Embedded optical fiber solution concentration measuring device and use method thereof

Abstract

The invention relates to the technical field of measurement, in particular to an embedded optical fiber solution concentration measuring device and a use method thereof. The photoelectric conversion module is used for converting an optical signal sent by the optical fiber receiving device from the optical fiber sending device through the solution in the reaction tank into an electric signal; the reaction tank is used for placing a to-be-detected solution, and the optical fiber transmitting device and the optical fiber receiving device are oppositely arranged on two end surfaces of the reaction tank; the fitting module is used for fitting the reference solution and a known-concentration solution of the same type as the to-be-detected solution on the basis of the Beer-Lambert law; the measuring module is used for substituting the detected electric signal of the to-be-detected solution into the linear relation obtained by the fitting module to obtain the concentration value of the to-be-detected solution; the invention has the advantages of low cost, easy operation, portability, real-time monitoring, light source conversion and compatibility with colored and colorless solution concentration measurement.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to an embedded optical fiber solution concentration measuring device and a use method thereof. Background Art

[0002] The concentration of a solution is one of the main parameters that characterize the characteristics of a solution. In the fields of biochemistry, environmental protection, medical treatment, and food processing, the measurement and control of the concentration of a solution plays a very important role in the modern industrial production process. It is an important technical means to ensure and improve product quality. Therefore, many methods for measuring the concentration of a solution have emerged. Traditional measuring instruments include commercial polarimeter, colorimeter, Abbe refractometer, etc., as well as broadband absorption spectroscopy, titration, and fluorescence quenching. However, most of these methods are not easy to carry, and cannot be monitored in real time and compatible with the measurement of colored and colorless solutions. Subsequently, some new technologies such as photoacoustics, fiber Bragg gratings, SPR sensors, and Raman spectroscopy have emerged one after another, but these methods are expensive and difficult to operate. Summary of the invention

[0003] In order to improve the cost-effectiveness of solution concentration measurement, the present invention proposes an embedded optical fiber solution concentration measurement device, including a light source control module, an optical fiber transmitting device, a reaction tank, an optical fiber receiving device, a photoelectric conversion module, a fitting module and a measurement module, wherein:

[0004] A light source control module, used to control the wavelength of the optical fiber emitted by the optical fiber transmitting device;

[0005] A reaction tank is used to place the solution to be detected, and the optical fiber transmitting device and the optical fiber receiving device are arranged on two end surfaces of the reaction tank opposite to each other;

[0006] A photoelectric conversion module, used for converting the optical signal sent by the optical fiber receiving device through the solution in the reaction tank from the optical fiber sending device into an electrical signal;

[0007] A fitting module is used to fit the reference solution and a solution of known concentration of the same type as the solution to be tested based on the Beer-Lambert law to obtain a fitted linear relationship;

[0008] The measuring module is used to substitute the detected electrical signal of the solution to be tested into the linear relationship obtained by the fitting module to obtain the concentration value of the solution to be tested.

[0009] Furthermore, the light source control module includes a multi-input and one-output optical fiber splitter, each input port of the optical fiber splitter is used to input a light source with a fixed wavelength, and the output end of the optical fiber splitter serves as the output end of the light source control module.

[0010] Furthermore, the photoelectric conversion module includes a photoresistor, an operational amplifier and a filter circuit, wherein:

[0011] A photoresistor is used to convert the optical signal received by the optical fiber receiving device into an electrical signal, that is, the voltage across the photoresistor is used as the electrical signal;

[0012] Operational amplifiers, used for signal processing and amplification of electrical signals;

[0013] The filter circuit is used to perform low-pass filtering on the amplified signal to remove noise and interference in the amplified signal.

[0014] Furthermore, the resistance of the photoresistor is compensated according to the current temperature value, which specifically includes the following steps:

[0015] Get the initial resistance value of the photoresistor;

[0016] A temperature detection module is set in the environment where the photoresistor is located, and the resistance value of the photoresistor is tested at various temperatures to obtain a temperature-resistance relationship table;

[0017] The resistance compensation value at each temperature is obtained by subtracting the resistance value of the photoresistor at each temperature from the initial resistance value of the photoresistor;

[0018] During the use phase, the current ambient temperature is obtained according to the temperature detection module, and the resistance compensation value of the current ambient temperature is obtained by looking up the table;

[0019] The target resistance value is obtained by subtracting the resistance compensation value from the factory set resistance value of the photoresistor.

[0020] Furthermore, a solution inlet is arranged at the top of the reaction tank, a solution outlet is arranged at the bottom, and a water stop clamp is arranged at the solution outlet.

[0021] Furthermore, the fitting module fits the reference solution and a solution of known concentration of the same type as the solution to be tested based on the Beer-Lambert law, and the process of obtaining the fitted linear relationship includes:

[0022] The light source control module selects a wavelength of light to emit, and then calculates the absorbance of the current type of solution based on the reference solution and the solution with known concentration;

[0023] Based on the Beer-Lambert law, the relationship between the absorbance and the known concentration of the current type of solution is fitted by the least square method to obtain the fitting relationship between the absorbance and the current type of solution;

[0024] Determine whether the ratio of the regression sum of squares to the total deviation sum of squares of the fitted linear relationship is greater than 0.99. If so, save the fitted relationship of the current type fusion;

[0025] Otherwise, a wavelength is reselected through the light source control module, and the above steps are repeated until the ratio of the regression sum of squares to the total deviation sum of squares of the fitted linear relationship is greater than 0.99.

[0026] Further, the process of calculating the molar absorption coefficient of the solution to be measured based on the reference solution and the solution with known concentration according to the Beer-Lambert law is expressed as:

[0027]

[0028] Where K represents the molar absorption coefficient of the solution to be measured; R represents the resistance of the photoresistor when the reaction tank contains a solution of known concentration; R 0 It represents the resistance value of the photoresistor when the reaction tank contains the reference solution; b represents the thickness of the light-absorbing layer; and c represents the known concentration of the solution.

[0029] Furthermore, the process of the measurement module calculating the concentration of the solution to be measured according to the molar absorption coefficient of the solution to be measured obtained by fitting includes:

[0030]

[0031] Where c' represents the resistance value of the photoresistor when the reaction tank contains the solution to be tested; R 0 It represents the resistance value of the photoresistor when the reaction tank contains the reference solution; b represents the thickness of the light-absorbing layer; K represents the molar absorption coefficient of the solution to be measured.

[0032] The present invention also provides a method for using an embedded optical fiber solution concentration measuring device, which is used for using an embedded optical fiber solution concentration measuring device, and specifically comprises the following steps:

[0033] For a certain type of solution, different concentrations of this type of solution are configured as known concentration solutions, and the reference solution is used to fit each known concentration solution, and the optimal light source wavelength of this type of solution is confirmed;

[0034] Fitting is performed based on the data collected under the optimal light source wavelength to obtain the fitting relationship between the absorbance of this type of solution and the solution concentration, and the fitting relationship and the light source wavelength are saved;

[0035] The type of the current solution to be tested is obtained, and the measurement module calls the best fitting relationship and light source wavelength corresponding to the type of solution;

[0036] The solution to be tested is injected into the reaction tank, and the resistance value of the photoresistor is substituted into the best fitting relationship to calculate the concentration of the solution to be tested. Compared with the prior art, the present invention has a novel structure, can achieve low cost, easy operation, portability, real-time monitoring, light source conversion, and compatibility with colored and colorless solution concentration measurement, and has strong pertinence, high universality, high flexibility, and high work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a preferred embodiment of an embedded optical fiber solution concentration measuring device of the present invention;

[0038] Figure 2 This is a schematic diagram of the reaction tank structure of an embedded optical fiber solution concentration measuring device of the present invention;

[0039] Figure 3 The present invention is a flowchart of a method for using an embedded optical fiber solution concentration measuring device. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] The present invention provides an embedded optical fiber solution concentration measuring device, comprising a light source control module, an optical fiber transmitting device, a reaction tank, an optical fiber receiving device, a photoelectric conversion module photoresistor, a fitting module and a measuring module, wherein:

[0042] A light source control module, used to control the wavelength of the optical fiber emitted by the optical fiber transmitting device;

[0043] A reaction tank is used to place the solution to be detected, and the optical fiber transmitting device and the optical fiber receiving device are arranged on two end surfaces of the reaction tank opposite to each other;

[0044] A photoelectric conversion module, used for converting the optical signal sent by the optical fiber receiving device through the solution in the reaction tank from the optical fiber sending device into an electrical signal;

[0045] A fitting module is used to fit the reference solution and a solution of known concentration of the same type as the solution to be tested based on the Beer-Lambert law to obtain a fitted linear relationship;

[0046] The measuring module is used to substitute the detected electrical signal of the solution to be tested into the linear relationship obtained by the fitting module to obtain the concentration value of the solution to be tested.

[0047] This embodiment provides a specific implementation of an embedded optical fiber solution concentration measuring device. In this embodiment, the device includes a data acquisition unit, which collects electrical signals of different solutions, and then transmits the data collected by the acquisition module to the display module of the host computer for display, and the host computer calculates according to the collected data to obtain the concentration corresponding to the current solution, wherein:

[0048] like Figure 1 The data acquisition unit 1 includes a light source 4, a microcontroller module 8, a data transceiver module 9, a power switch 10, and a power module 11. The microcontroller module 8 controls the light source to select the wavelength of the transmitting optical fiber, and then the optical fiber is split into a bundle of optical fibers through the optical fiber splitter 2 and sent to the reaction tank 3 through the optical fiber sending device;

[0049] The optical fiber receiving device in the reaction tank 3 transmits the optical signal to the photoelectric conversion module 6, converts the photoelectricity into a signal, and during the conversion process, the temperature measured by the temperature detection module 5 is used to compensate the converted electrical signal, and the temperature information is uploaded to the microcontroller module;

[0050] The electrical signal data collected by the photoelectric conversion module 6 is converted by the analog-to-electric conversion module 7 and then the electrical signal information is transmitted to the microcontroller module;

[0051] The power module 11 supplies power to the data transceiver module, the microcontroller module, the analog-to-electric conversion module, the photoelectric module, and the temperature detection module, and controls the on-off relationship with the power supply object through the power switch 10;

[0052] The microcontroller module sends the collected temperature data and electrical signal data to the data transceiver module, and then sends it to the host computer through the data receiving module;

[0053] The data analysis module 12 is used to perform real-time analysis based on the collected data and send the solution concentration results obtained by the analysis to the data transceiver module;

[0054] The data transceiver module sends the received solution concentration information to the display module 13, and the display module 13 is used to display the solution concentration calculated in real time.

[0055] In this embodiment, the photoelectric conversion module includes a photoresistor component of model GL5528, an operational amplifier of model LM393, and a low-pass filter, wherein:

[0056] The photoresistor component of model GL5528 is used to convert the optical signal received by the optical fiber receiving device into an electrical signal, that is, the voltage across the photoresistor is used as the electrical signal;

[0057] An operational amplifier of model LM393 is used for signal processing and amplification of electrical signals;

[0058] The filter circuit is used to perform low-pass filtering on the amplified signal to remove noise and interference in the amplified signal.

[0059] Before calculating the solution concentration, the data analysis module needs to compensate the resistance value of the thermistor calculated based on the electrical signal according to the real-time temperature information of the collected data, which specifically includes the following steps:

[0060] Get the initial resistance value of the photoresistor;

[0061] A temperature detection module is set in the environment where the photoresistor is located, and the resistance value of the photoresistor is tested at various temperatures to obtain a temperature-resistance relationship table;

[0062] The resistance compensation value at each temperature is obtained by subtracting the resistance value of the photoresistor at each temperature from the initial resistance value of the photoresistor;

[0063] During the use phase, the current ambient temperature is obtained according to the temperature detection module, and the resistance compensation value of the current ambient temperature is obtained by looking up the table;

[0064] The target resistance value is obtained by subtracting the resistance compensation value from the factory set resistance value of the photoresistor.

[0065] As an optional embodiment, the reaction tank structure used in this embodiment is as follows Figure 2 , an optical fiber transmitting device 23 and an optical fiber receiving device 304 are respectively arranged on the left and right sides of the reaction tank, and a condenser 303 is arranged at the outlet of the optical fiber transmitting device 23; a solution inlet channel 301 and a solution outlet channel 305 are respectively arranged on the upper and lower sides of the reaction tank. When the reaction tank is used, the solution outlet channel 305 is closed by a water stop clamp, and the solution fills the liquid carrier container 302 through the solution inlet channel 301. After the data is collected, the water stop clamp is opened to allow the solution to flow out from the solution outlet channel 305.

[0066] This embodiment also provides a method for using an embedded optical fiber solution concentration measuring device, which is used for using an embedded optical fiber solution concentration measuring device, and specifically includes the following steps:

[0067] For a certain type of solution, different concentrations of this type of solution are configured as known concentration solutions, and the reference solution is used to fit each known concentration solution, and the optimal light source wavelength of this type of solution is confirmed;

[0068] Fitting is performed based on the data collected under the optimal light source wavelength to obtain the fitting relationship between the absorbance of this type of solution and the solution concentration, and the fitting relationship and the light source wavelength are saved;

[0069] The type of the current solution to be tested is obtained, and the measurement module calls the best fitting relationship and light source wavelength corresponding to the type of solution;

[0070] The solution to be tested is injected into the reaction tank, and the resistance value of the photoresistor is substituted into the best fitting relationship to calculate the concentration of the solution to be tested.

[0071] Before calculating the concentration of a solution, the present invention needs to collect data of the solution in advance. When collecting the data of the solution, it is necessary to confirm that the solution can use the optimal wavelength of the light source, and the relationship between the solution concentration and the absorbance is obtained by fitting according to the selected optimal wavelength. After obtaining these data, the device of the present invention is used to select the optimal wavelength of the light source according to the type of solution to be measured, and a solution of known solution type but unknown concentration is placed in a reaction tank. The host computer calculates the absorbance of the solution of this type according to the collected electrical signal, and then substitutes the absorbance into the relationship between the solution concentration and the absorbance obtained by fitting, so as to obtain the solution concentration information corresponding to the solution.

[0072] In this embodiment, the scheme of the present invention is described in two stages. In the first stage, the scheme of the present invention needs to determine the optimal wavelength of the light source and obtain the relationship between the solution concentration and absorbance of a specific type of solution; in the second stage, the optimal wavelength of the light source is used to measure the electrical signal of unknown concentration and calculate the absorbance, and the solution concentration is calculated based on the absorbance. Specifically, the following steps are included:

[0073] (i) The first stage: determining the optimal wavelength of the light source to be used and obtaining the relationship between the solution concentration and the absorbance of a specific solution.

[0074] In this stage, it is first necessary to modulate multiple different concentrations of a specific type of solution. The modulated concentration information is known and used for subsequent fitting.

[0075] Secondly, you need to choose a reference solution, usually pure water.

[0076] Next, the corresponding absorbance is calculated by the collected reference solution and the different concentrations of each specific type of solution, and then a linear fit is performed between the absorbance and the solution concentration. If the linear correlation coefficient of the fitting curve is greater than 0.99, the current fitting data is saved and the wavelength of the light used is used as the optimal wavelength of the light source; otherwise, the wavelength data of the next group is used for fitting;

[0077] In particular, in order to obtain data conveniently at this stage, multiple commonly used wavelengths are set, and data at each commonly used wavelength is collected for one concentration, and the data at each wavelength is organized into a group for easy subsequent calls.

[0078] In this embodiment, the photoelectric conversion module collects the voltage across the photoresistor, and the process of converting it into resistance includes:

[0079]

[0080] Where R represents the resistance value calculated based on the voltage U across the photoresistor; R 串Indicates the resistance value of the resistor in series with the photoresistor, usually 10 4 Ω, this resistor is used to adjust the current of the photoelectric conversion module, which plays a role in protecting the photoelectric resistor, improving the circuit stability and optimizing the circuit response time; U 电源 Indicates the power supply voltage of the photoelectric conversion module, generally 3.3V.

[0081] The calculation of the molar absorptivity is based on the Beer-Lambert law. The absorbance is linearly related to the concentration of the substance, and the formula is:

[0082]

[0083] Where A is the absorbance; T is the transmittance, i.e. the ratio of the transmitted light intensity to the incident light intensity; I is the transmitted light intensity; I 0 is the incident light intensity; b is the absorption layer thickness, in cm, i.e., the distance between the optical fiber transmitting device and the optical fiber receiving device in the present invention; K is the molar absorption coefficient, which is related to the properties of the absorbing substance and the wavelength λ of the incident light; c is the solution concentration of the non-reference solution.

[0084] Assume that λ and b remain unchanged. According to the characteristics of the photoresistor sensor, the light intensity is inversely proportional to the photoresistance, and the formula is expressed as:

[0085]

[0086] Among them, R 0 is the incident resistance, that is, the resistance value calculated based on the measurement information when the reaction tank contains a non-reference solution; R is the transmission resistance, that is, the resistance value calculated based on the measurement information when the reaction tank contains a reference solution. Further deduction shows that the molar absorption coefficient is:

[0087]

[0088] In this stage, the solution concentration c and spacing b are all known, and the molar absorption coefficient can be obtained based on the resistance value.

[0089] Save the molar absorptivity of the solution of this characteristic type.

[0090] (ii) The second stage: Based on the fitting relationship and the optimal wavelength of the light source, the unknown solution is measured, and the data calculated based on the measurement results are substituted into the fitting curve to obtain the solution concentration information.

[0091] Similarly, in this stage, the resistance value corresponding to the solution needs to be obtained, and the concentration expression of the unknown solution is expressed as:

[0092]

[0093] Wherein, c' represents the resistance value of the photoresistor when the reaction tank contains the solution to be tested; the molar absorption coefficient K of the solution to be measured needs to be obtained in the first stage.

[0094] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "outside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0095] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "rotation" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0096] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An embedded optical fiber solution concentration measuring device, characterized in that: It includes a light source control module, an optical fiber transmitting device, a reaction tank, an optical fiber receiving device, a photoelectric conversion module, a fitting module and a measuring module, wherein: A light source control module, used to control the wavelength of the optical fiber emitted by the optical fiber transmitting device; A reaction tank is used to place the solution to be detected, and the optical fiber transmitting device and the optical fiber receiving device are arranged on two end surfaces of the reaction tank opposite to each other; A photoelectric conversion module, used for converting the optical signal sent by the optical fiber receiving device through the solution in the reaction tank from the optical fiber sending device into an electrical signal; A fitting module is used to fit the reference solution and a solution of known concentration of the same type as the solution to be tested based on the Beer-Lambert law to obtain a fitted linear relationship; The measuring module is used to substitute the detected electrical signal of the solution to be tested into the linear relationship obtained by the fitting module to obtain the concentration value of the solution to be tested.

2. The embedded optical fiber solution concentration measuring device according to claim 1, characterized in that: The light source control module includes a multi-input and one-output optical fiber splitter. Each input port of the optical fiber splitter is used to input a light source with a fixed wavelength, and the output end of the optical fiber splitter serves as the output end of the light source control module.

3. The embedded optical fiber solution concentration measuring device according to claim 1, characterized in that: The photoelectric conversion module includes a photoresistor, an operational amplifier and a filter circuit, wherein: A photoresistor is used to convert the optical signal received by the optical fiber receiving device into an electrical signal, that is, the voltage across the photoresistor is used as the electrical signal; Operational amplifier, used to amplify electrical signals; The filter circuit is used to perform low-pass filtering on the amplified signal to remove noise and interference in the amplified signal.

4. The embedded optical fiber solution concentration measuring device according to claim 1, characterized in that: The resistance of the photoresistor is compensated according to the current temperature value, which specifically includes the following steps: Get the initial resistance value of the photoresistor; A temperature detection module is set in the environment where the photoresistor is located, and the resistance value of the photoresistor is tested at various temperatures to obtain a temperature-resistance relationship table; The resistance compensation value at each temperature is obtained by subtracting the resistance value of the photoresistor at each temperature from the initial resistance value of the photoresistor; During the use phase, the current ambient temperature is obtained according to the temperature detection module, and the resistance compensation value of the current ambient temperature is obtained by looking up the table; The target resistance value is obtained by subtracting the resistance compensation value from the factory-set resistance value of the photoresistor.

5. The embedded optical fiber solution concentration measuring device according to claim 1, characterized in that: The top of the reaction tank is provided with a solution inlet, the bottom is provided with a solution outlet, and the solution outlet is provided with a water stop clamp.

6. The embedded optical fiber solution concentration measuring device according to claim 1, characterized in that: The fitting module fits the reference solution and the known concentration solution of the same type as the test solution based on the Beer-Lambert law. The process of obtaining the fitted linear relationship includes: The light source control module selects a wavelength of light to emit, and then calculates the absorbance of the current type of solution based on the reference solution and the solution with known concentration; Based on the Beer-Lambert law, the relationship between the absorbance and the known concentration of the current type of solution is fitted by the least square method to obtain the fitting relationship between the absorbance and the current type of solution; Determine whether the ratio of the regression sum of squares to the total deviation sum of squares of the fitted linear relationship is greater than 0.

99. If so, save the fitted relationship of the current type fusion; Otherwise, a wavelength is reselected through the light source control module, and the above steps are repeated until the ratio of the regression sum of squares to the total deviation sum of squares of the fitted linear relationship is greater than 0.

99.

7. The embedded optical fiber solution concentration measuring device according to claim 6, characterized in that: The process of calculating the molar absorption coefficient of the solution to be measured based on the Beer-Lambert law according to the reference solution and the solution of known concentration is expressed as: Wherein, K represents the molar absorption coefficient of the solution to be measured; R represents the resistance of the photoresistor when the reaction tank contains a solution of known concentration; R0 represents the resistance of the photoresistor when the reaction tank contains a reference solution; b represents the thickness of the absorption layer; and c represents the known concentration of the solution.

8. The embedded optical fiber solution concentration measuring device according to claim 6, characterized in that: The process of the measurement module calculating the concentration of the solution to be measured according to the molar absorption coefficient of the solution to be measured obtained by fitting includes: Wherein, c' represents the resistance of the photoresistor when the reaction tank contains the test solution; R0 represents the resistance of the photoresistor when the reaction tank contains the reference solution; b represents the thickness of the light-absorbing layer; and K represents the molar absorption coefficient of the solution to be measured.

9. A method for using an embedded optical fiber solution concentration measuring device, characterized in that: The use of the embedded optical fiber solution concentration measuring device according to claim 1 specifically comprises the following steps: For a certain type of solution, different concentrations of this type of solution are configured as known concentration solutions, and the reference solution is used to fit each known concentration solution, and the optimal light source wavelength of this type of solution is confirmed; Fitting is performed based on the data collected under the optimal light source wavelength to obtain the fitting relationship between the absorbance of this type of solution and the solution concentration, and the fitting relationship and the light source wavelength are saved; The type of the current solution to be tested is obtained, and the measurement module calls the best fitting relationship and light source wavelength corresponding to the type of solution; The solution to be tested is injected into the reaction tank, and the resistance value of the photoresistor is substituted into the best fitting relationship to calculate the concentration of the solution to be tested.

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