Non-contact liquid sensing technology

Abstract

To meet the need for non-contact sensing in most applications for liquid level sensing and liquid characteristic sensing.SOLUTION: A non-contact liquid sensing processing device includes a multi-port network, a capacitance measurement circuit, and a digital processing circuit. The processing device measures a first set of currents and a second set of currents associated with a first electrode and a second electrode coupled to an exterior surface of a container holding liquid. The processing device determines independent impedances of the container, the liquid, and the liquid and container using the first set of currents and the second set of currents. The processing device determines an electrical property of the liquid using the independent impedances of the liquid.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Background of the Invention There is a large and growing market for combined liquid level sensing and liquid property sensing in the automotive, Internet of Things (IoT) and consumer sectors. For example, some applications of liquid level sensing and liquid property sensing include windshield cleaning fluid, fuel level sensors, water hardness levels in coffee machines, smart sensing inside refrigerators, etc. Most of these applications require contactless sensing.

[0002] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. [Brief explanation of the drawings]

[0003] [Figure 1] FIG. 1 is a block diagram of a processing device for non-contact liquid sensing and determining electrical properties of a liquid in a container, according to at least one embodiment. [Figure 2] FIG. 1 is a flow diagram of the processing stages of a processing device with non-contact liquid sensing, according to at least one embodiment. [Figure 3] FIG. 1 is a flow diagram of a processing sub-stage of a processing apparatus with non-contact liquid sensing, according to at least one embodiment. [Figure 4A] FIG. 2 is a circuit diagram of a first circuit model according to at least one embodiment. [Figure 4B] FIG. 10 is a circuit diagram of a second circuit model according to at least one embodiment. [Figure 4C] FIG. 10 is a circuit diagram of a third circuit model according to at least one embodiment. [Figure 5A] FIG. 1 is a circuit diagram of a capacitance measurement circuit with multiple multiplexers for contactless liquid sensing, according to at least one embodiment. [Figure 5B] FIG. 1 is a circuit diagram of a capacitance measurement circuit with multiple receiver channels for contactless liquid sensing, according to at least one embodiment. [Figure 6] FIG. 1 is a circuit diagram of a charge measurement circuit with a receiver channel and a floating ground signal generator for non-contact liquid sensing according to at least one embodiment. [Figure 7A] FIG. 1 illustrates a sensor configuration with a first electrode, an active shield electrode, a second electrode, and two ground shield electrodes, according to at least one embodiment. [Figure 7B] FIG. 1 illustrates a sensor configuration with a transmitter electrode on one side of the container and a set of receiver electrodes on the other side of the container, according to at least one embodiment. [Figure 8] FIG. 1 is a flow diagram of a method of operating a processing device for non-contact liquid sensing to determine electrical properties of a liquid in a container, according to at least one embodiment. [Figure 9] FIG. 1 is a flow diagram of a method for determining electrical properties of a liquid in a container, according to at least one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0004] The following description provides numerous specific details, such as examples of particular systems, components, methods, etc., to provide a thorough understanding of various embodiments of the non-contact liquid sensing technology described herein. As noted above, there are a variety of applications that require non-contact liquid sensing, such as automotive, IoT, and consumer applications.

[0005] Traditionally, oscilloscope and bridge methods have been used to determine amplitude and phase shift with high oversampling and in-phase and quadrature (IQ) demodulation. These methods require the liquid to be placed in predefined conditions (e.g., in specialized equipment) to minimize environmental impact. Traditional methods cannot measure liquid properties in arbitrary or dynamic environments. These methods do not account for ground effects, resulting in baseline drift. Furthermore, these methods cannot handle liquid films and bubbles on the wall, resulting in erroneous level readings. Furthermore, there are manufacturing tolerances and temperature dependences in the electrical properties of the wall (or coating) that can cause problems with these methods. For example, these traditional methods cannot measure the electrical properties of the liquid itself or the absolute values ​​of the liquid's conductivity and permittivity, which can lead to changes in capacitance measurements due to sensitivity to the thickness of the container's plastic wall.

[0006] Various embodiments of techniques for non-contact liquid sensing are described herein. A multi-port network can be used to implement non-contact liquid sensing, which combines self-capacitance and mutual-capacitance sensing over multiple frequency ranges to enable measurement of absolute values ​​of electrical properties of a liquid. Non-contact liquid sensing can eliminate the effects of dielectric coatings (container walls) and ground effects caused by environmental changes. Non-contact liquid sensing can also distinguish the volume of liquid from bubbles and films on the container walls, as described in more detail below.

[0007] One processing device includes a multiport network, a current measurement circuit, and a digital processing circuit. The processing device measures a first set of currents and a second set of currents associated with a first electrode and a second electrode coupled to an exterior surface of a container holding a liquid. The container containing the liquid has an ambient ground caused by conductive objects around it. The processing device uses the first set of currents and the second set of currents to determine the container, the liquid, and the independent impedances of the liquid and the container. The processing device uses the independent impedance of the liquid to determine an electrical property of the liquid.

[0008] References in the description to "an embodiment," "one embodiment," "an exemplary embodiment," "some embodiments," and "various embodiments" mean that the particular feature, structure, step, operation, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Moreover, the appearances of the phrases "an embodiment," "one embodiment," "an exemplary embodiment," "some embodiments," and "various embodiments" in various places in the description do not necessarily all refer to the same embodiments.

[0009] The description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations by exemplary embodiments. These embodiments, which may also be referred to herein as "examples," are described in sufficient detail to enable those skilled in the art to practice embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable one skilled in the art to practice, manufacture, and / or use the subject matter.

[0010] 1 is a block diagram of a processing device 100 for non-contact liquid sensing and determining electrical properties of a liquid 108 in a container 106, according to at least one embodiment. The processing device 100 includes an analog processing block 110 and a digital processing block 120. The analog processing block 110 is coupled to a first electrode 102 and a second electrode 104, where the first electrode 102 is located at a first point on the exterior surface of the container 106 that holds the liquid 108, and the second electrode 104 is located at a second point on the exterior surface of the container 106. The container 106 has an ambient ground 124 that represents the ambient ground to surrounding objects. The analog processing block 110 includes a multi-port network that couples a signal generator 112 (or multiple signal generators or excitation sources), receiver channels 114 (also referred to as current measurement circuits), and ground potential to one or both of the first electrode 102 and the second electrode 104 to determine a set of currents associated with the first electrode 102, the second electrode 104. For example, the receiver channels 114 can be used to measure a first current associated with the first electrode 102 (flowing into or out of the first electrode 102) and a second current associated with the second electrode 104. The first and second currents can be used to determine a third current associated with the ambient ground 124. The analog processing block 110 can operate at various operating frequencies. Using various operating frequencies, currents at various frequencies can be determined, which can be used to determine a set of impedances that includes the combined impedance of the container 106 and the liquid 108 and the impedance of the container 106. These impedances can be used to determine the impedance of the liquid 108 .

[0011] In at least one embodiment, the signal generator 112 can be a wide frequency range harmonic signal generator. The signal generator 112 can generate low or high frequency excitation signals. The signal generator 112 can be an internal or external component. Using many frequencies (e.g., 10 frequencies) from low to high can improve the estimation of fluid quality.

[0012] In one embodiment, the analog processing block 110 includes a current measurement circuit coupled to the multiport network. The current measurement circuit includes a signal generator 112 that generates an excitation signal at a first frequency and a receiver channel 114 that measures a first set of currents associated with the first electrode 102 and the second electrode 104 at the first frequency. The current through the ambient ground 124 can be calculated for each corresponding frequency. In one embodiment, the signal generator 112 is configured to generate an excitation signal that includes a sine wave. Alternatively, the signal generator 112 is configured to generate other types of excitation signals, such as other periodic or rectangular excitation signals (e.g., square waves). This first set of currents can be used to determine the combined impedance of the container 106 and the liquid 108. The capacitance measurement circuit measures a second set of currents associated with the first electrode 102 and the second electrode 104 at a second frequency that is lower than the first frequency. In this embodiment, the second frequency is lower than the first frequency. In another embodiment, the second frequency is higher than the second frequency. The current through the ambient ground 124 can be calculated for each corresponding frequency. This second set of currents can be used to determine the impedance of the container 106. This can determine the impedance of the liquid 108 by removing the effects of the container 106 and environmental conditions. In some embodiments, an additional ground electrode (not shown in FIG. 1 ) can be placed in the container 106 to minimize the effects of ground variations.

[0013] The digital processing block 120 may include one or more digital processing circuits coupled to the analog processing block 110, such as using one or more digital-to-analog converters to convert analog signals to digital signals (also referred to as digital values ​​or counts). In some embodiments, the analog processing block 110 measures currents at one or more frequencies and sends the measured currents to the digital processing block 120 for further processing. For example, the analog processing block 110 measures a first set of currents at a first frequency and a second set of currents at a second frequency. The analog processing block 110 converts the first set of currents and the second set of currents to digital values ​​representing the first and second currents. The digital processing block 120 uses the digital values ​​representing the first and second set of currents to determine the independent impedances of the container 106, the liquid 108, and the liquid 108 and the container 106. In another embodiment, analog processing block 110 measures the capacitance (or charge indicative of the capacitance) associated with electrodes located on the exterior surface of container 106 and converts the capacitance into a digital value that digital processing block 120 uses to determine digital values ​​indicative of the first and second currents, which in turn use the digital values ​​indicative of the first and second set of currents to digital values ​​indicative of container 106, liquid 108, and the independent impedances of liquid 108 and container 106. Digital processing block 120 uses the digital values ​​indicative of the independent impedances of liquid 108 to determine the electrical properties of liquid 108.

[0014] In one embodiment, the processing device 100 hardware measures all currents within the configuration of the container 106, which includes at least the first electrode 102 and the second electrode 104. The processing device 100 can execute methods, such as firmware, to process the measured currents and determine liquid properties, such as the conductivity of the liquid 108 and the permittivity of the liquid 108. In some examples, a first set of electrodes is aligned on a first side of the container 106 and a second set of electrodes is aligned on a second side of the container 106, such that the level of the liquid 108 can be determined using the first and second sets of electrodes. The level of the liquid 108 can be used to determine a geometric model for determining the electrical properties of the liquid 108. The geometric parameters and the liquid level can link the resistance and capacitance of the liquid to the conductivity and permittivity. The geometric model can be simulated or measured for a particular liquid container and sensor design. The geometric parameters can be defined by the geometry of the liquid. If liquid is present in the container and can occupy different levels, the geometric parameters may vary. Combining liquid level and liquid properties can improve overall accuracy. Temperature sensors can also be used to classify liquids, as the electrical properties of liquids can change with temperature. To compensate for the variations in properties, a temperature sensor can be used.

[0015] In one embodiment, analog processing block 110, operating at a first frequency, measures a first current indicative of the self-capacitance of first electrode 102 and a second current indicative of the mutual capacitance between first electrode 102 and second electrode 104. Analog processing block 110, digital processing block 120, or both, can use the first and second currents to determine a third current flowing through ambient ground 124 at the first frequency. Analog processing block 110, operating at a second frequency different from the first frequency, measures a fourth current indicative of the self-capacitance of first electrode 102 and a fifth current indicative of the mutual capacitance between first electrode 102 and second electrode 104. As discussed herein, the second frequency can be lower or higher than the first frequency. Analog processing block 110, digital processing block 120, or both, can use the fourth current and the fifth current to determine a sixth current flowing through ambient ground 124 at the second frequency. Note that analog processing block 110 can convert the charge, capacitance, and impedance measurements into digital values, and digital processing block 120 can determine digital values ​​indicative of the charge, capacitance, and impedance measured by analog processing block 110.

[0016] In another embodiment, analog processing block 110 operating at a first frequency measures a first current indicative of the self-capacitance of first electrode 102 and a second current indicative of the self-capacitance of second electrode 104. Analog processing block 110, digital processing block 120, or both, can use the first and second currents to determine a third current flowing through ambient ground 124 at the first frequency. Analog processing block 110 operating at a second frequency different from the first frequency measures a fourth current indicative of the self-capacitance of first electrode 102 and a fifth current indicative of the self-capacitance of second electrode 104. Analog processing block 110, digital processing block 120, or both, can use the fourth and fifth currents to determine a sixth current flowing through ambient ground 124 at the second frequency.

[0017] In one embodiment, the digital processing block 120 determines the independent impedances of the container, the liquid, and the liquid and the container by determining the total impedance of the container 106 and the liquid 108 and the impedance of the container 106. The digital processing block 120 determines the total impedance of both the container 106 and the liquid 108 using a first current, a second current, and a third current flowing through the ambient ground 124 at a first frequency. The first current represents the self-capacitance of the first electrode 102, which may be located at a first point on the exterior surface of the container 106. The first electrode 102 may be part of a first set of electrodes. The second current represents the mutual capacitance between the first electrode 102 and the second electrode 104, which may be located at a second point on the exterior surface of the container. The second electrode 104 may be part of the first set of electrodes. In conjunction with, or in addition to, determining the electrical properties of the liquid 108, multiple sets of electrodes can be used to determine the level of the liquid 108. The digital processing block 120 uses digital values ​​corresponding to the fourth, fifth, and sixth currents flowing through the ambient ground 124 at the second frequency to determine a digital value indicative of the impedance of the container. The fourth current is indicative of the self-capacitance of the first electrode 102, and the fifth current is indicative of the mutual capacitance between the first electrode 102 and the second electrode 104. The digital processing block 120 uses the total impedance of the container 106 and the liquid 108 and the impedance of the container 106 to determine the impedance of the liquid 108.

[0018] 1, the multi-port network may include multiple switches, such as a first switch 116, a second switch 118, and a third switch 122. The first switch 116, the second switch 118, and the third switch 122 may be used to connect the first electrode 102 and the second electrode 104 to the signal generator 112, the receiver channel 114, the ambient ground 124, or any combination thereof. In another embodiment, the multi-port network may include multiple multiplexers, such as those shown in FIGS. 5A and 6.

[0019] As shown in Figure 1, the multi-port network is capable of coupling to a single receiver channel, receiver channel 114. In other embodiments, the multi-port network is capable of coupling to multiple receiver channels, such as a first receiver channel coupled to a first electrode 102 and a second receiver channel coupled to a second electrode 104, as shown in Figure 5B.

[0020] In one embodiment, the analog processing block 110 can use low- and high-frequency harmonic excitation signals to eliminate the effects of the physical characteristics of the container 106, such as the effects of a plastic container. The low- and high-frequency excitation signals allow a multi-port network to be used to measure currents in complex forms for various excitation source locations. The digital processing block 120 can implement a method for processing the measured currents using two or more circuit models. The circuit models are used to calculate the independent impedances of the system. After the impedances are determined, the digital processing block 120 can calculate the liquid electrical properties of the liquid 108 using geometric models. In one embodiment, the method calculates the independent impedances and calculates the liquid electrical properties of the liquid 108, which are performed in firmware executed by the processing device 100. Alternatively, the processing device 100 can implement the method using synthesis logic, a hardware accelerator, a hardware state machine, or the like.

[0021] It should be noted that although shown as dashed boxes within analog processing block 110 for ease of illustration, container 106 and first and second electrodes 102, 104 are not part of the analog processing block, but rather first and second electrodes 102, 104 are coupled to the exterior of container 106 and coupled to terminals of processing device 100, such as general purpose input / output (GPIO) pins.

[0022] While Figure 1 illustrates and describes a detailed analysis for a three-port solution, in other embodiments, additional ports can be used, with more ports resulting in a more accurate solution.

[0023] 2 is a flow diagram of processing stages of a processing device 200 with non-contact liquid sensing, according to at least one embodiment. Processing device 200 is similar to processing device 100, as indicated by like reference numerals. Processing device 200 has at least three stages: a first stage 210, a second stage 212, and a third stage 214. In first stage 210, analog processing block 110 can measure a first set of currents associated with a first set of electrodes at a first frequency (f0), the first set of electrodes being located on the exterior surface of a container 206 holding a liquid 208. In one embodiment, analog processing block 110 can measure a self-current I1 (I a ) and mutual current I2 (I m By measuring the self-current I1 and the mutual current I2, a third current I3 (I g(also referred to as ) can be determined. Such measurements can be performed for high excitation frequencies to obtain the total impedance of the container 206 and the liquid 208. In the first stage 210, the analog processing block 110 can measure a second set of currents associated with the first set of electrodes at a second frequency (f1), the second frequency being lower than the first frequency. As described herein, the excitation frequencies can be different first and second excitation frequencies. At low frequencies, the liquid 208 behaves as a conductor, and the impedance of the material of the container 206 can be isolated. For example, the container 206 can be plastic, and the liquid 208 behaves as a conductor compared to the plastic of the container 206, allowing the properties of the plastic to be determined. As a result, it is possible to extract the liquid impedance from the total impedance and the impedance of the container 206. In the first stage 210, the analog processing block 110 can output or otherwise store the measured currents 201, where the measured currents 201 include at least the first set of currents and the second set of currents.

[0024] In the second stage 212, the digital processing block 120 can process the measured currents 201 and, using a circuit model, can determine the independent impedances of the container 206, the liquid 208, and the liquid 208 and container 206 together at the first frequency and the second frequency using the first set of currents and the second set of currents. Additional details of the circuit model are described below with respect to FIG. 4. In the second stage 212, the digital processing block 120 can output or otherwise store the liquid impedance 203, which includes the independent impedances.

[0025] In a third stage 214, the digital processing block 120 can process the liquid impedance 203 and, using a geometric model of the container 206, determine an electrical property of the liquid using the independent impedance of the liquid 208. In the third stage 214, the digital processing block 120 can output or otherwise store one or more electrical properties 205 of the liquid 208.

[0026] In at least one embodiment, in the first stage 210, the analog processing block 110 measures a first current indicative of the self-capacitance of a first electrode (e.g., 102) of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container 206. The analog processing block 110 measures a second current indicative of the mutual capacitance between a first electrode (e.g., 102) of the first set of electrodes and a second electrode (e.g., 104) of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container 206. In the first stage 210, the analog processing block 110 or the digital processing block 120 uses the first current and the second current to determine a third current flowing through the ambient ground at a first frequency. In at least one embodiment, in the first stage 210, the analog processing block 110 measures a fourth current indicative of the self-capacitance of the first electrode (e.g., 102) and a fifth current indicative of the mutual capacitance between the first electrode (e.g., 102) and the second electrode (e.g., 104). In the first stage 210, the analog processing block 110 or the digital processing block 120 uses the fourth current and the fifth current to determine a sixth current flowing in the ambient ground (e.g., 124) at the second frequency.

[0027] In at least one embodiment, in the first stage 210, the analog processing block 110 measures a first current indicative of the self-capacitance of a first electrode (e.g., 102) of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container 206. A second current indicative of the self-capacitance of a second electrode (e.g., 104) of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container 206. In the first stage 210, the analog processing block 110 or the digital processing block 120 uses the first current and the second current to determine a third current flowing through the ambient ground at the first frequency.

[0028] In at least one embodiment, in the first stage 210, the analog processing block 110 measures the first set of currents (and the second set of currents) using multiple multiplexers and a sinusoidal floating ground sensing technique. The analog processing block 110 may include a signal generator that generates an excitation signal having a sine wave. The multiple multiplexers may be configured to couple the signal generator to either the first electrode or the second electrode. The multiple multiplexers may connect the first electrode to ground or a receiver channel, and the second electrode to ground or a receiver channel.

[0029] In at least one embodiment, in the first stage 210, the analog processing block 110 measures the first set of currents (and the second set of currents) using multiple receiver channels and a sinusoidal floating ground sensing technique. For example, a first measurement channel of the analog processing block 110 measures a first current indicative of the self-capacitance of a first electrode of the first set of electrodes, and a second measurement channel of the analog processing block 110 measures a second current indicative of the mutual capacitance between the first electrode and a second electrode of the first set of electrodes. The analog processing block 110 or the digital processing block 120 uses the first and second currents to determine a third current flowing through the ambient ground of the vessel at the first frequency. Similarly, a sixth current flowing through the ambient ground at the second frequency can be determined in a similar manner using the fourth and fifth currents.

[0030] In at least one embodiment, in the second stage 212, the digital processing block 120 determines a total impedance of the container 206 and the liquid 208 together using digital values ​​representing the first, second, and third currents flowing through the ambient ground at the first frequency. The first current can represent the self-capacitance of a first electrode of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container. The second current can represent the mutual capacitance between the first and second electrodes of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container. The digital processing block 120 determines the impedance of the container 206 using digital values ​​representing the fourth, fifth, and sixth currents flowing through the ambient ground at the second frequency. The fourth current can represent the self-capacitance of the first electrode. The fifth current can represent the mutual capacitance between the first and second electrodes. The digital processing block 120 determines the impedance of the liquid 208 using the total impedance of the container 206 and the liquid 208 and the impedance of the container 206. Additional details of determining and removing the effect of the dielectric walls of the container to calculate the liquid properties are shown and described below with reference to FIG.

[0031] In at least one embodiment, in the third stage 214, the digital processing block 120 determines the electrical properties of the liquid 208 by converting the impedance of the liquid 208 into an electrical property using a geometric model.

[0032] 3 is a flow diagram of a processing sub-stage 300 of a processing device with non-contact liquid sensing, according to at least one embodiment. The processing device with processing sub-stage 300 is similar to processing device 100 and processing device 200, as indicated by like reference numerals. The processing device has at least three stages: a first stage 210, a second stage 212, and a third stage 214, and during the second stage 212, the digital processing block 120 processes digital values ​​representing the currents measured in the three sub-stages (first sub-stage 312, second sub-stage 314, and third sub-stage 316). As described above, by measuring the self-current I1 and the mutual current I2, a third current I3 (I g3 ) can be determined. Such measurements can be performed for high excitation frequencies to obtain the total impedance of the container 306 and the liquid 308. These currents can be converted to digital values ​​for processing by the digital processing block 120. In the first sub-stage 312, the analog processing block 110 can determine all currents, including the first current 301, the second current 303, and the third current (not labeled in FIG. 3 ), flowing through the ambient ground 324 and convert the first current 301, the second current 303, and the third current to digital values. The digital processing block 120 uses the digital values ​​representing the currents to calculate the impedance at the first frequency (f0). That is, the signal generator 312 operates at the first frequency (f0). At low frequencies, the liquid 308 behaves as a conductor and can isolate the impedance of the material of the container 306. In the second sub-stage 314, the digital processing block 120 (or the analog processing block 110) can determine all currents, including the fourth current 305, the fifth current 307, and the sixth current (not labeled in FIG. 3 ) flowing through the ambient ground 324, and use the currents to calculate the impedance at a second frequency (f1) lower than the first frequency (f0). That is, the signal generator 312 operates at the second frequency (f1). For example, the container 306 can be plastic, and the liquid 308 can behave as a conductor compared to the plastic of the container 306. As shown in the third sub-stage 314, the plastic characteristics can be determined and removed to isolate the impedance of the liquid 308. In the third sub-stage 314, the impedance of the container 306 determined in the second sub-stage 314 can be subtracted from the total impedance determined in the first sub-stage 312 to obtain the impedance of the liquid 308.

[0033] In at least one embodiment, different topologies of a hardware circuit, such as a hardware circuit using a multi-port network, may have corresponding equivalent electrical circuits as shown in Figures 4A-4C and shown in Table 1 below.

[0034] 4A-4C are circuit diagrams of a first circuit model, a second circuit model, and a third circuit model, according to various embodiments. The first circuit model, the second circuit model, and the third circuit model are equivalent circuits used to calculate the total impedance, the impedance of the container, and ultimately the impedance of the liquid held in the container. For example, these equivalent circuits can be used to calculate the impedance of the plastic and the liquid. At least one advantage of such a circuit representation is that the impedance of the T-type equivalent circuit, as shown in FIGS. 4A-4C, is independent of the excitation source or load connections. As a result, different source connections create four linearly independent equations that can be solved to determine the impedance: [Table 1] This becomes:

[0035] 4A, a first circuit model 400 includes a signal generator 412 coupled to a first electrode (e.g., 102). The signal generator 412 is used to generate a self-current 402 (I a ) and mutual current 404 (I m ) can be measured using the voltage of the signal generator 412 and four linearly independent equations to calculate the first impedance 401 (Z pw,a ) and a second impedance 403 (Z pw,m ) and a third impedance 405 (Z pw,g For example, the equations of the first circuit model 400 can be used to determine the following equation (1):

number

[0036] 4B, a second circuit model 420 includes a signal generator 412 coupled to a second electrode (e.g., 102), but is otherwise similar to the first circuit model 400. The signal generator 412 is used to generate a self-current 422 (I a ) and mutual current 424 (I m ) can be measured. Using the voltage of the signal generator 412, the fourth impedance 421 (Z pw,a ) and the fifth impedance 423 (Z pw,m ) and the sixth impedance 425 (Z pw,g For example, the equations of the second circuit model 420 can be used to determine the mixed impedance Z of the system for high frequency measurements, as shown in equation (1) above. pw,a , Z pw,m and Z pw,g (The mixed impedance includes the impedance of the container and the liquid together).

[0037] 4C, a third circuit model 440 includes a signal generator 412 coupled to both a first electrode (e.g., 102) and a second electrode (e.g., 104). The signal generator 412 is used to generate a self-current 442 (I a ) and mutual current 444 (I m ) can be measured using the voltage of the signal generator 412 and the seventh impedance 441 (Z pw,a ) and the eighth impedance 443 (Z pw,m ) and the ninth impedance 445 (Z pw,g For example, the equations of the third circuit model 440 can be used to determine the mixed impedance Z of the system for high frequency measurements, as shown in equation (1) above. pw,a , Z pw,m , and Z pw,g (The mixed impedance includes the impedance of the container and the liquid together) For low frequency measurements, the following equation (2) is used:

number

[0038] Mixed impedance Z pw,a , Z pw,m and Z pw,g and the container impedance Z p,a , Z p,m and Z p,g Using and, the liquid impedance is given by the following equation (3): Z w,a =Z pw,a -Z p,a Z w,m =Z pw,m -Z p,m Z w,g =Z pw,g -Z p,g It can be calculated as shown below.

[0039] The liquid impedance is given by the following equation (4): Z w =Z w,a +Z w,m Y w =Z w -1 =G+iωC can be converted into capacitance and resistance as shown below.

[0040] The geometric parameters of the container can be simulated or measured. The simulated or measured geometric parameters (g C and g G ) to obtain Eq. (5), i.e.

number

[0041] The permittivity (ε) and conductivity (σ) are examples of electrical properties of a liquid that can be calculated. Note that the geometric parameters define the flow of current through the liquid from a first electrode (e.g., the Tx electrode) to a second electrode (e.g., the Rx electrode) without ground effects.

[0042] It should be noted that the self-current and the mutual current can be measured separately or simultaneously.

[0043] Referring back to Figure 3, to determine one or more electrical properties of the liquid in the container, the steps of measuring the mixed impedance using high-frequency excitation, defining the ground effect, estimating the impedance of the container wall using low-frequency excitation, defining the ground effect, dividing the liquid and plastic impedances, removing the effects of the container wall (e.g., the plastic wall), selecting appropriate electrodes for evaluating the liquid's electrical parameters (e.g., liquid level solution only), and converting the liquid impedance to liquid electrical parameters using geometric parameters can be performed. Note that the order is not important and the sequence of low-frequency and high-frequency measurements can be reversed.

[0044] FIG. 5A is a circuit diagram of a capacitance measurement circuit 500 with multiple multiplexers for contactless liquid sensing, according to at least one embodiment. The capacitance measurement circuit 500 includes a signal generator 512 that generates an excitation signal, receiver channels 510 (charge or current measurement circuits), a first multiplexer 514, and a second multiplexer 516. The first multiplexer 514 and the second multiplexer 516 can be part of a multi-port network that allows various connections between the signal generator 512, the receiver channels 510, and the first electrode 502 and the second electrode 504. As shown in FIG. 5A, the first multiplexer 514 is coupled to the first electrode 502, and the second multiplexer 516 is coupled to the second electrode 504. As described above, the first electrode 502 and the second electrode 504 are located on the exterior surface of a container 506 that holds a liquid 508. The container 506 has an ambient ground 524 caused by the environment. A first multiplexer 514 is coupled to the ambient ground 524, the signal generator 512, and the receiver channels 510. A second multiplexer 516 is coupled to the ambient ground 524, the signal generator 512, and the receiver channels 510. The first and second multiplexers 514 and 516 can be used to selectively connect the receiver channels 510 to one or both of the first electrode 502 and the second electrode 504. The first and second multiplexers 514 and 516 can be used to selectively connect the signal generator 512 to one or both of the first electrode 502 and the second electrode 504. The first and second multiplexers 514, 516 can be used to selectively connect the ambient ground 524 to one or both of the first electrode 502 and the second electrode 504. The signal generator 512 can also be selectively coupled to the receiver channel 510, the first multiplexer 514, and the second multiplexer 516 using a switch 518. In this embodiment, the receiver channel 510 can be a single receiver channel used for both measuring the self-current and the mutual current, as described herein. Alternatively, different circuits can be used to measure the self-current and the mutual current separately.In other embodiments, multiple receiver channels, multiple signal generators, or both multiple receiver channels and multiple signal generators can be used, as shown in FIG. 5B.

[0045] FIG. 5B is a circuit diagram of a capacitance measurement circuit 520 with multiple receiver channels for non-contact liquid sensing, according to at least one embodiment. The capacitance measurement circuit 520 includes a signal generator 512 that generates an excitation signal, a receiver channel 510, a second signal generator 522, and a second receiver channel 530. As shown in FIG. 5B, the receiver channel 510 is coupled to a first electrode 502, and the second receiver channel 530 is coupled to a second electrode 504. As described above, the first electrode 502 and the second electrode 504 are located on the exterior surface of a container 506 that holds a liquid 508. The container 506 has an ambient ground 524. The signal generator 512 can also be selectively coupled to the receiver channel 510 using a switch 518, and the second signal generator 522 can be selectively coupled to the second receiver channel 530 using a second switch 528. In this embodiment, receiver channel 510 and second receiver channel 530 may be receiver channels used in different combinations for both self-current and mutual current measurements, as described herein. Alternatively, different circuits with each receiver channel may be used to measure the self-current and mutual current separately.

[0046] It should be noted that current can be measured by connecting to different electrodes, and current to or from different electrodes can be measured for data processing. Current measurement can be performed as a sinusoidal floating ground sensing technique using a multiplexer, as shown in FIG. 5A. Current measurement can be performed as a sinusoidal floating ground sensing technique using multiple channels, as shown in FIG. 5B. In other embodiments, other circuits can be used to create a similar low-power source solution by combining a floating ground with sinusoidal excitation using self-capacitance and mutual capacitance measurements, as shown in FIG. 6. This provides a multi-electrode, non-contact liquid property sensing solution.

[0047] 6 is a circuit diagram of a charge measurement circuit 600 with a receiver channel 610 (e.g., a charge-to-code converter) and a floating ground signal generator 612 for contactless liquid sensing, according to at least one embodiment. The charge measurement circuit 600 is similar to the capacitance measurement circuit 500, as indicated by like reference numerals, but the receiver channel 610 can operate with or without a floating ground. The floating ground signal generator can be used as a power ground for an operational amplifier that is different from earth ground.

[0048] As mentioned above, the embodiments described herein are multi-port networks for determining current flow in a container configuration and extracting liquid properties, rather than using approaches that only measure self-capacitance or mutual capacitance. Using a multi-port network such as that shown in FIG. 1 and combining self-capacitance and mutual-capacitance sensing over multiple frequency ranges, environmental parameters can be determined, thereby separating liquid properties from properties of the container and environment. Other charge measurement solutions can be used in other embodiments.

[0049] Some electrodes may induce different parasitic capacitances during operation. To maintain the properties of the equivalent electrical circuit model as described in Table 1 above, greater accuracy can be achieved by using active shield and ground electrodes as shown in Figure 7A.

[0050] 7A illustrates a sensor configuration 700 with a first electrode, an active shield electrode, a second electrode, and two ground shield electrodes, according to at least one embodiment. The sensor configuration 700 includes a first electrode 702 located on a first side of a container 706 holding a liquid 708, a second electrode 704 located on a second side of the container 706, and an active shield electrode 710 disposed near the first electrode 702. The first ground shield electrode 712 is disposed near the first electrode 702, and the second ground shield electrode 714 is disposed near the second electrode 704. As discussed above, the active shield electrode 710, the ground shield electrode, or both can be used to achieve more accurate measurements.

[0051] The embodiments described herein enable the measurement of the permittivity and conductivity of a liquid. The embodiments described herein are insensitive to the ground and fluctuating properties of the dielectric walls. As described herein, self-current and mutual current measurements can eliminate the effects of grounding that may be present in some environmental conditions. High-frequency and low-frequency measurements allow the electrical properties of the liquid and container to be determined separately, providing a solution that is independent of manufacturing tolerances, temperature, and wall coatings. By combining the multi-port network and algorithms described herein, absolute values ​​of the liquid's electrical properties can be defined, stabilizing the solution against films and bubbles that may be present on the container walls. In some embodiments, standalone liquid level sensing can be performed. In other embodiments, liquid level sensing can be combined with liquid property sensing to achieve better accuracy, as shown in FIG. 7B. Note that in other embodiments, different ground electrodes or electrodes with different potentials can be present to minimize the effects of grounding. In other embodiments, self-capacitance measurements alone can be used, but this may result in less accurate liquid property estimation. In the equivalent electrical circuit, as set forth in Table 1 above, the current from the source at the two electrodes is measured, and the current passing through the liquid in the container is not measured.

[0052] FIG. 7B illustrates a sensor configuration 720 including a transmitter electrode on one side of a container and a set of receiver electrodes on the other side of the container, according to at least one embodiment. The sensor configuration 720 includes a first transmitter electrode 722 located on a first side of the container and a set of receiver electrodes 724 located on a second side of the container. The first transmitter electrode 722 can extend in a first direction across the height of the container. Meanwhile, the set of receiver electrodes 724 collectively extend in the first direction across the height of the container, but each electrode in the set of receiver electrodes is smaller in size than the transmitter electrode 722. An excitation signal can be applied to the transmitter electrode 722 and measured at each electrode in the set of electrodes 724 to determine a level 726 of a liquid 728 held by the container. Liquid property sensing, as described above, can be combined with liquid level sensing, as described above. Accordingly, different electrode combinations and numbers can be used in the multiport networks and sensing algorithms described herein. For example, one of the electrodes 724 covered by the liquid 728 can be used as a receiver, and the others can be used as transmitters. It should be noted that there can be implementations other than that shown in FIG. 7B for determining the level of liquid held by the container.

[0053] FIG. 8 is a flow diagram of a method 800 of operating a processing device for non-contact liquid sensing to determine an electrical property of a liquid in a container, according to at least one embodiment. Method 800 may be performed by processing logic including hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, etc.), software, firmware, or a combination thereof. In one embodiment, method 800 may be performed by any of the circuits described herein. In one embodiment, method 800 is performed by processing device 100 of FIG. 1. In another embodiment, method 800 is performed by processing device 200 of FIG. 2. In another embodiment, method 800 is performed by processing device 3 of FIG. 3. In another embodiment, method 800 is performed by a device including a capacitive touch sensing channel and a processing device coupled to the capacitive touch sensing channel. Alternatively, method 800 may be performed by other circuitry that performs various operations described herein.

[0054] 8 , method 800 begins with processing logic measuring a first set of currents associated with a first set of electrodes at a first frequency, the first set of electrodes being located on an exterior surface of a container holding a liquid (block 802). The processing logic measures a second set of currents associated with the first set of electrodes at a second frequency, different from the first frequency (block 804). The processing logic uses the first set of currents and the second set of currents, using a circuit model, to determine the container, the liquid, and independent impedances of the liquid and the container (block 806). The processing logic uses the independent impedance of the liquid, using a geometric model of the container, to determine an electrical property of the liquid (block 808), and method 800 ends.

[0055] In a further embodiment, processing logic measures the first set of currents by measuring a first current indicative of the self-capacitance of a first electrode of the first set of electrodes and a second current indicative of the mutual capacitance between a first electrode and a second electrode of the first set of electrodes. The first electrode is located at a first point on the exterior surface of the container, and the second electrode is located at a second point on the exterior surface of the container. The processing logic uses the first and second currents to determine a third current flowing through the ambient ground at the first frequency. The processing logic measures the second set of currents by measuring a fourth current indicative of the self-capacitance of the first electrode and a fifth current indicative of the mutual capacitance between the first electrode and the second electrode. The processing logic uses the fourth and fifth currents to determine a sixth current flowing through the ambient ground at the second frequency.

[0056] In at least one embodiment, the processing logic determines the container, the liquid, and the independent impedances of the liquid and the container by determining a total impedance of the container and the liquid using a first current, a second current, and a third current through the ambient ground at a first frequency. The first current indicates a self-capacitance of a first electrode of a first set of electrodes, and the second current indicates a mutual capacitance between a first electrode and a second electrode of the first set of electrodes. The first electrode is located at a first point on an outer surface of the container, and the second electrode is located at a second point on the outer surface of the container. The processing logic determines the container impedance using a fourth current, a fifth current, and a sixth current through the ambient ground at a second frequency. The fourth current indicates a self-capacitance of the first electrode, and the fifth current indicates a mutual capacitance between the first electrode and the second electrode. The processing logic determines the impedance of the liquid using the total impedance of the container and the liquid and the impedance of the container. In at least one embodiment, the electrical properties of the liquid are determined by converting the impedance of the liquid to an electrical property using a geometric model.

[0057] In some embodiments, the processing logic may control one or more multiplexers to measure the current. In other embodiments, the processing logic may control one or more signal generators. The signal generators may be used for sinusoidal floating ground sensing techniques.

[0058] In at least one embodiment, the processing logic uses a first measurement channel to measure a first current indicative of the self-capacitance of a first electrode of the first set of electrodes. The processing logic can use a second measurement channel to measure a second current indicative of the mutual capacitance between a first electrode and a second electrode of the first set of electrodes. The first electrode is located at a first point on the exterior surface of the container, and the second electrode is located at a second point on the exterior surface of the container. The processing logic uses the first current and the second current to determine a third current flowing through the ambient ground at the first frequency.

[0059] In another embodiment, the processing logic measures a first current indicative of a self-capacitance of a first electrode of the first set of electrodes and a second current indicative of a self-capacitance of a second electrode of the first set of electrodes. The first electrode is located at a first point on the exterior surface of the container and the second electrode is located at a second point on the exterior surface of the container. The processing logic uses the first current and the second current to determine a third current flowing through the ambient ground at the first frequency.

[0060] In another embodiment, the method 900 may be performed using more than two frequencies as described herein. Using more frequencies may improve the accuracy of the estimation.

[0061] FIG. 9 is a flow diagram of a method 900 for determining an electrical property of a liquid in a container, according to at least one embodiment. Method 900 may be performed by processing logic, including hardware (e.g., circuitry, dedicated logic, programmable logic, microcode, etc.), software, firmware, or a combination thereof. In one embodiment, method 900 may be performed by any of the circuits described herein. In one embodiment, method 900 is performed by processing device 100 of FIG. 1. In another embodiment, method 900 is performed by processing device 200 of FIG. 2. In another embodiment, method 900 is performed by processing device 3 of FIG. 3. In another embodiment, method 900 is performed by an apparatus including a capacitive touch sensing channel and a processing device coupled to the capacitive touch sensing channel. Alternatively, method 900 may be performed by other circuitry that performs various operations described herein.

[0062] Returning to FIG. 9 , method 900 begins by processing logic measuring a first current indicative of the self-capacitance of a first electrode at a first frequency and a second current indicative of the mutual capacitance between the first electrode and a second electrode at the first frequency (block 902). The first electrode is located at a first point on an exterior surface of a container holding a liquid, and the second electrode is located at a second point on the exterior surface of the container. Processing logic measures a third current indicative of the self-capacitance of the first electrode at a second frequency and a fourth current indicative of the mutual capacitance between the first electrode and the second electrode at the second frequency (block 904). Processing logic uses the first current and the second current to determine a fifth current flowing through the ambient ground at the first frequency, and uses the third current and the fourth current to determine a sixth current flowing through the ambient ground at the second frequency (block 906). The ambient ground cannot be removed because it is coupled to surrounding objects. Processing logic determines a first set of impedances at a first frequency using the first, second, and fifth currents, and a second set of impedances at a second frequency using the third, fourth, and sixth currents (block 908). The first set of impedances corresponds to the total impedance of the container and liquid, and the second set of impedances corresponds to the impedance of the container. Processing logic determines a third set of impedances by subtracting the second set of impedances from the first set of impedances (block 910). The third set of impedances corresponds to the impedance of the liquid held in the container. Processing logic determines an electrical property of the liquid using the third set of impedances corresponding to the impedance of the liquid (block 912), and method 900 ends.

[0063] In a further embodiment, the first frequency is higher than the second frequency, and the second frequency corresponds to a frequency at which the liquid behaves as a conductor relative to the type of material used in the container. In at least one embodiment, the first electrode is part of a first set of electrodes and the second electrode is part of a second set of electrodes. The first set of electrodes and the second set of electrodes can be positioned to correspond to different levels of liquid in the container. The processing logic uses the first set of electrodes and the second set of electrodes to determine the current level of the liquid in the container.

[0064] In at least one embodiment, the processing logic determining the first set of impedances includes solving a first system of equations using the first, second, and fifth currents and at least two circuit models, each having a T-type equivalent circuit. The T-type equivalent circuits have a first impedance at the first electrode, a second impedance at the second electrode, and a third impedance at the ambient ground. The processing logic determining the second set of impedances includes solving a second system of equations using the third, fourth, and sixth currents and at least two circuit models. In a further embodiment, the processing logic determines at least one of a liquid permittivity or a liquid conductivity using the third set of impedances and a set of geometric parameters of the container.

[0065] In the foregoing description, some of the detailed descriptions are presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is generally conceived to be a self-consistent sequence of steps leading to a desired result. The steps require physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It is sometimes convenient, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like.

[0066] It should be noted, however, that all of these and similar terms are associated with the appropriate physical quantities and are merely informative labels applied to these quantities. As is apparent from the above discussion, unless expressly stated otherwise, descriptions herein using terms such as "determining," "allocating," "dynamically allocating," "redistributing," "ignoring," "reallocating," "detecting," "executing," "polling," "registering," "monitoring," and the like are understood to refer to the actions and processes of a computing system or similar electronic computing device that manipulate and convert data represented as physical (e.g., electronic) quantities in the registers and memory of the computing system into other data that is similarly represented as physical quantities in the memory or registers of the computing system or other such information storage, transmission, or display device.

[0067] The terms "example" or "exemplary" are used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "example" or "exemplary" should not necessarily be construed as preferred or advantageous over other aspects or designs. Rather, use of the word "example" or "exemplary" is intended to present a concept in a concrete manner. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless expressly stated otherwise or clear from the context, "X includes A or B" is intended to mean any of the natural inclusive permutations. That is, "X includes A or B" is satisfied if X includes A, or X includes B, or X includes both A and B, in any of the foregoing cases. Furthermore, as used in this specification and the appended claims, the articles "a" and "an" should be construed generally to mean "one or more" unless specified otherwise or the context clearly directs to the singular form. Furthermore, use of the terms "embodiment" or "one embodiment" or "embodiment" or "one embodiment" throughout is not intended to refer to the same embodiment or embodiments unless so described.

[0068] The embodiments described herein may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes. Alternatively, this apparatus may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored on any type of non-transitory computer-readable storage medium, such as a disk, including, but not limited to, floppy disks, optical disks, CD-ROMs and magneto-optical disks, read-only memory (ROM), random-access memory (RAM), EPROM, EEPROM, magnetic or optical cards, flash memory, or any type of medium suitable for storing electronic instructions. The term "computer-readable storage medium" should be interpreted to include a single medium or multiple media (e.g., centralized or distributed databases and / or associated caches and servers) that store one or more sets of instructions. The term "computer-readable medium" should also be interpreted to include any medium that can store, encode, or transmit a set of instructions for execution by a machine, causing the machine to perform any one or more of the methodologies of the present embodiments. Accordingly, the term "computer-readable storage medium" is intended to include, but is not limited to, solid-state memory, optical media, magnetic media, and any medium capable of storing a set of instructions for execution by a machine, thereby causing the machine to execute any one or more of the methodologies of the present embodiments.

[0069] The methods and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs in accordance with the teachings herein, or it may prove beneficial to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent from the description below. Moreover, the present embodiments are not described with reference to any particular programming language. It will be understood that a variety of programming languages ​​can be used to implement the teachings of the embodiments described herein.

[0070] The above description sets forth numerous specific details, such as examples of particular systems, components, methods, etc., to provide a thorough understanding of some embodiments of the present disclosure. It is to be understood that the above description is intended to be illustrative, and not limiting. Many other embodiments will be apparent to those skilled in the art upon reading and understanding the above description. Accordingly, the scope of the present disclosure should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. 1. A method comprising: measuring, with a processing unit, a first set of currents associated with a first set of electrodes at a first frequency, the first set of electrodes being located on an exterior surface of a container holding a liquid; measuring, with the processing unit, a second set of currents associated with the first set of electrodes at a second frequency lower than the first frequency; determining, by the processing unit, using a circuit model, independent impedances of the container, the liquid, and the liquid and container using the first set of currents and the second set of currents; determining, by the processing unit, an electrical property of the liquid using the independent impedance of the liquid using a geometric model of the container; A method comprising:

2. The step of measuring the first set of currents comprises: measuring, with the processing device, a first current indicative of a self-capacitance of a first electrode of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container; measuring, with the processing device, a second current indicative of mutual capacitance between the first electrode and a second electrode of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container; determining, by the processing unit, a third current flowing through the ambient ground at the first frequency using the first current and the second current; Including, The method of claim 1.

3. The step of measuring the second set of currents comprises: measuring, with the processing device, a fourth current indicative of the self-capacitance of the first electrode; measuring, with the processing device, a fifth current indicative of mutual capacitance between the first electrode and the second electrode; determining, by the processing unit, a sixth current flowing through the ambient ground at the second frequency using the fourth current and the fifth current; Including, The method of claim 2.

4. determining independent impedances of the container, the liquid, and the liquid and the container using the first set of currents and the second set of currents, determining, with the processing device, a total impedance of the container and the liquid using first, second, and third currents flowing through an ambient ground at the first frequency, the first current being indicative of a self-capacitance of a first electrode of the first set of electrodes, the first electrode being located at a first point on an exterior surface of the container, and the second current being indicative of a mutual capacitance between the first and second electrodes of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container; determining, with the processing device, an impedance of the container using a fourth current, a fifth current, and a sixth current flowing through an ambient ground at the second frequency, the fourth current being indicative of a self-capacitance of the first electrode and the fifth current being indicative of a mutual capacitance between the first electrode and the second electrode; determining, by the processing device, the impedance of the liquid using the total impedance of the container and the liquid and the impedance of the container; Including, The method of claim 1.

5. determining the electrical properties of the liquid includes converting the impedance of the liquid to an electrical property using the geometric model; The method of claim 4.

6. measuring the first set of currents includes measuring the first set of currents using a plurality of multiplexers and a sinusoidal floating ground sensing technique; The method of claim 1.

7. The step of measuring the first set of currents comprises: measuring, with a first measurement channel of the processing device, a first current indicative of a self-capacitance of a first electrode of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container; measuring, with a second measurement channel of the processing device, a second current indicative of mutual capacitance between the first electrode and a second electrode of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container; determining, by the processing unit, a third current flowing through the ambient ground at the first frequency using the first current and the second current; Including, The method of claim 1.

8. The step of measuring the first set of currents comprises: measuring, with the processing device, a first current indicative of a self-capacitance of a first electrode of the first set of electrodes, the first electrode being located at a first point on the exterior surface of the container; measuring, with the processing device, a second current indicative of a self-capacitance of a second electrode of the first set of electrodes, the second electrode being located at a second point on the exterior surface of the container; determining, by the processing unit, a third current flowing through the ambient ground at the first frequency using the first current and the second current; Including, The method of claim 1.

9. 1. A method comprising: measuring with a processing device a first current indicative of self-capacitance of a first electrode at a first frequency and a second current indicative of mutual capacitance between the first electrode and a second electrode at the first frequency, the first electrode being located at a first point on an exterior surface of a container holding a liquid and the second electrode being located at a second point on the exterior surface of the container; measuring, with the processing device, a third current indicative of the self-capacitance of the first electrode at a second frequency, and a fourth current indicative of the mutual capacitance between the first electrode and the second electrode at the second frequency; determining, with the processing device, a fifth current flowing in the ambient ground at the first frequency using the first current and the second current, and a sixth current flowing in the ambient ground at the second frequency using the third current and the fourth current, the ambient ground being caused by coupling to surrounding objects; determining, with the processing unit, a first set of impedances at the first frequency using the first, second, and fifth currents and a second set of impedances at the second frequency using the third, fourth, and sixth currents, the first set of impedances corresponding to a total impedance of the container and the liquid, and the second set of impedances corresponding to an impedance of the container; determining, with the processing unit, a third set of impedances by subtracting the second set of impedances from the first set of impedances, the third set of impedances corresponding to the impedance of the liquid held in the container; determining, by the processing unit, an electrical property of the liquid using the third set of impedances corresponding to the impedance of the liquid; A method comprising:

10. the first frequency is higher than the second frequency, the second frequency corresponding to a frequency at which the liquid behaves as a conductor compared to the type of material used in the container; 10. The method of claim 9.

11. the first electrode is part of a first set of electrodes and the second electrode is part of a second set of electrodes, the first set of electrodes and the second set of electrodes being positioned to correspond to different levels of liquid in the container; The method further includes determining a current level of the liquid in the container using the first set of electrodes and the second set of electrodes.

10. The method of claim 9.

12. determining the first set of impedances includes solving a first set of simultaneous equations using the first, second, and fifth currents and at least two circuit models each having a T-type equivalent circuit, the T-type equivalent circuit having a first impedance at the first electrode, a second impedance at the second electrode, and a third impedance at an ambient ground; determining the second set of impedances includes solving a second system of equations using the third, fourth, and sixth currents and the at least two circuit models; 10. The method of claim 9.

13. determining the electrical property includes determining at least one of a dielectric constant of the liquid or a conductivity of the liquid using the third set of impedances and the set of geometric parameters of the container; 10. The method of claim 9.

14. a multi-port network; a capacitance measurement circuit coupled to the multi-port network; a digital processing circuit coupled to the capacitance measurement circuit; A processing device comprising: the multi-port network is configured to be coupled to a first electrode and a second electrode, the first electrode being located on an exterior surface of a container holding a liquid, and the second electrode being located on the exterior surface of the container; The capacitance measurement circuit measuring a first set of currents associated with the first electrode, the second electrode, and a surrounding ground at a first frequency; measuring a second set of currents associated with the first electrode, the second electrode, and an ambient ground at a second frequency lower than the first frequency; It is structured as follows: The digital processing circuit determining independent impedances of the vessel, the liquid, and the liquid and vessel using the first set of currents and the second set of currents; determining an electrical property of the liquid using the independent impedance of the liquid; It is configured as follows: Processing equipment.

15. The capacitance measurement circuit measuring a first current indicative of the self-capacitance of the first electrode; measuring a second current indicative of the mutual capacitance between the first electrode and the second electrode; It is further structured as follows: the digital processing circuit is further configured to use the first current and the second current to determine a third current flowing through the ambient ground at the first frequency. The processing device of claim 14.

16. The capacitance measurement circuit measuring a fourth current indicative of the self-capacitance of the first electrode; measuring a fifth current indicative of mutual capacitance between the first electrode and the second electrode; It is further structured as follows: the digital processing circuit is further configured to determine a sixth current using the fourth current and the fifth current. The processing device of claim 15.

17. The capacitance measurement circuit measuring a first current indicative of the self-capacitance of the first electrode; measuring a second current indicative of the self-capacitance of the second electrode; It is further structured as follows: the digital processing circuit is further configured to use the first current and the second current to determine a third current flowing through the ambient ground at the first frequency. The processing device of claim 14.

18. To determine the independent impedances of the container, the liquid, and the liquid and container, the digital processing circuit determining a total impedance of the container and the liquid using a first current, a second current, and a third current flowing through an ambient ground at the first frequency, the first current representing a self-capacitance of the first electrode, the first electrode being located at a first point on an exterior surface of the container, and the second current representing a mutual capacitance between the first electrode and a second electrode, the second electrode being located at a second point on the exterior surface of the container; determining an impedance of the container using a fourth current, a fifth current, and a sixth current flowing through an ambient ground at the second frequency, the fourth current being indicative of a self-capacitance of the first electrode and the fifth current being indicative of a mutual capacitance between the first electrode and the second electrode; determining an impedance of the liquid using the total impedance of the container and the liquid and the impedance of the container; and further configured to: The processing device of claim 14.

19. the capacitance measurement circuit includes a signal generator configured to generate an excitation signal, the excitation signal including a sine wave; The processing device of claim 14.

20. The multi-port network comprises: a first multiplexer coupled to the first electrode, the capacitance measurement circuit, the signal generator, and the ambient ground; a second multiplexer coupled to the second electrode, the capacitance measurement circuit, the signal generator, and the ambient ground; Including, 20. The processing device of claim 19.

21. The capacitance measurement circuit a first receiver channel coupled to the first electrode; a second receiver channel coupled to the second electrode; a second signal generator; and Including, 20. The processing device of claim 19.

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