Online fluid measurement system

Abstract

The invention relates to an online fluid measurement system. A fluid sensor system and a method of operating the fluid sensor system are disclosed herein. A fluid sensor device of the fluid sensor system may be connected online with the treatment system. The fluid sensor system may receive a second solution different from the first calibration fluid for use as a calibration fluid, thereby reducing costs associated with storing the calibration fluid within the fluid sensor device prior to use with the treatment system.

Description

Technical Field

[0001] The present application relates to an online fluid sensor system. More specifically, the online fluid sensor system can use an external calibration fluid source. Background Art

[0003] In-line fluid sensor systems may be used during many treatment procedures to measure and / or monitor properties of a sample fluid, such as a patient's blood. Calibration fluids are often used in such fluid sensor systems to calibrate the system's sensors before and / or after each measurement of the sample fluid, thereby allowing the sensors to be used for extended periods of time with sufficient accuracy. The operating life of a fluid sensor system is often determined by the amount of calibration fluid available and the number of calibration sequences that can be performed. The cost of storing and maintaining large quantities of calibration fluids can be high due to a larger footprint and more expensive storage solutions. Summary of the invention

[0004] The present invention generally relates to an in-line fluid sensor system.

[0005] One aspect relates to a method of calibrating a fluid sensor device connected in series with a therapeutic system. The method includes providing a first calibration fluid stored in a calibration compartment to a sensing element, performing a first measurement of the first calibration fluid with the sensing element, providing a second calibration fluid from a second calibration fluid source, performing a second measurement of the second calibration fluid with the sensing element, and calibrating the sensing element using the second calibration fluid.

[0006] Variations of the above aspect further include connecting an inlet of the fluid sensor device to a first point of a treatment circuit of the treatment system and connecting an outlet of the fluid sensor device to a second point of the treatment circuit of the treatment system.

[0007] Variations of the above aspect further include storing the second calibration fluid in a second calibration compartment.

[0008] A variation of the above aspect is wherein the second calibration compartment is empty prior to connection to the therapeutic system.

[0009] Variations of the above aspect further include determining a difference between a first measurement of the first calibration fluid and a second measurement of the second calibration fluid.

[0010] A variation of the above aspect is where calibrating the sensing element includes comparing the second calibrated measurement to a difference between a first measurement of the first calibration fluid and a second measurement of the second calibration fluid.

[0011] A variation of the above aspect is wherein the therapy circuit connects the patient and the second calibration fluid source.

[0012] A variation of the above aspect is wherein the second calibration fluid source is external to the fluid sensor device.

[0013] A variation of the above aspect is wherein the second calibration fluid comprises a physiological solution.

[0014] Variations of the above aspect further include providing a sample fluid from the patient to the sensing element via the therapy circuit.

[0015] Variations of the above aspect further include controlling a flow direction of fluid in the therapy circuit to provide the second calibration fluid from the second calibration fluid source to the sensing element after providing a sample fluid from a patient to the sensing element through the therapy circuit.

[0016] Another aspect of the present disclosure relates to a fluid sensor system configured to measure a sample fluid in-line with a treatment system. The fluid sensor system includes a fluid sensor device. The fluid sensor device includes a sensing channel configured to receive a sample fluid from the treatment system, a first calibration compartment including a first calibration fluid and in fluid communication with the sensing channel, a second calibration compartment configured to receive a second calibration fluid from a second calibration fluid source, and a sensing element configured to interact with the fluid in the sensing channel and convert a property of the fluid. The second calibration compartment is in fluid communication with the sensing channel.

[0017] A variation of the above aspect is wherein the volume of the first calibration compartment is in the range of 5-100 microliters.

[0018] A variation of the above aspect is wherein the second calibration fluid source is external to the fluid sensor system.

[0019] A variation of the above aspect is wherein the second source of calibration fluid comprises a therapy circuit of the therapy system.

[0020] A variation of the above aspect is where the second calibration fluid is a physiological fluid.

[0021] A variation of the above aspect also includes a processor configured to determine a difference between a first measurement value obtained by a sensing element of the first calibration fluid and a second measurement value obtained by a sensing element of the second calibration fluid, and to calibrate the sensing element based at least on the measurement value obtained by the sensing element of the second calibration fluid and the determined difference.

[0022] A variation of the above aspect is wherein the second calibration compartment is empty during a storage mode during which the fluid sensor system is not connected to the therapeutic system.

[0023] Another aspect of the present disclosure relates to a fluid sensor system configured to measure a sample fluid in-line with a treatment system. The fluid sensor system includes a fluid sensor device. The fluid sensor device includes a sensing channel configured to receive a sample fluid from the treatment system, a calibration compartment containing a first calibration fluid and in fluid communication with the sensing channel, and a sensing element configured to interact with the fluid in the sensing channel. The volume of the calibration compartment is in the range of 5-100 microliters.

[0024] Variations of the above aspects also include a controller configured to control one or more valves in a calibration mode to selectively direct only a second calibration fluid from the treatment system to the sensing channel, and to control the one or more valves in a sensing mode to selectively direct only the sample fluid from the treatment system to the sensing channel.

[0025] A variation of the above aspect also includes a processor, which is configured to determine a difference between a first measurement value obtained by a sensing element of the first calibration fluid and a second measurement value obtained by a sensing element of the second calibration fluid in a calibration mode, and to calibrate the sensing element based at least on the measurement value obtained by the sensing element of the second calibration fluid and the determined difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present disclosure is described with reference to the accompanying drawings, wherein like reference characters represent like elements, and wherein:

[0027] Figure 1 is a schematic system diagram of a fluid sensor system.

[0028] Figure 2 is a schematic system diagram of a fluid sensor system according to an embodiment of the present disclosure.

[0029] Figure 3A is a schematic system diagram of a fluid sensor system according to another embodiment of the present disclosure.

[0030] Figure 3B yes Figure 3A Schematic system diagram of a fluid sensor system during calibration mode.

[0031] Figure 3C yes Figure 3A Schematic system diagram of a fluid sensor system during a sample fluid sensing mode.

[0032] Figure 4 is a flow chart illustrating an exemplary method of operating a fluid sensor system according to the present disclosure.

[0033] Figure 5 It is shown Figure 2 or Figure 3A Block diagram of the electrical components in a fluid sensor system. DETAILED DESCRIPTION

[0034] In general, one or more aspects of the present disclosure relate to an online fluid sensor system. The online fluid sensor system can be connected to, for example, a treatment line of a treatment system and operate without interrupting treatment. In certain embodiments, the present invention relates to systems and methods for measuring a sample fluid using multiple calibration fluid sources. In some embodiments, the fluid sensor system may include an empty fluid compartment configured to receive and store a physiological fluid from a treatment line for use as a calibration fluid when the fluid sensor system is connected to the treatment system. In some embodiments, the fluid sensor system may be configured to receive a physiological solution directly from the treatment line and use it as a calibration fluid when the fluid sensor system is connected to the treatment system, without storing the physiological solution in a dedicated calibration fluid compartment of the fluid sensor. In other embodiments, the fluid sensor system may store a solution in a second calibration fluid compartment in addition to a first calibration fluid compartment for storing the calibration fluid.

[0035] like Figure 1 As shown, the fluid sensor system 1000 may include a fluid sensor device 100, which includes a sensing element 130, which includes a plurality of functionalized transducers or electrodes that, when exposed to a sample fluid, can measure a property or constituent of the sample fluid (e.g., a patient's blood) and transmit a signal indicative of the property or constituent of the sample fluid (e.g., the concentration of a specific constituent of the sample fluid). During a treatment procedure, the fluid sensor device 100 may be connected in series to a treatment circuit 150 of a treatment system and configured to operate in a plurality of modes. For example, during a sensing mode, the sample fluid 150 may enter the fluid sensor device 100 through an inlet 152 and exit the fluid sensor device 100 through an outlet 154. After the sample fluid 150 enters the fluid sensor device 100, the treatment circuit 150 may be directed to the sensing channel 132 to interact with the sensing element 130 and allow the sensing element 130 to perform a measurement.

[0036] During the calibration mode, the sample fluid 150 can be directed to bypass the electrodes of the sensing element 130, flowing directly from the inlet 152 to the outlet 154 without entering the sensing channel 132. Instead, a volume of calibration fluid (e.g., a biocompatible fluid such as water, saline, etc.) can be provided to the sensing element 130 from the calibration compartment 110 of the fluid sensor device 100. The calibration fluid can reset the fluid sensor device 100 by presenting a known property (e.g., a voltage representing a certain component concentration) that the sensing element 130 can measure and calibrate. For example, in some embodiments, the calibration fluid can have a known potassium level, and the sensing element 130 can measure the voltage of the calibration fluid representing the potassium concentration in the calibration fluid. In some embodiments, the sensing element 130 can be calibrated based on the offset between the measured voltage of the calibration fluid and the stored voltage value stored in the memory. In addition, the calibration fluid can improve the accuracy of the sensing element 130 by flushing the sensing channel 132 to remove residual sample fluid and / or other debris. In some embodiments, at the end of the calibration mode, the calibration fluid can leave the sensing channel 132 and enter the waste compartment 120 for storage therein. More details about how the fluid sensor device 100 operates (e.g., takes measurements, stores information, and transmits signals) can be found in U.S. Patent Application No. 18 / 055,799 (published as US 2023 / 0149608A1), the entire disclosure of which is incorporated herein by reference as if fully set forth herein.

[0037] like Figure 1 As shown, the fluid sensor device 100 can include a large calibration fluid compartment 110 that stores an amount of calibration fluid that can last for the entire operating life of the fluid sensor device 100. For example, the amount of calibration fluid stored in the calibration fluid compartment 110 may be sufficient to calibrate the sensing element 130 before and / or after each measurement of the sample fluid, for as many test or sample cycles as the fluid sensor device 100 is designed for. In order to ensure that the calibration fluid is fresh and has constant properties to calibrate the sensing element 130, maintaining a large amount of calibration fluid within the fluid sensor device 100 may be expensive and inconvenient, and may increase the overall size of the device 100. According to various embodiments disclosed herein, Figure 2-3C An embodiment of a fluid sensor system is shown that can utilize multiple calibration fluid sources and allow for filling of a reduced size calibration compartment during storage and transport prior to a treatment procedure. Unless otherwise noted, components of fluid sensor system 2000 can be the same or substantially similar to like numbered components of fluid sensor system 1000, where reference numerals are relative to Figure 1 The reference numerals of the devices are increased by 100 and may function or operate in a substantially similar manner.

[0038] The fluid sensor system 2000 disclosed herein may include: Figure 2 The fluid sensor device 200 shown in FIG. Figure 4 The fluid sensor device 200 may similarly include a sensing element 230 configured to interact with the fluid in the sensing channel 232. In some embodiments, the sensing element 230 may measure the fluid in the sensing channel 232 and transmit a signal indicating the measured value, such as a voltage relative to a reference electrode. In some embodiments, the reference electrode Figure 5 , the fluid sensor system 2000 may include a processor 280 and / or a memory 238 configured to process and / or store information transmitted from the sensing element 230. In some embodiments, the fluid sensor system 2000 may also include a controller 236 configured to control the fluid sensor device 200 to operate in multiple modes (e.g., calibration mode, sensing mode, etc.). In some embodiments, the controller 236 may be configured to control one or more valves 240 on the fluid sensor device 200 to guide the flow of fluid within the fluid sensor device 200. In some embodiments, the controller 236, the processor 280, and / or the memory 238 may be located on the fluid sensor device 300. In some embodiments, the controller 236, the processor 280, and / or the memory 238 may be located on a separate reader device that may be connected to the fluid sensor device 200. In some embodiments, the controller 236 and the processor 280 may be formed or disposed in the same chip or device, or may be formed or provided on a separate chip or device.

[0039] In some embodiments, the fluid sensor device 200 may include a calibration compartment 210 that is filled with a calibration fluid before the fluid sensor device 200 is connected to the treatment system. In some embodiments, the volume of the calibration compartment 210 may be less than the total volume of calibration fluid required for the entire working life of the fluid sensor device 200. In some embodiments, the calibration compartment 210 may have a volume in the range of, for example, 5-100 microliters, 10-50 microliters, 10-100 microliters, 20-40 microliters, 100-1000 microliters, or about 30 microliters.

[0040] In some embodiments, the fluid sensor device 200 may include a second calibration fluid compartment 258 that is empty before the fluid sensor device 200 is connected to the treatment system. In some embodiments, the second calibration fluid compartment 258 can remain empty during storage or transportation to reduce costs. In other embodiments, the second calibration fluid compartment 258 can be at least partially pre-filled with fluid during storage and / or transportation. In some embodiments, the fluid sensor device 200 can be connected in series with the treatment line 251 to connect to the treatment system. In some embodiments, only the second calibration fluid 250 (e.g., a physiological solution) can flow through the treatment line 251. In some embodiments, the second calibration fluid 250 and / or the sample fluid (e.g., the patient's blood) can selectively flow through the treatment line 251.

[0041] In some embodiments, when the fluid sensor device 200 is first connected to the treatment system, the controller 236 of the fluid sensor device 200 can be configured to initiate a first calibration mode, wherein the controller 236 can cause the calibration fluid in the calibration compartment 210 to enter the sensing channel 232 and interact with the sensing element 230. In some embodiments, the controller 236 can control one or more valves 240 to provide the calibration fluid to flow from the calibration compartment 210 to the sensing channel 232. During the first calibration mode, or as Figure 4 During block 402, the sensing element 230 may obtain a first measurement of the calibration fluid from the calibration compartment 210 and transmit a signal including the first measurement (e.g., a potential difference between an electrode of the sensing element 230 and a reference electrode) to the memory 230 of the fluid sensor system 2000 for storage and / or processing by the processor 280 (see Figure 5 ).

[0042] In some embodiments, after the calibration fluid from the calibration compartment 210 interacts with the sensing element 230 and passes down to the waste chamber 220, the controller 236 of the fluid sensor device 200 can then cause a second calibration fluid 250 (e.g., a physiological solution) from the treatment line 251 to enter the second calibration fluid compartment 258 through the inlet 252 of the fluid sensor device 200. Thereafter, in some embodiments, the controller 236 can cause the second calibration fluid 250 to be stored in the second calibration fluid compartment 258. In some embodiments, the controller 236 can cause the second calibration fluid 250 to enter and be stored in the second calibration fluid compartment 258 by controlling one or more valves 240.

[0043] In some embodiments, the second calibration mode may then be initiated by the controller 236 to provide the second calibration fluid 250 from the second calibration fluid compartment 258 to the sensing channel 232 and interact with the sensing element 230. Figure 4As shown, the sensing element 230 can perform a second measurement on the second calibration fluid 250 and transmit a signal including the first measurement (e.g., the potential difference between the electrode of the sensing element 230 and the reference electrode) to the memory 230 of the fluid sensor system 2000 for storage and / or processing by the processor 280 (see Figure 5 ). In some embodiments, in block 406, the processor 280 may then compare the first measurement made in block 402 and the second measurement made in block 404 to determine a difference to be stored in the memory 238. The stored difference may be used as a reference in a subsequent calibration mode for calibrating the sensing element 230 using a treatment solution or second calibration fluid 250 from an external source instead of a pre-existing calibration fluid from the calibration compartment 210. For example, in some embodiments, after a sample fluid sensing event, in which the sample fluid flows through the treatment line 251 to the sensing channel 232 to interact with the sensing element 230, the second calibration fluid 250 may be provided from the second calibration fluid compartment 258 to the sensing channel 232 to flush any remaining sample fluid or debris and interact with the sensing cell 230 to cause the sensing cell 230 to make a third measurement. In some embodiments, in block 410, the sensing element 230 may then use the third measurement and the stored difference as a reference to calibrate and reset the sensing element 230. Thus, sufficient calibration fluid for only one calibration event (eg, the first calibration event) may be stored in the calibration compartment 210 before the fluid sensor device 200 is connected to a therapeutic system.

[0044] In some embodiments, after the fluid is provided to the sensing channel 232 and interacts with the sensing element 230, the fluid flows down to the waste chamber 220. In some embodiments, one of the one or more valves 240 can be located between the sensing channel 232 and the waste chamber 220, so that the controller 236 can also be configured to control when and whether the fluid is directed to the waste chamber 220.

[0045] Figures 3A-3C Another embodiment of a fluid sensor system 3000 disclosed herein is shown. The fluid sensor system 3000 may include a fluid sensor device 300 configured to be connected to a treatment system. In some embodiments, the fluid sensor system 3000 may be connected to a treatment system. Figure 4 The illustrated fluid sensor system 2000 operates similarly. Unless otherwise noted, the components of the fluid sensor system 3000 may be the same or substantially similar to the like-numbered components of the fluid sensor system 2000, wherein the reference numerals are relative to Figure 2 The reference numerals of the devices are increased by 100 and may function or operate in a substantially similar manner.

[0046] In some embodiments, the fluid sensor device 300 can be configured to be connected in series with the treatment line 351, with the inlet 352 connected to one point on the treatment line 351 and the outlet 354 connected to another point on the treatment line 351. In some embodiments, one end of the treatment line 351 can be connected to the second calibration fluid source 304, and the other end of the treatment line 351 can be connected to the patient 302. In some embodiments, the second calibration fluid 350 (e.g., a physiological solution) and / or the sample fluid 353 (e.g., the patient's blood) can selectively flow through the treatment line 351. In some embodiments, the treatment line 351 can include a pump 360, which is configured to control the flow of fluid within the treatment line 351. In some embodiments, the pump 360 can be configured to flow the second calibration fluid 350 through at least a portion of the treatment line 351 and toward the fluid sensor device 300, or to flow the sample fluid 352 through at least a portion of the treatment line 351 and toward the fluid sensor device 300. When the fluid sensor device 300 is first connected to the treatment line 351, in some embodiments, the controller 336 (see Figure 5 ) One or more valves 340 may be controlled to keep the second calibration fluid 350 in the treatment circuit 351 without entering the sensing channel 332, such as Figure 3A shown.

[0047] In some embodiments, the fluid sensor device 300 may include a calibration compartment 310 having a volume that is less than the total volume of calibration fluid required for the entire operating life of the fluid sensor device 300. In some embodiments, the calibration compartment 310 may have a volume in the range of, for example, 5-100 microliters, 10-50 microliters, 20-40 microliters, or about 30 microliters. In some embodiments, the calibration compartment 310 may have a volume that is sufficient for only one calibration event as described above.

[0048] In some embodiments, different from Figure 2 The fluid sensor system 2000, with Figure 2 Compared to the embodiments of the present invention, the fluid sensor device 300 of the fluid sensor system 3000 can omit the second calibration compartment and instead draw the second calibration fluid 350 directly from the treatment line 351 to the sensing channel 332 during the calibration mode / event without storage or entering a separate compartment. During the first calibration mode, in some embodiments, the fluid sensor system 3000 can similarly provide the calibration fluid from the calibration compartment 310 to the sensing channel 332 and operate according to block 402 to perform a first measurement of the calibration fluid in 310 with the sensing element 330 (see Figure 4 ).

[0049] Thereafter, during the second calibration mode, the controller 236 may control the one or more valves 340 to direct the second calibration fluid 350 to flow to the sensing channel 332 and interact with the sensing element 330, such as Figure 3B The fluid sensor system 3000 can be operated according to block 404 to perform a second measurement of the second calibration fluid 350 using the sensing element 330 and determine the difference between the first measurement and the second measurement using the processor 380 (see Figure 5 ). Then, according to block 406, the fluid sensor system 3000 may store the difference in the memory 338 and use the stored difference to calibrate the sensing element 330 during the second and / or each subsequent calibration event.

[0050] In some embodiments, the first measurement of the calibration fluid from the calibration compartment 310 may also be stored in the memory 338. Thus, in some embodiments, the fluid sensor system 3000 may instead measure the second calibration fluid 350 and determine the difference from the first measurement during each subsequent calibration event and use the determined difference to calibrate the sensing element 330 without storing the difference.

[0051] In some embodiments, when the second calibration fluid source is changed to supply a third solution different from the second calibration fluid 350, the processor 280 of the fluid sensor system 3000 can receive input that the second calibration fluid source has been changed and configure the memory to erase any stored information (e.g., stored differences) about the previous calibration fluid. In some embodiments, the calibration compartment 310 can include enough calibration fluid for two or more calibration events so that new measurements can be made on the calibration fluid to determine the new difference.

[0052] After the initial calibration event, the fluid sensor system 3000 can provide sample fluid 352 by changing the fluid flow rate within the treatment circuit 351 using the pump 360, and provide the sample fluid 352 to the sensing channel 332 by controlling one or more valves 340 during the sensing mode, such as Figure 3C After the measurement of the sample fluid 352 occurs, the fluid sensor system 3000 can again initiate the calibration mode to flush out any residue and recalibrate the sensing element 330 as described above.

[0053] The above disclosure is not intended to limit the present disclosure to the precise form disclosed or to the specific field of use. Therefore, it is contemplated that various alternative embodiments and / or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the present disclosure. Having thus described the embodiments of the present disclosure, one of ordinary skill in the art will recognize that changes may be made in form and detail without departing from the scope of the present disclosure. Therefore, the present disclosure is limited only by the claims.

[0054] In the above description, the present disclosure has been described with reference to specific embodiments. However, those skilled in the art will appreciate that the various embodiments disclosed herein may be modified or otherwise implemented in various other ways without departing from the spirit and scope of the present disclosure. Therefore, the description should be regarded as illustrative and is intended to teach those skilled in the art how to make and use the various embodiments of the disclosed fluid sensor system. It should be understood that the disclosed forms shown and described herein will be regarded as representative embodiments. Equivalent elements, materials, processes or steps may replace those represented and described herein. In addition, certain features of the present disclosure may be used independently of the use of other features, all of which will be apparent to those skilled in the art after benefiting from the description of the present disclosure. Expressions such as "including", "comprising", "incorporating", "by", "having", "being" used to describe and advocate the present disclosure are intended to be interpreted in a non-exclusive manner, i.e., allowing items, components or elements not explicitly described to also exist. Mentioning the singular should also be interpreted as being related to the plural.

[0055] In addition, the various embodiments disclosed herein should be considered to have illustrative and explanatory meanings and should never be interpreted as limitations on the present disclosure. All joint references (e.g., attached, attached, coupled, connected, etc.) are only used to help the reader understand the present disclosure and may not cause limitations, especially limitations on the position, direction or use of the systems and / or methods disclosed herein. Therefore, if there is a reference to a combined lawsuit, it should be interpreted fairly. In addition, such a combined reference does not necessarily infer that the two elements are directly connected to each other. In addition, all numerical terms, such as but not limited to "first", "second", "third", "primary", "secondary" or any other ordinary and / or numerical terms, should also be regarded as identifiers only to help the reader understand the various elements, embodiments, variants and / or modifications of the present disclosure, and may not generate any limitations, especially with respect to the order or preference of any element, embodiment, variant and / or modification relative to or over another element, implementation, variant and / or modification.

[0056] It will also be appreciated that one or more of the elements depicted in the drawings / figures may also be implemented in a more separate or integrated manner, or in some cases even removed or rendered inoperable, as may be useful depending on the particular application.

Claims

1. A method for calibrating a fluid sensor device connected in series with a treatment system, the method comprising: providing a first calibration fluid stored in a calibration compartment to the sensing element, taking a first measurement of the first calibration fluid with the sensing element, providing a second calibration fluid from a second calibration fluid source, taking a second measurement of the second calibration fluid with the sensing element, The sensing element is calibrated using the second calibration fluid.

2. The method of claim 1 further comprising connecting an inlet of the fluid sensor device to a first point of a treatment circuit of the treatment system and connecting an outlet of the fluid sensor device to a second point of the treatment circuit of the treatment system. 3 . The method of claim 1 , further comprising storing the second calibration fluid in a second calibration compartment.

4. The method of claim 3, wherein the second calibration compartment is empty prior to being connected to the therapeutic system. 5 . The method of claim 1 , further comprising determining a difference between a first measurement of the first calibration fluid and a second measurement of the second calibration fluid. 6 . The method of claim 5 , wherein calibrating the sensing element comprises comparing the second calibrated measurement to a difference between a first measurement of the first calibration fluid and a second measurement of the second calibration fluid.

7. The method of claim 2, wherein the therapy circuit connects a patient and the second calibration fluid source.

8. The method of claim 1, wherein the second calibration fluid source is external to the fluid sensor device.

9. The method of claim 1, wherein the second calibration fluid comprises a physiological solution.

10. The method of claim 7, further comprising providing a sample fluid from the patient to the sensing element via the therapy circuit.

11. The method of claim 10, further comprising controlling a flow direction of fluid in the treatment circuit to provide the second calibration fluid from the second calibration fluid source to the sensing element after providing a sample fluid from a patient to the sensing element through the treatment circuit.

12. A fluid sensor system configured to measure a sample fluid in-line with a treatment system, the fluid sensor system comprising: A fluid sensor device, comprising: a sensing channel configured to receive a sample fluid from the therapeutic system; a first calibration compartment comprising a first calibration fluid and in fluid communication with the sensing channel; a second calibration compartment configured to receive a second calibration fluid from a second calibration fluid source, wherein the second calibration compartment is in fluid communication with the sensing channel; and A sensing element is configured to interact with the fluid in the sensing channel and convert a property of the fluid.

13. The fluid sensor system of claim 12, wherein the volume of the first calibration compartment is in the range of 5-100 microliters.

14. The fluid sensor system of claim 12, wherein the second calibration fluid source is external to the fluid sensor system.

15. The fluid sensor system of claim 14, wherein the second calibration fluid source comprises a therapy circuit of the therapy system.

16. The fluid sensor system according to claim 12 further includes a processor, which is configured to determine a difference between a first measurement value obtained by a sensing element of the first calibration fluid and a second measurement value obtained by a sensing element of the second calibration fluid, and to calibrate the sensing element based at least on the measurement value obtained by the sensing element of the second calibration fluid and the determined difference.

17. The fluid sensor system of claim 12, wherein the second calibration compartment is empty during a storage mode during which the fluid sensor system is not connected to the therapeutic system.

18. A fluid sensor system configured to measure a sample fluid in-line with a treatment system, the fluid sensor system comprising: A fluid sensor device, comprising: a sensing channel configured to receive a sample fluid from the therapeutic system; a calibration compartment containing a first calibration fluid and in fluid communication with the sensing channel, the calibration compartment having a volume in the range of 5-100 microliters; and A sensing element is configured to interact with the fluid in the sensing channel.

19. The fluid sensor system according to claim 18 further includes a controller, which is configured to control one or more valves to selectively direct only the second calibration fluid from the treatment system to the sensing channel in a calibration mode, and to control the one or more valves to selectively direct only the sample fluid from the treatment system to the sensing channel in a sensing mode.

20. The fluid sensor system according to claim 19 further includes a processor, which is configured to determine a difference between a first measurement value obtained by a sensing element of the first calibration fluid and a second measurement value obtained by a sensing element of the second calibration fluid in a calibration mode, and to calibrate the sensing element based at least on the measurement value obtained by the sensing element of the second calibration fluid and the determined difference.

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