阅读说明：本技术 一种基于平面电极阵列的水质电导率检测方法 (Water conductivity detection method based on planar electrode array ) 是由 王晓磊 王玉皞 于 2020-12-09 设计创作，主要内容包括：本发明提供一种基于平面电极阵列的水质电导率检测方法,包括以下步骤：设计基于平面电极阵列结构的水质电导率检测传感器；传感器包括三组不同电极常数的测量电极对和对应的参考电阻；测量电极对分别为低电极常数测量电极对、中电极常数测量电极对和高电极常数测量电极对；利用传感器进行目标水体的水质电导率检测,分别得到三组不同电极常数的测量电极对测量的水质电导率及其对应的权重系数；根据三组不同电极常数的测量电极对测量的水质电导率及其对应的权重系数,计算得到目标水体最终的水质电导率。本发明的有益效果是：在较低制造成本的情况下的提供宽量程、高精度和稳定性的水体电导率测量。(The invention provides a water conductivity detection method based on a planar electrode array, which comprises the following steps: designing a water conductivity detection sensor based on a planar electrode array structure; the sensor comprises three groups of measuring electrode pairs with different electrode constants and corresponding reference resistors; the measuring electrode pairs are respectively a low electrode constant measuring electrode pair, a middle electrode constant measuring electrode pair and a high electrode constant measuring electrode pair; detecting the water conductivity of the target water body by using a sensor to respectively obtain the water conductivity measured by three groups of measuring electrode pairs with different electrode constants and corresponding weight coefficients; and calculating to obtain the final water conductivity of the target water body according to the measured water conductivity of the three groups of measuring electrode pairs with different electrode constants and the corresponding weight coefficients. The invention has the beneficial effects that: the method provides water conductivity measurement with wide range, high precision and stability under the condition of lower manufacturing cost.)

1. A water conductivity detection method based on a planar electrode array is characterized in that: the method specifically comprises the following steps:

s101: designing a water conductivity detection sensor based on a planar electrode array structure; the sensor comprises three groups of measuring electrode pairs with different electrode constants and reference resistors corresponding to the measuring electrode pairs;

the three groups of measuring electrode pairs with different electrode constants are respectively a low electrode constant measuring electrode pair, a middle electrode constant measuring electrode pair and a high electrode constant measuring electrode pair;

s102: detecting the water conductivity of the target water body by using the sensor to respectively obtain the water conductivity measured by the three groups of measuring electrode pairs with different electrode constants and corresponding weight coefficients, namely the low water conductivity and the weight coefficient thereof, the medium water conductivity and the weight coefficient thereof, and the high water conductivity and the weight coefficient thereof;

s103: and calculating to obtain the final water conductivity of the target water body according to the measured water conductivity of the three groups of measuring electrode pairs with different electrode constants and the corresponding weight coefficients.

2. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 1, wherein: in step S102, the range of the low water conductivity is [ C ]₀,C₁) (ii) a The value range of the conductivity of the medium water is [ C ]₁,C₂) (ii) a The value range of the high water conductivity is [ C ]₂,C₃) (ii) a Wherein C is₀-C₃Are all preset values, and C₀<C₁<C₂<C₃。

3. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 2, wherein: in step S101, the electrode constants of the three sets of measuring electrode pairs with different electrode constants are determined by the shape of the electrode pair, and the calculation formula is as follows (1):

in the formula (1), κ is an electrode constant,s is the distance between the electrode pairs, w is the electrode width, and N is the total number of electrodes; l is the electrode length; k is a first class of complete elliptic integrals, calculated as formula (2):

in the formula (2), k is determined by the electrode shape,t is an integral term and dt is a infinitesimal term.

4. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 3, wherein: in step S102, the calculation formula of the weight coefficient is shown in formula (3):

in the formula (3), sigma is the water conductivity measured by any one group of three groups of measuring electrode pairs with different electrode constants; c_CThe central conductivity of the measuring electrode pair, which is the electrode constant corresponding to σ, is calculated as formula (4):

in the formula (4), C_HMeasuring the maximum value of the range of conductivity for the measuring electrode pair corresponding to the electrode constant of sigma, C_LThe minimum value of the conductivity range is measured for the measuring electrode pair corresponding to the electrode constant of sigma.

5. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 4, wherein: in step S101, a resistance value calculation formula of the reference resistor corresponding to the measurement electrode pair is shown in formula (5):

in the formula (5), R_rIs a reference resistance value.

6. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 5, wherein: in step S101, the three groups of measuring electrode pairs with different electrode constants and the reference resistances corresponding to the measuring electrode pairs are all in series relationship, and the three groups of measuring electrodes with different electrode constantsThe two ends of the pair are respectively provided with an external voltage V₁、V₂。

7. The method for detecting the water conductivity based on the planar electrode array as claimed in claim 6, wherein: in step S102, the formula of the conductivity of the water measured by the measuring electrode pair is shown as formula (6):

8. the method for detecting the water conductivity based on the planar electrode array as claimed in claim 7, wherein: in step S103, the final water conductivity calculation formula of the target water body is as shown in formula (7):

in the formula (7), i is the group number of the measuring electrode pairs with different electrode constants; beta is a_iThe weight coefficient of the water conductivity measured by the electrode pair is measured for the ith group of electrode constants, and the calculation formula is formula (3); sigma_iThe measured water conductivity of the electrode pair is measured for the ith group of electrode constants, and the calculation formula is formula (6).

Technical Field

The invention relates to the field of water quality detection, in particular to a water quality conductivity detection method based on a planar electrode array.

Background

Accurate water quality detection and timely pollution analysis are the basis for effectively treating water pollution. At present, the measurement of corresponding parameters of water bodies by various water quality sensors is the most effective means of water quality detection, wherein the conductivity sensor can reflect the overall situation of inorganic ions in the water bodies and has important significance.

The traditional conductivity sensor generally has only one pair of measuring electrodes, so that the measuring range and the accuracy of the sensor are limited, and the sensor is difficult to adapt to complex and variable water environments.

Disclosure of Invention

In view of this, the present invention provides a method for detecting water conductivity based on a planar electrode array, which is provided with a plurality of pairs of measuring electrodes, and can expand the overall measuring range and improve the measuring accuracy by optimizing and selecting the pairs of measuring electrodes, aiming at the detection defects of the conventional conductivity sensor.

The invention provides a water conductivity detection method based on a planar electrode array, which specifically comprises the following steps:

s101: designing a water conductivity detection sensor based on a planar electrode array structure; the sensor comprises three groups of measuring electrode pairs with different electrode constants and reference resistors corresponding to the measuring electrode pairs;

the three groups of measuring electrode pairs with different electrode constants are respectively a low electrode constant measuring electrode pair, a middle electrode constant measuring electrode pair and a high electrode constant measuring electrode pair;

s102: detecting the water conductivity of the target water body by using the sensor to respectively obtain the water conductivity measured by the three groups of measuring electrode pairs with different electrode constants and corresponding weight coefficients, namely the low water conductivity and the weight coefficient thereof, the medium water conductivity and the weight coefficient thereof, and the high water conductivity and the weight coefficient thereof;

s103: and calculating to obtain the final water conductivity of the target water body according to the measured water conductivity of the three groups of measuring electrode pairs with different electrode constants and the corresponding weight coefficients.

Further, in step S102, the range of the low water conductivity is [ C ]₀,C₁) (ii) a The value range of the conductivity of the medium water is [ C ]₁,C₂) (ii) a The value range of the high water conductivity is [ C ]₂,C₃) (ii) a Wherein C is₀-C₃Are all preset values, and C₀<C₁<C₂<C₃。

Further, in step S101, the electrode constants of the three sets of measuring electrode pairs with different electrode constants are determined by the shape of the electrode pair, and the calculation formula is as follows (1):

in the formula (1), κ is an electrode constant,s is the distance between the electrode pairs, w is the electrode width, and N is the total number of electrodes; l is the electrode length; k is a first class of complete elliptic integrals, calculated as formula (2):

in the formula (2), k is determined by the electrode shape,t is an integral term and dt is a infinitesimal term.

Further, in step S102, the calculation formula of the weight coefficient is shown in formula (3):

in the formula (3), sigma is the water conductivity measured by any one group of three groups of measuring electrode pairs with different electrode constants; c_CThe central conductivity of the measuring electrode pair, which is the electrode constant corresponding to σ, is calculated as formula (4):

in the formula (4), C_HMeasuring the maximum value of the range of conductivity for the measuring electrode pair corresponding to the electrode constant of sigma, C_LThe minimum value of the conductivity range is measured for the measuring electrode pair corresponding to the electrode constant of sigma.

Further, in step S101, a resistance value calculation formula of the reference resistor corresponding to the measuring electrode pair is shown as formula (5):

in the formula (5), R_rIs a reference resistance value.

Further, in step S101, the three groups of measuring electrode pairs with different electrode constants and the reference resistances corresponding to the measuring electrode pairs are all in series, and the two ends of the three groups of measuring electrode pairs with different electrode constants are respectively provided with an external voltage V₁、V₂。

Further, in step S102, the formula of the conductivity of the water measured by the measuring electrode pair is shown as formula (6):

in step S103, the final water conductivity calculation formula of the target water body is as shown in formula (7):

in the formula (7), i is the group number of the measuring electrode pairs with different electrode constants; beta is a_iThe weight coefficient of the water conductivity measured by the electrode pair is measured for the ith group of electrode constants, and the calculation formula is formula (3); sigma_iThe measured water conductivity of the electrode pair is measured for the ith group of electrode constants, and the calculation formula is formula (6).

The beneficial effects provided by the invention are as follows: the method provides water conductivity measurement with wide range, high precision and stability under the condition of lower manufacturing cost.

Drawings

FIG. 1 is a flow chart of a water conductivity detection method based on a planar electrode array according to the present invention;

FIG. 2 is a schematic illustration of water conductivity measurements;

FIG. 3 is a basic block diagram of a planar electrode sensor;

FIG. 4 is a schematic subdivision of the conductivity range;

FIG. 5 is a graph showing the variation of weight coefficients with measured conductivity;

FIG. 6 is a schematic illustration of sensor measurements;

FIG. 7 is a schematic diagram of the actual measurement of the present invention;

fig. 8 is a schematic view of an electrode array of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be further described with reference to the accompanying drawings.

Referring to fig. 1, a method for detecting water conductivity based on a planar electrode array includes the following steps:

s101: designing a water conductivity detection sensor based on a planar electrode array structure; the sensor comprises three groups of measuring electrode pairs with different electrode constants and reference resistors corresponding to the measuring electrode pairs;

the three groups of measuring electrode pairs with different electrode constants are respectively a low electrode constant measuring electrode pair, a middle electrode constant measuring electrode pair and a high electrode constant measuring electrode pair;

s102: detecting the water conductivity of the target water body by using the sensor to respectively obtain the water conductivity measured by the three groups of measuring electrode pairs with different electrode constants and corresponding weight coefficients, namely the low water conductivity and the weight coefficient thereof, the medium water conductivity and the weight coefficient thereof, and the high water conductivity and the weight coefficient thereof;

s103: and calculating to obtain the final water conductivity of the target water body according to the measured water conductivity of the three groups of measuring electrode pairs with different electrode constants and the corresponding weight coefficients.

To better explain the context of the present invention, the concept of water conductivity measurement is first explained herein;

referring to fig. 2, fig. 2 is a schematic diagram of water conductivity measurement;

when an alternating voltage is applied to the two ends of the electrode (10K Hz is a voltage frequency reference value, ions are accumulated on the electrode and the surface when the frequency is too low, and the whole system is capacitive when the frequency is too high), if the voltage value is U, the measured current value passing through the electrode is I, the calculation formula of the conductivity sigma is as follows:

where R is the water resistance and κ is the electrode constant determined by the shape of the measurement electrode, and for parallel plate electrodes κ is equal to the plate separation d divided by the parallel plate area A.

Referring to fig. 3, fig. 3 is a basic structure diagram of a planar electrode sensor;

the main parameters are the number of electrodes N, the width of electrodes w, the distance between electrodes s and the length of electrodes L. The planar electrode has the advantages of low manufacturing cost, stable structure, easy integration and the like, and the electrode constant k is as follows:

wherein K is a first complete elliptic integral, and the calculation formula is as follows:

k is determined by the electrode shape and can be expressed as:

alpha can be expressed as

From the above, it can be seen that the electrode constants can be designed by the geometric parameters of the planar electrode shape.

Referring to fig. 4, fig. 4 is a detailed schematic diagram of the conductivity measurement range.

For a wider measurement range, it may be divided into several small sub-ranges. In each sub-range, a central conductivity C can be determined_CTo characterize the whole conductivity subinterval, the calculation formula is

Wherein C is_HAnd C_LRespectively the maximum and minimum of the conductivity within this sub-interval. In the measurement, the conductivity is in direct proportion to the electrode constant of the measuring electrode and in inverse proportion to the measured resistance, so that in order to ensure the accuracy and stability of the measurement, the planar electrode pair with the small electrode constant can be responsible for the region with the smaller conductivity, and the planar electrode pair with the large electrode constant is responsible for the region with the larger conductivity. Therefore, the sensing electrode pairs form a one-to-one correspondence relation with the divided conductivity subintervals, and weight coefficients are designed to be embodied.

The calculation formula of the weight coefficient is as follows:

sigma is the conductivity measured by the measuring electrode pair; wherein C is_CIs the central conductivity of the conductivity subinterval corresponding to the measuring electrode. FIG. 5 is a graph showing the variation of weight factor with measured conductivity, as shown in FIG. 5;

the closer the currently measured conductivity is to the corresponding center conductivity, the higher the weight of the measurement electrode. Conversely, if the center conductivity corresponding to the measurement electrode is far from the measured conductivity, the lower the weight. This ensures that the measuring electrode corresponding to the center conductivity closest to the current conductivity has the highest weight when measured.

Referring to fig. 6, fig. 6 is a schematic diagram of sensor measurements;

an applied voltage is applied to a series circuit of a pair of measuring electrodes of the sensor and their respective reference resistances. Wherein each measuring electrode corresponds to a reference resistance R_rThe calculation formula of (2) is as follows:

by measuring the total input voltage V1 and the resistance division voltage V2, respectively, the conductivity result obtained by the measuring electrode can be calculated as follows:

rsensor is the resistance value of the measuring electrode;

the weight coefficient is updated by the above formula, that is:

it can be seen that the calculation of the current measured electrode conductivity and the weight of that conductivity in the final result can be done by subsequent circuitry.

Assuming that the conductivity interval of the water body to be measured is divided into 3 parts, correspondingly, 3 measurement pairs with different electrode constants are designed on the sensor array, and each pair of measurement electrodes corresponds to one conductivity subinterval. In actual measurement, each sensor pair can obtain a measurement result σ and a weighting coefficient β corresponding to the measurement result, so that the final test result is:

referring to fig. 7, fig. 7 is a schematic view illustrating actual measurement according to the present invention; when the sensor array is completely immersed in the water body to be measured, input signals required by the sensors, corresponding voltage measurement and final conductivity calculation are completed by a subsequent circuit.

The circuits involved are not the focus of the invention, and are all common circuit designs, and the invention is to protect the measurement method, so the circuits involved are not specially substituted.

Referring to fig. 8, fig. 8 is a schematic view of an electrode array according to the present invention; in fig. 8, (a) is a high electrode constant measuring electrode pair, (b) is an electrode constant measuring electrode pair, and (c) is a low electrode constant measuring electrode pair.

There are 3 pairs of measurement electrodes in the figure, each pair having a different electrode constant, accommodating different conductivity ranges.

The beneficial effects provided by the invention are as follows: the method provides water conductivity measurement with wide range, high precision and stability under the condition of lower manufacturing cost.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.