CN117723498A - Liquid concentration detection method and device based on optical fiber probe and optical fiber probe - Google Patents
Liquid concentration detection method and device based on optical fiber probe and optical fiber probe Download PDFInfo
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Abstract
The embodiment of the invention discloses a liquid concentration detection method and device based on an optical fiber probe and the optical fiber probe, wherein the method comprises the following steps: when the optical fiber probe is placed in the liquid to be measured, determining the optical path of light in the liquid to be measured for the propagation process that incident light enters the liquid to be measured in the optical fiber probe through the incident optical fiber and is emitted from the emergent optical fiber; the liquid concentration to be measured is obtained based on a nonlinear regression model between the optical path and the liquid concentration to be measured, and the problem of low efficiency when the liquid concentration is detected by using the optical fiber probe is solved by adopting the technical scheme.
Description
Technical Field
The embodiment of the invention relates to the technical field of liquid concentration detection, in particular to a liquid concentration detection method and device based on an optical fiber probe and the optical fiber probe.
Background
The rapid detection technology is a technology for performing rapid detection, rapid identification and rapid positioning through a certain technology and method, has the characteristics of rapidness, accuracy, sensitivity, portability and the like, and is widely applied to the fields of medical treatment, industry, military and the like. The optical fiber probe has the advantages of high sensitivity, long transmission distance, strong anti-interference capability and the like, and is often applied to the rapid detection of liquid and gas.
In the related art, when the optical fiber probe is used for detecting the concentration of the liquid, the optical path range of the optical fiber probe is fixed, so that the optical fiber probes with different optical paths need to be frequently replaced and a large amount of calculation needs to be performed for detecting the liquid with different concentrations, and the detection process is time-consuming and labor-consuming and has low efficiency.
Disclosure of Invention
The embodiment of the invention provides a liquid concentration detection method and device based on an optical fiber probe and the optical fiber probe, which are used for solving the problem that the efficiency of the optical fiber probe is low when the liquid concentration detection is carried out.
In a first aspect, the present invention provides a method for detecting a liquid concentration based on an optical fiber probe, applied to an optical fiber probe with an adjustable optical path, the method comprising:
when the optical fiber probe is placed in the liquid to be measured, determining the propagation distance of light in the liquid to be measured for the optical path of incident light entering the liquid to be measured in the optical fiber probe through the incident optical fiber and exiting from the emergent optical fiber;
based on a nonlinear regression model between the optical path and the concentration of the liquid to be measured, the concentration of the liquid to be measured is obtained, wherein the nonlinear regression model is expressed by the following formula:
wherein,indicating the concentration of the liquid to be measured, i indicating the optical path of light in the liquid to be measured, a and b respectively indicating the parameters of the nonlinear regression model, Represents the molar absorption coefficient.
Alternatively, the nonlinear regression model is constructed by:
determining the information of the intensity of incident light entering the optical fiber probe;
for sample liquids with different concentrations, determining emergent light intensity information of incident light after the incident light passes through the sample liquid of the optical fiber probe and is reflected by a reflecting mirror of the optical fiber probe;
according to the incident light intensity information and the emergent light intensity information, determining original absorbance values corresponding to sample liquids with various concentrations;
determining a parameter estimation value of a target nonlinear function based on concentration data of a plurality of groups of sample liquids and a data distribution diagram of corresponding original absorbance values of the sample liquids, and fitting the parameter estimation value to obtain the target nonlinear function based on the parameter estimation value, wherein the target nonlinear function is used for representing a nonlinear positive correlation relationship between the concentration of the sample liquids and the absorbance;
if the fitting degree correlation index between the curve graph corresponding to the target nonlinear function obtained by fitting and the data distribution graph reaches a preset threshold, taking the parameter value corresponding to the target nonlinear function as the parameter value of the nonlinear regression model;
wherein the target nonlinear function is:
wherein A is absorbance, c is sample liquid concentration, and a and b are parameters of nonlinear functions.
Optionally, the construction process of the nonlinear regression model further includes:
correcting the original absorbance value based on a temperature correction coefficient to obtain corrected absorbance values corresponding to sample liquids with various concentrations, wherein the temperature correction coefficient is the ratio of the refractive index correction factor of the sample liquid at the standard temperature to the refractive index correction factor of the sample liquid at the current test temperature;
correspondingly, determining the parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution map of the original absorbance values comprises the following steps:
and determining a parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution map of the corrected absorbance values.
Optionally, correcting the original absorbance value based on a temperature correction coefficient includes:
the original absorbance value is corrected according to the following formula:
wherein,the raw absorbance value is represented as such,the absorbance value after the correction is indicated,indicating the temperature correction coefficient.
In a second aspect, an embodiment of the present invention further provides a liquid concentration detection apparatus based on an optical fiber probe, where the apparatus includes:
the optical path determining module is used for determining the optical path of light in the liquid to be detected for the propagation process that incident light enters the liquid to be detected in the optical fiber probe through the incident optical fiber and is emitted from the emergent optical fiber when the optical fiber probe is placed in the liquid to be detected;
The liquid concentration determining module is used for obtaining the concentration of the liquid to be detected based on a nonlinear regression model between the optical path and the concentration of the liquid to be detected, wherein the nonlinear regression model is expressed by the following formula:
wherein,indicating the concentration of the liquid to be measured, i indicating the optical path distance of light in the liquid to be measured, a and b respectively indicating the parameters of the nonlinear regression model,represents the molar absorption coefficient.
Optionally, the nonlinear regression model is constructed by a model construction module comprising:
the incident light intensity information determining unit is used for determining the incident light intensity information entering the optical fiber probe;
the outgoing light intensity information determining unit is used for determining outgoing light intensity information of the incident light after passing through the sample liquid of the optical fiber probe and being reflected by the reflecting mirror of the optical fiber probe for the sample liquids with different concentrations;
the original absorbance value calculating unit is used for determining original absorbance values corresponding to sample liquids with various concentrations according to the incident light intensity information and the emergent light intensity information;
the function fitting unit is used for determining parameter estimation values of the target nonlinear function based on concentration data of a plurality of groups of sample liquids and a data distribution diagram of corresponding original absorbance values of the sample liquids, and fitting the parameter estimation values to obtain the target nonlinear function based on the parameter estimation values, wherein the target nonlinear function is used for representing nonlinear positive correlation between the concentration of the sample liquids and the absorbance;
The parameter value determining unit is used for taking the parameter value corresponding to the target nonlinear function as the parameter value of the nonlinear regression model if the fitting degree correlation index between the curve graph corresponding to the target nonlinear function obtained by fitting and the data distribution graph reaches a preset threshold;
wherein the target nonlinear function is:
wherein A is absorbance, c is sample liquid concentration, and a and b are parameters of nonlinear functions.
Optionally, the model building module further includes:
the correction unit is used for correcting the original absorbance value based on a temperature correction coefficient to obtain corrected absorbance values corresponding to sample liquids with various concentrations, wherein the temperature correction coefficient is the ratio of the refractive index correction factor of the sample liquid at the standard temperature to the refractive index correction factor of the sample liquid at the current test temperature;
correspondingly, the function fitting unit is specifically configured to:
and determining a parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution map of the corrected absorbance value, and fitting the parameter estimation value to obtain the target nonlinear function.
Optionally, the correction unit is specifically configured to:
the original absorbance value is corrected according to the following formula:
Wherein,the raw absorbance value is represented as such,the absorbance value after the correction is indicated,indicating the temperature correction coefficient.
In a third aspect, an embodiment of the present invention further provides an optical fiber probe, including an optical fiber probe body, an optical fiber bundle including an incident light ray and an outgoing optical fiber, and a reflecting mirror, where the optical fiber probe further includes: an optical path regulating device, a rear plug, a window sheet and a lens, wherein,
the side wall of the optical fiber probe body is provided with a groove, when the probe body is placed in liquid to be tested, the liquid to be tested flows into the groove, the groove divides the optical fiber probe body into an upper part and a lower part, through holes along the axial direction of the optical fiber probe body are respectively formed in the upper part and the lower part of the optical fiber body, a reflecting mirror is arranged at an opening of one end, communicated with the groove, of the through hole below the groove and used for reflecting light, a rear plug is arranged at the opening of the other end and used for supporting a window sheet placed in the through hole below, and the through hole above the groove is used for inserting an optical path adjusting device;
the optical path adjusting device is of a hollow structure, one end of the optical path adjusting device is provided with an optical fiber bundle in the hollow structure through an optical fiber locking cap, the other end of the optical path adjusting device stretches into the groove through a through hole above the groove, and the length of the optical path adjusting device stretching into the groove is adjustable, so that the optical path of light in liquid to be measured is adjustable, and the optical path adjusting device is provided with a lens at an opening of one end stretching into the groove.
Optionally, the outer surface of the optical path adjusting device is provided with external threads, the through hole above the groove is internally provided with internal threads corresponding to the external threads, and the optical path adjusting device is made to extend into the groove for adjustable length by matching the internal threads with the external threads.
In a fourth aspect, embodiments of the present invention also provide a computing device, including:
a memory storing executable program code;
a processor coupled to the memory;
the processor invokes the executable program code stored in the memory to perform the fiber probe-based liquid concentration detection method provided by any embodiment of the invention.
In a fifth aspect, embodiments of the present invention further provide a computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the method for detecting a concentration of a liquid based on a fiber optic probe according to any embodiment of the present invention.
According to the technical scheme provided by the embodiment of the invention, when the optical fiber probe with adjustable optical path is utilized to detect the concentration of the liquid, the optical path of the light in the liquid to be detected is determined, so that the concentration of the liquid to be detected can be directly obtained based on a nonlinear regression model, the process does not need to calculate absorbance, the calculated amount is saved, the problem of low detection efficiency caused by continuously replacing the optical fiber probes with different optical paths in the process of detecting the liquid to be detected with different concentrations is avoided, and the detection efficiency is effectively improved on the premise of ensuring the detection accuracy.
The innovation points of the embodiment of the invention include:
1. the optical path adjusting device is arranged on the optical fiber probe body, and the relative positions of the optical path adjusting device and the grooves of the optical fiber body are adjustable, so that the optical path of the light beam in the liquid to be measured can be adjusted, the measuring range of the optical fiber probe is widened, the problem of low detection efficiency caused by changing the optical fiber probes with different optical paths is avoided, and the optical fiber probe is one of the innovation points of the embodiment of the invention.
2. The parameter estimation value of the target nonlinear function can be determined through the concentration data of a plurality of groups of sample liquids and the data distribution diagram of the corresponding original absorbance value, the target nonlinear function can be obtained by fitting based on the target parameter estimation value, and under the condition that the fitting degree correlation index between the curve diagram of the target nonlinear function obtained by fitting and the concentration data of a plurality of groups of sample liquids and the data distribution diagram of the corresponding original absorbance value reaches the preset threshold value to reach the preset requirement, the parameter value of the target nonlinear function can be obtained, so that the parameter value of the nonlinear regression model between the concentration of the liquid to be measured and the optical path can be obtained. When the probe with adjustable optical path provided by the embodiment is used for detection, the establishment of the model provides great convenience for detection of different liquid concentrations, so that the detection efficiency of the liquid concentration can be effectively improved, and the method is one of innovation points of the embodiment of the invention.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1a is a schematic diagram of an optical fiber probe according to a first embodiment of the present invention;
FIG. 1b is a schematic diagram of a partial structure of an optical path adjusting device according to a first embodiment of the present invention;
FIG. 2 is a flowchart of a method for constructing a nonlinear regression model according to a second embodiment of the present invention;
FIG. 3 is a flow chart of a liquid concentration detection method based on an optical fiber probe according to a third embodiment of the present invention;
fig. 4 is a block diagram of a liquid concentration detection apparatus based on an optical fiber probe according to a fourth embodiment of the present invention;
fig. 5 is a schematic structural diagram of a computing device according to a fifth embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
It should be noted that the terms "comprising" and "having" and any variations thereof in the embodiments of the present invention and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
The embodiment of the invention discloses a liquid concentration detection method based on an optical fiber probe, which is implemented by the optical fiber probe with adjustable optical path, wherein for high-concentration liquid to be detected, the optical path can be reduced to expand the measurement range of the optical fiber probe, and for low-concentration liquid to be detected, the optical path can be increased to expand the measurement range of the optical fiber probe. The structure of the optical fiber probe with adjustable optical path is described first, and then the liquid concentration detection method based on the optical fiber probe with adjustable optical path is described in detail.
Example 1
Fig. 1a is a schematic structural diagram of an optical fiber probe according to an embodiment of the present invention, where the optical fiber probe is an optical fiber probe with an adjustable optical path. As shown in fig. 1a, the fiber optic probe includes: the optical fiber probe comprises an optical fiber probe body (10), an optical fiber bundle (9) containing incident light rays and emergent optical fibers and a reflecting mirror (3), and is characterized in that the optical fiber probe further comprises: an optical path regulating device (11), a rear plug (1), a window sheet (2) and a lens (4), wherein,
The side wall of the optical fiber probe body (10) is provided with a groove (5), when the probe body (10) is placed in liquid to be tested, the liquid to be tested flows into the groove (5), the groove (5) divides the optical fiber probe body into an upper part and a lower part, through holes along the axial direction of the optical fiber probe body (10) are respectively formed in the upper part and the lower part of the optical fiber body, a reflecting mirror (3) is arranged at an opening of one end, which is communicated with the groove (5), of the through hole (7) below the groove (5) for reflecting light, a rear plug (1) is arranged at the opening of the other end for supporting a window sheet (2) placed in the through hole below, and a through hole (6) above the groove (5) is used for inserting an optical path adjusting device (11);
the optical path adjusting device (11) is of a hollow structure, one end of the optical path adjusting device is provided with an optical fiber bundle (9) through an optical fiber locking cap (8) in the hollow structure, the other end of the optical path adjusting device stretches into the groove (5) through a through hole (6) above the groove (5), the length of the optical path adjusting device stretching into the groove (5) is adjustable, so that the optical path of light in liquid to be measured is adjustable, and the optical path adjusting device (11) is provided with a lens at an opening at one end of the optical path adjusting device stretching into the groove (5) to focus the light.
Optionally, in order to make the optical path adjusting device stretch into the adjustable of length of recess, can adopt threaded connection's mode between optical path adjusting device and the fiber probe body, specifically, the surface of optical path adjusting device (11) is provided with the external screw thread, is provided with the internal thread corresponding with the external screw thread in through-hole (6) of recess (5) top, through the internal screw thread with the external screw thread cooperatees for the optical path adjusting device (11) stretches into the adjustable of length of recess (5), thereby widens fiber probe's measuring range.
Optionally, fig. 1b is a schematic partial structure diagram of an optical path adjusting device according to the first embodiment of the present invention, as shown in fig. 1b, a hemispherical round hole may be formed on an outer surface of the optical path adjusting device (11), for installing a positioning protrusion (12), where the positioning protrusion is fixed in the hemispherical round hole by a compression spring, and the positioning protrusion may be pressed under the action of an external force due to the action of the compression spring. Specifically, a plurality of positioning protrusions are provided along the axial direction of the optical path adjusting device at set intervals, and each positioning protrusion may specifically be a positioning light bead. Correspondingly, a positioning concave hole corresponding to the positioning bulge is formed in the optical fiber probe body and is used for fixing the optical path adjusting device by fixing the positioning bulge in the positioning concave hole when the optical path adjusting device stretches into the groove. After the optical path adjusting device is fixed on the light body, the compression spring in the optical path adjusting device can deform under the action of external force, so that the positioning bulge of the optical path adjusting device leaves the positioning concave hole, and the adjustable extension length of the optical path adjusting device in the groove is realized.
In the embodiment, the optical fiber locking cap (8) can be in threaded connection with the optical path adjusting device (11), and a through hole is formed in the optical fiber locking cap (8) and used for accommodating the optical fiber bundle (9). The outside of the optical fiber bundle (9) is provided with a wrapping layer to ensure the vertical downward incidence of light. In addition, the outer edge of the lens and the outer edge of the reflecting mirror can be wrapped with sealing rings, so that the light is prevented from leaking outwards, and when the optical fiber probe is placed in liquid, the liquid is prevented from flowing into the through hole below the optical fiber probe and the through hole of the optical path adjusting device, so that the effect of isolating the liquid is achieved.
In this embodiment, the optical fiber probe body and the optical path adjusting device may be made of stainless steel, so as to avoid corrosion of the liquid. The length of the optical fiber can be set according to the actual detection requirement, and the embodiment is not particularly limited, for example, in the case of long light length, remote detection can be supported.
The detection principle of the optical fiber probe in the embodiment is as follows: when the optical fiber probe is placed in the liquid to be measured, the liquid to be measured flows into the groove of the optical fiber probe. Light emitted by the light source enters the optical path regulating device from the incident optical fiber, passes through the lens in the optical path regulating device, and then vertically enters the liquid to be measured. After being reflected by the reflecting mirror of the optical fiber probe body, the incident light passes through the lens of the optical path regulating device and then is emitted by the emergent optical fiber. Because the light emitted from the emergent optical fiber is reflected by the reflecting mirror after passing through the liquid to be detected, the reflected light can carry information of the liquid to be detected, namely the intensity of the reflected light is closely related to the concentration of the liquid to be detected, namely the concentration of the liquid to be detected can be obtained through the intensity of the incident light and the intensity of the reflected light.
In this embodiment, through setting up optical path adjusting device on the fiber optic probe body to through setting up optical path adjusting device and the relative position of light body recess adjustable, realized that the optical path of light beam in the liquid that awaits measuring is adjustable, widened fiber optic probe's measuring range, avoided changing the low problem of detection efficiency that the fiber optic probe of different optical paths brought.
It will be appreciated by those skilled in the art that the relationship between the change in optical path length and the concentration of the liquid to be measured can be expressed by Beer-Lambert-Beer Law, i.e
Wherein A represents absorbance,indicating the intensity of the incident light and,indicating the intensity of the transmitted light,represents the molar absorption coefficient, which reflects the absorption capacity of the substance to be measured for specific light,indicating the concentration of the liquid to be measured,the optical path is shown.
From the above equation, it can be seen that the change in the optical path l directly affects the value of absorbance a and thus the sensitivity and dynamic range of the measurement result. In particular, increasing the optical path, i.e. increasing the distance travelled by the light in the sample, results in an increase in absorbance a, which makes the instrument more sensitive to lower concentrations of substances. In other words, increasing the optical path can expand the measurement range, making it suitable for low concentration samples. Decreasing the optical path results in a decrease in absorbance a, which makes the instrument more sensitive to high concentrations of sample. Thus, reducing the optical path can extend the measurement range, making it suitable for high concentration samples.
In the related art, when detecting liquids with different concentrations, the optical fiber probe with different optical paths needs to be replaced. In this embodiment, a nonlinear relationship between the optical path and the absorbance (see the following objective nonlinear function) may be established, and a nonlinear regression model between the optical path and the concentration may be constructed based on beer-lambert-beer law. When the optical fiber probe structure with the adjustable optical path is used for detecting the liquid concentration, the concentration of the liquid to be detected can be directly obtained based on the nonlinear regression model under the condition that the optical path of the light beam in the liquid to be detected is determined, and the problem of low detection efficiency caused by changing optical fiber probes with different optical paths is avoided. Wherein the optical pathThe target nonlinear function with absorbance can be expressed by the following formula:
wherein A represents absorbance, a and b represent parameters of a nonlinear regression model, and c represents the concentration of the liquid to be measured.
Since the absorbance in the target nonlinear function satisfies the above beer-lambert-beer law, a nonlinear regression model between the optical path and the concentration of the liquid to be measured can be obtained based on the target nonlinear function and the beer-lambert-beer law, and can be expressed by the following formula: 。
The following examples describe the construction method of the nonlinear regression model in detail.
Example two
Fig. 2 is a flowchart of a method for constructing a nonlinear regression model according to a second embodiment of the present invention, and the structure of the optical fiber probe on which the method depends is described in the above embodiment, which is not repeated here. As shown in fig. 2, the method includes:
s210, determining the information of the intensity of the incident light entering the optical fiber probe.
S220, for sample liquids with different concentrations, determining emergent light intensity information of incident light after the incident light passes through the sample liquid of the optical fiber probe and is reflected by the reflecting mirror of the optical fiber probe.
Specifically, if it is desired to measure the concentration of a certain liquid, a series of liquid solutions of different concentrations, for example, 0.01 mol/L, 0.02 mol/L, 0.03 mol/L, 0.04 mol/L, 0.05 mol/L, should be prepared. Sample liquids of different concentrations can be prepared using a dilution method, for example, by diluting 1mL of a 0.1mol/L dye solution to 10 mL, resulting in a 0.01 mol/L dye solution.
S230, determining original absorbance values corresponding to the sample liquid with various concentrations according to the incident light intensity information and the emergent light intensity information.
Alternatively, can utilizeThe beer-lambert-beer law And obtaining the original absorbance values corresponding to the sample liquids with various concentrations.
Optionally, the absorbance of each solution is also measured using a spectrophotometer. Specifically, a blank solution (without dye) can be used as a reference, and its absorbance can be set to zero. Then, the liquid of each concentration is poured into a cuvette, placed into a sample cell of a spectrophotometer, and the absorbance value on a display screen is read. The measurement can be repeated three times and the average taken as the final result.
Specifically, if the liquid to be measured has a maximum absorption peak at a certain target wavelength (e.g., 500 nm) during the detection process, each measurement can measure the absorbance of a different concentration of liquid at that target wavelength (e.g., 500 nm).
S240, determining a parameter estimation value of the target nonlinear function based on the concentration data of a plurality of groups of sample liquids and the data distribution diagram of the corresponding original absorbance value, and fitting the parameter estimation value to obtain the target nonlinear function.
For example, the target nonlinear function can be obtained by fitting a plurality of groups of concentration data of the sample liquid and corresponding data distribution of original absorbance values. For example, a scattergram can be drawn with the concentration of the liquid to be measured on the abscissa and the absorbance on the ordinate. Based on the data distribution in the scatter plot, a suitable nonlinear function, such as a power function, an exponential function, a logarithmic function, an S-shaped curve function, etc., can be selected as the regression model, in this embodiment a power function is selected as the target nonlinear function, i.e 。
In determining the parameters of the target nonlinear function, a Python language or other programming languages may be used to import corresponding libraries or modules, such as scipy (advanced scientific computing library), numpy (open source Python scientific computing library), matplotlib (Python 2D drawing library), and the like. Using a cut_fit function in the scipy libraryNonlinear function of targetAnd experimental data (concentration data of a plurality of groups of sample liquids and corresponding data of original absorbance values) are used as parameter input to obtain estimated values of parameters a and b in the nonlinear function. By using a poly1d function (polynomial function) in the numpy library, a nonlinear function can be constructed from the parameter estimates.
Specifically, a specific estimation method of the target nonlinear function parameter value is described in detail below through simulation data.
By way of example, a simulation scenario may be to measure the concentration of a drug in blood, and in particular a fluorescence-based sensor probe may be used.
First, according to the relationship between the absorbance of a certain compound in a drug and its concentration, absorbance values at different concentrations can be measured by the above-described fiber probe structure, as shown in the following data set in table 1:
TABLE 1 liquid concentration and corresponding absorbance data
| Concentration (c) | Absorbance (A) |
| 0.01 | 0.100 |
| 0.02 | 0.205 |
| 0.05 | 0.502 |
| 0.1 | 0.998 |
| 0.2 | 2.032 |
| 0.5 | 5.001 |
| 1.0 | 10.120 |
| 2.0 | 20.300 |
Next, a calibration curve, i.e., a target nonlinear function, can be established using a nonlinear correction method, whereby absorbance is related to concentration by the target nonlinear function. Specifically adopted is a nonlinear regression modelFitting the data to obtain a parameter estimation value of the target nonlinear function: a=0.1, b=1.992.
Specifically, in determiningThe process of parameters a and b in (c) typically requires the use of data analysis tools such as statistical software or regression analysis functions in a programming language. In this example, a non-linear fit may be performed using a scipy library in Python to obtain estimates of parameters a and b, as follows.
First, it is ensured that the scipy library is installed in the Python environment. Then, a nonlinear fit may be performed as follows:
import numpy as np
from scipy.optimize import curve_fit
# provides exemplary data, i.e., concentration and absorbance data in Table 1 above
concentration = np.array([0.01, 0.02,0.05,0.1, 0.2,0.5,1.0, 2.0])
absorbance=np.array([0.100,0.205,0.502,0.998,2.032,5.001,10.120,20.3])
# definition nonlinear regression model function
def nonlinear_model(c, a b):
return a* np.power(c，b)
Initial value of initial estimation parameter #, initial estimation parameter
initial_guess = [0.1,2.0]
# perform nonlinear fitting
params,covariance = curve_fit(nonlinear_model,concentration,absorbance,params)
# acquisition of parameter estimation values
a_estimate, b_estimate = params
The code will use the example data to perform a non-linear fit to obtain the values of parameters a and b.
After the values of the parameters a and b are obtained, a target nonlinear function can be established based on the parameters for subsequent measurement, namely, under the condition that the absorbance value is obtained by measurement, the absorbance value can be converted into a concentration value according to a formula of the target nonlinear function, so that the concentration of a certain substance in a sample to be measured is measured. Wherein the formula of the target nonlinear function is as follows:
for another exemplary scenario for measuring the activity of an enzyme in a reaction solution, a color-based sensor probe may be used to measure the fluorescence intensity values at different concentrations, resulting in the concentration and fluorescence intensity data shown in Table 2 below.
TABLE 2 liquid concentrations and corresponding absorbance data
| Concentration (c) | Fluorescence intensity (F) |
| 0.01 | 0.050 |
| 0.02 | 0.103 |
| 0.05 | 0.256 |
| 0.1 | 0.512 |
| 0.2 | 1.024 |
| 0.5 | 2.560 |
| 1.0 | 5.120 |
| 2.0 | 10.240 |
Next, a calibration curve, i.e., a target nonlinear function, can be established using a nonlinear correction method to correlate fluorescence intensity with concentration. In particular, a nonlinear regression model can be adoptedTo fit the data.
To find the values of parameters a and b, the fitting error can be optimized with a least squares method. The principle of least squares is to minimize the sum of squares of the distances between the actual data points and the fitted curve. In this example, results of a=0.05 and b=2 are available, which means that the fitted curve can well describe the trend of the data. The data fitting manner may be implemented based on the codes in the above examples, which are not described herein.
Finally, a target nonlinear function can be established based on the parameters for subsequent measurement, namely, under the condition that the fluorescence intensity value is obtained by measurement, the fluorescence intensity value can be converted into a concentration value according to a formula of the target nonlinear function, so that the concentration of a certain drug in a sample to be measured is measured. Wherein the formula of the target nonlinear function is as follows:
s250, if the fitting degree correlation index between the curve graph corresponding to the fitted target nonlinear function and the concentration data of the plurality of groups of sample liquids and the data distribution graph of the corresponding original absorbance value reaches a preset threshold, taking the parameter value corresponding to the target nonlinear function as the parameter value of the nonlinear regression model.
In this embodiment, a plot function (drawing function) in a matplotlib library may be used to draw a plot of experimental data and a plot of a target nonlinear function after fitting, and the fitting degrees of the plot and the plot may be compared, specifically, the fitting goodness of the nonlinear regression model may be evaluated by using the correlation index R or R2, and the closer R or R2 is to 1, the better the fitting effect is. In this embodiment, experiments prove that the nonlinear target function can very accurately reflect the nonlinear positive correlation between the absorbance and the concentration of the liquid to be measured. From the nonlinear positive correlation, a nonlinear function can be determined The parameter values of the parameters a and b of the parameter are nonlinear regression modelsParameter values of the parameters.
Further, take care ofIn consideration of the influence of the liquid temperature on the absorbance, the embodiment corrects the absorbance by adopting a temperature correction coefficient, specifically, the original absorbance value corresponding to the sample liquid with various concentrations is determined according to the incident light intensity information and the emergent light intensity informationAfter that, the original absorbance value is combined with the temperature correction coefficientThe product is carried out to obtain corrected absorbance values corresponding to the sample liquids with various concentrationsParameter estimates for the nonlinear function may then be determined based on the concentration data for the plurality of sets of sample liquids and the corresponding data distribution map of corrected absorbance values.
Wherein the temperature correction coefficientIs the refractive index correction factor of the sample liquid at standard temperature (generally set to 25℃)The ratio to the refractive index correction factor f of the sample liquid at the current test temperature, i.e。
Wherein the refractive index correction factor of the sample liquid at the standard temperatureThe refractive index correction factor f of the sample liquid at the current test temperature can be obtained by experimental measurement or reference, and can be calculated based on the following lorentz-lorentz equation:
Where n denotes the refractive index of the sample liquid, this value can be obtained by experimental measurement or by reference.
The process of correcting absorbance using a temperature correction coefficient is described below by way of one specific example:
it is assumed that a concentration measurement method of a liquid sample whose absorbance is greatly affected by temperature is studied. The array optical filter spectrum sensor based on the micro-nano surface structure is used for measurement, and a nonlinear regression model is adopted for establishing the relation between the optical path and the concentration, and the specific implementation process is as follows.
First, a set of sample liquid data of different concentrations is collected, while temperature information is recorded. The concentration of the sample liquid data and the corresponding absorbance data are shown in table 3 below:
TABLE 3 sample liquid concentrations and corresponding absorbance data
| Concentration (M) | Absorbance (A) |
| 0.1 | 0.15 |
| 0.2 | 0.25 |
| 0.3 | 0.35 |
| 0.4 | 0.45 |
| 0.5 | 0.55 |
Next, a temperature correction coefficient is calculated. The standard temperature is typically set at 25℃and the refractive index correction factor of the sample fluid is known at this temperature0.9. At a current test temperature of 30 ℃, the refractive index n of the sample liquid is 1.33, using the lorentz-lorentz equationThe refractive index correction factor of the sample liquid at the current temperature can be calculated 。
Then, a temperature correction coefficient is calculated according to the following formula：
≈3.25
Next, the temperature correction coefficient can be corrected based on the raw absorbance value ACalculating corrected absorbance values：
And drawing the sample liquid concentration data and the corrected absorbance data into a scatter diagram, so as to obtain a data distribution diagram.
Finally, fitting the data using a nonlinear model to determine a nonlinear functionIs used for the parameter estimation of (a). By fitting a curve, the concentration of the sample liquid can be predicted from a given absorbance value.
The above examples show how the temperature correction factor can be used to correct the absorbance data and calculate the concentration of the liquid to be measured from the experimental data and known parameters. By introducing temperature correction, the concentration of the liquid sample can be measured more accurately, and the reliability of the measurement result can be improved.
In this embodiment, by correcting the absorbance with the temperature correction coefficient, more accurate absorbance data can be obtained, so that the parameter value of the target nonlinear function obtained based on the absorbance data is more accurate, which is helpful for improving the accuracy of the liquid concentration.
In another alternative embodiment, when determining the parameter values of the parameters a and b, the values of the parameters a and b of the nonlinear regression model can be directly obtained according to the above-mentioned parameter value determination method based on the known concentrations of the plurality of sample liquids and the optical path length l of the light in each sample liquid, thereby constructing the nonlinear regression model.
According to the technical scheme provided by the embodiment, the parameter estimation value of the target nonlinear function can be determined through the concentration data of the plurality of groups of sample liquids and the data distribution diagram of the corresponding original absorbance value, the target nonlinear function can be obtained through fitting based on the target parameter estimation value, and under the condition that the fitting degree correlation index between the curve diagram of the target nonlinear function obtained through fitting and the concentration data of the plurality of groups of sample liquids and the data distribution diagram of the corresponding original absorbance value reaches the preset threshold value to reach the preset requirement, the parameter value of the target nonlinear function can be obtained, and therefore the parameter value of the nonlinear regression model between the concentration of the liquid to be measured and the optical path can be obtained. When the probe with the adjustable optical path provided by the embodiment is used for detection, the establishment of the model provides great convenience for detection of different liquid concentrations, and in the detection process, the concentration of the liquid to be detected can be obtained by determining the optical path of light in the liquid to be detected without changing the probe with different optical paths for the liquid with different concentrations. The nonlinear regression model is applied to the liquid concentration detection process, so that the replacement of an optical fiber probe is avoided, the calculation of absorbance data is not needed, and the detection efficiency is effectively improved. The following examples describe the detection of liquid concentration using a non-linear regression model.
Example III
Fig. 3 is a flowchart of a liquid concentration detection method based on an optical fiber probe according to a third embodiment of the present invention, where the method of the present embodiment is applied to an optical fiber probe with an adjustable optical path, and the structure of the optical fiber probe can be described with reference to the foregoing embodiments, which is not repeated herein. The method provided in this embodiment may be performed by a liquid concentration detection apparatus based on a fiber optic probe, which may be implemented in hardware and/or software, as shown in fig. 3, and includes:
s310, when the optical fiber probe is placed in the liquid to be measured, determining the optical path of the light in the liquid to be measured for the propagation process that the incident light enters the liquid to be measured in the optical fiber probe through the incident optical fiber and is emitted from the emergent optical fiber.
Because the optical path of the optical fiber probe is adjustable, the measuring range of the optical fiber probe can be enlarged by increasing the optical path for the liquid to be measured with lower concentration. For the liquid to be measured with higher concentration, the measuring range of the optical fiber probe can be widened by reducing the optical path.
S320, obtaining the concentration of the liquid to be measured based on a nonlinear regression model between the optical path and the concentration of the liquid to be measured.
Wherein the nonlinear regression model is represented by the following formula:
Wherein,indicating the concentration of the liquid to be measured, l indicating the optical path length of light in the liquid to be measured, and the a and b partsAnd each represents a parameter of the nonlinear regression model. The parameter values of the parameters of the nonlinear regression model can be determined by the above-described embodiments. After the nonlinear regression model is constructed, the liquid concentration can be detected by using the model by determining the optical path of light in the liquid to be detected.
In the embodiment, when the optical fiber probe with adjustable optical path is used for detecting the concentration of the liquid, the optical path of the light in the liquid to be detected is determined, so that the concentration of the liquid to be detected can be directly obtained based on a nonlinear regression model, the process does not need to calculate absorbance, the calculated amount is saved, the problem of low detection efficiency caused by continuously replacing the optical fiber probes with different optical paths in the process of detecting the liquid to be detected with different concentrations is avoided, and the detection efficiency is effectively improved on the premise of ensuring the detection accuracy.
Example IV
Fig. 4 is a block diagram of a liquid concentration detection apparatus based on an optical fiber probe according to a fourth embodiment of the present invention, as shown in fig. 4, the apparatus includes: an optical path length determination module 410, and a liquid concentration determination module 420, wherein,
An optical path determining module 410, configured to determine an optical path of light in the liquid to be measured for a propagation process of incident light entering the liquid to be measured in the optical fiber probe through the incident optical fiber and exiting from the exit optical fiber when the optical fiber probe is placed in the liquid to be measured;
the liquid concentration determining module 420 is configured to obtain a concentration of the liquid to be measured based on a nonlinear regression model between the optical path and the concentration of the liquid to be measured, where the nonlinear regression model is expressed by the following formula:
wherein,indicating the concentration of the liquid to be measured, i indicating the optical path of light in the liquid to be measured, a and b respectively indicating the parameters of the nonlinear regression model,represents the molar absorption coefficient.
Optionally, the nonlinear regression model is constructed by a model construction module comprising:
the incident light intensity information determining unit is used for determining the incident light intensity information entering the optical fiber probe;
the outgoing light intensity information determining unit is used for determining outgoing light intensity information of the incident light after passing through the sample liquid of the optical fiber probe and being reflected by the reflecting mirror of the optical fiber probe for the sample liquids with different concentrations;
the original absorbance value calculating unit is used for determining original absorbance values corresponding to sample liquids with various concentrations according to the incident light intensity information and the emergent light intensity information;
The function fitting unit is used for determining parameter estimation values of the target nonlinear function based on concentration data of a plurality of groups of sample liquids and a data distribution diagram of corresponding original absorbance values of the sample liquids, and fitting the parameter estimation values to obtain the target nonlinear function based on the parameter estimation values, wherein the target nonlinear function is used for representing nonlinear positive correlation between the concentration of the sample liquids and the absorbance;
the parameter value determining unit is used for taking the parameter value corresponding to the target nonlinear function as the parameter value of the nonlinear regression model if the fitting degree correlation index between the curve graph corresponding to the target nonlinear function obtained by fitting and the data distribution graph reaches a preset threshold;
wherein the target nonlinear function is:
wherein A is absorbance, c is sample liquid concentration, and a and b are parameters of nonlinear functions.
Optionally, the model building module further includes:
the correction unit is used for correcting the original absorbance value based on a temperature correction coefficient to obtain corrected absorbance values corresponding to sample liquids with various concentrations, wherein the temperature correction coefficient is the ratio of the refractive index correction factor of the sample liquid at the standard temperature to the refractive index correction factor of the sample liquid at the current test temperature;
Correspondingly, the function fitting unit is specifically configured to:
and determining a parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution map of the corrected absorbance value, and fitting the parameter estimation value to obtain the target nonlinear function.
Optionally, the correction unit is specifically configured to:
the original absorbance value is corrected according to the following formula:
wherein,the raw absorbance value is represented as such,the absorbance value after the correction is indicated,indicating the temperature correction coefficient.
Example five
Referring to fig. 5, fig. 5 is a schematic structural diagram of a computing device according to a fifth embodiment of the present invention. As shown in fig. 5, the computing device may include:
a memory 501 in which executable program codes are stored;
a processor 502 coupled to the memory 501;
the processor 502 invokes executable program codes stored in the memory 501 to execute the method for detecting the concentration of the liquid based on the fiber probe according to any embodiment of the present invention.
The embodiment of the invention discloses a computer readable storage medium which stores a computer program, wherein the computer program enables a computer to execute the liquid concentration detection method based on the optical fiber probe provided by any embodiment of the invention.
In various embodiments of the present invention, it should be understood that the sequence numbers of the foregoing processes do not imply that the execution sequences of the processes should be determined by the functions and internal logic of the processes, and should not be construed as limiting the implementation of the embodiments of the present invention.
In the embodiments provided herein, it should be understood that "B corresponding to a" means that B is associated with a from which B may be determined. It should also be understood that determining B from a does not mean determining B from a alone, but may also determine B from a and/or other information.
In addition, each functional unit in the embodiments of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units described above, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer-accessible memory. Based on this understanding, the technical solution of the present invention, or a part contributing to the prior art or all or part of the technical solution, may be embodied in the form of a software product stored in a memory, comprising several requests for a computer device (which may be a personal computer, a server or a network device, etc., in particular may be a processor in a computer device) to execute some or all of the steps of the above-mentioned method of the various embodiments of the present invention.
Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the above embodiments may be implemented by a program that instructs associated hardware, the program may be stored in a computer readable storage medium including Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), programmable Read-Only Memory (Programmable Read-Only Memory, PROM), erasable programmable Read-Only Memory (Erasable Programmable Read Only Memory, EPROM), one-time programmable Read-Only Memory (OTPROM), electrically erasable programmable Read-Only Memory (EEPROM), compact disc Read-Only Memory (Compact Disc Read-Only Memory, CD-ROM) or other optical disk Memory, magnetic disk Memory, tape Memory, or any other medium that can be used for carrying or storing data that is readable by a computer.
Those of ordinary skill in the art will appreciate that: the drawing is a schematic diagram of one embodiment and the modules or flows in the drawing are not necessarily required to practice the invention.
Those of ordinary skill in the art will appreciate that: the modules in the apparatus of the embodiments may be distributed in the apparatus of the embodiments according to the description of the embodiments, or may be located in one or more apparatuses different from the present embodiments with corresponding changes. The modules of the above embodiments may be combined into one module, or may be further split into a plurality of sub-modules.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A liquid concentration detection method based on an optical fiber probe, which is applied to an optical fiber probe with adjustable optical path, and is characterized in that the method comprises the following steps:
when the optical fiber probe is placed in the liquid to be measured, determining the optical path of light in the liquid to be measured for the propagation process that incident light enters the liquid to be measured in the optical fiber probe through the incident optical fiber and is emitted from the emergent optical fiber;
Obtaining the concentration of the liquid to be measured based on a nonlinear regression model between the optical path and the concentration of the liquid to be measured, wherein the nonlinear regression model is expressed by the following formula:
wherein,cindicating the concentration of the liquid to be measured,lindicating the optical path of light in the liquid to be measured, a and b respectively indicating the parameters of the nonlinear regression model,represents the molar absorption coefficient.
2. The method of claim 1, wherein the nonlinear regression model is constructed by:
determining the information of the intensity of incident light entering the optical fiber probe;
for sample liquids with different concentrations, determining emergent light intensity information of incident light after the incident light passes through the sample liquid of the optical fiber probe and is reflected by a reflecting mirror of the optical fiber probe;
determining original absorbance values corresponding to sample liquids with various concentrations according to the incident light intensity information and the emergent light intensity information;
determining a parameter estimation value of a target nonlinear function based on concentration data of a plurality of groups of sample liquids and a data distribution diagram of original absorbance values corresponding to the concentration data, and fitting the parameter estimation value to obtain the target nonlinear function based on the parameter estimation value, wherein the target nonlinear function is used for representing a nonlinear positive correlation relationship between the concentration of the sample liquids and the absorbance;
If the fitting degree correlation index between the curve graph corresponding to the target nonlinear function obtained by fitting and the data distribution graph reaches a preset threshold, taking the parameter value corresponding to the target nonlinear function as the parameter value of a nonlinear regression model;
wherein the target nonlinear function is:
wherein A is absorbance, c is sample liquid concentration, and a and b are parameters of nonlinear functions.
3. The method of claim 2, wherein the process of constructing the nonlinear regression model further comprises:
correcting the original absorbance value based on a temperature correction coefficient to obtain corrected absorbance values corresponding to sample liquids with various concentrations, wherein the temperature correction coefficient is the ratio of the refractive index correction factor of the sample liquid at the standard temperature to the refractive index correction factor of the sample liquid at the current test temperature;
correspondingly, the determining the parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution diagram of the original absorbance values comprises the following steps:
and determining a parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution map of the corrected absorbance values.
4. A method according to claim 3, wherein said correcting said raw absorbance value based on a temperature correction coefficient comprises:
the original absorbance value is corrected according to the following formula:
A' = AK
s
wherein,Athe raw absorbance value is represented as such,A' the absorbance value after the correction is indicated,K s indicating the temperature correction coefficient.
5. A liquid concentration detection apparatus based on an optical fiber probe, comprising:
the optical path determining module is used for determining the optical path of light in the liquid to be detected for the propagation process that incident light enters the liquid to be detected in the optical fiber probe through the incident optical fiber and is emitted from the emergent optical fiber when the optical fiber probe is placed in the liquid to be detected;
the liquid concentration determining module is used for obtaining the concentration of the liquid to be detected based on a nonlinear regression model between the optical path and the concentration of the liquid to be detected, wherein the nonlinear regression model is expressed by the following formula:
wherein,cindicating the concentration of the liquid to be measured,lindicating the optical path of light in the liquid to be measured, a and b respectively indicating the parameters of the nonlinear regression model,represents the molar absorption coefficient.
6. The apparatus of claim 5, wherein the nonlinear regression model is constructed by a model construction module comprising:
The incident light intensity information determining unit is used for determining the incident light intensity information entering the optical fiber probe;
an outgoing light intensity information determining unit for determining outgoing light intensity information of incident light after passing through the sample liquid of the optical fiber probe and being reflected by the reflecting mirror of the optical fiber probe for sample liquids with different concentrations;
the original absorbance value calculating unit is used for determining original absorbance values corresponding to sample liquids with various concentrations according to the incident light intensity information and the emergent light intensity information;
the function fitting unit is used for determining a parameter estimation value of a target nonlinear function based on concentration data of a plurality of groups of sample liquids and a data distribution diagram of corresponding original absorbance values of the sample liquids, and fitting the parameter estimation value to obtain the target nonlinear function based on the parameter estimation value, wherein the target nonlinear function is used for representing a nonlinear positive correlation relationship between the concentration of the sample liquids and the absorbance;
the parameter value determining unit is used for taking the parameter value corresponding to the target nonlinear function as the parameter value of the nonlinear regression model if the fitting degree correlation index between the curve graph corresponding to the target nonlinear function obtained by fitting and the data distribution graph reaches a preset threshold;
Wherein the target nonlinear function is:
wherein A is absorbance, c is sample liquid concentration, and a and b are parameters of nonlinear functions.
7. The apparatus of claim 6, wherein the model building module further comprises:
the correction unit is used for correcting the original absorbance value based on a temperature correction coefficient to obtain corrected absorbance values corresponding to sample liquids with various concentrations, wherein the temperature correction coefficient is the ratio of the refractive index correction factor of the sample liquid at the standard temperature to the refractive index correction factor of the sample liquid at the current test temperature;
correspondingly, the function fitting unit is specifically configured to:
and determining a parameter estimation value of the target nonlinear function based on the concentration data of the plurality of groups of sample liquids and the corresponding data distribution diagram of the corrected absorbance value, and fitting based on the parameter estimation value to obtain the target nonlinear function.
8. The apparatus according to claim 7, wherein the correction unit is specifically configured to:
the original absorbance value is corrected according to the following formula:
A' = AK
s
wherein,Athe raw absorbance value is represented as such,A' the absorbance value after the correction is indicated, K s Indicating the temperature correction coefficient.
9. A fiber optic probe for liquid concentration detection using the method of claim 1, the fiber optic probe comprising a fiber optic probe body (10), a fiber optic bundle (9) containing incident light and outgoing fibers, and a mirror (3), the fiber optic probe further comprising: an optical path regulating device (11), a rear plug (1), a window sheet (2) and a lens (4), wherein,
the optical fiber probe comprises an optical fiber probe body (10), a groove (5) is formed in the side wall of the optical fiber probe body (10), when the probe body (10) is placed in liquid to be measured, the liquid to be measured flows into the groove (5), the optical fiber probe body is divided into an upper part and a lower part by the groove (5), through holes along the axial direction of the optical fiber probe body (10) are respectively formed in the upper part and the lower part of the optical fiber body, a reflecting mirror (3) is arranged at an opening at one end, communicated with the groove (5), of the through hole (7) below the groove and used for reflecting light, a rear plug (1) is arranged at the opening at the other end and used for supporting a window piece (2) placed in the through hole below, and a through hole (6) above the groove (5) is used for being inserted into an optical path adjusting device (11);
The optical path adjusting device (11) is of a hollow structure, one end of the optical path adjusting device is provided with an optical fiber bundle (9) through an optical fiber locking cap (8) and the other end of the optical path adjusting device stretches into the groove (5) through a through hole (6) above the groove, the length of the optical path adjusting device stretches into the groove (5) is adjustable, so that the optical path of light in liquid to be measured is adjustable, and the optical path adjusting device (11) is provided with a lens (4) at an opening at one end of the optical path adjusting device stretching into the groove.
10. The fiber optic probe according to claim 9, wherein the outer surface of the optical path adjusting device (11) is provided with external threads, the through hole above the groove is internally provided with internal threads corresponding to the external threads, and the length of the optical path adjusting device (11) extending into the groove is adjustable by matching the internal threads and the external threads.
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