Pipetting robot for determining at least one water property

Description

[0001] The invention relates to a pipetting robot for determining at least one predetermined property of sample water, in particular aquarium water. In a further aspect, the invention relates to a use of the pipetting robot and a method for determining the at least one predetermined property using the pipetting robot.

[0002] It is well known in aquarium technology that water quality in aquariums has a significant impact on the lifespan of the living creatures kept there. Therefore, aquarium owners strive to maintain consistent water quality and perform regular maintenance.

[0003] To assess water quality, key water parameters are measured regularly. This is usually done using drop tests. Measuring water parameters in an average aquarium takes approximately 30 to 45 minutes and is prone to errors if done manually. Therefore, it is a general goal to check water parameters automatically and regularly.

[0004] KR 20200064967 A is known from the prior art, which discloses a system for measuring the water properties of an aquarium. Reagents can be mixed with sample water, and the color change is determined using a colorimeter.

[0005] EP 3 566 573 A1 describes an automatic system for adjusting the water quality of aquarium water and an automatic method for adjusting the water quality, wherein the system comprises a reaction container, a sample dropping device, a titran dropping device, a color sensor, a light barrier, a waste disposal device, a control unit and an additive device, and wherein the water quality adjusting system quantifies the content of a specific element in an aqueous solution by titration and adds an additive to the aqueous solution to adjust the water quality in order to stabilize the content of the specific element in the aqueous solution.

[0006] WO 2013 / 104365 A1 describes an automatic machine for inspecting containers. It uses various graphic patterns to test various optical properties of a test station, such as focus, contrast, alignment, etc. The color detection and evaluation of the test stations can be tested by varying the color of lines, areas, and colored fields, possibly in combination with grayscale fields, such as those found on television test cards. The test stations use color sensors, color cameras, and / or evaluation algorithms that take color into account.

[0007] From more remote areas not directly specialized for aquarium technology, US 2007178010 A1, WO 2006037941 A1, US 2005276724 A1, US 2005 276724 A1, CN 109839490 A, DE 202008006338 U1, DE102008050092 A1, and JP2000121411 A are known. These documents each show that either the color or the fill level of water can be measured using a colorimeter or a camera, respectively. However, none of these systems is directly suitable for the application area of ​​aquarium technology, where as many functions as possible should be automated for the end user.

[0008] The present invention is defined in claim 1.

[0009] It is the object of the invention to provide a fully automated method and an associated pipetting robot for determining at least one predetermined property of sample water, in particular aquarium water, which can determine the predetermined property particularly accurately and error-free.

[0010] This object is achieved according to the invention by a pipetting robot for determining at least one predetermined property of sample water, in particular of aquarium water, comprising a measuring cuvette for holding the sample water, at least one reagent container for holding a liquid reagent, by means of which reagent a color change representative of the predetermined property can be brought about in the sample water, a pump for transferring the reagent from the reagent container into the measuring cuvette via a reagent inlet on a top side of the measuring cuvette, whereby the reagent can be dripped into the measuring cuvette, a camera for taking images of the measuring cuvette and the sample water in the measuring cuvette, a background which is arranged on the side of the measuring cuvette facing away from the camera and lies in the field of view of the camera, wherein areas in at least two different colors are depicted on the background in a predetermined pattern to create contrast, wherein the pattern is preferably a checkerboard pattern with black and white areas,and wherein at least three reference color points are depicted on the background for color referencing, of which at least one is red, one is green, and one is blue, and an evaluation unit which is designed to determine the fill level of the sample water in the measuring cuvette based on the images recorded by the camera, to count the number of reagent droplets dripped into the measuring cuvette, and to determine the at least one predetermined property of the sample water from the counted number of reagent droplets in combination with a color change of the sample water determined from the images.

[0011] The pipetting robot according to the invention enables fully automated analysis of sample water and can therefore be easily combined, especially with an aquarium. Due to its error-free operation and autonomy, the pipetting robot is particularly suitable for home use, allowing even users without laboratory experience to determine the properties of aquarium water.

[0012] To perform this fully automated analysis, the pipetting robot automatically dispenses a predetermined amount of aquarium water and one or more reagents into the measuring cuvette. The evaluation unit, in combination with the camera and the inventive background, enables both the precise counting of reagent droplets and the precise determination of a color change in the sample water. This completely eliminates the need for the user to make a subjective assessment of the color change.

[0013] In the pipetting robot according to the invention, the background contributes to the particularly precise determination of the color change and the correct counting of drops. The pattern allows a drop to stand out more clearly in the image, as the contours of the pattern move in the image due to the refraction of light within the drop. The reference color dots allow, on the one hand, to calibrate the position of the camera if it was not installed precisely, and, on the other hand, to compensate for color tolerances of the camera and the LEDs that illuminate the measuring cuvette.

[0014] In contrast to the system of KR 20200064967 A, the camera is used for more than just color determination, namely, in particular, for determining the water level and counting droplets. Furthermore, the use of the background according to the invention also allows for significantly better determination of the color of the sample water in the measuring cuvette.

[0015] In a preferred embodiment, the reagent inlet is configured to dispense reagent droplets with a predetermined droplet size, wherein said surfaces have an average height and / or an average length corresponding to a maximum of half the droplet size. This allows the reagent droplets to be more easily detected by the evaluation unit, further increasing the accuracy and error tolerance of the pipetting robot.

[0016] In a first preferred embodiment, the pump is designed to build up overpressure in the reagent container in order to transfer the reagent to the reagent inlet of the measuring cuvette via a tube extending into the reagent container. This enables particularly efficient transfer of the reagent into the measuring cuvette, since the pump does not need to be directly connected to the reagent container. This option is particularly advantageous when multiple reagent containers are provided in the pipetting robot.

[0017] In a second preferred embodiment, the pump can comprise at least one motorless pump head and a pump motor that can be coupled to the motorless pump head, wherein the pipetting robot preferably comprises at least two reagent containers and a separate motorless pump head for each of the at least two reagent containers, and wherein the pump motor is mounted on a guide and can be selectively coupled to the pump heads of the at least two reagent containers by sliding on the guide. In this embodiment, it is particularly advantageous that the pump motor can be coupled to the pump heads, whereby it can be provided, for example, that several pump heads share a single pump motor. This makes it possible to reduce the number of motors in the system, which makes the pipetting robot less prone to errors. The pump heads comprise, for example, a rotatable eccentric and can be designed as positive displacement pumps orPeristaltic pumps can be designed, each without a motor and preferably also without a gear. The pump motor, for example a stepper motor, can be arranged on the aforementioned guide, which is usually a linear guide, and can be selectively coupled to one of the pump heads by moving along the linear guide to the desired pump head.

[0018] In the aforementioned embodiment, the pump motor preferably comprises a rotatable coupling unit which, for coupling to the motorless pump head, can be inserted into an oppositely arranged receptacle of the motorless pump head, wherein the receptacle of the pump head preferably has at least two pins arranged symmetrically around a rotation axis, which have the shape of a triangle or circular sector in cross section. The rotatable coupling unit has proven to be the preferred interface to the pump heads in tests. In the simplest case, the coupling unit can have the shape of a cuboid, i.e. have a rectangular cross-section normal to the rotation axis, and thus rotate the receptacle of the pump head and thus, for example, its eccentric in the manner of a flat-head screwdriver, so that the pump head pumps fluid when it is connected to the pump motor.It has been found that a cuboid-shaped coupling unit must be positioned extremely precisely if the mount is formed by two diametrically opposed cuboids between which the coupling unit is inserted. If the angle of attack is not precisely adjusted, the pump motor can easily collide with the pump head mount. However, if the mount is formed by two pins with a triangular or circular cross-section, the angle of attack does not need to be as precise, and collisions occur less frequently.

[0019] It is particularly advantageous if the pipetting robot has at least two, preferably at least ten, reagent containers, each of which is connected to the pump and the measuring cuvette. Each reagent container comprises a controllable valve, preferably a solenoid valve, for selective connection to the pump and / or the measuring cuvette. This allows various reagents to be stored in the pipetting robot to sequentially determine different properties of the sample water. The solenoid valves allow a single pump to be used for multiple reagent containers, with the solenoid valves being individually controllable.

[0020] In order to enable the reagents to be replaced or refilled, the reagent container(s) can be provided in an interchangeable manner in the pipetting robot, whereby the reagent container(s) can be inserted into the pipetting robot in a hanging position for particularly easy handling.

[0021] In the simplest embodiment, a predetermined amount of sample liquid could be poured into the measuring cuvette manually. However, it is preferred if the pipetting robot is connected to a source of sample water and is designed to pump sample water into the measuring cuvette until the evaluation unit detects a desired fill level in the measuring cuvette based on the images recorded by the camera. This allows the pipetting robot to start measuring processes automatically without the sample water having to be manually poured into the measuring cuvette in a predetermined fill level. Alternatively or additionally, the evaluation unit can be used to calibrate the pumps. For example, the evaluation unit can determine that the pump needs 12 seconds to dispense 10 ml of sample water. This determines the time for all other volumes that can be dispensed.

[0022] The fill level of sample water can be detected in various ways. However, it is preferred if the evaluation unit is designed to determine when the desired fill level has been reached by comparing the images recorded by the camera with a reference position stored in the evaluation unit. The reference position can be stored in the evaluation unit, for example, by previously manually introducing sample water with the desired fill level into the measuring cuvette and the evaluation unit storing the fill level of this fill level as a reference position, e.g., a pixel value. Alternatively or additionally, markers can be applied to the measuring cuvette or the background to indicate the fill level.

[0023] If the fill level is determined by means of the evaluation unit, it is particularly preferred if the measuring cuvette has a transparent sample water inlet for supplying the sample water, and the pipetting robot is designed to pump the sample water into the measuring cuvette at a first sample water pumping speed until the evaluation unit detects the presence of sample water in the sample water inlet, and to perform the pumping process at a second sample water pumping speed, which is lower than the first sample water pumping speed, until the evaluation unit detects sample water at the reference position. This is preferred because the sample water supply hose may be empty, and therefore there may be air in the supply hose. According to the invention, pumping can therefore initially be faster until sample water is actually introduced into the measuring cuvette. Once the desired fill level is reached, the pumping process is terminated.

[0024] A similar process can also be performed for the dropwise addition of the reagent. The reagent inlet can be transparent, and the pump is configured to pump the reagent at a first speed until the evaluation unit detects the presence of the reagent in the reagent inlet, and to pump the reagent at a second speed, which is lower than the first speed, until the evaluation unit has counted a predetermined number of reagent droplets or detected a color change in the sample water.

[0025] It is understood that it is preferred if the evaluation unit is designed to count the reagent droplets dripping from the reagent inlet into the measuring cuvette and to switch off the pump as soon as a predetermined number of reagent droplets or a predetermined color change of the sample water has been detected.

[0026] However, the pipetting robot can also be designed to determine properties of the sample water that are not determined using a reagent. To determine the salt content, the background or the measuring cuvette can, for example, have a vertical stripe, preferably a vertical red stripe, to determine the salt content.

[0027] In this embodiment, the measuring cuvette can have a magnifying glass, with the camera, the magnifying glass, and the vertical stripe positioned such that the vertical stripe is magnified in the images captured by the camera at a predetermined salinity, preferably 3.5%, in the sample water. This allows the particularly preferred measurement range to be analyzed even more precisely.

[0028] Furthermore, the background or the measuring cuvette can have at least one horizontal stripe, preferably at least one horizontal green stripe, to verify the plausibility of the fill level. This further reduces the susceptibility of the pipetting robot to errors when filling the measuring liquid.

[0029] To avoid having to manually empty the sample water in the measuring cuvette, the measuring cuvette can be provided with an outlet opening on the bottom for emptying the measuring cuvette. This allows multiple measurements of the sample water to be performed sequentially and fully automatically.

[0030] In the latter embodiment, it is preferred that the pipetting robot be configured to allow at least one air bubble to flow through said outlet opening to mix the sample water and the added reagent. This allows rapid mixing of the sample water with the reagent without the need for additional aids or vibration or shaking of the measuring cuvette.

[0031] The reagents described above can be used, for example, to determine the pH of the sample water. However, in order to measure the pH continuously, i.e. also while determining other properties of the sample water using reagents, the pipetting robot can be connected to its own probe for measuring the pH. Calibration of this probe can be achieved if the predetermined property is a pH value, wherein the reagent is selected such that it causes a color change in the sample water as a function of the pH value, wherein the evaluation unit is designed to determine the pH of the sample water as a function of the color change, wherein a probe for measuring the pH value is inserted into the measuring cuvette and the evaluation unit is designed to calibrate the probe using the pH value determined by the evaluation unit via the color change.

[0032] The correct determination of the color change depends not only on the camera or its calibration, but also on the light illuminating the sample cuvette. Therefore, the pipetting robot preferably comprises an opaque chamber in which the sample cuvette is located. At least one light, preferably an LED light, is arranged in the chamber to illuminate the sample cuvette, and the light is preferably located next to the sample cuvette. Another light can be located above or below the sample cuvette if necessary. This allows the color change or the fill level of the sample water to be determined particularly precisely.

[0033] In order to prevent incorrect measurements of the predetermined property, the pipetting robot can comprise an acceleration sensor and / or an inclination sensor, wherein the evaluation unit is designed to invalidate a measurement of the predetermined property if the acceleration sensor and / or the inclination sensor indicates an inclination or a shock of the pipetting robot.

[0034] Particularly preferably, the pipetting robot comprises a vessel in which a powder is stored, by means of which powder a color change representative of the predetermined property can be brought about in the sample water, wherein the vessel is closed at least on a first side, preferably on the top, by means of a first film, wherein the pipetting robot preferably further comprises a needle and is designed to pierce the film by means of the needle, fill a liquid for dissolving the powder into the vessel and transfer the powder dissolved in the liquid into the measuring cuvette, wherein the vessel is preferably also closed on a second side, preferably on the bottom, by means of a second film, through which the powder dissolved in the liquid can be transferred into the measuring cuvette.This creates a simple way to use not only liquid reagents for determining water properties, but also powdered reagents. The foil allows the powder to be stored dry for long periods of time, while also allowing the powder to be easily released. The needle allows for easy opening of the foil, eliminating the need to peel it off. Dissolving the powder before transferring it to the measuring cuvette has the advantage that the camera can be used to precisely verify that the powder has been transferred and that no powder remains in the vessel. The second foil has the advantage that the vessel does not have to be tilted to transfer the dissolved powder into the measuring cuvette.

[0035] In the aforementioned embodiment, it is further preferred if the pipetting robot comprises a plastic ring, which can preferably be inserted modularly into the pipetting robot and comprises at least two of the aforementioned vessels, in each of which powder is stored, wherein the vessels are arranged distributed around the circumference of the plastic ring and the pipetting robot comprises a stepping motor for rotating the plastic ring, by means of which the vessels can be rotated selectively relative to the needle, the feed point of the liquid and / or the transfer point to the measuring cuvette. This creates the possibility of providing several doses of powder simultaneously but separately from one another in order to carry out several measuring processes without having to manually change vessels. After all vessels are empty, the entire plastic ring can be replaced. If necessary, the liquid for dissolving the powder is added directly above the measuring cuvette, i.e.the second position and the third position can coincide, which is particularly advantageous if the second film is water-soluble.

[0036] In a second aspect, the invention relates to a use of the pipetting robot according to one of the aforementioned embodiments for determining a predetermined property of sample water, wherein the sample water is aquarium water and the predetermined property is preferably an alkalinity, a calcium hardness, a magnesium hardness, a phosphate value, a nitrate value and / or a pH value.

[0037] In a third aspect, the invention relates to a method for determining a predetermined property of sample water by means of a pipetting robot according to one of the aforementioned embodiments, comprising the steps: Filling sample water into the measuring cuvette, transferring the reagent from the reagent container into the measuring cuvette using the pump, taking images of the measuring cuvette with the camera, counting reagent droplets that are dripped into the measuring cuvette via the reagent inlet, and determining a color change in the sample water using the evaluation unit based on the images taken by the camera, and determining the predetermined property based on the number of counted reagent droplets and / or the determined color change. For example, a test may require a specific number of reagents, and the corresponding water value is determined from the color change of the sample water. For a phosphate measurement, for example, the following applies: the darker blue the sample water becomes, the higher the phosphate value.

[0038] The use and method have the same advantages and can be carried out with the same modifications as explained for the pipetting robot.

[0039] Advantageous and non-limiting embodiments of the invention are explained in more detail below with reference to the drawings. Figure 1 shows an exemplary arrangement of reagent containers and the measuring cuvette of the pipetting robot according to the invention in a schematic perspective view. Figure 2 shows the arrangement of the camera, the measuring cuvette and the background of the pipetting robot according to the invention in a schematic perspective view. Figure 3 shows an exemplary embodiment of the background of the pipetting robot according to the invention.

[0040] The Figures 4 and 5 show preferred embodiments of the pump system of the pipetting robot according to the invention.

[0041] Figure 6shows an embodiment for transferring a powder into the measuring cuvette.

[0042] Figure 1 shows a pipetting robot 1 with a measuring cuvette 2, eleven reagent containers 3 and a pump 4. The pipetting robot 1 is designed to determine at least one predetermined property of sample water 5, which was taken from an aquarium (not shown) and fed to the measuring cuvette 2. In order to determine the predetermined property, the pipetting robot 1 further comprises the Figure 2 The image capture unit 8 includes the camera 6 shown, the background 7, and the evaluation unit 8. For the purposes described below, the camera 6 preferably captures images at a rate of 90 fps (frames per second). The evaluation unit 8 can be a simple processor, a single-board computer such as a Raspberry Pi, or another computing unit. For the purposes described below, the evaluation unit 8 can control the pump and / or the camera 6.

[0043] The predetermined property can be, for example, a pH value or alkalinity. Once the pipetting robot 1 has determined the predetermined property, it can be displayed on a screen, possibly with a warning light if a threshold value is exceeded or undershot, or it can be transmitted to a control device that maintains the aquarium depending on the measured property, for example, by adding additives such as salt or calcium level regulators.

[0044] It should be noted, however, that the pipetting robot 1 described herein is not limited to the application of measuring aquarium water, but can also be used to measure seawater or pool water. However, the measurement of water properties in saltwater or freshwater aquariums is preferred.

[0045] The measuring cuvette 2 has a volume that is in any case larger than the measuring volume of sample water 5 required to determine the predetermined property, which measuring volume is typically 2 ml, 5 ml, 10 ml, or 15 ml. The measuring cuvette 2 is at least partially transparent so that the camera 6 can capture images of the liquid contained in the measuring cuvette 2. The shape of the measuring cuvette 2 is preferably cylindrical or rectangular.

[0046] To transfer sample water 5 from the aquarium into the measuring cuvette 2, a hose (not shown) can be connected from the aquarium to a sample water inlet 9. The sample water inlet 9 is located, for example, on the top side of the measuring cuvette 2, so that the sample water 5 can flow or drip into the measuring cuvette 2. The aforementioned pump 4 or another pump can be used to transfer the sample water 5 from the aquarium into the measuring cuvette 2.

[0047] To determine how much sample water 5 is in the measuring cuvette 2, a predetermined amount of water, in particular sample water 5, can initially be poured into the measuring cuvette 2 in order to determine which fill level corresponds to which fill quantity. Typically, only those defined fill quantities are recorded that are required to determine the predetermined property, i.e., 2 ml, 5 ml, 10 ml, and / or 15 ml. After a defined fill quantity has been poured into the measuring cuvette 2, the camera 6 takes an image of the filled measuring cuvette 2, which is evaluated by the evaluation unit 8. The evaluation unit 8 then records the position in the image at which the fill level is visible and saves this as a reference position for the fill quantity, e.g., as "2 ml corresponds to x = 234 pixels, y = 123 pixels."If a sample liquid 5 is now to be filled into the measuring cuvette 2, in the simplest case the sample liquid 5 is pumped until the evaluation unit 8 at which the sample liquid reaches the previously stored reference position or fill level in the image.

[0048] In an extended method, it can be provided that sample liquid 5 is initially pumped until the evaluation unit 8 detects sample water inlet 9 in the sample liquid 5, which is designed to be transparent for this purpose. This is provided because sample water 5 does not usually begin to flow into the measuring cuvette 2 immediately, as the hose is usually emptied after filling or measuring. This can be technically implemented, for example, by placing a "region of interest" in the image over the sample water inlet 9 in OpenCV. As soon as sample water 5 is detected in the sample water inlet 9, the pumping speed can be reduced and sample liquid 5 continues to be pumped until the evaluation unit 8 detects sample liquid 5 at the previously saved reference position or fill level in the image. For this purpose, the "region of interest" in OpenCV can, for example, be set to the area of ​​the reference position orThe invention is not limited to this method of filling the sample water 5 into the measuring cuvette 2, but could also be carried out in other ways.

[0049] After a specific amount of sample water 5 has been poured into the measuring cuvette 2, a reagent 10 is transferred from one of the reagent containers 3 into the measuring cuvette 2 in order to determine the predetermined property from the resulting color change using the camera 6 and the evaluation unit 8. The reagents 10 are commercially available and can be selected by the expert depending on the property to be measured.

[0050] In the embodiment of Figure 1Eleven reagent containers 3 are provided, each containing different reagents 10. In more general embodiments, only one reagent container 3 or more than one reagent container 3 can be provided. The reagent containers 3 are preferably provided in an interchangeable manner in the pipetting robot 1 in order to replace a reagent container 3 when there is no more reagent 10 in it. The reagent containers 3 are preferably designed to be open at the top so that they can be closed with a cap in a transport state and can be inserted, e.g. screwed, into the pipetting robot 1 in a hanging state for the operating state.

[0051] As in Figure 1As shown, a tube 11 extends into the reagent container 3 when the latter is inserted into the pipetting robot 1. The tube 11 extends almost all the way to the bottom of the reagent container 3 so that a maximum amount of reagent 10 can be withdrawn from it. The tube 11 thus runs from the reagent container 3 to a reagent inlet 12 of the measuring cuvette 2. The reagent inlet 12 is provided on the top of the measuring cuvette 2 so that the reagent 10 can drip into the sample water 5. Preferably, a reagent inlet 12 is provided on the surface of the measuring cuvette for each reagent container 3, as well as the sample water inlet 9, an osmosis water inlet 22 (described in more detail below), and a further inlet for a reference solution. If the pipetting robot 1 thus has ten to twelve reagent containers 3, thirteen to fifteen inlets are provided on the measuring cuvette 2. In other embodiments, inlets could also be combined.

[0052] In order to pump reagent 10 from the reagent container 3 into the measuring cuvette 2, the pump 4 is connected to the reagent container 3 via a connection 13, for example another hose, in order to generate overpressure therein. Due to the overpressure, the reagent 10 flows from the reagent container 3 via the hose 11 into the measuring cuvette 2. What is particularly special here is that the pump 4 is connected to all reagent containers 3 via connections 13. However, since generally only one reagent 10 is to be transferred into the measuring cuvette 2, a solenoid valve 14 is provided for each of the reagent containers, which can cut off or open the connection between the pump 4 and the reagent container. The solenoid valves 14 can be controlled individually so that the desired reagent 10 can be specifically transferred from a certain reagent container 3 into the measuring cuvette 2.

[0053] In order to make the pipetting robot 1 as compact as possible, the reagent containers 3 can be arranged in a ring around the pump 4, as shown. In this variant, the components of the pipetting robot 1 can be particularly easily enclosed by a dome-shaped housing, for example. However, it goes without saying that other design variants are also possible. The pipetting robot 1 according to the invention can be designed to be particularly small, for example dome-shaped with a diameter of approximately 25 cm and a height of 20 cm. In other design variants, the pipetting robot 1 can also be cube-shaped with a maximum edge length of 25 cm, 20 cm, or 15 cm. The pipetting robot is therefore preferably designed as a portable handheld device.

[0054] When the reagent 10 is present at the reagent inlet 12, a reagent droplet 15 will detach from it and drip through the measuring cuvette 2 into the sample water 5. To determine the predetermined property, the correct counting of the reagent droplets 15 is essential, since the counted number provides information about the property. For example, if the alkalinity of the sample water 5 is to be determined, the reagent 10 is dripped into the measuring cuvette 2 until a color change of the sample water 5 is visible. The number of reagent droplets 15 thus provides information about the alkalinity of the water. In another measurement, for example the determination of the pH value, a predetermined number of reagent droplets 15 are dripped into the sample water 5, and the property is determined from the color value of the achieved color change.

[0055] To determine the number of reagent droplets 15 dripping into the sample water 5, the aforementioned camera 6 and the evaluation unit 8 are used. The camera 6 captures images during the dripping process, and the evaluation unit 8 determines the number of reagent droplets 15 dripping into the sample water 5. Preferably, the reagent inlet 12 is spaced a predetermined minimum distance from the fill level of the sample water 5 so that the reagent droplet 15 is fully visible before it drips into the sample water 5. The minimum distance can be at least 1 cm, for example.

[0056] In a concrete implementation, the evaluation unit 8 can first detect whether reagent 10 is located in the reagent inlet 12, which can be made transparent for this purpose. If the detection is performed in OpenCV, the "region of interest" can be set to the area where the transparent reagent inlet 12 is located. The evaluation unit 8 then determines whether a reagent droplet 15 detaches and falls through the measuring cuvette 2, whereby a counter for the number of reagent droplets 15 can be incremented by one. If the detection is performed in OpenCV, the "region of interest" can, for example, be set to an area located 5 mm below the reagent inlet 12. The dropping of the reagent droplet 15 through the "region of interest" can be detected via "movement detection." For droplet detection, the camera's frame rate is preferably 90 fps.

[0057] However, it has now become apparent that drop detection and the correct detection of the color change are not easily feasible. For this reason, a background 7 is provided, which Figure 3 is shown in detail. The background 7 is arranged with respect to the camera 6 and the measuring cuvette 2 such that the measuring cuvette 2 is located between the camera 6 and the background 7. An image recorded by the camera 6 thus comprises a representation of the measuring cuvette 2 and the background 7 behind the at least partially transparent measuring cuvette 2. The background 7 is designed such that it offers, on the one hand, a contrast for drop detection and, on the other hand, reference colors for detecting the color change. To provide contrast, the background 7 has black and white areas 16 in a predetermined pattern, for example a checkerboard pattern as in Figure 3In other embodiments, the predetermined pattern may be as shown in Figure 2 As indicated, it can be a solid white color with black rectangles arranged at a regular distance from one another. Preferably, the predetermined pattern is a regular pattern, so that, for example, a honeycomb pattern with regularly arranged hexagons can also be used. In yet other embodiments, the pattern can be an irregular, mosaic-like pattern. Furthermore, it is preferred that black areas only border white areas. If necessary, individual areas 16 can also be formed in shades of gray or other colors.

[0058] If the predetermined pattern is a checkerboard pattern, the side length of the rectangular areas 16 is preferably a maximum of half the width or diameter of a reagent droplet 15. The width or diameter of the reagent droplet 15 is generally determined by the shape of the reagent inlet 12. In general, even if the pattern is not a checkerboard pattern, the average height or average width of the areas 16 is preferably a maximum of half the width or diameter of a reagent droplet 15. The pattern is depicted at least in that area of ​​the background 7 which is located between the reagent inlet 12 and the sample liquid 5 in the recorded image. The pattern, i.e. the shape of the areas and their colors, is preferably stored in advance in the evaluation unit 8.

[0059] Due to the surfaces 16 arranged in the pattern, dripping reagent droplets 15 are particularly clearly visible in the image recorded by the camera 6, in particular when at least two surfaces 16 lie at least partially within the image of a reagent droplet 15, thereby achieving the contrast of the background 7. To achieve the reference color, three reference color points 17 are also imaged on the background, at least one of which is red, one green, and one blue. This enables the evaluation unit 8 to determine a reference for the entire color range from an image recorded by the camera 6, which can be determined from the three primary colors red, green, and blue, as is generally known to those skilled in the art.On the one hand, the position of the camera 6 can be calibrated by the reference color points 17 if it has not been installed precisely, and on the other hand, color tolerances of the camera 6 and of the LEDs described in more detail below that illuminate the measuring cuvette 2 can be compensated.

[0060] In general, the reference color points 17 can be imaged at any position on the background 7, as long as they are within the image range of the camera 6. The reference color points 17 can have any shape. In particular, the surfaces of the aforementioned pattern can also serve as shaping elements of the reference color points 17, as in the example of Figure 3 with three reference color points 17 in a checkerboard pattern. Preferably, the position and color value of the reference color points 17 are stored in advance in the evaluation unit 8.

[0061] Using the aforementioned method, it is possible to determine a predetermined property of the sample water 5, which can be determined by a color change caused by the reagent 10. Other properties of the sample water 5 can also be determined without adding a reagent 10. To determine a salt content, the background 7 can, for example, comprise a vertical stripe 18, which is preferably colored, in particular red, for easier recognition by the evaluation unit 8 and thus stands out from the pattern. The vertical stripe 18 is imaged on the background 7 in such a way that it is at least partially located in the sample water 5 in the image recorded by the camera. In the horizontal direction, the vertical stripe 18 is arranged off-center with respect to the measuring cuvette 2 in the image recorded by the camera. Due to light refraction, the vertical stripe 18 is displayed offset below the water surface.Water has the physical property that a higher salt content results in a higher optical density and thus a stronger light refraction, which leads to a higher offset of the vertical strip 18. This allows the salt content of the sample water 5 to be determined.

[0062] To determine the salinity even more precisely, a magnifying glass 19 can be mounted on, in front of, or behind the measuring cuvette 2 to better detect the deviation. The magnifying glass 19, for example, has a 10x magnification and is positioned such that a salinity of 3.5% can be detected more accurately. If the stripe 18 is not visible in the image section magnified by the magnifying glass 19, it can be concluded that the salinity of the sample water 5 deviates too significantly from the observed salinity, in this example 3.5%, which can cause the evaluation unit 8 to output a corresponding message.

[0063] In OpenCV, the salinity detection function can be implemented as follows. Initially, a "region of interest" can be set in an area below the water surface and within the measurement chain 2. Using "object find," the preferred red line 18 can be searched for and the salinity determined based on its position. If a magnifying glass 19 is available, the "region of interest" can be set in the area of ​​the magnifying glass 19 in a second step to determine an even more precise position of the line 18.

[0064] Returning to the determination of the fill level, the background 7 can also have an element imaged thereon for this purpose, namely at least one horizontal stripe 20, preferably at least one horizontal green stripe. If the horizontal stripe 20 is located below the water level, it is distorted by the refraction of light. The horizontal stripe 20 can also be arranged off-center with respect to the measuring cuvette 2 in the image recorded by the camera. Typically, the horizontal stripe 20 serves to check the plausibility of the fill level, i.e. is used in addition to the method described above. In other embodiments, the method for determining the fill level could also be carried out using only the horizontal stripe 20. Preferably, more than one horizontal stripe 20 can also be used.The horizontal stripe(s) are typically located at a height corresponding to a predetermined fill level, for example 2 ml, 5 ml, 10 ml or 15 ml, and / or just below, e.g. 0.1 ml below and / or just above, e.g. 0.1 ml above.

[0065] As described, the vertical stripe 18 and the horizontal stripe 20 can be imaged on the background 7. In other embodiments, however, these stripes 18, 20 can also be printed directly on the measuring cuvette 2. Typically, the background 7 is a flat or curved image surface, for example, made of cardboard or plastic. Alternatively, the background 7 could be printed directly onto the measuring cuvette 2. The background 7 is preferably opaque behind the entire area of ​​the measuring cuvette 2 in the excluded image. The stripes 18, 20 could also be applied to an additional image surface located in front of the image surface with the pattern and the reference color dots 17.

[0066] Furthermore, additional sensors can be used to determine further properties of the sample water 5. For example, a temperature probe and / or a pH probe can be provided, each of which is connected to the pipetting robot 1 and can each be located on a hose inserted into the aquarium, through which the sample water 5 is conveyed into the measuring cuvette 2. Using the pH probe, the pH value can be measured even without a suitable reagent 10. Thus, for example, alkalinity can be determined using a reagent 10 and the pH value can be determined simultaneously using the pH probe. However, the pH probe should be calibrated regularly so that the pipetting robot 1 can measure the pH value using a reagent 10 and calibrate the pH probe based on this measured value.

[0067] Furthermore, an outlet opening 21 can be located on the underside of the measuring cuvette 2, through which the sample water 5 contained in the measuring cuvette 2 can be discharged from the measuring cuvette 2 in order to empty it. For this purpose, a dosing pump provided beneath the measuring cuvette 2 can be used, for example. The emptying process is carried out, for example, after a measurement process to determine the aforementioned property or after an error message. An error message can be output, for example, by an acceleration sensor and / or the inclination sensor after detecting an inclination or an impact of the pipetting robot 1. Alternatively or additionally, such an error message could also invalidate a measurement.

[0068] After the sample water 5 has been discharged through the outlet opening 21, the measuring cuvette 2 can be rinsed with osmotic water, which is introduced into the measuring cuvette 2 via an osmosis water inlet 22 on the top of the measuring cuvette 2. This allows residues to be removed from the measuring cuvette 2, ensuring good measurement values ​​for the next measurement. The water level detection function described above can also be used for this purpose to determine whether the correct amount of osmosis water is being pumped into the measuring cuvette 2.

[0069] To enable the evaluation unit 8 to determine color values ​​more accurately, the measuring cuvette 2 is typically located in an opaque chamber illuminated by at least one light 23, preferably at least one LED light. This allows for homogeneous and constant illumination of the measuring cuvette 2. To make it easier to determine the height of the water surface and thus the fill level in the measuring cuvette 2, the light 23 is preferably mounted next to the measuring cuvette 2. Alternatively or additionally, the light 23 can also be arranged above or below the measuring cuvette 2. Due to the refraction of light at the water surface, the water surface then appears clearer.

[0070] It should also be noted that the color depends not only on the color of the sample water 5 mixed with the reagent 10, but also on the color spectrum of the illuminating lamp 23. It has been found that it is more efficient and cost-effective for the present purposes to use at least two LED lamps. In particular, a first LED lamp can be used, which has intensity peaks in the range of 450 nm and 650 nm, and a second LED lamp, which has an intensity peak in the range of 500 nm. These LED lamps 23 are preferably positioned at a 90° angle to the camera 6. Since reflections can occur in the measuring chamber, the color of the sample water 5 may appear different depending on its position in the image. To determine the color value, color tones can be averaged, preferably located within a "region of interest," if a corresponding implementation is carried out in OpenCV.

[0071] As already explained, the reagents 10 are pumped into the measuring cuvette 2 by the pump 4. The sample water 5 can, in turn, be pumped from the aquarium into the measuring cuvette using its own pump. Osmosis water can be pumped into the measuring cuvette 2 using another pump. The dosing pump can be used to empty the measuring cuvette 2 and generate air bubbles to mix the contents of the measuring cuvette 2. Thus, the pipetting robot 1 can comprise four pumps, for example. In other embodiments, the number of pumps can also be reduced, for example, if suitable connections or valves are provided.

[0072] As an alternative to the embodiment described above, in which the pumps generate overpressure in the reagent container 3, the pumps can also be designed as positive displacement pumps, as will be explained below with reference to the Figures 4 and 5described. This shows a plurality of pump heads 24, each of which is assigned to a reagent container 3. In one embodiment, the pump heads 24 could each have their own pump motor 25; however, in the preferred embodiment shown, the plurality of pump heads 24 each share a common pump motor 25. For this purpose, the pump motor 25, e.g., a stepper motor, is displaceably mounted on a linear guide 26 so that it can be selectively connected to one of the pump heads 24.

[0073] The pump heads 24 have, for example, a hose with a hose inlet 27 and a hose outlet 28, wherein the hose inlet 27 is guided into the respective reagent container 3. Furthermore, the pump head 24 can have an eccentric (not shown in detail) that acts on the hose and thereby conveys fluid from the hose inlet 27 to the hose outlet 28 when it is rotated about a rotation axis A by the pump motor 25.

[0074] In order to couple the pump motor 25 with the respective pump head 24 or its eccentric, the pump motor 25 has a rotatable coupling unit 29, which has, for example, a rectangular or non-circular cross-section normal to the rotation axis A. The pump head 24 has a counter-equivalent receptacle 30, which in the embodiment of Figure 4is formed by two cuboids, between which the coupling unit 29 of the pump motor 25 can be inserted. If the pump motor 25 is now moved to the pump head 24 by means of the guide 26, the coupling unit 29 enters the receptacle 30. If the coupling unit 29 is now rotated about the rotation axis A, the receptacle 30 also rotates about the rotation axis A. This allows the eccentric to rotate and fluid to be pumped.

[0075] Figure 5 shows that the cuboids can also be replaced by two or more extruded triangles, i.e., three-sided prisms, arranged around the rotation axis A. As a result, the angle of attack between the coupling unit 29 and the receptacle 30 needs to be selected less precisely in order to couple the pump motor 25 to the respective pump head 24.

[0076] The pump heads 24 can be provided not only for the reagent containers 3, but also for introducing sample water 5 or rinsing water into the measuring cuvette 2 and / or for dosing additional liquids. Furthermore, two or more pump motors 25 can be used on different guides 26 or, alternatively, on the same guide 26, wherein the pump motors 25 can preferably each be coupled to a different set of pump heads 24. For example, the pipetting robot 1 could comprise twenty pump heads 24 and two pump motors 25, each with its own guide 26, wherein one of the pump motors 25 can be coupled to ten pump heads 24 and the other of the pump motors 25 can be coupled to the ten other pump heads 24.

[0077] In Figure 6A further addition to the pipetting robot 1 described above is shown. In this embodiment, the pipetting robot 1 can have a plastic ring 31 on which a plurality of vessels 32 are formed, for example at least two, at least ten, or at least fifty. A powder is stored in each vessel 32, by means of which a color change representative of the predetermined property can be brought about in the sample water. The powder is usually used in combination with the aforementioned liquid reagents to measure specific values ​​(e.g., the calcium or nitrate concentration). For example, calcium requires two liquid reagents and one powder.

[0078] The containers 32 are sealed on a first side, usually the top, with a film 33, which is made of aluminum, polyethylene, or polyvinyl alcohol, for example. This ensures that the powder remains dry until use. To release the powder, the film 33 is pierced by a needle 34. The needle 34 can, for example, be arranged on a solenoid valve, so that the puncturing movement of the needle 34 is carried out by the solenoid valve. Figure 6 the needle 34 is located at the point S1, ie by controlling the solenoid valve the film 33 of the vessel 32 is pierced at the point S1.

[0079] The plastic ring 31 is then rotated by a stepper motor 35, so that the vessel 32 with the pierced foil 33 is moved to a second location S2, where a liquid, for example, sample water or osmosis water, is poured into the vessel 32 through the pierced foil 33. The powder thereby dissolves in this liquid.

[0080] The vessel 32 with the pierced film 33 and dissolved powder is then moved to a third location S3 in order to transfer the dissolved powder into the measuring cuvette 2. The third location S3 can, for example, be located directly above the measuring cuvette 2 or above a chute or a hose which transports the dissolved powder to the measuring cuvette 2. In order to release the powder dissolved in the liquid, a second film which forms the underside of the vessel 32 can, for example, be pierced. In this case, the vessel 32 comprises, for example, an annular plastic wall which is formed integrally on the plastic ring 31, and two films which close the top and bottom of the annular plastic wall. The second film can be pierced by means of a further needle 36 which can, for example, pierce through the vessel 32 from above in order to release the powder dissolved in the liquid.

[0081] Alternatively, the second film could be water-soluble and consist of, for example, water-soluble polyvinyl alcohol (PVA). In this case, one waits until the second film breaks of its own accord after the liquid has been poured in and the powder dissolved in the liquid falls into the measuring cuvette 2. In this case, the second point S2 preferably coincides with the third point S3. Using the aforementioned camera 6, it can again be detected when the liquid with dissolved powder drips into the measuring cuvette 2 in order to continue with the next process step. In the case of the water-soluble film, the mixing process can optionally be further stimulated by moving the plastic ring 31, for example by turning it back and forth several times using the stepper motor. The movement on the water-soluble film has the same effect as stirring and causes it to dissolve more quickly.

[0082] However, the embodiments for introducing the dissolved powder into the measuring cuvette 2 are not exclusively limited to the aforementioned rotatable plastic ring; rather, a vessel could generally also be used that is tilted to pour a powder dissolved in a liquid into the measuring cuvette. Alternatives to opening the foil are also conceivable, for example, peeling it off. In general, the liquid reagents described above could be prepared by previously dissolving solid powder using a liquid.

Claims

1. Pipetting robot (1) for determining at least one predetermined property of sample water (5), in particular aquarium water, comprising - a measuring cuvette (2) for holding the sample water (5), - at least one reagent container (3) for holding a liquid reagent (10), by means of which reagent (10) a color change representative of the predetermined property can be brought about in the sample water (5), - a pump (4) for transferring the reagent (10) from the reagent container (3) into the measuring cuvette (2) via a reagent inlet (12) at an upper side of the measuring cuvette (2), whereby the reagent (10) can be dripped into the measuring cuvette (2), and - a camera (6) for recording images of the measuring cuvette (2) and the sample water (5) in the measuring cuvette (2), - a background (7) which is arranged on the side of the measuring cuvette (2) facing away from the camera (6) and lies in the field of view of the camera (6), wherein areas (16) in at least two different colors are depicted on the background (7) in a predetermined pattern for providing contrast, wherein the pattern is preferably a checkerboard pattern with black and white areas (16), and wherein at least three reference color points (17) are depicted on the background (7) for providing color reference, of which at least one is red, one is green and one is blue, and - an evaluation unit (8) which is designed to determine the filling quantity of the sample water (5) in the measuring cuvette (2) on the basis of the images recorded by the camera (6), to count the number of reagent droplets (15) dripping into the measuring cuvette (2) and to determine the at least one predetermined property of the sample water (5) from the counted number of reagent droplets (15) in combination with the color change of the sample water (5) determined from the images.

2. The pipetting robot (1) according to claim 1, wherein the reagent inlet (12) is designed to dispense reagent droplets (15) having a predetermined droplet size, and wherein said surfaces (16) have an average height and / or an average length corresponding to at most half the droplet size.

3. The pipetting robot (1) according to claim 1 or 2, wherein the pump (4) comprises at least one motorless pump head (24) and a pump motor (25) which can be coupled to the motorless pump head (24), wherein the pipetting robot (1) preferably comprises at least two reagent containers (3) and a separate motorless pump head (24) for each of the at least two reagent containers (3), and wherein the pump motor (25) is mounted on a guide (26) and can be selectively coupled to the pump heads (24) of the at least two reagent containers (3) by displacement on the guide (26), wherein the pump motor (25) preferably comprises a coupling unit (29) which is rotatable about an axis of rotation (A) and which can be introduced into an opposing receptacle (30) of the motorless pump head (24) for coupling with the motorless pump head (24), wherein the receptacle (30) of the pump head (24) preferably has at least two pins which are arranged symmetrically about an axis of rotation (A) and which have the shape of a triangle or sector of a circle in cross-section.

4. The pipetting robot (1) according to any one of claims 1 to 3, wherein the pipetting robot (1) has at least two, preferably at least ten, reagent containers (3), which are each connected to the pump (4) and the measuring cuvette (2), wherein the reagent containers (3) each comprise a controllable valve, preferably a solenoid valve (14), for selective connection to the pump (4) and / or to the measuring cuvette (2), and / or wherein the reagent container(s) (3) is / are provided in the pipetting robot (1) so as to be exchangeable and can preferably be inserted into the latter in a suspended manner.

5. The pipetting robot (1) according to any one of claims 1 to 4, wherein the pipetting robot (1) is connected to a source of the sample water and is designed to pump sample water (5) into the measuring cuvette (2) until the evaluation unit (8) recognizes a desired filling quantity in the measuring cuvette (2) on the basis of the images recorded by the camera (6), wherein the evaluation unit (8) is preferably designed to determine whether the desired filling quantity has been reached by comparing a reference position stored in the evaluation unit (8) in the images recorded by the camera (6), wherein the measuring cuvette (2) particularly preferably has a transparent sample water inlet (9) for supplying the sample water (5) and the pipetting robot (1) is designed to carry out a pumping process of the sample water (5) into the measuring cuvette (2) at a first sample water pumping speed until the evaluation unit (8) is able to recognize the sample water (5) in the measuring cuvette (2), until the evaluation unit (8) detects the presence of the sample water (5) in the sample water inlet (12), and to carry out the pumping process at a second sample water pumping speed which is lower than the first sample water pumping speed until the evaluation unit (8) recognizes sample water (5) at the reference position.

6. The pipetting robot (1) according to any one of claims 1 to 5, wherein the reagent inlet (12) is transparent and wherein the pump (4) is designed to carry out a pumping operation of the reagent (10) at a first reagent pumping speed until the evaluation unit (8) detects the presence of the reagent in the reagent inlet, and to carry out the pumping process at a second reagent pumping speed which is lower than the first reagent pumping speed until the evaluation unit (8) has counted a predetermined number of reagent droplets (15) or has detected a color change in the sample water (5).

7. The pipetting robot (1) according to any one of claims 1 to 6, wherein the evaluation unit (8) is designed to count the reagent droplets (15) dripping from the reagent inlet (12) into the measuring cuvette (2) and to switch off the pump (4) as soon as a predetermined number of reagent droplets (15) or a predetermined color change of the sample water (5) has been detected.

8. The pipetting robot (1) according to any one of claims 1 to 7, wherein the background (7) or the measuring cuvette (2) has a vertical strip (18), preferably a vertical red strip, for determining a salt content, wherein the measuring cuvette (2) further preferably has a magnifying glass (19) and the camera (6), the magnifying glass (19) and the vertical strip (18) are positioned in such a way that the vertical strip (18) is shown enlarged on the images recorded by the camera (6) at a salt content of 3.5% in the sample water (5), and / or wherein the background (7) or the measuring cuvette (2) has at least one horizontal strip (20), preferably at least one horizontal green strip, for plausibilisation of a filling quantity.

9. The pipetting robot (1) according to any one of claims 1 to 8, wherein the measuring cuvette (2) has an outlet opening (21) on the underside for emptying the measuring cuvette (2), wherein the pipetting robot (1) is preferably designed to allow at least one air bubble to flow in via said outlet opening (21) for mixing the sample water (5) and the dripped reagent (10).

10. The pipetting robot (1) according to any one of claims 1 to 9, wherein the predetermined property is a pH value, wherein the reagent (10) is selected such that it causes a color change in the sample water (5) as a function of the pH value, wherein the evaluation unit (8) is designed to determine the pH value of the sample water (5) as a function of the color change, wherein furthermore a probe for measuring the pH value is connected to the pipetting robot (1) and the evaluation unit (8) is designed to calibrate the probe by means of the pH value which was determined by the evaluation unit (8) via the color change.

11. The pipetting robot (1) according to any one of claims 1 to 10, wherein the pipetting robot (1) comprises an opaque chamber in which the measuring cuvette (2) is located, wherein at least one light (23), preferably an LED light, is arranged in the chamber for illuminating the measuring cuvette (2), and wherein the light (23) is preferably located next to the measuring cuvette (2).

12. The pipetting robot (1) according to any one of claims 1 to 11, comprising an acceleration measurement sensor and / or an inclination sensor, wherein the evaluation unit (8) is designed to invalidate a measurement of the predetermined property when the acceleration measurement sensor and / or the inclination sensor indicates an inclination or an impact of the pipetting robot (1).

13. The pipetting robot (1) according to any one of claims 1 to 12, further comprising a vessel (32) in which a powder is stored, by means of which powder a color change representative of the predetermined property can be brought about in the sample water (5), wherein the vessel (32) is closed at least on a first side, preferably on the upper side, by means of a first foil (33), wherein the pipetting robot (1) further comprises a needle (34) and is designed to pierce the first foil (33) by means of the needle (34), to fill a liquid for dissolving the powder into the vessel (32) and to transfer the powder dissolved in the liquid into the measuring cuvette (2), wherein the vessel (32) is preferably also closed on a second side, preferably on the underside, by means of a needle (34), preferably on the underside, by means of a second film, through which the powder dissolved in the liquid can be transferred into the measuring cuvette (2), the pipetting robot (1) preferably comprising a plastic ring (31), which can optionally be inserted into the pipetting robot (1) in a modular manner, and at least two of the said vessels (32), in each of which powder is stored, wherein the vessels (32) are arranged distributed around the circumference of the plastic ring (31) and the pipetting robot (1) comprises a stepper motor (35) for rotating the plastic ring (31), by means of which the vessels can be rotated selectively towards the needle (34), towards the liquid feed point and / or towards the transfer point to the measuring cuvette (2).

14. Use of the pipetting robot (1) according to any one of claims 1 to 13 for determining a predetermined property of sample water (5), wherein the sample water (5) is aquarium water and the predetermined property is preferably an alkalinity, a calcium hardness, a magnesium hardness, a phosphate value, a nitrate value and / or a pH value.

15. A method for determining a predetermined property of sample water (5) by means of a pipetting robot (1) according to any one of claims 1 to 13, comprising the steps of: - Filling sample water (5) into the measuring cuvette (2), - Transferring the reagent (10) from the reagent container (3) to the measuring cell (3) using the pump (4), - Recording images of the measuring cuvette (2) by the camera (6), - Counting of reagent droplets (15) which are dropped into the measuring cuvette (2) via the reagent inlet (12), and determination of a color change of the sample water (5) by the evaluation unit (8) on the basis of the images recorded by the camera (6), and - Determining the predetermined property on the basis of the counted reagent droplets (15) and / or the determined color change.