Apparatus for concentrating a fluid

Abstract

The present invention relates to a device (2) for collecting a fluid, the device (2) comprising a spill bottle (4) for containing said fluid, a reservoir (8) having an outlet (10) towards the spill bottle (4), the reservoir, the reservoir (8) and the spill bottle (4) being in communication with each other via a valve (12) provided in the outlet (10), a suction hole (14) which can be connected with a suction pump for creating a vacuum in the reservoir (8), an optical sensing means (22) operatively coupled to the reservoir (8) and adjusted to measure the volume of fluid in the reservoir (8), the optical sensing means (22) comprising a light source (26) and a detector (28), wherein the light source (26) is configured to emit light towards the reservoir (8) and the detector (28) is configured to detect the intensity of the light emanating from the reservoir (8), and at least one light guiding means (30, 32) for guiding the light on its path from the light source (26) to the detector (28).

Description

TECHNICAL FIELD

[0001] The present invention relates to a device for collecting a fluid. BACKGROUND

[0002] WO 2018 / 045349 A1 discloses a device comprising a collection vessel for containing milk, a breast interface for forming a fluid seal against a breast, and a pumping arrangement operably coupled to the breast interface to extract milk from the breast and collect it in the collection vessel. The device further comprises a sensor for characterizing the quantity and / or quality of the expressed milk. For determining the quantity, i.e. the volume of the fluid contained in the collection container, a capacitive sensor is coupled to an inner wall of the collection vessel.

[0003] There is still room for improvement of the prior known devices. SUMMARY

[0004] It is an object of the present invention to provide an improved device for collecting a fluid. In particular, the invention aims at providing a device for collecting a fluid which is capable of monitoring parameters of the fluid entering the device in an improved manner.

[0005] As a solution to the above object, the invention proposes a device having the features of claim 1.

[0006] The device comprises a venting bottle for containing a fluid. Typically, the fluid is milk extracted from a female breast. However, in principle, the device can be used for any other fluid, preferably a liquid. The venting bottle can be shaped as a bottle, in particular a baby bottle. Thus, the venting bottle preferably has a bottom surface and a circumferential enclosing wall extending from the bottom surface to form a container. Typically, the bottom surface is adapted to be placed on a horizontal surface and typically, the venting bottle has an opening opposite to the bottom surface.

[0007] Further, the device comprises a reservoir having an outlet facing the venting bottle, the reservoir and the venting bottle being in communication with each other via a valve provided in the outlet. The reservoir is typically provided inside a bottle top accessory which is detachably mountable on the opening of the venting bottle. A suction pump is connectable with a suction hole of the device for creating a vacuum in the reservoir. Preferably, the suction hole is provided at the bottle top accessory.

[0008] Typically, the bottle top accessory of the device comprises a port for connecting a breast interface to form a fluid seal against a breast, wherein the reservoir is adapted to be in communication with the port such that milk extracted at the breast interface is guided into the reservoir via a suction force of the suction pump, which can be supported by gravity in case the device is held in a position with the bottom surface of the venting bottle facing downwards.

[0009] The bottle top attachment can be detachable from the vented bottle, so that the vented bottle, when filled, can be connected to a baby bottle teat for feeding a baby. The bottle top attachment is releasably connectable, typically screwed, to the threads of the bottle neck of the vented bottle.

[0010] The bottle top attachment is arranged at the opening of the vented bottle, which opening is typically formed by the bottle neck of the vented bottle. The bottom surface of the vented bottle is typically arranged at the opposite end from the bottle neck. Typically, the vented bottle is designed to be able to stand upright and freely on the bottom surface of the vented bottle.

[0011] In all cases, directional information such as top, bottom, vertical, horizontal, etc. is related to the device standing on a flat horizontal surface with the bottom surface. Although the position of the bottom surface of the vented bottle facing downwards is the preferred position of use, the device can be used in different positions. For example, the device can be used for collecting milk in a position in which the device is inverted, i.e. with the bottom surface facing upwards.

[0012] The vented bottle according to the present application is typically made of at least partially transparent thermoplastic material or glass. It is particularly preferred to use polypropylene. The vented bottle made of plastic material can be produced as a disposable bottle or a recyclable bottle and typically has a weight of 7.5 to 30 g. The recyclable bottle preferably has a wall thickness of approximately 0.9 mm.

[0013] The nominal volume of the vented bottle is typically 80 to 250 ml, in particular 80 ml, 150 ml or 250 ml. The maximum volume that the vented bottle can hold is typically not more than 330 ml.

[0014] The vented bottle preferably has a height of approximately 60 to 160 mm, preferably 66 mm, 99.5 mm, 102 mm, 136 mm or 148.5 mm. The diameter of the bottle neck is typically 33 mm. The maximum diameter of the vented bottle is typically not more than 50 to 70 mm, preferably not more than 53 mm, 60 mm or 65 mm. All dimensions are to be understood with a tolerance of ±10%, preferably ±5%.

[0015] The vented bottle typically has a substantially cylindrical bottle body comprising a circumferential enclosing wall of the vented bottle and which tapers conically to form the bottle neck. The diameter of the bottle body can also vary over its length. For example, the bottle body can have multiple cylindrical sections of different diameters, which can be connected by one or more conical sections, among others. The bottle neck typically has the smallest diameter. The bottle neck is preferably provided with an outer thread, which can be connected with an inner thread of the bottle top attachment.

[0016] The reservoir is usually designed such that milk drops cannot directly drip through the reservoir. The lower side wall of the reservoir is preferably fluid-tight. The geometry of the reservoir defines a cavity with a certain volume. This volume is usually between 0.5 ml and 4 ml, preferably between 0.8 ml and 1.5 ml, and more preferably between 1.0 ml and 1.3 ml.

[0017] The reservoir has an outlet towards the discharge bottle, and a valve is arranged in the outlet. The valve is usually adapted to retain at least a certain amount of milk in the reservoir. The valve is preferably designed to bear against the outflow opening of the outlet in the closed position during dropwise priming. If the fluid pressure in the reservoir exceeds a resistance threshold of the valve, the valve is forced into the open position so that a certain amount of milk can flow out of the reservoir into the baby bottle. For example, the valve can be designed according to WO 2014 / 161099 A1 from the applicant or in the form of a flap valve according to US 2015 / 0283311 A1. Usually, the reservoir is not completely emptied when the reduction in fluid pressure causes the valve to return to the closed position.

[0018] Preferably, the resistance threshold of the valve is adjustable. The valve can be pre-tensioned against the outflow opening. The priming height is preferably between 10 mm and 30 mm, more preferably between 15 mm and 25 mm. The residual amount usually remaining in the reservoir after the valve has closed again is usually 0.1 ml to 0.3 ml.

[0019] The fluid pressure of the milk in the reservoir acting on the valve is the hydrostatic pressure. The valve is preferably designed as a one-way valve. Furthermore, preferably, the valve has a valve membrane which, due to its geometry, remains in a resting position during the application of fluid pressure from the outside of the reservoir on the valve membrane. In the resting position, the valve membrane rests against the outflow opening of the outlet. The outflow opening is usually provided on the side wall of the reservoir, thereby forcing the valve membrane (preferably pivoting) away from the vertical position to the open position. The valve membrane is preferably made of a flexible plastic material, in particular silicone.

[0020] Subsequently, the flow rhythm caused by the vacuum cycle of the pump, i.e. the partial outflow of the milk into the discharge bottle, can be achieved in a simple and energy-saving manner. At the end of the vacuum cycle, the suction of the vacuum pump essentially disappears, which usually leads to the outflow of the milk from the reservoir into the discharge bottle. Usually, the volume of milk in the reservoir is measured for each vacuum cycle of the pump before the valve at the outlet of the reservoir is opened.

[0021] The device comprises an optical sensing arrangement operably coupled to the reservoir and adjusted to measure the volume of fluid located in the reservoir. The optical sensing arrangement comprises a light source and a detector, wherein the light source is configured to emit light towards the reservoir and the detector is configured to detect the intensity of light emanating from the reservoir. The device comprises at least one light guiding means for guiding the light on its path from the light source to the detector. The terms "optical" and "light" herein are not limited to visible light, but refer essentially to the entire electromagnetic spectrum. The optical sensing arrangement is preferably suitable for the infrared range.

[0022] The light guiding means according to the present application can comprise or be designed as any optical element cable that receives and transmits or reflects light, preferably infrared light. Typically, the light guiding means according to the present application is adjusted to transmit or reflect at least 30%, preferably at least 50%, more preferably at least 70% of the intensity of the incident light. The light guiding means can reflect the light at an angle equal to the angle of incidence or transmit the light at an angle different from the angle of incidence. The light guiding means according to the present application can guide the light over a distance, preferably parallel or tangential to the reservoir wall, before the light guiding means redirects the light towards the reservoir, preferably orthogonally through the reservoir wall. Alternatively, the light guiding means according to the present application can not redirect the incident light, i.e. the light guiding means can be formed by a translucent window on the reservoir wall, accordingly allowing the light to enter or exit the reservoir.

[0023] The light guiding means is preferably adapted to guide the light such that the light passes through the reservoir transversely to the path of the milk through the reservoir. Furthermore, the optical sensing arrangement is arranged to detect different signals with the detector, depending on whether the light passes through milk or air on its way through the reservoir. Thus, the optical sensing arrangement can determine the stratification of the milk that has accumulated in the reservoir. Since the geometry of the reservoir is typically known, conclusions can be drawn about the amount of milk filling in the reservoir.

[0024] Preferably, the optical sensing device is configured as a structure unit that is detachable from the reservoir. Thus, the optical sensing device can be separated from the let-down bottle and the reservoir, which are typically cleaned more carefully than the rest of the device. The let-down bottle including the reservoir and the bottle top attachment can be cleaned in a dishwasher, while the optical sensing device can be cleaned manually. More preferably, the optical sensing device is accommodated in a cover that is detachably mounted to the bottle top attachment. Typically, the bottle top attachment comprises a receiving section in which a reservoir wall is exposed and which is adapted to receive the optical sensing device. Thus, the optical sensing device is arranged laterally to the reservoir. According to a preferred solution, the light source and the detector are provided on the same side of the reservoir, which side corresponds to the side of the reservoir that is exposed in the receiving section. For this preferred solution, the light source and the detector substantially face the same direction, and a light guiding means is provided for guiding the light on its path from the light source to the detector.

[0025] Preferably, the light source and the detector are provided at the same level along the path of the milk through the reservoir (hereinafter referred to as "milk path"). In the upright position of the device, the milk path typically extends substantially in the vertical direction, so that the light source and the detector are provided at the same vertical level in this position.

[0026] Preferably, the light source and the detector are spatially separated from the reservoir wall. That is, preferably, the light source and the detector are not directly connected to the reservoir wall. This facilitates the disconnection of the optical sensing device from the reservoir. Typically, a cover is provided between the optical sensing device and the reservoir for shielding light that does not belong to the light source of the device, wherein the cover comprises apertures assigned to the light source and the detector, respectively.

[0027] Preferably, the spatial distance between the light source and the detector corresponds at least to the width of the reservoir transverse to the milk path. This directly occurs when the light source and the detector are provided on opposite sides of the reservoir and face each other. In case the light source and the detector are provided on the same side of the reservoir and substantially face the same direction, at least one light guiding means is provided for guiding the light on its path from the light source to the detector. In particular, the light source can face a direction parallel to or tangential to a side wall of the reservoir located in the vicinity of the exposed side of the reservoir, and the receiver can face a direction parallel to or tangential to the other side wall of the reservoir located in the vicinity of the exposed side of the reservoir. Typically, the two side walls of the reservoir located in the vicinity of the exposed side of the reservoir are opposite side walls. Preferably, at least one light guiding means is provided on each of these two side walls. Thus, light emitted from the light source enters the light guiding means associated with the light source, which is subsequently re-directed by the light guiding means to enter the reservoir on one side, and after the light has passed through the reservoir, the light is re-directed by the other light guiding means on the opposite side to the detector.

[0028] Preferably, the at least one light guiding device comprises at least one of the following optical elements: a reflector, a prism, an optical fiber or any other optical element known in the art suitable for redirecting incident light at an angle of deviation.

[0029] More preferably, the at least one light guiding device is arranged between the light source and the reservoir such that light emitted from the light source is redirected by the light guiding device to pass through the reservoir wall at a right angle. Furthermore, preferably, the at least one light guiding device is arranged between the reservoir and the detector such that light emitted from the reservoir is redirected towards the detector substantially at a right angle with respect to the reservoir wall. Thus, losses due to scattering at the reservoir wall are reduced. The reservoir wall is at least substantially translucent for wavelengths within the operating range of the light source and the detector.

[0030] According to a preferred embodiment of the present application, the plurality of light sources is arranged in an array, wherein each light source is arranged at a different level along the milk path, the plurality of detectors is arranged in an array, wherein each detector is arranged at a different level along the milk path, and each light source forms a pair with one of the detectors arranged at the same level. Typically, the plurality of light sources and detectors covers at least the lower half of the milk path in the reservoir and preferably substantially the entire milk path. Thus, a detailed resolution of the milk in the reservoir can be achieved.

[0031] Typically, the light sources (and the corresponding detectors) are spaced apart from each other by about 0.2 to 1.0 mm, preferably 0.3 to 0.8 mm, and more preferably about 0.4 mm. The spacing between the centers of the light sources is preferably about 1.2 mm. Typically, infrared LEDs are provided as light sources, which infrared LEDs typically have a dome shape and a radiation angle of about 60°. The detectors are typically infrared light receiving phototransistors, which can have a spectral bandwidth in the range of 730 to 1100 nm. The wavelength of the peak sensitivity of the phototransistors can be around 940 nm. The viewing angle of the phototransistors can be about 130°.

[0032] In a preferred embodiment, two elements of the light guiding device are arranged at opposite sides of the reservoir, wherein the elements extend along the milk path. Preferably, the elements have a reflective surface for reflecting light of the light sources, which reflective surface forms an angle (preferably about 45°) with the reservoir wall.

[0033] In the upright position of the device, the milk path extends in a substantially vertical direction. Thus, the array of light sources and the array of detectors are substantially vertically oriented in the upright position of the device, respectively, wherein each light source forms a pair with a detector having the same vertical level. Subsequently, the vertical extension of the reflective surfaces of the elements of the light guiding device corresponds at least to the vertical extension of the arrays.

[0034] The reflective surfaces are arranged such that light emitted from the light source illuminates one of the reflective surfaces at an angle different from a right angle, and light coming out of the reservoir and passing through the reservoir wall at a right angle illuminates the other reflective surface at an angle different from a right angle. The light path between the light source and the detector can have a U-shape in a top view on the reservoir bottom, wherein the sides of the U-shape extend between the light source and one of the reflective surfaces and between the detector and the other reflective surface in a direction parallel to or tangential to the opposite side wall, and wherein the base of the U-shape extends between the reflective surfaces of the light guiding device, the base of the U-shape passing through the reservoir and preferably through the center of the reservoir.

[0035] In a top view on the reservoir bottom, the cross-section of the reservoir can be square, rectangular, polygonal, circular or elliptical.

[0036] According to a preferred aspect of the application, in the upright position, the plurality of light sources is arranged in a substantially horizontal row to face the light guiding device arranged between the light sources and the reservoir in a substantially vertical direction, and the plurality of detectors is arranged in a substantially horizontal row to face the light guiding device arranged between the reservoir and the detectors in a substantially vertical direction. That is, in this preferred aspect, the arrays of light sources and detectors are arranged transversely to the milk path, while in the above-mentioned aspect, the arrays of light sources and detectors are arranged parallel to the milk path.

[0037] Since the arrays of light sources and detectors are arranged transversely to the milk path, the light guiding device arranged between the light sources and the reservoir comprises a plurality of reflective surfaces arranged at or in steps of the reservoir wall, each reflective surface being arranged at a different height (at a different level along the milk path) of the reservoir wall and assigned to one of the light sources, and the light guiding device arranged between the reservoir and the detectors comprises a plurality of reflective surfaces arranged at or in steps of the opposite reservoir wall, each reflective surface being arranged at a different height (at a different level along the milk path) of the opposite reservoir wall and assigned to one of the detectors. According to this preferred aspect, each light source forms a pair with one of the detectors arranged at the same horizontal level. Likewise, the light path between the light sources and the detectors can have a U-shape. However, in this preferred aspect, the U-shape can be seen in a side view on the reservoir. In any case, for different pairs of light sources and detectors, the base of the U-shape has a different vertical level (different height along the milk path). BRIEF DESCRIPTION OF DRAWINGS

[0038] Further details and advantages of the application will be obtained from the following description of embodiments and the drawings, in which:

[0039] Figure 1 A side view of an embodiment is shown in connection with a breast interface,

[0040] Figure 2 a cross-sectional view of this embodiment is shown,

[0041] Figure 3 a further side view of this embodiment is shown,

[0042] Figure 4 a cross-sectional view according to cutting line A-A in Figure 3 is shown,

[0043] Figure 5 a further side view of this embodiment is shown,

[0044] Figure 6 a cross-sectional view according to cutting line B-B in Figure 5 is shown,

[0045] Figure 7 a cross-sectional view according to cutting line C-C in Figure 5 is shown, and

[0046] Figure 8 a cross-section is schematically shown in a top view on the reservoir bottom, traversing the milk path through the reservoir. DETAILED DESCRIPTION

[0047] Figure 1 A device 2 for collecting a fluid is shown, which device 2 comprises a drain bottle 4 for containing the fluid and a bottle top attachment 6 screwed on a bottle neck of the drain bottle 4. A reservoir 8 is arranged within the bottle top attachment 6, wherein the reservoir 8 has an outlet 10 towards the drain bottle 4, and wherein the reservoir 8 and the drain bottle 4 are in communication with each other via a valve 12 arranged in the outlet 10 (see Figure 2 ). The bottle top attachment 6 has a collar 7 which is screwed to the drain bottle and is connected by laser welding to an upper housing part 9 of the bottle top attachment 6.

[0048] The bottle top attachment 6 is provided with a suction hole 14 which can be connected with a suction pump for creating a vacuum in the reservoir 8, and a port 16 which is connected (in Figure 1 ) to a breast interface 18 for creating a fluid seal against a breast. Within the bottle top attachment 6, a diaphragm 20 is arranged which interacts via the suction hole 14 with the suction pump for creating a vacuum in the bottle top attachment chamber comprising the reservoir. Furthermore, the diaphragm 20 forms a medium separation for air sucked by the suction pump and milk drawn at the breast interface (see Figure 4 ).

[0049] The optical sensing device 22 is covered by a lid 24 which is detachably mounted on the bottle top attachment 6. The optical sensing device 22 is operatively coupled to the reservoir 8 and is adjusted to measure the volume of fluid present in the reservoir 8. Further, the optical sensing device 22 comprises a light source 26 configured to emit light towards the reservoir 8 and a detector 28 configured to detect the intensity of light emanating from the reservoir 8. The light guiding means comprise a first light guiding element 30 arranged at a side wall of the reservoir 8, in this embodiment having a square cross section, which directs light from the light source 26 towards the reservoir 8 (see Figure 8 ). The light guiding means further comprise a second light guiding element 32 arranged at an opposite side wall of the reservoir 8 for directing light emanating from the reservoir 8 towards the detector 28. Each of the light guiding elements 30, 32 comprises a reflecting surface 34, 36 which forms a 45° angle with the reservoir wall 38, 40. In a top view on the reservoir bottom as shown in Figure 8 , the light path between the light source 26 and the detector 28 has a U-shape.

[0050] The light source 26 and the detector 28 are arranged at the same level along the milk path through the reservoir. Typically, the device 2 is held in an upright position such that the milk passes through the reservoir in a substantially vertical direction. Therefore, typically, the light source 26 and the detector 28 are arranged at the same vertical level.

[0051] The valve 12 arranged in the outlet 10 is typically kept closed as long as the suction force of the suction pump is maintained. If the accumulated milk forms a milk column in the reservoir and the light emitted from the light source 26 passes through this milk column on its way to the detector 28, the light will be absorbed or scattered by the milk column. Therefore, in this case, the intensity of the light detected by the detector 28 is lower compared to the case where less milk is accumulated in the reservoir and the milk column does not reach the level of the light source 26 and the detector 28.

[0052] The optical sensing device 22 is configured as a structural unit which is accommodated by the lid 24 and which can be detached from the reservoir 8 together with the lid 24. In this embodiment, the lid 24 is releasably locked to the bottle top attachment 6. Therefore, the optical sensing device 22 and the bottle top attachment 6 comprising the reservoir 8 can be cleaned separately. Further, the lid 24 protects the optical sensing device 22 from damage and stray light.

[0053] The cover 42 is provided to spatially separate the reservoir wall from the light source 26 and the detector 28 and to prevent light from entering the reservoir 8 without passing the first light guiding element 30.

[0054] Figure 2The diaphragm 20 in the bottle top attachment 6 is shown to separate an air suction chamber 44, which is to be communicated with a suction pump, and a milk suction chamber 46 comprising the reservoir 8, which is communicated with the let-down bottle 4 via a valve 12 provided in the outlet 10 of the reservoir 8 and with the breast via a breast interface 18 which is connectable to the port 16. The vacuum generated in the air suction chamber 44 by the suction pump generates a negative pressure (suction force) in the milk suction chamber 46 acting on the breast. In the upright position of the device 2, the port 16 comprises an inclined lower surface 48. The top end of the reservoir 8 is in close proximity to the inclined surface 48, wherein an opening 50 towards the reservoir 8 is provided between the diaphragm 20 and the inclined surface 48. In the upright position of the device 2, the milk path P extends in a substantially vertical direction. The milk path P extends between the opening 50 of the reservoir 8 and a bottom surface 51 of the reservoir 8. Depending on the orientation in which the device 2 is held, the milk path P can not be parallel to a vertical axis.

[0055] In Figure 2 In the substantially upright position shown, the reservoir 8 is provided in a side wall of the reservoir 8 at a lower left corner of the reservoir towards the outlet 10 of the let-down bottle 4. According to this embodiment, the valve 12 provided in the outlet 10 is a flap valve which opens towards the central longitudinal axis of the device 2. The optical sensing arrangement 22 is provided in close proximity to a side wall of the reservoir 8 opposite to the side wall comprising the outlet 10.

[0056] The optical sensing arrangement 22 comprises a plurality of light sources 26 and detectors 28 arranged in two arrays extending along the milk path P, wherein each light source 26 forms a pair with a detector 28 provided at the same level along the milk path P. Between each pair, a light path 52 is formed in a U-shape having two side portions 54 and a base portion 56. The base portions 56 of the light paths 52 pass through the reservoir 8 orthogonally to the milk path P, wherein each base portion 56 passes through the central longitudinal axis of the reservoir 8, and wherein each base portion 56 of the light paths 52 passes through the reservoir at a different level along the milk path P. Thus, by comparing the intensities measured by the different detectors 28, it can be determined how much light is absorbed at different levels along the path P. Thus, by knowing the geometry of the reservoir 8 and knowing the height of the milk column along the milk path P to reach a certain level as determined by the optical sensing arrangement 22, the volume of milk contained in the reservoir 8 can be determined.

[0057] List of reference signs

[0058] 2 Device

[0059] 4 Let-down bottle

[0060] 6 Bottle top attachment

[0061] 7 Collar

[0062] 8 Reservoir

[0063] 9 upper housing part

[0064] 10 outlet

[0065] 12 valve

[0066] 14 suction hole

[0067] 16 port

[0068] 18 breast interface

[0069] 20 septum

[0070] 22 optical sensing device

[0071] 24 cover

[0072] 26 light source

[0073] 28 detector

[0074] 30 first light guide element

[0075] 32 second light guide element

[0076] 34, 36 reflective surface

[0077] 38, 40 reservoir wall

[0078] 42 cover

[0079] 44 air suction chamber

[0080] 46 milk suction chamber

[0081] 48 inclined surface

[0082] 50 reservoir opening

[0083] 51 bottom surface of the reservoir

[0084] 52 U-shaped light path

[0085] 54 side of the U-shaped light path

[0086] 56 base of the U-shaped light path

[0087] D spatial distance between the light source and the pair of detectors

[0088] P milk path

Claims

1. A device (2) for collecting a fluid, the device (2) comprising: a drain bottle (4) for containing the fluid, a reservoir (8) having an outlet (10) towards the drain bottle (4), the reservoir (8) and the drain bottle (4) being in communication with each other via a valve (12) provided in the outlet (10), a suction hole (14) connectable with a suction pump for creating a vacuum in the reservoir (8), an optical sensing arrangement (22) operatively coupled to the reservoir (8) and adjusted to measure the volume of fluid in the reservoir (8), the optical sensing arrangement (22) comprising a light source (26) and a detector (28), wherein the light source (26) is configured to emit light towards the reservoir (8) and the detector (28) is configured to detect the intensity of light emanating from the reservoir (8), and at least one light guiding means for guiding light on its path from the light source (26) to the detector (28), wherein the spatial distance (D) between the light source (26) and the detector (28) corresponds at least to the width of the reservoir (8) transversely to the milk path (P) in the reservoir (8), wherein a plurality of light sources (26) is provided as an array, each light source (26) having a different level along the milk path (P), a plurality of detectors (28) is provided as an array, each detector (28) having a different level along the milk path (P), and each of the light sources (26) forms a pair with one of the detectors (28) provided at the same level.

2. The device (2) according to claim 1, characterized in that The optical sensing arrangement (22) is configured as a structural unit that can be detached from the reservoir (8).

3. The device (2) according to claim 2, characterized in that The optical sensing arrangement (22) is housed by a cover (24) that is detachably mounted to a bottle top accessory (6) connected with the drain bottle (4), the reservoir (8) being provided in the bottle top accessory (6).

4. The apparatus of any one of claims 1-2, wherein, The light source (26) and the detector (28) are spatially separated from the reservoir wall.

5. The apparatus of any one of claims 1-2, wherein, The at least one light guiding means is provided at or in a side wall of the reservoir (8).

6. The apparatus of any one of claims 1-2, wherein, The at least one light guiding means comprises a reflective surface (34, 36).

7. The apparatus of any one of claims 1 to 3, wherein, At least one first light guiding element (30) of the light guiding means is provided between the light source (26) and the reservoir (8) such that light emitted from the light source (26) is redirected by the first light guiding element (30) to pass through a reservoir wall (38) at right angles.

8. The apparatus of claim 7, wherein, At least one second light guiding element (32) of the light guiding means is provided between the reservoir (8) and the detector (28) such that light emanating from the reservoir (8) substantially at right angles to a reservoir wall (40) opposite the reservoir wall (38) is redirected towards the detector (28).

9. The device according to claim 8, wherein The plurality of light sources (26) is arranged in a row to face a first light guide element (30) arranged between the light sources (26) and the reservoir (8) in a direction substantially parallel to the milk path (P), The plurality of detectors (28) is arranged in a row to face a second light guide element (32) arranged between the reservoir (8) and the detectors (28) in a direction substantially parallel to the milk path (P), The first light guide element (30) arranged between the light sources (26) and the reservoir (8) comprises a plurality of reflective surfaces arranged in steps at or in the reservoir wall, each reflective surface being arranged at a different height of the reservoir wall and being assigned to one of the light sources (26), The second light guide element (32) arranged between the reservoir (8) and the detectors (28) comprises a plurality of reflective surfaces arranged in steps at or in opposite reservoir walls, each reflective surface being arranged at a different height of the opposite reservoir walls and being assigned to one of the detectors (28), and Each of the light sources (26) forms a pair with one of the detectors (28) arranged at the same height in a direction transverse to the milk path (P).

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