Wireless communication probe system with removable sensor probe

Abstract

A probe configured to measure a parameter of a liquid, such as water, is described. The probe includes a probe head and a sensor probe removably coupled to the probe head. The probe head and the sensor probe each include a radio frequency (RF) transceiver. The sensor probe measures a parameter of the liquid and transmits data regarding the measured parameter to the probe head by the RF transceiver. The probe can optionally include an inductive power coupling between the probe head and the sensor probe, and the interface between the probe head and the sensor probe can be free of a conductive connection.

Description

[Technical Field]

[0001] This application claims the benefit of the earlier filing date of U.S. Patent Application No. 17 / 687,999, filed March 7, 2022, which relates to a probe system including a sensor probe, and is incorporated herein by reference in its entirety. [Background technology]

[0002] Sensor probes have been developed that are capable of measuring and monitoring liquid parameters such as pH, dissolved oxygen, conductivity, and oxidation-reduction potential (ORP) to assess the quality of water and other liquids, and that can measure these and other parameters quickly and easily without the need for laboratory testing.

[0003] In some applications, the sensor probe is removably connected to an upstream probe head, allowing the sensor probe to be easily replaced, repaired, or reconfigured in the field as needed. The probe head can receive measurement information from the sensor probe and transmit the measurement information to an upstream processing device, such as a computer or mobile device. The probe head also provides power to the detachable sensor probe from a power source.

[0004] Probes operating underwater or in other wet environments can experience issues with the conductive and galvanic connections between the detachable probe and the probe head. Specifically, these connections are known to easily fail when pins bend, break, corrode, or become misaligned. Conductive connectors also require mounting holes in the probe head and sensor probe housing, which create a path for liquids to enter and potentially damage the probe and / or probe head. These issues can reduce the life and reliability of probes used to measure parameters in liquids. Summary of the Invention [Problem to be solved by the invention]

[0005] One object of the present invention is to provide a reliable, long-lasting probe by reducing or eliminating failures associated with the conductive communication connection between the sensor probe and the probe head. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a probe comprising: (i) a probe head having a first low-power radio frequency (RF) transceiver; and (ii) a sensor probe removably coupled to the probe head and including a second low-power RF transceiver. The sensor probe is capable of measuring a parameter of a liquid while in contact with the liquid. The first low-power RF transceiver and the second low-power RF transceiver are capable of forming a communication network for transmitting information regarding the measured parameter from the second low-power RF transceiver to the first low-power RF transceiver.

[0007] In another aspect, the present disclosure provides a probe comprising: (i) a probe head having a first radio frequency (RF) transceiver and a housing forming a socket on an exterior surface of the probe head; and (ii) a sensor probe capable of measuring a parameter of a liquid while in contact with the liquid. The sensor probe has a second RF transceiver that transmits information regarding the measured parameter to the first RF transceiver. The sensor probe has a proximal end that fits into the socket to removably couple the sensor probe to the probe head. When the sensor probe is removably coupled to the probe head, the socket and the proximal end of the sensor probe form an interface that does not include any conductive connection. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a probe used to measure a liquid parameter according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram of a probe used to measure a liquid parameter according to one embodiment. [Figure 3]FIG. 3 is a schematic diagram of a probe having multiple sensor probes used to measure liquid parameters. [Figure 4] FIG. 4 is a schematic diagram of a probe used to measure a liquid parameter according to one embodiment. [Figure 5] FIG. 5 is a schematic diagram showing an enlarged view of a probe according to one embodiment. [Figure 6] FIG. 6 is a schematic diagram showing an enlarged view of a probe according to one embodiment. [Figure 7] FIG. 7 is a schematic block diagram of a sensor probe for use in measuring one or more liquid parameters. [Figure 8] FIG. 8 is a schematic block diagram of a probe head for use with multiple sensor probes. [Figure 9] FIG. 9 is a perspective view of a sensor probe being used to measure water parameters. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present disclosure describes a probe configured to measure one or more parameters of a liquid by immersing the probe in the liquid. The probe includes one or more sensor probes removably coupled to a probe head, allowing the sensor probe to be easily replaced or repaired in the field as needed. The sensor probe can measure one or more parameters of a liquid, such as pH, conductivity, ORP, dissolved oxygen, turbidity, total suspended solids, carbon dioxide concentration, ozone concentration, chlorine concentration, hydrogen concentration, nitrogen concentration, nitrate concentration, and ammonium concentration. The probe can be used to measure parameters of any liquid, including, for example, water, hydrocarbon solvents, oil, and oil and gas production fluids. This radio frequency communication, described in more detail below, allows information to be transmitted between the sensor probe and the probe head without the use of a conductive connection and without the need for openings in the sensor probe housing and / or the probe head housing. Optionally, the probe may include a wireless inductive power coupling for transmitting power from the probe head to the sensor probe.

[0010] FIG. 1 illustrates a probe 100 including a sensor probe 110 removably coupled to a probe head 120. The probe head 120 includes a socket 140 formed on the exterior of the housing of the probe head 120, such that a proximal end 111 of the sensor probe 110 fits within and is surrounded by the socket 140 (i.e., the socket extends 360° around the proximal end 111). The sensor probe 110 can be mechanically restrained within the socket 140 by known means, such as by a corresponding locking structure or other mechanical restraint, a magnet, an interference fit, or the like. The mechanical restraint can be configured to allow the sensor probe 110 to be easily removed from the probe head 120, for example, by hand, so that it can be replaced, repaired, or reconfigured as needed. The probe 100 includes a transmission cable 130 that connects to an upstream power source (not shown) and transmits power to the probe head 120. The transmission cable 130 may also include wires or optical fibers capable of transmitting information from the probe head 120 to an upstream processing unit / controller or logging device external to the probe head 120. Similarly, information such as control signals that can change operating parameters of the probe 100 can be sent from upstream devices to the probe 100.

[0011] The sensor probe 110 is configured to contact a liquid and detect its properties. The sensor probe 110 may include, for example, a pH sensor probe, a dissolved oxygen sensor probe, a conductivity sensor probe, or an oxidation-reduction potential (ORP) probe. The probe 100 may be configured to allow the sensor probe 110 and probe head 120 to be immersed in the liquid to measure liquid parameters. As shown in connection with FIG. 4 below, the sensor probe 110 communicates with the probe head 120 using short-range and / or low-power radio frequency signals. Thus, the sensor probe 110 can wirelessly communicate measurement information to the probe head 120 without requiring a conductive coupling interface between the sensor probe 110 and the probe head 120.

[0012] Also shown in FIG. 1 is an inductive power coupling 150 between the sensor probe 110 and the probe head 120. The inductive power coupling is shown in the embodiments illustrated in FIGS. 1-6. The inductive power coupling feature is an optional feature of the probe, allowing power transfer from the probe head to the sensor probe without the use of wires or conductive connections. In an alternative, power can be transferred from the probe head to each sensor probe using wires or conductive connections. In another alternative, the sensor probe may be powered by an internal power source, such as a battery, so that the sensor probe does not receive power from the probe head. The probes illustrated in FIGS. 2-9 may include similar features with respect to power transfer and wireless communication as the probe of FIG. 1 or the alternatives described above.

[0013] FIG. 2 illustrates an embodiment of a probe 200 that includes a sensor probe 210 removably attached to a probe head 220. In this embodiment, the probe head 220 includes a battery power source 235 that provides power to operate the sensor probe 210. The probe 200 can wirelessly communicate with an external computing device 280 (e.g., a mobile phone) by sending and receiving information to and from a wireless transceiver 270. This allows information measured by the sensor probe 210 to ultimately be transmitted to the computing device 280, which can then further process, analyze, store, and display the information. FIG. 3 illustrates an embodiment of a probe 300 with a multi-sensor probe head that includes three sensor probes 312, 314, and 316, each measuring a different fluid parameter. As with the previous embodiment, each sensor probe 312, 314, and 316 is removably mechanically restrained within a corresponding socket 342, 344, and 346 in the probe head 320.

[0014] 4 shows a probe 400 including a sensor probe 410 removably mounted in a socket 440 of a probe head 420. The probe includes a transmission cable 430 that can connect to an upstream power source (not shown) to transmit power to the probe head. The transmission cable 430 may include wires or optical fibers that can transmit information from the sensor probe 410 and / or probe head 420 to upstream equipment. The probe 400 includes an inductive power coupling 450 between the sensor probe 410 and the probe head 420, allowing power to be transferred from the probe head to the sensor probe without the use of wires or conductive connections.

[0015] The sensor probe 410 also wirelessly communicates with the probe head 420 to transmit information to the probe head 420. More specifically, FIG. 4 shows a first RF transceiver 425 in the probe head 420 and a second RF transceiver 415 in the sensor probe 410, which form a short-range wireless network to enable measurement data regarding the measured fluid parameter to be transmitted from the sensor probe 410 to the probe head 420. As used herein, the terms "transceiver" or "RF transceiver" refer to a device capable of transmitting and receiving radio frequency signals, or a device capable of both transmitting and receiving radio frequency signals. The RF transceivers 415, 425 may be low-power wireless transceivers that form a data communication channel based on protocols such as Bluetooth®, Bluetooth Low Energy (LE), IEEE 802.15.4 (e.g., Zigbee®, MiWi, Thread, WirelessHART), Near Field Communication (NFC), and the like. A low-power wireless transceiver can advantageously transmit RF signals over short distances between the sensor probe and the probe head and can operate at low power levels that are within the limits of inductive power coupling. In some embodiments, the transceiver can operate for extended periods of time on battery power, if necessary. The maximum power output of the low-power RF transceiver can be 80 mW or less, 50 mW or less, 0.05 mW to 10 mW, 0.1 mW to 5 mW, or 0.5 mW to 2.5 mW. Typically, the sensor probe transceiver (e.g., 415) is powered by power received from the probe head, for example, via inductive power coupling 450. In some embodiments, for sensor probes with very low power requirements, a passive RF receiver can be used as the sensor probe transceiver to transmit measurement information to the probe head, and the passive RF transceiver is powered by radio waves sent from the probe head transceiver.

[0016] The RF transceiver can transmit and / or receive radio transmissions in the ISM band. In some embodiments, the transceiver can operate at high frequencies, such as 1-6 GHz, 2-4 GHz, or 2.2-3 GHz. For example, Bluetooth and Bluetooth LE operate in the 2.400-2.4835 GHz spectral range. Typically, high-frequency radio signals are attenuated in liquids, such as water, or the liquid can substantially interfere with the signal, reducing the reliability of the data communication channel. However, in some embodiments, the coupling between the sensor probe and the probe head is positioned to minimize the presence of liquid between the transceiver and the sensor, allowing for reliable high-frequency transmission.

[0017] In particular, the socket 440 may be configured to tightly engage the proximal end 411 of the sensor probe 410 to prevent liquid from entering between the sensor probe 410 and the probe head 420. As shown in FIG. 4 , the RF transceiver 415 may be positioned at the proximal end 411 of the sensor probe 410 such that the socket 440 surrounds at least a portion of the RF transceiver 415 when the sensor probe 410 is attached to the probe head 420. In some embodiments, the sensor probe transceiver (e.g., 415) may be positioned at the proximal end of the sensor probe, e.g., within one-quarter of the length of the sensor probe from the proximal end of the probe head. Thus, even if the sensor probe and probe head are immersed in liquid during use of the probe 400, the liquid will not interfere with the transmission of information from the sensor probe 410 to the probe head 420. Furthermore, when the sensor probe 410 is connected to the socket 440, any liquid that was present between the interface of the sensor probe 410 and the probe head 420 is displaced.

[0018] The transmission distance between the RF transceiver (e.g., 415) on the sensor probe side and the RF transceiver (e.g., 425) on the probe head side may be relatively short. For example, the distance between the RF transceivers when the sensor probe is attached to the probe head may be 0.5 m or less, such as 0.5 cm to 30 cm, 1 cm to 10 cm, or 2 cm to 8 cm. Thus, the RF transceivers may be short-range transceivers with a maximum range of 20 m or less, 10 m or less, 1 m or less, or 0.5 m or less.

[0019] The RF transceivers 415, 425 can establish a data communication network that allows measurement data collected by the sensor probe to be communicated to the probe head 420. In some embodiments, the probe head 420 can, for example, send control signals to the sensor probe 410 to change the operation of the sensor probe 410, instruct the sensor probe 410 to take measurements, or send firmware updates to the sensor probe 410. The RF transceiver 415 can form a point-to-point network with the transceiver 425. In embodiments where the probe head has multiple sensor probes, such as in FIG. 3, the probe head can include multiple probe-head transceivers that form a point-to-point network with corresponding transceivers on the sensor probes. Alternatively, as shown in FIG. 8 below, the probe head can include a single RF transceiver that forms a star topology network that can communicate with each of the transceivers on the multiple sensor probes. In other embodiments of probes with multiple sensor probes, the probe head can include one or more transceivers that form a mesh network with the transceivers on the sensor probes. Forming a mesh network allows sensor probes to transmit data to each other, extending the range over which the sensor probes can communicate without requiring high-power transceivers.

[0020] 5 is an enlarged cross-sectional view of the vicinity of the socket 540 of the probe head 520. The socket 540 is recessed relative to the distal end wall 522 of the probe head housing. In this embodiment, the socket 540 includes a first cylindrical wall 562, a ring-shaped shoulder wall 565, a second cylindrical wall 564, and an end wall 567. The proximal end 511 of the sensor probe 510 includes corresponding walls that can abut against and contact the socket walls. For example, the sensor probe 510 may include a protrusion 546 at its proximal end that fits within the second cylindrical wall 564 of the socket 540 such that an end wall 557 of the sensor probe 510 abuts against an end wall 567 of the probe head 520 when the sensor probe 510 is attached to the probe head 520. The protrusion 546 forms a ring-shaped shoulder wall 568 on the sensor probe 510 that abuts against and contacts the shoulder wall 565 of the probe head 520. The socket may optionally include a sealing element 561, such as a rubber O-ring, to further prevent or limit the inflow of liquid into the space between the sensor probe 510 and the probe head 520 when immersed in water during use. As mentioned above, the probe head 520 and / or the sensor probe 510 may include mechanical or magnetic securing means (not shown) to secure the sensor probe 510 within the socket 540 so that the socket is easily removable from the probe head 520.

[0021] The sensor probe 510 includes an RF transceiver 515 and the probe head includes an RF transceiver 525. These may be arranged in a similar manner as described above in relation to Figure 4, and the same protocols may be used to create a short-range wireless network connecting the sensor probe 510 to the probe head 520, so that measurement data detected by the sensor probe 510 can be transmitted to the probe head 520.

[0022] The probe includes an inductive power coupling 550. The inductive power coupling 550 includes a transmitting coil 552 on the probe head 520 side and a receiving coil 556 on the sensor probe 510 side. The inductive coupling includes ferromagnetic materials (not shown) disposed on each of the probe head 520 and the sensor probe 510.

[0023] The inductive power coupling 550 allows power to be transferred from the probe head 520 to the sensor probe 510 without requiring electrical connections or conductive protrusions on the housings of the sensor probe 510 and the probe head 520. Wireless data transmission between the sensor probe 510 and the probe head 520 is also possible, eliminating the need for conductive connections or openings in the housing surface at the interface between the probe head 520 and the sensor probe 510, i.e., at least the mating surface between the socket 540 and the proximal end 511. This prevents corrosion and other damage that could cause failure of the conductive pins, improving reliability and longevity. This arrangement also prevents liquids from leaking into the sensor probe 510 housing or the probe head 520 housing, improving probe longevity and reliability.

[0024] FIG. 6 illustrates a different embodiment of a socket 640 that can be used in connection with the present invention. The probe head 620 illustrated in FIG. 6 has a socket 640 recessed from the distal end wall of the probe head housing. However, the socket 640 includes a protrusion 663 in its center. The sensor probe 610 includes a cylindrical recess 667 that extends into the proximal end 618 of the sensor probe 610. When the sensor probe 610 is attached to the probe head 620, the recess 667 surrounds the protrusion 663. Additionally, when the sensor probe 610 is attached to the probe head 620, the proximal end 666 of the sensor probe 610 abuts the end wall 664 of the socket 640. The probe includes an inductive power coupling 650 that includes a sending coil 652 on the probe head side and a receiving coil 656 on the sensor probe side.

[0025] It should be understood that the socket may have a configuration different from that shown in the illustrated embodiment. In general, the socket may be configured to fit within a recess in the probe head such that the proximal end of the sensor probe is surrounded by the proximal end of the probe head. This arrangement may reduce the amount of liquid that enters the interface between the sensor probe and the probe head when the probe is immersed in liquid during use, thereby enabling reliable RF transmission of measurement data collected by the sensor probe.

[0026] FIG. 7 shows a high-level schematic block diagram of a sensor probe 714. The sensor probe 714 can be, for example, a combined pH / ORP sensor probe, a conductivity sensor probe, a luminescent dissolved oxygen (LDO) sensor probe, or a turbidity sensor probe. The sensor probes can be used individually with their corresponding probe heads, or one or more such sensor probes can be used together in a multi-sensor probe head. FIG. 8 shows a multi-sensor probe head configured to operate with four sensor probes.

[0027] The sensor probe 714 includes a power conditioning chip 734 that manages the power it receives from the probe head, for example, by changing the voltage or converting the current from AC to DC. The sensor probe 714 includes an RF transceiver 724 that can send RF signals to a corresponding RF transceiver in the probe head. The sensor probe 714 includes a microcontroller 744 that controls the operation of the sensor probe and, optionally, a memory (not shown) that can store firmware for operating the sensor probe. The sensor probe 714 includes at least one analog sensing element 784 that can detect a parameter of a liquid while in contact with the liquid. The analog sensing element 784 varies depending on the type of probe. For example, the analog sensing element 784 in a pH / ORP combination sensor probe can detect the pH and ORP of a liquid in contact with the analog sensing element. The analog sensing element 784 in a conductivity sensor probe can detect the conductivity of a liquid by passing a current through the liquid between electrodes and measuring the liquid's conductivity or resistivity. The analog sensing element 784 of the LDO probe may include an LED that emits pulses of blue light onto a light-emitting coating and a photodiode that measures the light emitted from the light-emitting coating. The light-emitting coating may be disposed within a removable sensor cap. The analog sensing element 784 of the turbidity sensor probe may include an emitter / detector that emits light into a liquid in contact with the turbidity sensor probe and measures the amount of light scattered by solids in the liquid.

[0028] In some embodiments, the analog sensing element may include a removable element. For example, an LDO sensor probe may include a removable sensor cap that includes a luminescent coating. To further reduce the presence of conductive connectors that may be exposed to liquid, in one embodiment, the removable sensor cap or removable sensing element wirelessly communicates measurement information to the sensor probe using an RF transceiver. In some embodiments with very low power requirements, the removable sensing element may include a passive RF module that is powered by radio waves.

[0029] Each sensor probe may include signal conditioning and signal acquisition circuitry 764 capable of converting detected analog signals to digital signals. Although not shown, the sensor probe 714 may also include a separate temperature sensing element that measures the temperature of the liquid. The sensor probe may compensate or adjust a measured liquid parameter (e.g., pH) based on the liquid temperature.

[0030] FIG. 8 is a high-level schematic diagram illustrating a probe head 820 operating with four sensor probes, sensor port 1 (818), sensor port 2 (817), sensor port 3 (816), and sensor port 4 (815), removably coupled to the probe head 820. The probe head 820 is connected to an upstream device 880 by a cable 830. The probe head 820 receives power from the upstream device via the cable 830 and transmits measurement information to the upstream device 880 via the cable 830. The probe head may include a power conditioning module 875 that manages the power received from the upstream device 880, for example, by varying the voltage. Power is distributed to each of the sensor ports by a power bus 870. Each sensor port includes an isolated power supply 858, 856, 854, 852 that provides power to the sensor probes. The isolated power supplies can support the inductive power coupling at the probe head as described above. The probe head may include an RF transceiver 825 that is networkable with each of the RF transceivers on the four sensor probes and can receive RF signals from each of the sensor probes corresponding to measurement information, as described above in connection with Figure 4. The probe head may include a communications interface 860 that manages communications with an upstream device 880.

[0031] The probe head 820 may include a memory 890 that allows the probe head to store measurement information received from the sensor probe. The probe head 820 may include a depth sensor 840 that measures the depth into the liquid at which the sensor probe measures a liquid parameter.

[0032] 9 shows one embodiment of a probe 900 that includes a probe head 920 having three sensor probes 912A, 912B, 912C. Each sensor probe is removably coupled to the probe head 920 in the manner described above, and each sensor probe is capable of measuring at least one property of water 950. The probe 900 is connected to a handheld upstream processing device 980 by a cable 930. The upstream processing device 980 includes a user interface 966, a display 984, and a processor (not shown).

[0033] In this embodiment, the probe 900 is used as a handheld field measurement device, allowing an operator to continuously measure properties of water 950 by immersing the probe head 920 and sensor probes 912A, 912B, 912C in the water 950. As can be seen, at least the area of ​​the probe head 920, including the socket connections to the sensor probes 912A, 912B, 912C, may be fully submerged in water during use. The operator can view measurement information on the display 984 and control the operation of the display and sensor probes via the user interface 966. The above configuration enables a wireless communication interface and a wireless power interface between the probe head 920 and the sensor probes 912A, 912B, 912C, which is reliable even when immersed in water for extended periods of time.

[0034] In other embodiments, the probe can be configured to be installed in the liquid system for an extended period of time (e.g., days, weeks, or longer), and the sensor probe measures parameters of the liquid over that period of time. In such cases, the probe can take measurements periodically or at predetermined intervals and communicate the measurement data to the probe head. The probe head can store or record the measurement data, which can be collected by a user at a later time, and / or the measurement data can be transmitted to an external device, such as an external computer or other processing system, which can store and process the data.

[0035] While several embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications can be made in the illustrated embodiments without substantially departing from the disclosed embodiments, and all such modifications are intended to be included within the scope of the present disclosure as defined in the following claims.

Claims

1. (i) a probe head including a first low power radio frequency (RF) transceiver; (ii) a sensor probe removably coupled to the probe head, the sensor probe including a second low power RF transceiver, the sensor probe configured to measure a parameter of the liquid while in contact with the liquid, The probe, wherein the first low power RF transceiver and the second low power RF transceiver form a communications network that transmits information regarding the measured parameter from the second low power RF transceiver to the first low power RF transceiver.

2. The probe of claim 1 , wherein the probe head includes a housing forming a socket on an outer surface of the probe head, and the sensor probe includes a proximal end that fits into the socket to removably couple the sensor probe to the probe head.

3. The probe of claim 2 , wherein the socket surrounds the proximal end of the sensor probe when the sensor probe is removably coupled to the probe head.

4. The probe of claim 2 , wherein the socket is configured to prevent liquid from entering a space between the probe head and the sensor probe when the sensor probe is removably coupled to the probe head.

5. The probe of claim 2 , wherein the proximal end of the sensor probe is mechanically constrained within the socket when the sensor probe is removably coupled to the probe head.

6. The probe of claim 1 , wherein the probe head is configured to transmit the information about the measured parameters to a processing or logging device external to the probe head.

7. The probe of claim 1 , further comprising an inductive power coupling configured to transfer power from the probe head to the sensor probe.

8. The probe of claim 7 , wherein the inductive power coupling comprises a transmitting coil disposed in the probe head and a receiving coil disposed in the sensor probe.

9. The probe of claim 1 , wherein the first low power RF transceiver is located at a distance of 0.5 m or less from the second low power RF transceiver.

10. The probe of claim 1 , wherein the first low power RF transceiver is positioned at a distance ranging from 0.5 cm to 30 cm from the second low power RF transceiver.

11. The probe of claim 1 , wherein the communication network is based on a protocol selected from one of Bluetooth, Bluetooth Low Energy, IEEE 802.15.4, and Near Field Communication (NFC).

12. The probe of claim 1 , wherein the first low power RF transceiver and the second low power RF transceiver have a maximum power output in the range of 0.05 mW to 10 mW.

13. The probe of claim 1 , wherein the first low power RF transceiver and the second low power RF transceiver have a maximum power output in the range of 0.1 mW to 5 mW.

14. The probe of claim 1 , wherein the first low power RF transceiver and the second low power RF transceiver operate at a frequency in the range of 2 GHz to 4 GHz.

15. 10. The probe of claim 1, wherein the sensor probe is configured to measure at least one parameter of the liquid selected from pH, conductivity, ORP, dissolved oxygen, turbidity, total suspended solids, carbon dioxide concentration, ozone concentration, chlorine concentration, hydrogen concentration, nitrogen concentration, nitrate concentration, and ammonium concentration.

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