Sensor arrangement

Abstract

Method and sensor arrangement 1 for detecting the position of a liquid surface in a container; 1 ', said sensor arrangement being configured to be attached to a container 13; 13 '; 11'; 11 ') for storing a liquid in a table-top fluid treatment system 101. The sensor is arranged 1; 1'comprises a millimeter-wave radar sensor 21, a sensor housing 24 comprising said radar sensor 21 and a container attachment part 23; and a container attachment means (23, 23 ') connected to the sensor housing (24) and configured for attaching the sensor arrangement (1, 1') to the top opening (11, 11 ') of the container (13, 13') such that the radar sensor (21) can be provided in an operating position to detect the position of the liquid surface within the container (13, 13 ').

Description

Technical Field

[0001] The present invention relates to a sensor arrangement for detecting the position of a liquid surface within a container, and to a method for detecting the position of a liquid surface within a container, the container being for storing liquid in a bench top fluid handling system. Background Art

[0002] In fluid handling systems, such as liquid analysis systems, separation systems, and chromatography systems, it is important to record the contents within bottles and other containers for different liquids, such as solvents and waste liquids processed in the system. If a container becomes empty, the process is disrupted, and if a container is overfilled, liquid may be wasted and there may be contamination problems. Liquid spills can also be a safety issue with a risk of personal injury. There are different commonly used methods for monitoring the liquid level within containers in these types of systems. One possibility is to use dead reckoning, i.e., information from pumps in the system regarding how much liquid is pumped into and out of the container. However, for such systems, it is important that the user always correctly updates the contents within the container when it is refilled or emptied again.

[0003] Another method for monitoring the liquid level in a chromatography system is disclosed in US7419598, where a bubbler is positioned within a solvent reservoir bottle, with the opening of the bubbler near the bottom of the system to measure the pressure of the solvent, thereby monitoring the level of the solvent. However, this measurement method depends on the density of the liquid, and it often does not provide good enough measurement accuracy to predict whether the amount of solvent is sufficient for the method run, or whether the remaining unoccupied volume in the waste liquid container is sufficient for the method run.

[0004] In US2003 / 0175157, a method for controlling the fluid contents within a container is disclosed, where a weighing scale is used to detect the weight of the fluid within the container. In this method, it is also necessary to know or estimate the density of the fluid, so the measurement accuracy may not be precise, especially for a mixed fluid such as in a waste liquid container. In addition, the weight of the container, the weight of the tubing provided to the container, and the weight of any other possible components of the system in contact with the container will affect the measured weight of the container, thus affecting the measurement accuracy. Therefore, the container also needs to be freely positioned without contacting anything that may be problematic. Summary of the Invention

[0005] An object of the present invention is to provide an improved sensor arrangement and a method for monitoring the liquid level within a container.

[0006] Another object of the present invention is to provide a sensor arrangement that is easy to handle, and by which the liquid level can be reliably monitored.

[0007] This is achieved in a sensor arrangement and by the method according to the independent claims.

[0008] According to one aspect of the present invention, there is provided a sensor arrangement configured to be attached to a top opening of a container for storing liquid in a benchtop fluid handling system. The sensor arrangement comprises:

[0009] - a millimeter-wave radar sensor;

[0010] - a sensor housing including the millimeter-wave radar sensor; and

[0011] - a container attachment member connected to the sensor housing and configured to attach the sensor arrangement to the top opening of the container such that the millimeter-wave radar sensor can be provided in an operating position to detect the position of the liquid surface within the container.

[0012] According to another aspect of the present invention, there is provided a method for detecting the position of a liquid surface within a container for storing liquid in a benchtop fluid handling system. The method comprises the steps of:

[0013] - attaching the container attachment member of the sensor arrangement according to the present invention to the top opening of the container; and

[0014] - detecting the position of the liquid surface within the container when the millimeter-wave radar sensor is in the operating position.

[0015] Thus, reliable monitoring of the liquid level within the container is achieved. The monitoring directly measures the distance to the liquid level, thereby measuring the liquid levels of all types of liquids and liquid mixtures regardless of their density. According to the present invention, a millimeter-wave radar sensor is used. This is a radar technology that transmits signals with a short wavelength in the millimeter range. Due to the short wavelength, the size of the system components can be relatively small, and thus small and compact radar sensors have been provided, which also measure with high precision. For example, the radar sensor can operate at 55 - 85 GHz. Such a radar sensor can measure a closer distance than previous types of radar sensors, which were larger and less compact and not suitable for use in containers of smaller sizes. According to the present invention, such a millimeter-wave radar sensor is attached to the top opening of the container, so that the liquid level within the container can be monitored. This is a direct measurement of the liquid level independent of the liquid density, so the measurement accuracy and reliability are good for both pure liquids and liquid mixtures such as those in waste liquid containers. Thus, both the emptying of the liquid within the container and the overfilling of the liquid within the container can be effectively avoided. Therefore, the fluid handling process in the system is more efficient, and the risks of pollution and personal injury caused by overfilling the waste liquid container are reduced. By positioning the millimeter-wave radar sensor attached to the top opening of the container, the radar sensor will be positioned at a suitable distance above the liquid level within the container, and the liquid level can always be conveniently and accurately measured. Thus, the user always knows how much liquid is in the container, so the user can easily see whether the liquid will be sufficient for the process to be run. In addition, the user never needs to manually input any information about the liquid volume, so the user's operation is convenient and the risk of accidents is reduced.

[0016] According to an embodiment of the present invention, the sensor housing can be provided in at least two different positions relative to the container attachment member, one position being a closed position in which the sensor housing covers at least a part of the top opening of the container, and the other position being an open position in which the sensor housing does not cover the top opening, wherein when the sensor housing is provided in the closed position, the radar sensor is provided in the operating position. Thus, the container can be refilled with new liquid without removing the entire sensor arrangement, and during refilling only the sensor housing needs to be provided in the open position.

[0017] According to an embodiment of the present invention, in the sensor arrangement, the sensor housing is connected by a hinge, so that the sensor housing can be flipped upward from the closed position to the open position, enabling access to the top opening of the container.

[0018] According to an embodiment of the present invention, the sensor housing includes an angle sensor. Accordingly, the tilt angle of the sensor housing and / or the entire container can be detected. The tilt angle of the sensor housing can indicate whether the sensor housing is in the closed position or the open position. The tilt angle of the entire container can indicate that the container has been mispositioned or that the user is tilting the container for the purpose of using only the remaining portion of the contents.

[0019] According to an embodiment of the present invention, the sensor arrangement further includes a position indicating device configured to indicate whether the radar sensor is in the operating position. In one embodiment, this position indicating device is an angle sensor.

[0020] According to an embodiment of the present invention, the sensor arrangement further includes a tube holder member that can be attached to the container attachment member and is configured to hold the tube to be provided into the container towards the side with the top opening. Accordingly, the tube can be prevented from obstructing the measurement channel between the radar sensor and the liquid level. Otherwise, the tube may impede and interfere with the liquid level detection.

[0021] According to an embodiment of the present invention, the tube holder member includes a rail that extends from the top opening of the container into the container and extends outwards from the container when the sensor arrangement is provided to the container, and the rail can support one or more tubes provided to the container. Accordingly, the tubes are held in a suitable position within the container. The tubes can also be guided outwards from the container in a suitable direction. Accordingly, the connections in the system are convenient. The tubes can also be positioned and held at a suitable height within the container. Accordingly, there is no risk that the tubes are moved to a position above the liquid level inside the container.

[0022] According to an embodiment of the present invention, the tube holder member further includes an annular fixing member connected to the rail, wherein when the sensor housing is provided in the closed position, the annular fixing member is provided between the container attachment member and the sensor housing, so that the annular fixing member is connected to the container attachment member such that it can rotate relative to the container attachment member, and is connected to the sensor housing such that the housing member can be provided in at least two different positions relative to the container attachment member, wherein the two positions include the open position and the closed position. By rotating the annular fixing member and the rail together, the tubes provided to the rail can be guided as desired in the connected system while the container attachment member is held attached to the container.

[0023] According to one embodiment of the present invention, the sensor arrangement includes a processor connected to a radar sensor, wherein the processor is configured to determine the amount of liquid in the container based on the detected position of the liquid surface and based on pre-stored container geometry information. By fully allocating intelligence to the sensor arrangement, communication from the sensor arrangement out to an external control system is less complex and more stable (i.e., requires less power (capacity)), and smaller and cheaper cables can be used for the communication.

[0024] According to one embodiment of the present invention, the container attachment member includes a thread for threaded connection to a threaded top opening of the container, or includes a magnet for magnetic connection to the top opening of the container.

[0025] According to one embodiment of the present invention, the sensor arrangement further includes a connection device such that in a bench-top fluid handling system using the container and the sensor arrangement, the radar sensor and possibly the processor and / or angle sensor can be connected to a control system.

[0026] According to one embodiment of the present invention, the sensor arrangement is configured to be attached to a container having a height between 10 - 100 cm and / or a volume between 0.5 - 20 liters. Thus, the sensor arrangement is suitable for use in bench-top fluid handling systems such as chromatography systems.

[0027] According to one embodiment of the present invention, the method further includes the step of positioning one or more tubes to be provided into the container within a tube rack member of the sensor arrangement.

[0028] According to one embodiment of the present invention, the method further includes the step of rotating the tube rack member relative to the container attachment member such that the tubes provided in the tube rack member are guided for convenient connection in a bench-top fluid handling system.

[0029] According to one embodiment of the present invention, the method further includes the step of indicating whether the radar sensor is in an operating position by a position indicating device.

[0030] According to one embodiment of the present invention, the step of indicating whether the radar sensor is in an operating position by the position indicating device includes: measuring the tilt angle of the sensor housing, wherein the position indicating device includes an angle sensor provided in the sensor housing.

[0031] According to one embodiment of the present invention, the method further includes the following steps:

[0032] - Position the sensor housing of the sensor arrangement relative to the container attachment part in a closed position to detect the liquid level in the container, wherein the closed position is a position where the sensor housing covers at least a part of the top opening of the container, and wherein when the sensor housing is provided in the closed position, the radar sensor is provided in an operating position;

[0033] - Position the sensor housing of the sensor arrangement relative to the container attachment part in an open position to refill the liquid into the container, wherein the open position is a position where the sensor housing does not cover the top opening.

[0034] Other embodiments are described in the detailed description and the dependent claims. Description of the Drawings

[0035] Figure 1 A bench-top fluid handling system is schematically shown, in which the sensor arrangement according to the present invention can be used.

[0036] Figure 2a A perspective view of a sensor arrangement according to an embodiment of the present invention is shown.

[0037] Figure 2b As shown Figure 2a A cross-section of the sensor arrangement is shown.

[0038] Figure 3a Is a perspective view of the container, in which the sensor arrangement as Figure 2a And Figure 2b Shown is attached and provided in the closed position.

[0039] Figure 3b Is the same as Figure 3a Shown container and the same sensor arrangement, wherein the sensor arrangement is provided in the open position.

[0040] Figure 3c Is a cross-section of the container with the attached sensor arrangement as Figure 3a Shown.

[0041] Figure 3d Is as Figure 3c Shown close-up view of the cross-section of the sensor arrangement.

[0042] Figure 4a Is a perspective view of a sensor arrangement according to another embodiment of the present invention.

[0043] Figure 4b Is a perspective view showing only a part of the sensor arrangement as Figure 4a Shown.

[0044] Figure 5a Is a perspective view of the container, wherein asFigure 4a and Figure 4b the sensor arrangement shown is attached and provided in a closed position.

[0045] Figure 5b is the same container and the same sensor arrangement as shown in Figure 5a wherein the sensor arrangement is provided in an open position.

[0046] Figure 5c is a cross-section of a container having an attached sensor arrangement as shown in Figure 5a Figure.

[0047] Figure 6 is a flow chart of a method according to an embodiment of the present invention. Detailed Description

[0048] Figure 1 Schematically shown is a benchtop fluid handling system 101, to which a sensor arrangement 1; 1' according to the present invention can be attached and used when attached to a container 13; 13' for storing liquid in the benchtop fluid handling system. In this specific embodiment, the benchtop fluid handling system 101 is a chromatography system 101 (e.g., a laboratory chromatography system, also referred to as a small-scale chromatography system), and thus one or more chromatography columns 103 can be connected to the chromatography system 101. In other types of benchtop fluid handling systems in which this invention can be used, other types of components for handling or analyzing fluids, instead of chromatography columns, can be connected to the system. Other embodiments of benchtop fluid handling systems include, for example, filtration systems, evaporation systems, and other types of separation and analysis systems. In addition, the chromatography system 101 includes one or more pumps 113 for pumping liquid to and from the container 13; 13' and the chromatography columns 103. Fluid lines 114 connect the container 13; 13' to one or more chromatography columns 103. Further, the chromatography system 101 includes a control system 111 and possibly a display 112. The display can be adapted to present information to the user, but can be replaced by other alternatives, such as visible or audible signals, automatic stops, and / or a display connected to a connecting device (such as a computer or a phone). The control system 111 is connected to the display 112, one or more pumps 113, and one or more sensor arrangements 1; 1'. The control system 111 can collect information from one or more sensor arrangements 1; 1' regarding the liquid level within the container 13; 13', and also possibly information from one or more pumps 113 regarding the volume pumped to and from the container 13; 13'. In addition, the control system 111 can appropriately present the information regarding the liquid level on the display 112 and control one or more pumps 113 based on this information.

[0049] Two different embodiments of the sensor arrangement 1; 1' are shown in FIGS. 2 - 5. In FIGS. 2 - 3, the sensor arrangement 1 includes a container attachment member 23 having a threaded connection portion 61 configured to be attached to a container 13 having a threaded top opening 11. The top opening 11 is located in the upper part of the container 13 and may also be referred to as a filling hole or filling inlet. For containers without a threaded top opening, an adapter may be used to provide a threaded top opening suitable for connection to the sensor arrangement according to the invention. Such an adapter includes a threaded member having a thread that is adapted to the thread of the container attachment member of the sensor arrangement according to the invention and should be positioned within the container opening. In FIGS. 4 - 5, the sensor arrangement 1' includes a container attachment member 23' that includes a magnet 61'. Thus, this is a sensor arrangement 1' suitable for connection to a container having a non-threaded top opening 11'. If the container is a metal container, a magnetic connection may be suitable. Other possible connections may include snap connections, clamping connections, or screw connections. Most of the other details of the sensor arrangements 1; 1' are the same, so the same or similar reference numerals are given in the two different embodiments and the invention will be described below with reference to all of the figures.

[0050] Provided is a sensor arrangement 1; 1' according to the present invention, which is configured to be attached to the top opening 11; 11' of a container 13; 13' for storing liquid in a benchtop fluid handling system 101. The sensor arrangement 1; 1' includes a millimeter-wave radar sensor 21, which is a small and compact new type of radar sensor that can be used to measure relatively small distances compared to previously larger radar sensors. A millimeter-wave radar sensor is a radar technology that transmits signals with short wavelengths in the millimeter range. Due to the short wavelength, the size of the system components can be relatively small, and thus small and compact radar sensors have been provided, which can also measure with high precision. For example, the radar sensor can operate at 55 - 85 GHz. For example, the millimeter-wave radar sensor can be a pulsed coherent radar sensor (e.g., operating at 60 GHz, or 55 - 80 GHz, or 55 - 65 GHz), or it can be another type of millimeter-wave radar sensor, also known as a miniaturized radar sensor. Previously types of radar sensors were larger and bulkier and not suitable for smaller-sized containers. The millimeter-wave radar sensor can be provided as a single-chip solution that includes all necessary components within one chip, so it is a small, compact, and easily integrated radar sensor suitable for this invention. According to this invention, it has been recognized that this type of millimeter-wave radar sensor can be used for smaller-sized containers in a benchtop fluid handling system, such as in the range of 10 - 100 cm in height and / or in the range of 0.5 - 220 liters or 0.5 - 20 liters in volume, for reliably and accurately monitoring the liquid level. According to the present invention, the millimeter-wave radar sensor 21 (hereinafter also only referred to as the radar sensor 21) is provided in the sensor arrangement 1; 1', which is configured to be attached to the top opening 11; 11' of the container 13; 13', thereby enabling convenient and reliable liquid level monitoring.

[0051] The sensor arrangement 1; 1' includes a sensor housing 24, which includes the radar sensor 21, and a container attachment member 23; 23', which is connected to the sensor housing 24 and is configured to attach the sensor arrangement 1; 1' to the container 13; 13' such that the radar sensor 21 can be provided in an operating position to detect the position of the liquid surface within the container 13; 13'. As discussed above, the container attachment member 23; 23' can include different types of connection devices depending on the type of container to be attached, such as a thread 61 for a container 13 with a threaded top opening 11, or a magnet 61' for a metal container.

[0052] According to some embodiments of the present invention, and as shown in two embodiments of FIGS. 2-5, the sensor arrangement 1; 1' further comprises a position indicating device 25 configured to indicate whether the radar sensor 21 is in an operating position. By detecting the correct position of the radar sensor 21, i.e., whether the radar sensor 21 is positioned in the correct operating position, the liquid level monitoring within the container can be made more reliable. For example, if the sensor arrangement 1; 1' is moved or removed to refill the container 13 again, during this period the radar sensor 21 will not be able to correctly read the liquid level, and it will be beneficial to determine those periods when the radar sensor 21 is not in the correct operating position. In order to be able to continue the process during, for example, refilling the container with liquid again, dead reckoning can be used to estimate the liquid level within the container during the periods when the radar sensor 21 is not positioned in the correct operating position, i.e., information from one or more pumps 113 in the system 101 can be used during the above-mentioned periods. However, once the position indicating device 25 indicates the correct operating position again, the liquid level can be updated based on the readings from the radar sensor. For example, the position indicating device 25 can include an angle sensor 25' or another type of sensor that can detect the position of the radar sensor 21 or the position of the sensor housing 24 that includes the radar sensor 21, which will be discussed in more detail below.

[0053] In some embodiments of the present invention, and as shown in two embodiments of FIGS. 2-5, the sensor housing 24 can be provided in at least two different positions relative to the container attachment member 23; 23', one position being a closed position in which the sensor housing 24 covers at least a part of the top opening 11; 11' of the container 13; 13', and the other position being an open position in which the sensor housing 24 does not cover the top opening 11; 11'. When the sensor housing 24 is provided in the closed position, the radar sensor 21 is provided in the operating position. When the sensor housing 24 is provided in the open position, the top opening 11; 11' or at least a part of the top opening 11; 11' is exposed, i.e., it is possible to access the container and fill and / or refill the container with liquid. Thus, the container can be refilled without removing the entire sensor arrangement 1; 1'. It is only necessary to move the sensor housing 24 to the open position. Therefore, during refilling the container, the tube 41 provided within the container 13; 13' can be kept in the container.

[0054] The sensor housing 24 is a housing that encloses the radar sensor 21 and other components such as a suitable lens 26 disposed within the sensor housing, which lens is arranged for focusing electromagnetic waves from the radar sensor. For example, this can be a hyperbolic lens or an FZP (Fresnel zone plate) lens. Additionally, the sensor housing 24 may include a processor 31 connected to the radar sensor 21 and may also include an angle sensor 25’, which will be described in more detail below. The material of the sensor housing 24 should be such that the radar sensor 21 can transmit and receive electromagnetic waves through the material, such as a plastic material. Suitably, the material is also resistant to chemical vapors that may emanate from the contents within the container. Examples of suitable materials for the sensor housing are PEEK (polyetheretherketone), PPS (polyphenylene sulfide), and PP (polypropylene).

[0055] In some embodiments of the present invention (and as shown in two of the embodiments in FIGS. 2 - 5), in the sensor arrangement 1; 1’, the sensor housing 24 is connected by a hinge 27 such that the sensor housing 24 can be flipped upwards from a closed position to an open position, enabling access to the top opening 11; 11’ of the container 13; 13’. Another embodiment of the connection of the sensor housing 24 in the sensor arrangement 1; 1’ can be a swing - out connection or a magnetic connection. In some embodiments, the sensor arrangement 1; 1’ further includes a pipe rack member 33, which can be an integrated member within the container attachment member 23; 23’, or as shown in the embodiments in FIGS. 2 - 5, the pipe rack member can be a separate component that can be attached to the container attachment member 23; 23’. The pipe rack member 33 is then provided between the sensor housing 24 and the container attachment member 23; 23’, and will be described in further detail below. In Figure 3b and Figure 5b the hinge 27 can be best seen, where the sensor housing 24 is provided in the open position. In Figure 3a and Figure 5a the sensor housing 24 is provided in the closed position. Another alternative is to connect the sensor housing 24 (possibly via the pipe rack member 33, by a magnet, possibly together with alignment pins for correct alignment) to the container attachment member 23; 23’. Also in one embodiment with a magnet, the sensor housing can be provided in a closed position covering the top opening of the container, and the sensor housing can be removed from the container attachment member, i.e., provided in an open position where at least a portion of the top opening 11; 11’ of the container is exposed, enabling access to fill the container. When the sensor housing 24 is provided in the open position and at least partially exposes the top opening 11; 11’ of the container 13; 13’, new liquid can be filled into the container.

[0056] As briefly discussed above, in some embodiments, the sensor housing 24 may include an angle sensor 25', and thus the tilt angle of the sensor housing 24 can be measured. The measured tilt angle can be used to indicate whether the sensor housing 24 is in the open position or the closed position, i.e., it can be used as a position indicating device 25 to detect whether the radar sensor 21 is in the operating position. It can also be used to determine whether the container 13; 13' to which the sensor arrangement 1; 1' is attached is tilted. If the container is tilted, the measurement result of the radar sensor may be disturbed because the measurement channel between the radar sensor and the liquid surface may not be unobstructed. Therefore, if it is detected that the container may be tilted, it is suitable to warn the user. According to some embodiments of the present invention, the sensor housing 24 includes the hinge 27 as described above. This hinge 27 can be provided as an extension member of the sensor housing 24, so that if the sensor housing 24 is to be detached from the container attachment member 23; 23' and, for example, the sensor housing is positioned on a table or desk beside the container, due to the extended hinge 27, it will not lie flat horizontally, and thus the angle sensor 25' will indicate the tilt angle of the sensor housing 24, i.e., not the operating position of the radar sensor 21. This can be advantageous to avoid incorrect liquid level measurements. Different tilt angle ranges can be pre-stored for different common recognized situations, such as a container tilted due to an error, a container tilted for the purpose of being able to use only the remaining liquid in the container, a removed sensor housing lying flat on a table as discussed above, the open position of the sensor housing, and the closed position of the sensor housing (i.e., the operating position of the radar sensor). Therefore, the angle sensor 25' can be used to identify different situations, and thus the liquid level measurement can be made more reliable. In some embodiments, the angle sensor 25' can measure and distinguish tilts along different axes (such as both the x-axis and the y-axis). Therefore, it is easier to distinguish the differences between different possible situations, such as the difference between the position of the sensor housing and the tilt of the entire container. Possibly, the tilt of the entire container often may include tilting around more than one axis. The angle sensor 25' can be connected to a processor 31 within the sensor housing 24 and / or a control system 111 within the separation system 101. Another alternative for the position indicating device 25 can be a sensor provided within the container attachment member 23; 23' or within the sensor housing 24, where the sensor can (e.g., mechanically, magnetically, or optically) detect the presence of the proximity of the other of the two components.

[0057] As briefly discussed above, in some embodiments (and as shown in two of the embodiments of FIGS. 2 - 5), the sensor arrangement 1; 1' may include a pipe rack member 33. The pipe rack member 33 may be a separate member or an integral part of the container attachment member 23; 23'. In some embodiments, the pipe rack member 33 may be a detachable member that can be attached to and detached from the container attachment member 23; 23'. The pipe rack member 33 is configured to hold the pipe 41 provided within the container 13; 13' towards the side of the top opening 11; 11'. Thus, when the sensor arrangement 1; 1' is attached to the container, there will be an unobstructed measurement path between the radar sensor 21 (when provided in the operating position) and the liquid surface within the container 13; 13', without the pipe 41 interfering.

[0058] In these embodiments, the pipe rack member 33 includes a track 34 that extends from the top opening 11; 11' of the container into and out of the container when the sensor arrangement 1; 1' is provided to the container. The track 34 can support one or more pipes 41 provided to the container. Suitably, the track 34 may extend from the top opening 11; 11' towards the bottom 42 of the container 13; 13' by, for example, at least 5 cm or at least 6 cm. In some embodiments, the track 34 is curved such that the pipe 41 provided to the pipe rack member 33 is guided away from the measurement path between the radar sensor and the liquid surface. Suitably, the track 34 may have a length such that when attached to the container 13; 13', it extends downward towards the bottom 42 of the container by at least a distance such that it passes through the neck of a container (such as a bottle) having a neck. Thus, the pipe 41 held by the track 34 will be out of the measurement path and will not be bent back into the measurement path, which would be the case if the track 34 were curved and made very short and did not extend downward to pass through the neck of the container. Suitably, the sensor arrangement 1; 1' may be designed to fit different sized containers. Thus, when the sensor arrangement is attached to the container, the length of the track 34 measured from the top opening of the container towards the bottom of the container may be, for example, at least 5 cm or at least 6 cm in one embodiment of the present invention and at least 8 cm in other embodiments of the present invention.

[0059] In the embodiments shown in FIGS. 2 - 5, the pipe support member 33 further includes an annular fixing member 35 connected to the track 34, wherein the annular fixing member is disposed between the container attachment members 23; 23' and the housing member 24. However, another design for attaching the track 34 in the sensor arrangement 1; 1' would be possible. For example, the track 34 could be an integral part of the container attachment member 23; 23'. The annular fixing member 35 can be connected to the container attachment members 23; 23' such that it can rotate relative to the container attachment members 23; 23', and connected to the housing member 24 such that the housing member 24 can be provided in at least two different positions relative to the container attachment members 23; 23', wherein the two positions include an open position and a closed position. The annular fixing member 35 is annular, i.e., includes an open center, so as to allow access to the top opening 11; 11' to fill the container 13; 13' when the housing member 24 is provided in the open position. The annular fixing member 35 can be connected to the container attachment members 23; 23' such that it can rotate relative to the container attachment members, and thus, similarly, the housing member 24 will rotate relative to the container attachment members 23; 23'. This is suitable when it is necessary to adjust the position of the track 34 and thus the position of the pipe 41 provided within the container 13; 13'. A locking member 52 can be provided for locking the connection between the annular fixing member 35 and the container attachment members 23; 23'. The housing member 24 includes a recess 51 for receiving the track 34. The housing member 24 and the pipe support member 33 together with the pipe 41 can be removed from the container attachment members 23; 23' while the container attachment members 23; 23' remain in place connected to the container 13; 13'. Thus, the pipe can be conveniently replaced. The connection between the annular fixing member 35 of the pipe support member 33 and the sensor housing 24 can be a hinge 27 connection or a magnetic connection, as discussed above. Thus, during filling of the container with a new liquid, the pipe 41 provided in the pipe support member 33 can remain in place within the container. Thus, during filling of the new liquid into the container 13; 13', the process can continue. There can also be additional snap connection portions 53 which can be used to fix the closed position of the housing member 24. In Figure 3bIn [the above], the snap connection part 53 can be regarded as two small extension parts on the sensor housing 24. These extension parts 53 will snap into the recess or opening of the pipe support part 33. Possibly, the snap connection part 53 can also be used as an alternative to the position indicating device 25 to detect the housing part 24 in the closed position, so as to detect that the radar sensor 21 is in the operating position. This can be detected by a sensor connected to the snap connection part 53. The track 34 is configured to hold the pipe 41 so that during different processes and for different volumes of contents in the container, they are generally held at the same position in the container, that is, so that they are held at the same level inside the container, often near the bottom 42 of the container, which is suitable for preventing the pipe from being positioned above the liquid surface in the container.

[0060] In some embodiments, the sensor arrangement includes a processor 31 connected to the radar sensor 21, wherein the processor 31 is configured to determine the amount of liquid in the container 13; 13' according to the detected position of the liquid surface and according to the pre-stored container profile dimension information. By allocating intelligence entirely to the sensor arrangement, the communication from the sensor arrangement to the external control system is less complex and more stable (i.e., requires less capacity), and smaller and cheaper cables can be used for the communication.

[0061] Suitably, the sensor arrangement 1; 1' further includes a connection device 51, so that in the bench-top fluid processing system 101 using the container 13; 13' and the sensor arrangement 1; 1', the radar sensor 21, the processor 31, and the angle sensor 25' can be connected to the control system 111. The connection device 51 can be connected to the control system 111 either wired or wirelessly.

[0062] Suitably, the sensor arrangement 1; 1' according to the present invention is configured to be attached to the container 13; 13', and the height of the container is between 10 - 100 cm and / or the volume is between 0.5 - 220 liters or 0.5 - 20 liters. Therefore, it can be used in, for example, a chromatography system or another bench-top fluid processing system.

[0063] According to the present invention, there is also provided a method for detecting the position of the liquid surface in the container 13; 13', and the container is used for storing liquid in the bench-top fluid processing system 101. Figure 6 The method is illustrated in the flowchart of [the following]. The method steps will be briefly described below with reference to Figure 6 in sequence.

[0064] S1: Attach the container attachment part 23; 23' of the sensor arrangement 1; 1' as defined above according to the present invention to the top opening 11; 11' of the container 13; 13'.

[0065] S2: If the sensor arrangement 1; 1' includes a pipe support member 33, position one or more pipes 41 to be provided within the container 13; 13' within the pipe support member 33 of the sensor arrangement 1; 1'. This is thus an optional step.

[0066] S3: Rotate the pipe support member 33 relative to the container attachment member 23; 23' such that the pipes 41 provided in the pipe support member 33 are guided for convenient connection within the bench-top fluid handling system. This is thus an optional step and is only performed if the sensor arrangement 1; 1' includes a pipe support member 33 and the pipe support member is connected within the sensor arrangement 1; 1' such that it can be rotated.

[0067] In some embodiments of the present invention, the sensor housing 24 can be provided in at least two different positions relative to the container attachment member 23; 23', as discussed above. In these embodiments, the method includes the following steps S4 and S6.

[0068] S4: Position the sensor housing 24 of the sensor arrangement 1; 1' relative to the container attachment member 23; 23' in a closed position to measure the liquid level within the container 13; 13'. The closed position is a position where the sensor housing 24 covers at least a portion of the top opening 11; 11' of the container 13; 13', wherein when the sensor housing 24 is provided in the closed position, the radar sensor 21 is provided in an operating position.

[0069] S5: If the radar sensor 21 is in the operating position, detect the position of the liquid surface within the container 13; 13'.

[0070] S6: Position the sensor housing 24 of the sensor arrangement 1; 1' relative to the container attachment member 23; 23' in an open position to refill the liquid into the container 13; 13', wherein the open position is a position where the sensor housing does not cover the top opening 11; 11'.

[0071] The method further includes the following optional steps:

[0072] S7: Measure the tilt angle of the sensor housing 24 via an angle sensor 25' provided within the sensor housing 24. The tilt angle can be used to indicate whether the sensor housing 24 is in the closed position or the open position and to indicate whether the container is tilted, which tilt may be problematic. A warning that the container may be tilted can be presented to the user.

[0073] S8: Indicate whether the radar sensor 21 is in the operating position via a position indicating device 25. In some embodiments, the position indicating device 25 can be an angle sensor 25', as discussed above.

[0074] The measured inclination angle of the sensor housing 24 can be used to detect the inclination of the entire container 13; 13' and the flipping of the sensor housing 24, i.e., whether the sensor housing 24 is in the open position or the closed position, for example, in order to fill the container with fresh liquid. Different ranges of the inclination angle can be preset in the processor 31 of the sensor housing 24 or within the control system 111, such as a range in which the sensor housing 24 is detected to be in the open position, and a range in which the sensor housing 24 is detected to be in the closed position. Another range of the inclination angle can be set, and the said range of the inclination angle can indicate that the entire container has been inadvertently inclined. In this case, the sensor measurement can be disturbed, and the user can be warned, for example, by sound or a displayed message. If the entire container 13; 13' is inclined, the liquid level detection may not be accurate, or may not even work, and the user can be required to check whether the container 13; 13' has been correctly positioned. If the inclination angle is outside the preset inclination angle range for the closed position, the user can also be required to check whether the sensor housing 24 has been provided in the correct closed position. Possibly, another preset range of the inclination angle can also be such a range: within this range, the most likely cause of the inclination is that the user tries to use the remaining liquid in the container by inclining the container. In this case, the pump can be allowed to run even if the radar sensor 21 cannot measure the liquid level.

[0075] When the sensor housing 24 is detected to be in the open position, for example, for refilling fresh liquid into the container again, the pump 113 in the system 101 is suitably allowed to continue pumping the liquid. During this period, the pump metric can be used to measure the volume of the liquid in the container, i.e., during the period when the sensor housing 24 is in the open position, dead reckoning is used to replace the radar sensor liquid level detection. As long as the sensor housing 24 is flipped back to the closed position, the radar sensor 21 will start measuring again, and the position of the liquid surface in the container will be updated accordingly.

[0076] The materials used for the sensor arrangement 1; 1' need to be suitable for use with the chemicals used in the processes operating in the system 101. In addition, the sensor housing 24 surrounding the radar sensor needs to be made of a material through which the radar sensor can transmit and receive electromagnetic waves. Suitable materials can include, for example: PEEK (polyetheretherketone) or PPS (polyphenylene sulfide) or PP (polypropylene).

Claims

1. A sensor arrangement (1; 1'), configured to be attached to a top opening (11; 11') of a container (13; 13') for storing liquid in a benchtop fluid handling system (101), the sensor arrangement (1; 1') comprises: - a millimeter-wave radar sensor (21); - a sensor housing (24) including the millimeter-wave radar sensor (21); and - a container attachment member (23; 23'), connected to the sensor housing (24) and configured to attach the sensor arrangement (1; 1') to the top opening (11; 11') of the container (13; 13') such that the millimeter-wave radar sensor (21) can be provided in an operating position to detect the position of the liquid surface within the container (13; 13').

2. The sensor arrangement (1; 1') according to claim 1, wherein the sensor housing (24) can be provided in at least two different positions relative to the container attachment member (23; 23'), one position being a closed position in which the sensor housing (24) covers at least a part of the top opening (11; 11') of the container (13; 13'), and another position being an open position in which the sensor housing (24) does not cover the top opening (11; 11'), and wherein when the sensor housing (24) is provided in the closed position, the millimeter-wave radar sensor (21) is provided in the operating position.

3. The sensor arrangement (1; 1') according to claim 2, wherein the sensor housing (24) is connected in the sensor arrangement (1; 1') by a hinge (27) such that the sensor housing (24) can be flipped upward from the closed position to the open position to enable access to the top opening (11; 11') of the container (13; 13').

4. The sensor arrangement (1; 1') according to claim 2 or 3, wherein the sensor housing (24) includes an angle sensor (25').

5. The sensor arrangement (1; 1') according to any one of the preceding claims, further comprising a position indicating device (25) configured to indicate whether the millimeter-wave radar sensor (21) is in the operating position.

6. The sensor arrangement (1; 1') according to any one of the preceding claims, further comprising a tube rack member (33) that can be attached to the container attachment member (23; 23') and is configured to hold a tube (41) provided within the container (13; 13') towards one side of the top opening (11; 11').

7. The sensor arrangement (1; 1') according to claim 6, wherein the pipe support member (33) includes a track (34) which, when the sensor arrangement (1; 1') is provided to the container, extends from the top opening (11; 11') of the container (13; 13') into the container and extends outwards from the container, and the track (34) is capable of supporting one or more pipes (41) provided to the container.

8. The sensor arrangement (1; 1') according to claims 7 and 2, wherein the pipe support member (33) further includes an annular fixing member (35) connected to the track (34), and when the sensor housing is provided in the closed position, the annular fixing member is provided between the container attachment member (23; 23') and the sensor housing (24), so that the annular fixing member (35) is connected to the container attachment member (23; 23') such that the annular fixing member can rotate relative to the container attachment member (23; 23'), and is connected to the sensor housing (24) such that the housing member (24) can be provided in at least two different positions relative to the container attachment member (23; 23'), and the two positions include an open position and a closed position.

9. The sensor arrangement (1; 1') according to any one of the preceding claims, wherein the sensor arrangement includes a processor (31) connected to the radar sensor (21), and the processor (31) is configured to determine the amount of liquid in the container (13; 13') according to the detected position of the liquid surface and according to pre-stored container profile dimension information.

10. The sensor arrangement (1; 1') according to any one of the preceding claims, wherein the container attachment member (23; 23') includes a thread for threaded connection to a threaded top opening (11) of the container (13), or includes a magnet for magnetic connection to the top opening (11') of the container (13').

11. The sensor arrangement (1; 1') according to any one of the preceding claims, further comprising a connection device (51), in the desktop fluid handling system (101) using the container (13; 13') and the sensor arrangement (1; 1'), through which the radar sensor (21) and possibly the processor (31) and / or the angle sensor (25) can be connected to the control system (111).

12. The sensor arrangement (1; 1') according to any one of the preceding claims, wherein the sensor arrangement is configured to be attached to a container (13; 13') having a height between 10 - 100 cm and / or a volume between 0.5 - 20 liters.

13. A method for detecting the position of the liquid surface in a container (13; 13') for storing liquid in a desktop fluid handling system (101), the method comprises the following steps: -Attach (S1) the container attachment member (23; 23') of the sensor arrangement (1; 1') according to any one of the preceding claims to the top opening (11; 11') of the container (13; 13'). -Detect (S5) the position of the liquid surface in the container (13; 13') when the millimeter-wave radar sensor (21) is in the operating position.

14. The method according to claim 13, further comprising the steps of: -Position (S2) one or more tubes (41) to be provided into the container (13; 13') within the tube rack member (33) of the sensor arrangement (1; 1').

15. The method according to claim 14, further comprising the steps of: -Rotate (S3) the tube rack member (33) relative to the container attachment member (23; 23') such that the tubes (41) provided in the tube rack member (33) are guided for convenient connection in the bench-top fluid handling system (101).

16. The method according to any one of claims 13 - 15, further comprising the steps of: -Indicate (S8) by the position indicating device (25) whether the radar sensor (21) is in the operating position.

17. The method according to claim 16, wherein the step of indicating (S8) by the position indicating device (25) whether the radar sensor (21) is in the operating position comprises: Measuring the tilt angle of the sensor housing (24), wherein the position indicating device (25) includes an angle sensor (25') provided in the sensor housing (24).

18. The method according to any one of claims 13 - 17, further comprising the steps of: -Position (S4) the sensor housing (24) of the sensor arrangement (1; 1') relative to the container attachment member (23; 23') in a closed position to detect the liquid level in the container (13; 13'), wherein the closed position is a position where the sensor housing (24) covers at least a part of the top opening (11; 11') of the container (13; 13'), and wherein when the sensor housing (24) is provided in the closed position, the radar sensor (21) is provided in the operating position; -Position (S6) the sensor housing (24) of the sensor arrangement (1; 1') relative to the container attachment member (23; 23') in an open position to refill the container (13; 13') with liquid again, wherein the open position is a position where the sensor housing (24) does not cover the top opening (11; 11').

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