Zeta potential detection device and method based on Coulter principle

Abstract

The invention discloses a Zeta potential detection device and method based on the Coulter principle. The device comprises a sample cell, a microfluidic chip and a voltage loop, wherein a to-be-detected sample with a first preset concentration is introduced into one end of the sample pool, a to-be-detected sample with a second preset concentration is introduced into the other end of the sample pool, the micro-flow chip is arranged in the sample pool, and a micro-flow channel for particles in the to-be-detected sample to pass through is formed in the micro-flow chip; and the voltage loop and a to-be-tested sample in the sample pool form a conductive loop so as to apply a direct-current voltage to the sample pool. In the detection process, electrodes are connected to the two sides of the sample cell, direct-current voltage is applied, and particles are subjected to electrophoresis; when particles pass through the microfluidic channel in the center of the sample cell, micro-current signal fluctuation is generated, and the electrophoresis mobility is obtained through the micro-current signal fluctuation; the defect that particles are affected by Brownian motion in existing Zeta potential measurement is overcome, and the precision of Zeta potential measurement is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of potential detection, and in particular to a Zeta potential detection device and method based on the Coulter principle. Background Art

[0002] The Zeta potential of particles in solution is measured by electrophoretic light scattering and electroacoustic methods. The electrophoretic method measures the Zeta potential based on the characteristic that charged particles move toward the electrode with opposite electrical properties under the action of an external electric field. The methods with higher measurement accuracy include electrophoretic light scattering and phase light scattering. The electroacoustic method uses the electroacoustic phenomenon generated by the coupling between the acoustic field and the electric field in the liquid containing ions to measure the Zeta potential of particles. These two methods cannot accurately measure the Zeta potential of a single particle when measuring the Zeta potential of particles, but can only measure the average Zeta potential of particles in the sample. At the same time, the Brownian motion of particles in the solution is irregular, and the Brownian motion of particles will affect the trajectory and speed of the particles under the electric field. The optical method and the acoustic method will be affected by the Brownian motion when measuring. Therefore, the electroacoustic method and the electrophoretic method cannot accurately measure the Zeta potential of particles.

[0003] At present, phase analysis light scattering is the most commonly used method to observe the electrophoretic velocity of particles. Its principle is to obtain the electrophoretic velocity of particles by analyzing the phase change of the scattered light signal generated when light passes through the particles. This measurement method has at least the following technical problems:

[0004] (1) The randomness of Brownian motion broadens the peak of the mobility spectrum, making it difficult to accurately measure electrophoretic mobility;

[0005] (2) When the particle size in the sample solution is complex, the light signal of large particles easily blocks the light signal of small particles, resulting in large mobility measurement errors;

[0006] (3) The light scattering method can only measure the average Zeta potential of a group of particles in a solution, but cannot measure the Zeta potential of a single particle.

[0007] In view of this, the present invention provides a Zeta potential detection device and method based on the Coulter principle to solve the problem that the Zeta potential of particles cannot be accurately measured in the prior art. Summary of the invention

[0008] To this end, an embodiment of the present invention provides a Zeta potential detection device and method based on the Coulter principle to solve the problem in the prior art that the Zeta potential of particles cannot be accurately measured, avoid the particles being affected by the distribution movement during the potential measurement process, improve the accuracy of the potential measurement, and realize the potential measurement of a single example.

[0009] In order to achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0010] The present invention provides a Zeta potential detection device based on the Coulter principle, the detection device comprising:

[0011] A sample pool, wherein a sample to be tested of a first preset concentration is introduced into one end of the sample pool, and a sample to be tested of a second preset concentration is introduced into the other end of the sample pool;

[0012] A microfluidic chip, wherein the microfluidic chip is disposed in the sample pool and is provided with a microfluidic channel for particles in the sample to be tested to pass through;

[0013] A voltage loop forms a conductive loop with the sample to be tested in the sample cell to apply a direct current voltage to the sample cell.

[0014] In some embodiments, the voltage loop includes:

[0015] DC power supply;

[0016] The electrode is installed in the sample pool, and the electrode includes a cathode and an anode, and the cathode and the anode are respectively located on two sides of the microfluidic chip.

[0017] In some embodiments, the voltage loop further includes:

[0018] A micro-electric signal detection device is used to obtain the fluctuation value of the electric signal in the voltage loop.

[0019] In some embodiments, the microfluidic chip is a silicon nitride chip.

[0020] In some embodiments, the pore size of the microfluidic channel ranges from 1.75 μm to 2.25 μm.

[0021] The present invention also provides a Zeta potential detection method based on the Coulter principle, the method comprising:

[0022] Using the detection device as described above, applying a DC voltage of a preset voltage value to the sample cell;

[0023] Collect the electrical signal fluctuation value of the sample to be tested under the electrical disturbance state;

[0024] The electrophoretic mobility and Zeta potential are calculated according to the electrical signal fluctuation value.

[0025] In some embodiments, the preset voltage value ranges from 200mV to 20V.

[0026] In some embodiments, collecting the electrical signal fluctuation value of the sample to be tested under the electrical disturbance state specifically includes:

[0027] A micro-electric signal detection device is provided in the voltage circuit of the detection device, and the electrical signal fluctuation value of the sample to be tested is collected by the micro-electric signal detection device.

[0028] In some embodiments, the electrophoretic mobility U of the particle is calculated using the first expression: E , the first expression is:

[0029]

[0030] Among them, E a is the electric field strength in the microfluidic channel, and v is the electrophoretic intensity of the particles.

[0031] In some embodiments, the zeta potential is calculated using a second expression, wherein the second expression is:

[0032]

[0033] Among them, η is the viscosity of the medium, ε0 is the vacuum dielectric constant of the medium, and ε r is the relative dielectric constant of the medium.

[0034] The Zeta potential detection device based on the Coulter principle provided by the present invention comprises a sample pool, a microfluidic chip and a voltage circuit; wherein, a sample to be tested of a first preset concentration is introduced into one end of the sample pool, and a sample to be tested of a second preset concentration is introduced into the other end of the sample pool, the microfluidic chip is arranged in the sample pool, and a microfluidic channel for particles in the sample to be tested to pass through is opened on the microfluidic chip; the voltage circuit forms a conductive circuit with the sample to be tested in the sample pool to apply a DC voltage to the sample pool. During the detection process, the sample to be tested is located at one end of the sample pool, and a diluted solvent of the pure sample to be tested is introduced into the other end. Electrodes are connected on both sides of the sample pool, and a DC voltage is applied, so that the particles in the sample to be tested undergo electrophoresis. When the particles pass through the microflow channel in the center of the sample pool, microcurrent signal fluctuations are generated, and the electrophoretic mobility is obtained through the microcurrent signal fluctuations. This method solves the shortcoming that particles in the existing Zeta potential measurement are affected by Brownian motion, improves the accuracy of Zeta potential measurement, solves the problem in the prior art that particles are affected by Brownian motion, and large particles block small particles, resulting in inaccurate Zeta potential measurement, avoids the influence of Brownian motion on particles during potential measurement, improves the accuracy of potential measurement, and can realize potential measurement of a single example. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0036] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0037] Figure 1 This is a schematic diagram of the structure of a Zeta potential detection device based on the Coulter principle provided by the present invention;

[0038] Figure 2 The present invention provides a flow chart of the Zeta potential detection method based on the Coulter principle.

[0039] Description of reference numerals:

[0040] 1-direct current power supply, 2-microelectric signal detection device, 3-sample pool, 4-microfluidic chip, 5-cathode electrode; 6-anode electrode. DETAILED DESCRIPTION

[0041] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are 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.

[0042] Zeta potential is a key parameter for measuring colloid stability and analyzing the properties of particles in solution. In order to solve the problems existing in the prior art, the present invention proposes a Zeta potential detection device and method based on the Coulter method. A microfluidic chip is arranged in a sample pool, and a microfluidic channel is opened in the center of the microfluidic chip. A DC voltage is connected on both sides of the microfluidic chip in the center of the rectangular channel where the sample moves, so that the particles in the rectangular channel produce electrophoresis. When the particles pass through the small hole, current signal fluctuations are generated, thereby calculating the Zeta potential. This method is based on electrical principles, does not need to consider the influence of Brownian motion of particles, can measure the Zeta potential of a single particle, and can achieve accurate measurement of the Zeta potential.

[0043] Please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of the Zeta potential detection device based on the Coulter principle provided by the present invention.

[0044] In a specific embodiment, the Zeta potential detection device based on the Coulter principle provided by the present invention includes a sample pool, a microfluidic chip and a voltage circuit. Among them, a sample to be tested of a first preset concentration is passed through one end of the sample pool, and a sample to be tested of a second preset concentration is passed through the other end of the sample pool; taking a polystyrene particle sample to be tested with a particle size of 1 μm as an example, the first preset concentration is about 0.001% polystyrene microspheres, and a pure solution can be passed through the other end; for example, a sodium tetraborate solution of 0.001% polystyrene microspheres is passed through one end, and a pure sodium tetraborate solution is passed through the other end. In this embodiment, in order to facilitate the clamping of the microfluidic chip and prevent leakage, the sample pool is rectangular, and the microfluidic chip is arranged in the middle of the long side of the rectangle, so that the sample to be tested can form a rectangular channel during the flow process, which is convenient for forming fluctuations in electrical signals. The microfluidic chip is arranged in the sample pool, and a microfluidic channel for the particles in the sample to be tested to pass through is provided on the microfluidic chip. In order to realize accurate measurement of the potential of a single particle, the microfluidic channel is a single microfluidic channel. It should be understood that in order to realize the potential measurement of a single particle, the aperture of the microfluidic channel should be larger than the maximum width of a single particle and smaller than the sum of the minimum widths of the two examples. In other words, the aperture of the microfluidic channel should satisfy that only one particle can pass through at a time, and each particle passes through the microfluidic channel independently. The microelectric signal fluctuation generated at this time is generated by the particle currently passing through the microfluidic channel, so that the Zeta potential of a single particle can be accurately measured according to the microelectric signal fluctuation. In theory, the microfluidic channel can be a microfluidic channel with a circular hole, an elliptical hole or other shapes. Taking a circular hole as an example, the aperture range of the microfluidic channel is 1.75μm-2.25μm. It should be understood that the aperture of the microfluidic channel may be different depending on the particle size of the particle to be measured. For example, when the particle size of the particle to be measured is 1 μm, the aperture of the microfluidic channel may be 2 μm.

[0045] The voltage circuit and the sample to be tested in the sample pool form a conductive circuit to apply a DC voltage to the sample pool so as to stimulate the particles in the sample to be tested to undergo electrophoresis through the DC voltage. During the movement of the particles, when passing through the microfluidic channel on the microfluidic chip, microcurrent signal fluctuations will be generated, and the electrophoretic mobility can be obtained through the microcurrent signal fluctuations.

[0046] In the field of nanoscience, Zeta potential is a very important concept. It is a measure of the strength of mutual repulsion or attraction between particles. Based on the Zeta potential, we can understand the dispersion mechanism of molecules or particles in detail, which is crucial for electrostatic dispersion control. Zeta potential can be used to measure the solid-liquid interface electrical properties (ζ potential) of particles in a dispersed system, can be used to measure the interface electrical properties of emulsion droplets, and can also be used to determine the isoelectric point and study the mechanism of the interface reaction process. Determining the Zeta potential of particles and finding the isoelectric point is an important method to understand the surface electrical properties of particles, and it is also an important means in particle surface treatment. At present, the measurement of Zeta potential is widely used in cosmetics, mineral processing, papermaking, medical and health, building materials, ultrafine materials, environmental protection, marine chemistry and other industries. At the same time, Zeta potential is also one of the important physical and chemical parameters in the fields of chemistry, chemical engineering, medicine, building materials, etc.

[0047] In principle, the Coulter principle (also known as the resistance method, electric pulse method and electric induction zone technology) was proposed by Wallace H. Coulter and his brother Joseph R. Coulter, Jr. of Beckman Coulter Company in the United States. The Coulter principle states that when particles suspended in an electrolyte pass through a pinhole tube with the electrolyte, they replace the same volume of electrolyte, which causes an instantaneous change in the resistance between the two electrodes inside and outside the pinhole tube in a constant current design circuit, generating a potential pulse. The size and number of pulse signals are proportional to the size and number of particles. When using the Coulter principle for potential measurement, the measurement principle of the Coulter method can be summarized as: a small hole is opened in the center of an insulated rectangular sample cell, a pair of electrodes are placed on both sides of the rectangular sample cell and a DC voltage is applied to form an electric sensitive area around the small hole. As the particles pass through the small hole, the particles will displace an equivalent volume of conductive liquid, instantly increasing the resistance of the electric induction zone and forming a potential pulse. By analyzing the pulse, the particle size and Zeta potential of the particles can be obtained.

[0048] Specifically, the voltage circuit includes a DC power supply and an electrode, the electrode is installed in the sample pool, the electrode includes a cathode and an anode, and the cathode and the anode are respectively located on both sides of the microfluidic chip; during use, the electrodes are connected to both sides of the sample pool, and a DC voltage is applied to cause electrophoresis of the particles. The DC power supply can be a battery or a storage battery, etc.

[0049] In order to ensure that the microcurrent signal fluctuations generated by particles passing through the microfluidic channel can be collected in a timely manner, thereby improving the accuracy and timeliness of signal collection, the voltage loop also includes a microelectric signal detection device, which is used to obtain the fluctuation value of the electrical signal in the voltage loop.

[0050] In some embodiments, the microfluidic chip is a silicon nitride chip, so that the microfluidic chip has good mechanical properties and electrical insulation, and has good acid and alkali resistance, thereby extending the service life of the microfluidic chip.

[0051] like Figure 1 As shown, in a specific embodiment, the Coulter method Zeta potential detection process provided by the present invention is that the sample to be tested is passed through the sample pool 3, a DC voltage is applied to the sample pool 3 through the DC power supply 1, the sample to be tested forms a loop with the cathode electrode 5 and the anode electrode 6, and the generated current signal is received by the micro-electric signal detection device 2; when the particles in the sample to be tested pass through the microfluidic channel opened on the microfluidic chip 4, an electrical signal fluctuation is generated, and the electrophoretic mobility and Zeta potential are calculated by analyzing the fluctuation of the electrical signal in the micro-electric signal detection device 2.

[0052] In addition to the above detection device, the present invention also provides a Zeta potential detection method based on the Coulter principle, such as Figure 2 As shown, the method comprises the following steps:

[0053] S210: Using Figure 1 The detection device shown applies a DC voltage of a preset voltage value to the sample cell; wherein the preset voltage value ranges from 200mV to 20V.

[0054] S220: Collecting the electrical signal fluctuation value of the sample to be tested under the electrical disturbance state; specifically, a micro-electric signal detection device is provided in the voltage circuit of the detection device, and the electrical signal fluctuation value of the sample to be tested is collected by the micro-electric signal detection device.

[0055] S230: Calculating electrophoretic mobility and Zeta potential according to the electrical signal fluctuation value.

[0056] The pulse width of the fluctuation of the particle electrical signal is the time of electrophoretic fluctuation. The first expression is used to calculate the electrophoretic mobility U of the particle. E , the first expression is:

[0057]

[0058] Among them, E a is the electric field strength in the microfluidic channel, and v is the electrophoretic intensity of the particles.

[0059]

[0060] Where V is the applied voltage, R a is the resistance value in the channel when the particle passes through, R 总 is the resistance value of the entire sample pool when the particle passes through, where l a is the distance the particle travels through the hole.

[0061] Electrophoretic velocity of particles:

[0062]

[0063] The zeta potential is calculated using the second expression, which is:

[0064]

[0065] Among them, η is the viscosity of the medium, ε0 is the vacuum dielectric constant of the medium, and ε r is the relative dielectric constant of the medium.

[0066] In the above specific embodiment, the Zeta potential detection device based on the Coulter principle provided by the present invention includes a sample pool, a microfluidic chip and a voltage circuit; wherein, a sample to be tested of a first preset concentration is introduced into one end of the sample pool, and a sample to be tested of a second preset concentration is introduced into the other end of the sample pool, the microfluidic chip is arranged in the sample pool, and a microfluidic channel for particles in the sample to be tested to pass through is opened on the microfluidic chip; the voltage circuit forms a conductive circuit with the sample to be tested in the sample pool to apply a DC voltage to the sample pool. During the detection process, the sample to be tested is located at one end of the sample pool, and a diluted sample with a lower concentration is passed into the other end. Electrodes are connected on both sides of the sample pool, a DC voltage is applied, and the particles undergo electrophoresis. When the particles pass through the microflow channel in the center of the sample pool, microcurrent signal fluctuations are generated, and the electrophoretic mobility is obtained through the microcurrent signal fluctuations. This method solves the shortcoming that particles in existing Zeta potential measurements are affected by Brownian motion, improves the accuracy of Zeta potential measurement, solves the problem in the prior art that the Zeta potential of particles cannot be accurately measured, avoids the particles being affected by Brownian motion during potential measurement, improves the accuracy of potential measurement, and can achieve potential measurement of a single example.

[0067] In some embodiments, in response to the problem that existing optical and acoustic Zeta potential detection methods cannot accurately measure the Zeta potential of a single particle, the Zeta potential detection device and method based on the Coulter method provided by the present invention can ensure that the detection signal is the potential signal of a single particle during the potential detection process. At the same time, there is no interference between particles during detection, thereby ensuring the accuracy of the measurement results.

[0068] In some embodiments, the Zeta potential detection device and method based on the Coulter method provided by the present invention adopts the absolute method to measure and count the Zeta potential of a batch of particles. The zeta potential of a single particle is first measured, and then the Zeta potential values ​​exceeding the center value of 5mV are eliminated after statistics, and finally the average of the statistical values ​​is taken. The measurement results are more accurate. At the same time, compared with the optical method, this method has a strong advantage in tracing the source. The refraction angle is a relative parameter in the tracing process of the optical method, while there is no relative parameter in the tracing process of the Coulter method. The tracing method is clear, and the tracing process is simpler and more convenient than the optical method.

[0069] In addition, the Zeta potential detection device proposed in this application uses a microfluidic method to allow particles to pass through micropores in an orderly manner, distinguishes particle sizes based on the fluctuation size of the electrical signal, and can also accurately measure the particle size. It is a measurement device that integrates particle size and Zeta potential detection.

[0070] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made on the basis of the technical solutions of the present invention should be included in the scope of protection of the present invention.

Claims

1. A Zeta potential detection device based on the Coulter principle, It is characterized in that The detection device comprises: A sample pool, wherein a sample to be tested of a first preset concentration is introduced into one end of the sample pool, and a sample to be tested of a second preset concentration is introduced into the other end of the sample pool; A microfluidic chip, wherein the microfluidic chip is disposed in the sample pool and is provided with a microfluidic channel for particles in the sample to be tested to pass through; A voltage loop forms a conductive loop with the sample to be tested in the sample cell to apply a direct current voltage to the sample cell.

2. The Zeta potential detection device based on the Coulter principle according to claim 1, It is characterized in that The voltage loop comprises: DC power supply; The electrode is installed in the sample pool, and the electrode includes a cathode and an anode, and the cathode and the anode are respectively located on two sides of the microfluidic chip.

3. The Zeta potential detection device based on the Coulter principle according to claim 2, It is characterized in that The voltage loop also includes: A micro-electric signal detection device is used to obtain the fluctuation value of the electric signal in the voltage loop.

4. The Zeta potential detection device based on the Coulter principle according to claim 1, It is characterized in that The microfluidic chip is a silicon nitride chip.

5. The Zeta potential detection device based on the Coulter principle according to claim 4, It is characterized in that The pore size of the microfluidic channel ranges from 1.75 μm to 2.25 μm.

6. A Zeta potential detection method based on the Coulter principle, It is characterized in that The method comprises: Using the detection device according to any one of claims 1 to 5, applying a DC voltage of a preset voltage value to the sample cell; Collect the electrical signal fluctuation value of the sample to be tested under the electrical disturbance state; The electrophoretic mobility and Zeta potential are calculated according to the electrical signal fluctuation value.

7. The Zeta potential detection method based on the Coulter principle according to claim 6, It is characterized in that The preset voltage value ranges from 200mV to 20V.

8. The Zeta potential detection method based on the Coulter principle according to claim 6, It is characterized in that Collect the electrical signal fluctuation value of the sample to be tested under electrical disturbance, including: A micro-electric signal detection device is provided in the voltage circuit of the detection device, and the electric signal fluctuation value of the sample to be tested is collected by the micro-electric signal detection device.

9. The Zeta potential detection method based on the Coulter principle according to claim 6, It is characterized in that The first expression is used to calculate the electrophoretic mobility U of the particles. E , the first expression is: Among them, E a is the electric field strength in the microfluidic channel, and v is the electrophoretic intensity of the particles.

10. The Zeta potential detection method based on the Coulter principle according to claim 6, It is characterized in that The zeta potential is calculated using the second expression, which is: Among them, η is the viscosity of the medium, ε 0 is the vacuum dielectric constant of the medium, ε r is the relative dielectric constant of the medium.

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