be distinguished from the sensor active area.

[0074] In order to maximize the linearization of the drag force-target displacement relationship, the magnetic repulsion force should be maximized when the target deflection angle is equal to 'α'. This means that the preferred orientation of the fixed magnet 107 should be The permanent magnet 106 on the target and the fixed magnet 107 are arranged so that the faces with the same polarity become parallel and the centers of the two are aligned ideally. The value of 'α' that maximizes the flow rate should be calculated based on the desired measurement range and channel parameters for the chosen application.

[0075] Another important aspect of the design of the sensing unit is the selection of the parameters of the permanent magnet 106 integrated into or arranged on the moving member 104. The magnetic strength of the magnet 106 should be of a suitable value so that the Hall effect sensor can operate in its linear range without saturation, while the thickness of the magnet 106 should allow the magnet 106 to move within the sensing range of the Hall effect sensor to obtain the most accurate resolution possible. The cross-sectional area of ​​the magnet 106 should be selected according to two main design constraints: the ratio between the cross section of the channel and the cross section of the moving element 104 should maximize the resistance exerted by the fluid on the moving element; the surface area of ​​the magnet 106 should be such that, in the position of the maximum channel aperture, the faces of the magnet 106 and the fixed magnet 107 with the same polarity will be aligned, and any edge effects due to the magnetic field lines escaping from the side of the magnet will be minimized. In fact, the edge will cause the moving element 104 to deviate from its trajectory and flip from the central axis of the magnet, so that the opposite magnetic pole is exposed to the fixed magnet 107. Once the correct geometry of the magnet 106 on the moving element 104 is defined, the dynamic range of the measurement can be further adjusted by selecting the correct thickness of the fixed magnet 107, the strength of the two magnetic elements 106, 107 and the spacing of the two in the channel. Another advantage of the present teachings is that keeping all geometric parameters constant, the dynamic range can be adjusted by replacing the magnetic element with another element with a different magnetic strength to adapt the Hall effect sensor to operate within its linear range, or by using multiple magnetic elements, adding or removing magnets until the desired magnetic repulsion force is obtained.

[0076] In another exemplary arrangement, the sensing member is a magnetoresistive element, wherein the change in the resistance of the sensor is proportional to the magnetic field applied to the sensor. The sensing member can be based on one of the magnetoresistive effects typical of different materials, such as: geometric magnetoresistance, positive magnetoresistance, and Shubnikov-de Haas oscillations, i.e., oscillations of the material's electrical conductivity in the presence of very strong magnetic fields, commonly found in bulk non-magnetic metals and semiconductors; negative magnetoresistance or anisotropic magnetoresistance (AMR), commonly found in magnetic metals; giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), colossal magnetoresistance (CMR), and extraordinary magnetoresistance (EMR), commonly found in multi-component or multi-layer systems.

[0077] In this arrangement, electronics are connected to the sensing element 109 by a flexible cable 110, by which changes in sensor resistance due to movement of the target 104 are measured and sent to a processing unit where they are converted into a flow measurement.

[0078] An example of a permanent magnet that can be integrated in the sensing unit is a neodymium (NdFeB) magnet. The advantage of a neodymium magnet is its high strength: compared to other magnetic compounds such as iron oxide or even samarium cobalt, neodymium magnets have a high level of magnetism and are very resistant to demagnetization. Neodymium magnets also have the advantage of being relatively cheap and are manufactured in a wide range of sizes, even with diameters as small as 1 mm, which allows neodymium magnets to be used in miniaturized applications.

[0079] In the context of flow measurement, the advantage is to protect the magnetic elements in contact with the fluid medium from moisture penetration, which can cause corrosion and thus adversely affect the structural integrity and performance of the magnet, especially in applications where it is crucial to avoid any contamination of the measured fluid (medicine, food industry, etc.).

[0080] To address this problem, the magnet can be encapsulated with an inert coating such as, but not limited to, epoxy or a polymer material such as silicone rubber.

[0081] like Figure 1B and Figure 1C , the hinge region 113 can advantageously comprise a feature of semicircular cross-section that is recessed in the polymer structure that provides the living hinge, and the hinge region 113 should extend to nearly the entire width of the living hinge 105. The vertical positioning of the hinge region 113 should also be far enough from the channel wall that the living hinge 105 will allow the flexible support to flex without interfering with the channel wall structure.

[0082] Another useful configuration of the hinge region 113 is that it should ideally be located on the side of the living hinge 105 that faces the channel input 102 so that when the mobile member 104 is displaced due to the flow rate, the edges of the hinge region 113 will not contact each other. It should be understood that the ideal geometry and cross-sectional depth of the living hinge 113 should be determined based on the selected application and the material selected for the living hinge 105.

[0083] The present invention also solves the already mentioned problem of hinges present in known target flow meters in that a living hinge is no longer required to provide repulsive forces to the flow, since the magnets now satisfy this requirement. Therefore, in a preferred arrangement, the living hinge 105 supporting the magnet 106 on the moving member can be made of a polymer non-magnetic material, provided that the hinge area 113 is thin enough so that the internal friction forces are negligible compared to the magnetic repulsive forces. Polymeric materials such as, but not limited to, silicone rubber with an appropriate Shore hardness can provide several advantages for the manufacture of living hinges:

[0084] It is suitable for the preparation of the living hinge itself and the entire supporting structure of the magnetic element, ensuring its complete encapsulation and insulation from the fluid medium while being easy to manufacture via injection molding;

[0085] Like a seal 114 between the channel structure and any clamping device 115, the living hinge 105 itself can become part of a more complex structure to conveniently seal the flow channel; and

[0086] The desired amount of compression of the gasket 114 can be achieved by appropriately sizing the rubber thickness and Shore hardness for each application.

[0087] Be able to realize that reference Figure 1B and Figure 1C Another important aspect of the present invention is that the cross-section of the flow channel defined by the rigid shell 101 and the cross-section of the moving element 104 should preferably be circular to limit the vorticity or turbulence in the flow channel and maximize the effect of the fluid resistance on the moving element 104. In addition, the ratio between the cross-sectional area of ​​the flow channel and the cross-sectional area of ​​the moving element 104 should be optimized so that the pressure difference between the port 102 of the channel input and the port 103 of the channel output can be suitable for the opening of the channel even at a flow rate as low as 10 μl / s.

[0088] The ability to resolve this low flow rate and extend the dynamic range of the measurement to higher volumes depends on the chosen geometry of the channel and the parameters of the sensor unit assembly, and the possibility of measuring different fluids including air makes the flow sensor of the present invention suitable for a range of applications. Furthermore, the sensor construction and its fast response time make it particularly suitable for real-time measurement of pulsatile flows common in biomedical applications.

[0089] In biomedical applications, flow sensors of the present teachings can have particular advantages, but are not limited to:

[0090] Blood flow monitoring, where blood flow rate is highly dependent on the distance from the heart and the size of the vessel, and can range from 20 μl / s up to 16 ml / s in small vessels when blood is pumped directly from the heart into the aorta;

[0091] Respiratory monitoring, e.g., measurement of peak expiratory flow rate, with typical values ​​ranging from 130 L / min in pediatric subjects to 600 L / min in adult males;

[0092] Milk secretion, e.g., during breastfeeding, typical milk flow rates range from 10 μl / s to at least 5 ml / s; and

[0093] Urine excretion, with typical flow rates ranging from 10 ml / s to 21 ml / s in adults.

[0094] In another arrangement, such as Figure 3 In one arrangement presented in , the magnet located on the target 306 can be fixed to the flexible support structure 1 which also constitutes the living hinge 305 by gluing or other clamping means. The structure should be made of a thin flexible polymer film such as but not limited to PEEK or polyimide. As mentioned above, the geometry and thickness of the flexible structure will be selected to obtain the best mechanical properties in the range of flow rates to be measured and to minimize the internal friction against the magnetic repulsion force. In addition, an anti-wetting coating should be applied to the flexible film-magnet assembly to protect the integrity of the magnetic element 306 and the adhesive layer 2.

[0095] Figure 4 Represented in cross-section Figure 1A An alternative arrangement of the device is shown in which a fixed magnet 407 is placed between the port 402 of the input and the port 403 of the output of the flow channel, near the port 403 of the output and transverse to the fluid flow. The fixed magnet 407 can be conveniently placed in a suspended position along the middle axis 408 of the channel and aligned with the static position of the articulated target 404 by gluing or other clamping means. In this arrangement, the fixed magnet 407 will restrict the cross-sectional area of ​​the flow channel, and the fluid flow passes between the fixed magnet and the channel wall.

[0096] Figure 5A An alternative exemplary arrangement of an apparatus of the present teachings is shown in cross-section, wherein the articulated target 504 is an electromagnet and the fixed magnet 507 is angularly oriented relative to the flow channel central axis 508. Embedded in the channel wall. The electromagnet can be conveniently constructed from a conductive path 1 such as a flat flexible cable (FFC) or flexible printed circuit (FPC) on a flexible substrate 2, or by conventional methods that can alternatively use flat windings such as magnet wire. In this arrangement, current is driven into the conductor 1 so that when the target is deflected by the fluid flow, the target is subject to a repulsive magnetic force from a fixed magnet 507 located on the opposite side of the channel, and the repulsive magnetic force is proportional to the resistance force.

[0097] Figure 5B Represented in cross-section Figure 5A An alternative exemplary arrangement of the device, wherein a fixed magnet 507 is placed between a port 502 of the input portion and a port 503 of the output portion of the flow channel proximate to the port 503 of the output portion and transverse to the fluid flow, and the fixed magnet 507 is placed in a suspended position along the central axis 508 of the channel and aligned with the stationary position of the articulated target 504.

[0098] In another arrangement, Figure 5A and Figure 5B The sensor unit described in can include an electromagnet in place of a fixed magnet at the channel output, thereby generating an opposing magnetic force on the articulated target 504. It should be understood that the sensor unit can be composed of a combination of permanent magnets and electromagnets, depending on the selected application.

[0099] when Figure 5B When the two magnets of the embodiment in are electromagnets, the displacement of the moving member 504 can also be measured via inductive sensing techniques. In this arrangement, current is driven into a conductor 1 located on the moving member 504 and a conductor 507 fixed downstream in the channel so that when the target is deflected by the fluid flow, the target is subjected to a repulsive magnetic force from the fixed electromagnet 507 that is proportional to the resistance. At the same time, the mutual inductance on the electromagnets will change in proportion to the distance between the moving element 504 and the fixed electromagnet 507, and this change represents the displacement of the target and is measured on the fixed electromagnet 507. Inductive measurement can be performed by modulating the magnetizing current of one coil with an AC signal and measuring the amplitude change of this AC coupled signal on the other coil. The AC signal frequency is typically at least an order of magnitude higher than the blade displacement frequency to obtain sufficient sensing resolution.

[0100] In an alternative arrangement, in order to maximize the coupling between the two inductor circuits, the measuring electromagnet 3 can be placed at the channel input, and the mutual inductance change caused by the displacement of the moving element 504 can be measured between the electromagnet 3 at the channel input and the electromagnet 1 located on the moving element 504, while the electromagnet 507 located downstream of the flow channel will only provide a magnetic repulsion force. The advantage is that the gap between the electromagnet 1 located on the moving element 504 and the measuring electromagnet 3 is minimized to enhance the response. It should be understood that in this alternative arrangement, the fixed electromagnet 507 may be replaced by a permanent magnet.

[0101] In the arrangement described above, the electronics are connected to the measuring electromagnet by a flexible cable 710, by which the change in inductance across the electromagnet is measured and sent to a processing unit where it is converted into a flow measurement.

[0102] refer to Fig. 6A and Figure 6B , in normal sensor operation, the articulated target 604 is subject to different forces, mainly the drag force 1 from the fluid medium, which is generated by the flow of fluid through the fluid channel, and the magnetic repulsion force 2 from the fixed magnet 607 located downstream of the channel. The additional forces that the articulated target 604 is subject to during sensor operation are gravity 3 and the opposing buoyancy force of the fluid 4, which depends on the volume of the target and the density of the fluid medium.

[0103] Fig. 6A A general operating condition is depicted, in which the rigid housing 601 of the flow sensing unit is placed horizontally and the fluid flow is perpendicular to the direction of the gravitational force 3 acting on the target 604. In this arrangement, the component of the gravitational force parallel to the flow direction 608 is zero, and the target deflection and the resulting opening of the channel depends only on the balance between the drag force 1 and the magnetic repulsion force 2.

[0104] Figure 6B Depicts the angle of the flow channel housing 601 relative to the horizontal An alternative operating condition. In this case, the component 5 of the gravity force 3 parallel to the flow direction 608 is no longer zero and its effect on the articulated target 604 will add to the total balance of forces 1, 2, which leads to measurement errors in the target displacement and therefore also in the fluid flow, especially at very low flow rates, where the gravity effect may be comparable to the drag. In order to improve the accuracy and reliability of the sensing unit in any orientation, it is advantageous to implement buoyancy compensation of the articulated target in the flow channel to remove or reduce the gravity effect. Buoyancy compensation can be achieved by design, by manufacturing the moving target with appropriate materials / geometry, so that the equivalent density of the target assembly matches the density of the fluid being studied. Alternatively, or in addition, numerical compensation can be introduced and the output from sensors such as accelerometers, gyroscopes or position sensors can be calibrated to continuously detect the orientation of the sensing unit during the measurement and digitally remove the gravity effect.

[0105] Fig. 7A A side cross section of a flow channel in an alternative arrangement of a sensing unit of the present teachings is represented, wherein the displacement of a moving target 704 is measured via a capacitive sensing technique. In this arrangement, the moving element 704 is constituted by a permanent magnet 706 and an element constituting one plate 1 of a variable capacitor, while the other plate 2 is positioned on the fluid channel near the channel input 702 and transversely to the flow direction. Under conditions of non-zero flow, the displacement of the target 704 will result in a change in the distance between the two capacitor plates 1, 2, and therefore also in a change in the capacitance reading, with the fluid medium as electrolyte. The sensing electronics 709 are connected to the capacitor plates 1, 2 by a flexible cable 710, by which the capacitance is measured and sent to a processing unit where it is converted into a flow measurement. As an exemplary arrangement, the fixed capacitor plate 2 can be annular for easy mounting on the channel wall, or can have a circular cross section and be suspended in the channel, as long as the multiple capacitor plates have as large a common area as possible to maximize the capacitance.

[0106] Figure 7B Relative to Fig. 7A Side cross-section of a flow channel in an alternative arrangement to the one presented in , in which the fixed plate 2 of the variable capacitor is a plate with a circular cross-section and is placed close to the channel output 703 and transverse to the flow direction.

[0107] It is important that the capacitor plate 1 located on the moving element 704 always faces the fixed plate 2 located in the flow channel, so that Fig. 7A In the exemplary arrangement of FIG. 1 , capacitor plate 1 is placed on the left side of permanent magnet 706 on moving target 704. Figure 7B In the exemplary arrangement of , capacitor plate 1 is placed to the right of permanent magnet 706 on moving target 704 . Fig. 7A and Figure 7B The capacitor plates can advantageously be covered with an insulating layer to avoid contact with the fluid and prevent scaling and corrosion, which could cause errors in the capacitance readings.

[0108] In either arrangement, adding static capacitor plates on the channel walls may help solve for a baseline dielectric constant of the fluid dielectric to use as a reference value for the variable capacitance.

[0109] Fig. 8A and Figure 8B Represents a side cross-section of a flow channel in an alternative arrangement of a sensing unit of the present teachings, wherein displacement of an articulated target 804 is detected via optical sensing techniques.

[0110] exist Fig. 8A In an exemplary arrangement of, one or more optical transducers 1, 2 are positioned on a channel wall 3 within the flow channel parallel to the flow direction and in contact with the fluid. According to the optical sensing method selected for each application, the transmitting member 1 sends a series of light pulses towards the mobile member 804, which reflects the series of light pulses back to the receiving member 2. Under non-zero flow conditions, the displacement of the mobile member 804 can be detected via optical time flight, Doppler shift or interference methods, depending on the characteristics of the light reflected by the mobile member 804. The electronics are connected to the sensing unit by a flexible cable 810, by which the signals from the optical transducers 1, 2 are measured and sent to the processing unit, where they are converted into flow measurement.

[0111] Figure 8B express Fig. 8A An alternative arrangement to the one depicted in , in which one or more optical transmitters 1, 2 are positioned outside the channel wall 3 and parallel to the flow direction. In this arrangement, the flow channel should be made of optically transparent material to allow light to be transmitted between the optical transmitters 1, 2 and the moving member 804 through the channel wall 3.

[0112] Fig. 9A and Fig. 9BAnother low friction arrangement of the present teaching under zero flow conditions is represented, wherein a moving member 904 is installed in a rigid housing 901 forming a flow channel transverse to the direction of fluid flow and near the port 902 of the channel input, the moving member 904 being a target consisting of a permanent magnet 906 and a support member 1 parallel to the flow direction, on which the fluid will exert resistance. A fixed member 907 as a permanent magnet is placed between the port 902 of the input of the flow channel and the port 903 of the output transverse to the fluid flow. The faces of the two permanent magnets 906, 907 facing each other have the same polarity so that the fixed member 907 exerts a counteracting magnetic force on the moving member 904 and limits the displacement of the moving member 904 in proportion to the magnitude of the resistance. The fixed member 907 can advantageously be annular to provide a sliding constraint for the support member 1 of the target 906, thereby minimizing the friction of the sliding movement.

[0113] like Fig. 9B As shown in the exemplary arrangement of , the fixed member 907 can be suspended in the channel by one or more support structures 2, 3 so as not to block the channel output. In this exemplary arrangement, the displacement of the moving member in the channel is parallel to the fluid flow, and the permanent magnet 906 located on the target no longer requires a living hinge. The sensing device 909 can be positioned outside the flow channel perpendicular to the moving member 904 and near it, and the sensing device measures the displacement of the moving member 904. The signal received by the sensing device 909 is sent to the processing unit via the flexible cable 910 and converted into a flow measurement.

[0114] Fig. 10A 1 represents an alternative arrangement of the present teaching under conditions of zero flow, wherein a moving member 1004 is transverse to the direction of fluid flow and is mounted in a rigid housing 1001 forming a flow channel near a port 1002 at the channel input, the moving member 1004 being a target consisting of a permanent magnet 1006 and supported by a plurality of living hinges 1, 2, 3 so that the movement of the moving member 1004 remains transverse to the flow. Fig. 10B As shown in , living hinges 1, 2, 3 allow the mobile member 1004 to be suspended in the middle of the flow channel, and the geometry and materials of the living hinges 1, 2, 3 are defined according to the selected application.

[0115] A fixing member 1007 consisting of a permanent magnet is placed between the port 1002 of the input portion and the port 1003 of the output portion of the flow channel, near the port 1003 of the output portion and transverse to the fluid flow, and the faces of the two permanent magnets 1006, 1007 face each other with the same polarity to generate a magnetic repulsion force. As shown in this exemplary arrangement, the fixing member 1007 can have a circular cross-section and be suspended in the channel by gluing or other clamping means, however, as Fig. 9A and Fig. 9B As shown in the exemplary arrangement of , the fixed member 1007 can also be annular and clamped to the channel wall to not restrict the cross-sectional area of ​​the flow channel. The fixed member 1007 will apply a counteracting magnetic force to the magnet 1006 located on the mobile member 1004 and will restrict its displacement in proportion to the flow rate. In this exemplary arrangement, the sensing device 1009 can be positioned outside the flow channel perpendicular to the mobile member 1004 and near it, and the sensing device measures the displacement of the mobile member 1004. The signal received by the sensing device 1009 is sent to the processing unit via the flexible cable 1010 and converted into a flow measurement.

[0116] Fig.11 The relationship of the magnetic force between two cylindrical shaped magnets of radius R and length L is depicted, where R=L, and the separation distance z of the two magnets is plotted as a ratio of their radius R, where the force is attractive if the opposite poles of the two magnets are facing each other, and repulsive if the same poles of the magnets are facing each other. It is clear from the trend lines in the graph how the magnetic force between the two magnets becomes very high when the two magnets are close to each other, and decreases rapidly when the two magnets are separated, ideally following a 4th order polynomial law when the magnets are aligned along the axis of their magnetic dipoles.

[0117] Fig.12 The calibration function of the flow sensor of the present teachings is depicted, and in particular, the relationship between the magnetic field reading d of the sensing unit, which is proportional to the target displacement, and the flow rate U of the fluid in the channel is shown.

[0118] Under conditions of zero flow (U=0), the distance between the magnet located on the target and the fixed magnet located in the flow channel is the largest, the target is in its static position against the channel input, and the sensor output corresponds to the saturation point a. When the pressure difference between the channel input and the channel output exceeds the magnetic repulsion between the two magnets, the target moves away from the channel input and the channel opens. As the flow rate increases, the target moves further away from the channel input, and the magnetic repulsion offsets the resistance of the fluid to the target, thereby limiting its displacement. This causes the relationship between the sensor output d representing the target displacement and the flow rate U to become linear in the b area of ​​the graph.

[0119] Once the target reaches its maximum displacement position, the magnetic repulsion force is maximized and the magnetic field reading from the sensing unit reaches its opposite saturation point. The dynamic range of the sensor will then correspond to the linearization curve in region b, which can be extended according to the parameters of the selected magnets and the selected separation distance of the magnets in the flow channel.

Claims

1. A flow measurement device, comprising: a. a rigid housing defining a flow channel having a channel input and a channel output, the flow channel being configured to allow a fluid medium to flow from the channel input to the channel output; b. a moving member, the moving member being hingedly mounted in the flow channel and extending transversely to the flow direction of the fluid medium, the moving member comprising a moving member magnet, the moving member being operable to move under the action of the resistance generated by the fluid passing through the flow channel, wherein the moving member is composed of a flexible support structure forming a living hinge, the moving member magnet being coupled to the flexible support structure; c. a fixed magnet disposed at least close to a side wall of the flow channel, the fixed magnet having the same polarity relative to the moving member magnet and arranged to operably apply a repulsive force to the moving member magnet, thereby limiting the displacement of the moving member in proportion to the magnitude of the resistance exerted by the fluid flow, so as to linearize the relationship between the flow rate of the fluid medium and the displacement of the moving member; d. A sensing element positioned relative to the moving member and configured to provide an output indicative of movement of the moving member within the flow channel.

2. The device according to claim 1, wherein: Either or both magnets in the flow channel are permanent magnets or electromagnets.

3. Apparatus according to any preceding claim, wherein: The channel has a channel center axis, the fixed magnet is integrated inside the flow channel or in the side wall of the flow channel, and the magnetic poles of the fixed magnet are provided at an angle 'θ' relative to the channel center axis and the flow direction, and the angle 'θ' matches the angle 'α' between the channel center axis and the position of the maximum displacement of the moving member.

4. Apparatus according to any preceding claim, wherein: The dimensions of the flow channel and the moving member are designed so that their respective geometric structures and the ratio of the cross-section of the flow channel to the cross-section of the moving member maximize the resistance of the fluid flow to the moving member, and when the flow rate of the fluid medium is at least 10 μl / s, the pressure difference between the port of the channel input and the port of the channel output allows the channel to open.

5. Apparatus according to any preceding claim, wherein: The moving member comprises an articulation zone defining a cutting portion extending across a width of the articulation zone, the cutting portion being provided on a surface of the articulation zone facing the channel input.

6. The device according to claim 1, wherein: The stationary magnet is suspended in the channel, the stationary magnet being transverse to the fluid flow and parallel to the stationary position of the moving element.

7. Apparatus according to any preceding claim, wherein: The shell is made of a rigid material with low magnetic permeability, wherein the rigid material is any one of austenitic stainless steel or engineering plastics, and wherein the engineering plastics are preferably polyetheretherketone or polyoxymethylene.

8. Apparatus according to any preceding claim, wherein: The moving members are articulatedly coupled via a plurality of hinges such that the movement of the members remains perpendicular to the flow.

9. Apparatus according to any preceding claim, wherein: The bending force of the articulated material resisting the flow is small compared to the magnetic repulsion force between the two magnets.

10. Apparatus according to any preceding claim, wherein: The flexible supporting structure is composed of a flexible polymer film, wherein the polymer film is any one of a polyetheretherketone film and a polyimide film.

11. The device according to claim 10, wherein: The flexible film is encapsulated with a moisture barrier coating.

12. Apparatus according to any preceding claim, wherein: The moving member is composed of a permanent magnet encapsulated into a polymer matrix such as silicone rubber, the moving member acting both as the living hinge and as an encapsulation layer for the permanent magnet.

13. Apparatus according to any preceding claim, wherein: The geometry and strength of the plurality of magnets in the channel, the spacing distance of the plurality of magnets, and the geometry of the channel are calibrated for a specific measurement range.

14. Apparatus according to any preceding claim, wherein: The device is configured such that the measurement range can be adjusted dynamically by changing parameters of the plurality of magnets or by adding magnetic elements or removing magnetic elements from the sensing element.

15. Apparatus according to any preceding claim, wherein: The moving member is made of a material having a density matching that of the fluid medium.

16. Apparatus according to any preceding claim, wherein: The sensing element uses a sensing technology based on one of the following principles: Hall effect, magnetoresistance, inductance, capacitance, optical.

17. The device according to claim 16, wherein: The sensing technology is magnetoresistance technology, and the magnetoresistance technology is selected from one of the following: geometric magnetoresistance, positive magnetoresistance, Shubnikov-de Haas oscillation, negative magnetoresistance or anisotropic magnetoresistance AMR, giant magnetoresistance GMR, tunnel magnetoresistance TMR, colossal magnetoresistance CMR or extraordinary magnetoresistance EMR.

18. The apparatus according to claim 16, wherein: The sensing technique is an inductive technique, inductive sensing is achieved using a first electromagnet located on the moving member and a second electromagnet fixed downstream of the first electromagnet in the flow channel, the second electromagnet being transverse to the fluid flow and facing the first electromagnet, the second electromagnet also providing a magnetic repulsive force against the moving member, and wherein a change in mutual inductance between the two electromagnets caused by the displacement of the moving member is indicative of the flow rate.

19. The apparatus according to claim 16, wherein: The sensing technique is an inductive technique, inductive sensing is achieved using a first electromagnet located on the moving member and a second electromagnet mounted near the flow channel input, the second electromagnet being transverse to the fluid flow and facing the first electromagnet located on the moving member, and wherein a change in mutual inductance between the two electromagnets caused by the displacement of the moving member is indicative of the flow rate, and wherein a third electromagnet or permanent magnet fixed downstream of the moving member provides a magnetic repulsion force against the moving member.

20. The apparatus according to claim 18 or 19, wherein: The distance between the first electromagnet and the second electromagnet is minimized to maximize the signal response.

21. The apparatus of claim 16, wherein: The sensing technology is a capacitive technology, which uses a pair of capacitor plates to achieve capacitive sensing, one capacitor plate is located in the moving member, and one capacitor plate is fixedly installed in the flow channel and faces the capacitor plate in the moving member, and the pair of capacitor plates uses the fluid medium as a dielectric, wherein the displacement of the moving member causes a change in the distance between the pair of plates, thereby causing the capacitance between the pair of plates to change in proportion to the flow rate.

22. The apparatus according to claim 21, wherein The pair of capacitor plates have as large a common area as possible to maximize capacitance.

23. The apparatus of claim 21, wherein: The fixing plate of the capacitor is installed close to the channel input part or the channel output part.

24. The apparatus of claim 16, wherein: The sensing technology is an optical technology, and optical sensing is achieved using at least one transmitting component and at least one receiving component.

25. The apparatus of claim 24, wherein: The position of the mobile member is detected via optical time-of-flight, Doppler shift or interferometric methods based on the characteristics of the light reflected by the mobile member on the at least one receiving member.

26. The apparatus of claim 24, wherein: The sensor housing is manufactured using optically transparent materials.

27. Apparatus according to any preceding claim, wherein: The moving member is configured as a check valve to prevent flow in an undesired direction.

28. A flow measurement device, comprising: a. a rigid housing defining a flow channel having a channel input and a channel output, the flow channel being configured to allow a fluid medium to flow from the channel input to the channel output; b. a moving member installed in the flow channel and extending transversely to the flow direction of the fluid medium, the moving member comprising a moving member magnet, the moving member being operable to move under the resistance generated by the fluid passing through the flow channel; c. a fixed magnet disposed at least close to a side wall of the flow channel, the fixed magnet having the same polarity relative to the moving member magnet and arranged to operably apply a repulsive force to the moving member magnet, thereby limiting the displacement of the moving member in proportion to the magnitude of the resistance exerted by the fluid flow, so as to linearize the relationship between the flow rate of the fluid medium and the displacement of the moving member; d. a sensing element positioned relative to the moving member and configured to provide an output indicative of movement of the moving member within the flow channel, wherein the moving member magnet comprises a permanent magnet positioned transversely to the fluid flow, the displacement of the permanent magnet being parallel to the flow direction of the fluid medium and being connected to a bracket parallel to the flow direction of the fluid medium, and wherein the fixed magnet is placed in a downstream position and in the middle of the flow channel and transverse to the fluid flow.

29. The apparatus of claim 28, wherein: The moving member is connected to a sliding pin coupled to the flow channel through a sliding constraint to minimize friction during the sliding movement.

30. The apparatus of claim 28, wherein: The fixed magnet is annular so as not to block the cross section of the channel and to provide support for the moving member.

31. The apparatus of claim 28, wherein: The position of the moving member is detected via the sensing technique mentioned in any preceding claim.

32. Apparatus according to any preceding claim, wherein: The sensing element is coupled to a connecting cable to enable communication of an output signal to a peripheral device, and the device further includes an amplifier configured to amplify the output signal near the flow channel and before transmission through the connecting cable to avoid external interference coupled in through the cable.

33. Apparatus according to any preceding claim, wherein: The device is configured to provide active amplification of the output signal, the active amplification being provided by at least one amplifier configured to amplify the output signal to a level such that a signal reading at zero flow is close to a maximum value of a subsequent analog-to-digital converter ADC to maximize signal resolution.

34. Apparatus according to any preceding claim, wherein: The device includes a processing unit in communication with the sensing element, the processing unit configured to receive the output signal and convert the output signal into a flow measurement using a calibration function employing a parameterized model, a lookup table LUT, interpolated values, or any combination thereof.

35. Apparatus according to any preceding claim, wherein: The device comprises a storage element for storing calibration coefficients for the sensing element.

36. Apparatus according to any preceding claim, wherein: The device comprises a storage element for storing wear and / or usage information of the sensor.

37. Apparatus according to any preceding claim, wherein: The device comprises a cable extending from the sensor unit and connected to the processing unit.

38. Apparatus according to any preceding claim, wherein: The device includes a wireless transmitter for transmitting measurement readings to an external device.

39. Apparatus according to any preceding claim, wherein: The device is a biomedical device and is configured to detect linear or pulsed flow in real time in biomedical applications.

40. Apparatus according to any preceding claim, wherein: The device is configured to measure the flow of the fluid, wherein the fluid is in the form of a gas or a liquid.

41. A measurement system comprising a processing unit, a visual display and an apparatus according to any preceding claim, the processing unit being configured to receive sensing element data from the apparatus and to provide a visual indication of the measured flow rate in the visual display.

42. The system of claim 41, wherein: The processing unit is a smartphone and the visual display is a screen of the smartphone, the smartphone having application software running thereon, the application software receiving and processing flow sensor data from a sensor and providing the visual indication of the measured flow in the visual display.

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