CN113589047A - Detection apparatus integrating EIS liquid impedance measurement and refractometer - Google Patents

Abstract

The invention relates to a detection device integrating EIS liquid impedance measurement and a refractometer, which comprises an optical measurement system, an impedance measurement system and a processing system, wherein the optical measurement system comprises a light source, a light source controller and a light source controller; the optical measurement system comprises a light source system, a reflecting prism and an optical receiver system; the impedance measurement system comprises an electrode system and a circuit system; the processing system is connected with the optical receiver system and the circuit system; the testing device comprises a reflecting prism, a ring-shaped piece, an electrode system and a liquid storage tank, wherein the reflecting prism is arranged on one surface of the reflecting prism, a hollow-out part in the middle of the ring-shaped piece is matched with one surface of the reflecting prism to form the liquid storage tank for containing liquid to be tested, an electrode of the electrode system extends into the liquid storage tank to be contacted with the liquid to be tested, and the liquid to be tested in the liquid storage tank forms an interface between the surface of the prism and the liquid level on the reflecting prism so as to realize simultaneous testing of refraction and liquid impedance.

Description

Detection apparatus integrating EIS liquid impedance measurement and refractometer

Technical Field

The invention relates to the field of liquid measurement, in particular to a detection device integrating EIS liquid impedance measurement and a refractometer.

Background

Measurements using refractometer and EIS (electrochemical impedance spectroscopy) are common methods for existing liquid measurements. Wherein, because the refractive index of the liquid can be increased after the solid soluble substance is dissolved, the measurement of the content of the solid soluble substance can be achieved through the refractive index measurement, and therefore, the refractometer can be used for measuring the content of the solid soluble substance in the liquid; EIS is very effective for the detection of systems involving ionic conduction, and in particular multi-ion mixing systems, a considerable portion of the information in mixed ionic solutions can be readily obtained using EIS systems.

However, the refractometer only reflects the concentration of soluble solids in the liquid in the measurement process, and such a measurement mode has disadvantages in measuring many liquids, for example, when measuring a liquid with a low ion concentration, the refractometer cannot be very accurately evaluated, and then is a mixed solution mixed with ions, active substances, cells and the like, and the refractometer only reflects the properties of soluble parts in the liquid, but cannot reflect the properties of insoluble proteins, cells and the like. For example, when the sucrose aqueous solution is prepared by ultrapure water, the sucrose has no other ionized ions except for sucrose molecules, and the sucrose exists in a molecular crystal state, and the ionization condition does not exist, so that information displayed by the sucrose aqueous solution during electrical impedance measurement is not greatly different from that of water, and thus the concentration of the sucrose aqueous solution cannot be simply judged by electrical impedance measurement.

Therefore, both the refractometer and the EIS system have problems of being unable to measure or inaccurate in measurement, and although the accuracy can be increased by separate measurement of the refractometer and the EIS system, new problems arise, such as the risk of contamination of the sample during the transfer process, and particularly, the problem of insufficient sample amount in the case of a small sample amount in separate measurement.

Disclosure of Invention

The invention aims to provide a detection device integrating EIS liquid impedance measurement and a refractometer.

The specific scheme is as follows:

a detection device integrating EIS liquid impedance measurement and refractometer comprises an optical measurement system, an impedance measurement system and a processing system; the optical measurement system comprises a light source system, a reflecting prism and an optical receiver system, wherein light rays emitted by the light source system are received by the optical receiver system after interface reflection occurs on the reflecting prism; the impedance measuring system comprises an electrode system and a circuit system, wherein the circuit system applies a current signal to the electrode system and adopts a potential signal of the electrode system; the processing system is connected with the optical receiver system and the circuit system and processes the information acquired by connecting the optical receiver system and the circuit system; the electrode system comprises a reflecting prism, a ring-shaped piece, a liquid storage tank, an electrode system and a liquid level control system, wherein the reflecting prism is arranged on one surface of the reflecting prism, the hollow-out part in the middle of the ring-shaped piece is matched with one surface of the reflecting prism to form the liquid storage tank for containing liquid to be measured, the electrode of the electrode system extends into the liquid storage tank to be contacted with the liquid to be measured, and the liquid to be measured in the liquid storage tank forms an interface between the surface of the prism and the liquid level on the reflecting prism.

Further, the electrodes of the electrode system are embedded from the reflecting prism and extend into the liquid storage tank.

Further, the electrodes of the electrode system penetrate into the liquid storage tank from the peripheral wall of the annular piece.

Further, the electrodes serve as the ring-shaped member, and the electrodes are insulated and isolated from each other.

Further, the light source system is an LED linear array light source, the LED linear array light source comprises a circuit board and a plurality of LED chips, the linear array is attached to the circuit board, and a light homogenizing piece is further arranged on the light emitting side of each LED chip.

Further, the light homogenizing piece is a light diffusion plate or a light homogenizing piece.

Further, the light source system further comprises a collimation system, and the collimation system performs collimation operation on the light rays of the water discharged from the light source system.

Further, the collimation system is one of a cylindrical lens, a convex lens or a slit.

Further, the electrode system is a two-electrode system, a three-electrode system or a four-electrode system.

Further, the electrode of the electrode system is one of a platinum electrode, a titanium electrode, a carbon electrode or a metal compound electrode or a combination of at least two of the platinum electrode, the titanium electrode, the carbon electrode and the metal compound electrode.

Compared with the prior art, the detection device fusing EIS liquid impedance measurement and the refractometer has the following advantages: the detection device provided by the invention can be used for measuring soluble solids and insoluble solids in a liquid system by simultaneously realizing refraction measurement and electrochemical impedance measurement on liquid, so that the measurement robustness is improved, and the refraction measurement and the impedance measurement are finished by simultaneously measuring the same liquid to be measured, so that the liquid to be measured does not need to be transferred, the possibility of sample pollution is avoided, the measurement accuracy is greatly improved, and the measurement time is shortened.

Drawings

Fig. 1 shows a schematic structural framework of the detection device.

Fig. 2 shows a schematic view of an optical measuring system.

Figure 3 shows a schematic of a two-electrode system.

Fig. 4 shows a schematic of a three-electrode system.

Figure 5 shows a schematic of a four electrode system.

Fig. 6 shows a schematic view of the reservoir mounted on the reflecting prism.

Figure 7 shows a schematic assembly of a three-electrode system.

Figure 8 shows a schematic assembly of a four electrode system.

Fig. 9 shows an impedance plot of an aqueous sucrose solution.

FIG. 10 shows the refractive index of water and a 40% aqueous solution of sucrose.

Fig. 11 shows a liquid system for milk.

Detailed Description

To further illustrate the various embodiments, the invention provides the accompanying drawings. The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the embodiments. Those skilled in the art will appreciate still other possible embodiments and advantages of the present invention with reference to these figures. Elements in the figures are not drawn to scale and like reference numerals are generally used to indicate like elements.

The invention will now be further described with reference to the accompanying drawings and detailed description.

As shown in fig. 1 and 2, the present embodiment provides a detection apparatus that combines EIS liquid impedance measurement and refractometer, which includes an optical measurement system, an impedance measurement system, and a processing system.

The optical measurement system includes a light source system 11, a reflection prism 12, and an optical receiver system 13. The light source system 11 provides sufficient controllable light to the whole system, and the wavelength and intensity of the light used depend on the system according to the requirements of the whole system for the test sample, for example, the optical receiver is sensitive to the light reception of the G channel, so that the wavelength of the green part can be used in the light source part.

In this embodiment, referring to fig. 2, the light source system 11 adopts a method of an LED linear array light source to implement a light source, and the LED linear array light source can be implemented by attaching a plurality of LED chips 110 to a PCB 111. Because there is the clearance between the inside LED chip unit of LED linear array light source, this can influence the homogeneity of the light of final formation of image, consequently increase even light piece 112 at the light-emitting side of LED chip and realize the effect of even light, even light piece can adopt such as even light piece that light diffuser plate, various materials made to realize the even of light, and it is also more even to make formation of image finally, can reach better measuring effect.

In addition, since the exiting light of the existing LED chip has a certain spread angle, some non-parallel light may affect the measurement accuracy, and some non-parallel light may cause an artifact or some factors disturbing the measurement of the light collected by the optical receiver, so that the collimation system 14 is further adopted in this embodiment to ensure that the exiting light has a certain parallelism, so as to ensure the accuracy of the final measurement. Generally, the collimating system can collimate the light by other means such as a cylindrical lens, a convex lens, a slit, and the like.

The reflecting prism 12 is a condition required for realizing that the light emitted by the light source can be reflected with the liquid at a certain interface of the prism, so as to realize the normal receiving of the optical receiver in the next step.

The optical receiver system 13 includes an optical filter 131 and an optical receiver 132. Since the optics in the optical receiver are sensitive to different wavelengths to different degrees, the filter functions to preferentially select the light source within the wavelength range for the light source system. Secondly, in order to filter out other wavelengths of stray light entering the optical receiver in the environment, the stray light may be due to other light sources, such as other wavelengths of light entering the optical system from the sunlight, and the like.

The optical receiver mainly comprises a CMOS, a CCD or other optical receiving components, and can effectively receive the light emitted by the light source and reflected by the prism system, so as to obtain effective light information for a subsequent measuring system to perform relevant measurement. Since it is prior art to perform relevant processing on the light information received by the optical receiver via the processing system and feed back the corresponding result, details are not described herein, and reference may be made to the measurement principle of the refractometer in the prior art.

The impedance measurement system includes an electrode system and a circuit system.

The electrode system can determine the system of the measuring electrode according to the system of the measuring liquid during the impedance measurement, and generally comprises three electrode systems, namely a two-electrode system, a three-electrode system and a four-electrode system.

When the electrode potential of the auxiliary electrode is determined to be unchanged or change is negligible in the test process during impedance measurement, a reference electrode is not needed, that is, a two-electrode system can be used for measurement, and a schematic diagram of the two-electrode system refers to fig. 3.

In order to reduce the influence of the electrode potentials of the working electrode and the auxiliary electrode (counter electrode) changing during the test, a three-electrode system can be used, which has a working electrode (research electrode), a reference electrode and an auxiliary electrode (counter electrode) for measuring and monitoring the potential difference between the reference electrode and the working electrode with high input impedance, almost no current passes through the reference electrode, current passes between the working electrode and the auxiliary electrode, and the schematic diagram of the three-electrode system is shown in fig. 4.

In order to overcome the influence of electrode polarization and environmental fluctuation, a four-electrode test system can be adopted, which utilizes a pair of external electrodes to introduce exciting current into liquid and measures the voltage on a pair of internal electrodes, an alternating current impedance method is mainly adopted to test the resistance, and the schematic diagram of the four-electrode system refers to fig. 5.

The circuit system mainly comprises a signal driving part and a signal amplifying part. Because the counter electrode and the reference electrode are main nodes for measuring potential and impedance, a potential or current with certain frequency and amplitude needs to be applied to the working electrode, and a corresponding potential signal applied to the working electrode by the driving amplifier needs to be excited by the MCU, and the part mainly comprises an operational amplifier. The signal excited at the electrodes may be a static dc signal, which enables measurement of conductivity, static potential, etc. measurement information. Or an alternating current signal excited according to a certain frequency and amplitude, wherein the frequency range can be 0.0001Hz-10MHz, and the amplitude can be-10V-10V, so that the response parameters of the potential and the impedance of the liquid under different frequencies can be measured.

The signal amplification part mainly collects signals through a reference electrode and a counter electrode, most of the collected potential signals are analog signals, and the analog signals can be converted into digital signals through the ADC to be received by a processing system (MCU).

Since it is the prior art that the digital signals measured by the electrode system and the impedance measurement system are processed by the processing system and corresponding results are fed back, details are not described herein, and reference may be made to the measurement principle of EIS in the prior art.

Referring to fig. 6, a ring-shaped member 15 is disposed on a surface of the reflection prism 12, a hollow-out portion of the middle of the ring-shaped member 15 cooperates with a surface of the reflection prism to form a liquid storage tank 151 for containing liquid to be measured, an electrode 21 (for example, a dual-electrode member in fig. 6) of the electrode system extends to the liquid storage tank 151, the liquid to be measured can form a prism-liquid level interface on the reflection prism, and light is filtered by the optical filter and received by the optical receiver by reflection of the prism-liquid level interface. Meanwhile, the electrode system for measuring the liquid excites sinusoidal signals with certain frequency width and amplitude in the liquid through the same electrode, multi-dimensional information is formed through detecting the impedance, potential and phase of the liquid between the electrodes and through the relation between the electrodes and the frequency, the obtained multi-dimensional information and the signals measured by the optical receiver instrument can describe the properties of the liquid together, the properties of the liquid to be measured can be judged more accurately, and the refraction measurement and the impedance measurement are finished by adopting the same liquid to be measured and simultaneously measuring, the liquid to be measured does not need to be transferred, the possibility of sample pollution is avoided, the measurement accuracy is greatly improved, and the measurement time is shortened.

The material of the electrode can be a platinum electrode, a titanium electrode, a carbon electrode and other metal compound electrodes. The electrodes may be mounted in such a manner that the electrodes 21 are embedded in the reflective prism and extend into the liquid storage tank (see fig. 7, fig. 7 taking a three-electrode system as an example), penetrate into the liquid storage tank from the outer peripheral wall of the ring-shaped member (see fig. 6, fig. 6 taking a two-electrode system as an example), or the electrodes 21 are directly taken as the ring-shaped member (see fig. 8, fig. 8 taking a four-electrode system as an example), and are insulated and isolated from each other, so as to measure the optical property and the electrical property simultaneously on the reflective prism.

The following illustrates the advantages of the detection apparatus provided by this embodiment over existing refractometers and EIS impedance measurements.

Example 1

In a non-conductive liquid system, since liquid is not ionized, such as a sucrose aqueous solution, in the case of preparing a sucrose aqueous solution with ultrapure water, since there is no ionized ion except for sucrose molecules inside the sucrose aqueous solution, sucrose exists in a state of molecular crystal, and there is no ionized state, therefore, information displayed by the sucrose aqueous solution during electrical impedance measurement is not greatly different from water (see fig. 9 for an impedance diagram of the sucrose aqueous solution), and thus the concentration of sucrose aqueous solution cannot be simply determined by electrical impedance measurement.

However, the concentration of the sucrose aqueous solution causes a change in the refractive index of the liquid, and thus a very large difference is exhibited in the measurement results of the refractometer (the refractive index of water and a 40% sucrose aqueous solution is shown in fig. 10, where the left part is water and the right part is a 40% sucrose aqueous solution in fig. 10).

It can therefore be seen that the refractometer can detect the optical properties of the liquid to achieve detection of the liquid under wakefulness which is not electrochemically measurable.

Therefore, by simultaneously carrying out electrochemical property measurement and refraction measurement on the solution to be measured, the robustness of the measurement result can be greatly improved. For another example, honey in the market is classified more, but the honey is not very different in concentration, for example, honey of different flowers such as sophora flower honey is about 75% in sugar degree. When the honey is measured, the measurement result of the refractometer cannot directly reflect the specific variety of the honey, but the electrochemical impedance measurement method can directly reflect the conditions of other components except sugar in the honey, and the measurement mode can more quickly distinguish the quality and variety of the honey.

Example 2

There are also numerous soluble ionic systems (calcium, potassium, phosphorus, etc.) and insoluble adipocytes, proteins, etc. in milk, these insoluble substances also being very important nutrient elements in milk. Soluble solids contained in milk can only be determined by refractometry, but the parameters of milk that we are most concerned with are protein content and fat content. The milk can be regarded as a liquid system as in fig. 11, where the grey parts in fig. 11 represent fat cells which are liquid and the circled parts. When an impedance meter is used to excite electrical signals of different frequencies (0.01Hz-100000Hz), (i) is often the path for low frequency currents, and (ii) is the path for high frequency currents. Therefore, two peaks of the corresponding impedance at different frequencies can be detected, so that the amount of the fat component in the milk can be judged. Even specific electrodes can be manufactured to detect specific elements in the milk, such as CPE electrodes can specifically react with serum in the milk and be reflected on an electrochemical impedance spectrum.

The detection device fusing EIS liquid impedance measurement and the refractometer provided by the specific embodiment has the following advantages:

1. the measurement of soluble solids and insoluble solids in a liquid system is carried out on the liquid by simultaneously realizing refraction measurement and electrochemical impedance measurement, so that the measurement robustness is improved; especially for concentration measurements and for species measurements of liquids.

2. And when the optical properties cannot be distinguished, the electrochemical properties are distinguished, so that complementary measurement is realized.

3. When the liquid is capable of being measured for both measurement modes, the advantages of a certain measurement scheme can be utilized to achieve a more accurate measurement.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (10)

1. A detection device for fusing EIS liquid impedance measurement and refractometer is characterized in that: the system comprises an optical measurement system, an impedance measurement system and a processing system; the optical measurement system comprises a light source system, a reflecting prism and an optical receiver system, wherein light rays emitted by the light source system are received by the optical receiver system after interface reflection occurs on the reflecting prism; the impedance measuring system comprises an electrode system and a circuit system, wherein the circuit system applies a current signal to the electrode system and adopts a potential signal of the electrode system; the processing system is connected with the optical receiver system and the circuit system and processes the information acquired by connecting the optical receiver system and the circuit system; the electrode system comprises a reflecting prism, a ring-shaped piece, a liquid storage tank, an electrode system and a liquid level control system, wherein the reflecting prism is arranged on one surface of the reflecting prism, the hollow-out part in the middle of the ring-shaped piece is matched with one surface of the reflecting prism to form the liquid storage tank for containing liquid to be measured, the electrode of the electrode system extends into the liquid storage tank to be contacted with the liquid to be measured, and the liquid to be measured in the liquid storage tank forms an interface between the surface of the prism and the liquid level on the reflecting prism.

2. The detection device according to claim 1, wherein: the electrodes of the electrode system are embedded from the reflecting prism and extend into the reservoir.

3. The detection device according to claim 1, wherein: the electrodes of the electrode system penetrate into the liquid storage tank from the peripheral wall of the annular part.

4. The detection device according to claim 1, wherein: the electrodes serve as the annular member, and the electrodes are insulated and isolated from each other.

5. The detection device according to claim 1, wherein: the LED linear array light source comprises a circuit board and a plurality of LED chips, wherein the linear array light source is attached to the circuit board, and the light emitting side of each LED chip is provided with a light homogenizing piece.

6. The detection device according to claim 5, wherein: the light homogenizing piece is a light diffusion plate or a light homogenizing piece.

7. The detection device according to claim 5, wherein: the light source system further comprises a collimation system, and the collimation system is used for collimating the light rays discharged by the light source system.

8. The detection device according to claim 7, wherein: the collimation system is one of a cylindrical lens, a convex lens or a slit.

9. The detection device according to claim 1, wherein: the electrode system is a double-electrode system, a three-electrode system or a four-electrode system.

10. The detection device according to claim 9, wherein: the electrode of the electrode system is one of a platinum electrode, a titanium electrode, a carbon electrode or a metal compound electrode or a combination of at least two of the platinum electrode, the titanium electrode, the carbon electrode and the metal compound electrode.

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