An instrument and method for determining gelation time based on light scattering effect

Abstract

This invention discloses a gelation time measuring instrument and method based on the light scattering effect. The gelation time measuring instrument includes a laser source, a chopper, a first condensing lens, a second condensing lens, a sample carrier, a photosensor, and a controller. The laser source generates incident light; the chopper converts the incident light into alternating sample light and reference light in different directions; the reference light is projected into the photosensor through the first condensing lens; the sample light is projected onto the sol loaded in a sample tube of the sample carrier, forming scattered light; the second condensing lens is fixed at a certain angle to the path of the sample light, and the scattered light is projected into the photosensor through the second condensing lens; the photosensor is connected to a host computer; the controller is connected to the laser source and the host computer. This gelation time measuring instrument employs a reference light design, which can effectively prevent measurement errors caused by fluctuations in the light source signal itself.

Description

Technical Field

[0001] This invention relates to the field of gelation time measurement, and more particularly to a gelation time measuring instrument and method based on the light scattering effect. Background Technology

[0002] The time required for a solution to transform from a highly fluid liquid to a completely non-flowing gel under suitable conditions is called gelation time. Gelation time is an important parameter with applications in industry, construction, materials science, biology, and chemical engineering, as well as in scientific research and experimental teaching. Currently, there are two methods for measuring gelation time: the visual method and the viscometer-based gelation time measuring instrument method. The former involves manually observing the sample to be gelled at constant intervals, measuring the time when the sample completely loses its fluidity. The visual method is obviously subjective and prone to measurement errors. The latter is a more accurate method. The liquid sample is placed in a container, and a standard rotor is rotated within the liquid sample under rated torque. As the degree of gelation increases, the viscosity increases, and the rotor speed decreases. When the viscosity increases to a certain value, the rotor stops rotating, and the time of gelation is recorded. This method can quantitatively measure gelation time, but it has several drawbacks: it requires a stir bar or stirring rod, and some samples need to be tested for gelation time without disturbance, which makes it impossible to test these samples with this instrument; it cannot be used for batch testing, as one instrument can only test one sample; and the unit is expensive, generally costing more than 50,000 RMB.

[0003] Light scattering refers to the phenomenon that a portion of light rays deviates from their original propagation direction when passing through an inhomogeneous medium. The most important component of scattered light is Rayleigh scattering, the intensity of which can be calculated using the Rayleigh light scattering formula. The larger the particle size of the dispersed phase, the stronger the Rayleigh scattering.

[0004] Patent document 1 (Japanese Patent No. 3199850) uses a laser light source to irradiate a blood sample. When platelets aggregate, the size and number of platelet aggregates change. The detector receives the 90-degree side-scattered light from the platelets, and the size and number of platelet aggregates are determined based on the results.

[0005] Patent document 2 (Japanese Patent Application Publication No. 2004-93536) describes a gelation reaction measuring device using turbidimetric time analysis, which measures the change in transmitted light intensity of a mixture of sample and horseshoe crab reagent over time, and determines the endotoxin concentration of the sample based on the change over a specified time.

[0006] Patent documents 1 and 2 require a reaction time of approximately 90 minutes at low concentrations to generate agglomerates. That is, although the gelation time of the reaction solution is proportional to the concentration of the target substance in the sample, the sensitivity limitations prevent the accurate detection of the gelation start time. Therefore, the reaction amount can only be calculated based on the gelation end time, using this gelation time as a benchmark.

[0007] Patent 3 (application number 200980107268.2) describes a gel particle measuring device for measuring the time of gel particle appearance through a gelation reaction. The principle is that endotoxins or β-D-glucan do not gel during stirring, but when a horseshoe crab reagent is added, it causes gelation. The gelation rate is related to the concentration of the target substance. The formation state of gel particles is inferred by measuring the change in the intensity of transmitted light. The time when the transmitted light changes from a stable state is the time of gel particle appearance.

[0008] Patent application number 200680055919.4 provides a gelation reaction measuring device and test kit. The device can highly sensitively determine the concentration of endotoxin or β-D-glucan through gelation reaction in a short time. Its principle is to irradiate a solution containing the target substance and a gelation-generating reagent with a laser. Under stirring, the solution generates gel particles, which scatter the incident laser light. The scattered light is detected by a photodiode array, and the diameter and quantity of the generated gel particles are determined by computer processing over time.

[0009] The above-mentioned testing devices all have the following problems: they use the absolute value of transmitted or scattered light as the basis for testing, and the signal fluctuations or background changes of the light source itself can lead to large testing errors; they can only perform single-sample measurements, resulting in low efficiency; and the light source is always on during operation, resulting in short lifespan and high energy consumption. Summary of the Invention

[0010] The present invention aims to provide a gelation time measuring instrument and method based on light scattering effect, so as to solve at least one of the above-mentioned problems.

[0011] Therefore, the specific technical solution adopted by the present invention is as follows:

[0012] According to a first aspect of the present invention, a gelation time measuring instrument based on light scattering effect is provided, comprising a laser light source, a chopper, a first condenser lens, a second condenser lens, a sample carrier, a photosensor, and a controller;

[0013] The laser source is used to generate incident light;

[0014] The chopper is used to convert the incident light into alternating sample light and reference light in different directions;

[0015] The reference light is projected onto the photosensor through a first focusing lens;

[0016] The sample carrier is provided with at least one socket for placing a sample tube; the sample light is projected onto the sol loaded in a sample tube of the sample carrier and forms scattered light.

[0017] The second condenser lens is fixed on the path that forms a certain angle with the sample light, and the scattered light is projected into the photosensor through the second condenser lens;

[0018] The photosensor is connected to the host computer to upload data of the reference light and the sample light.

[0019] The controller is connected to the laser source and the host computer, and is used to receive instructions from the host computer and configure the light source parameters of the laser source.

[0020] Furthermore, the incident light is a pulsed laser.

[0021] Furthermore, the cutter is a rotating fan-shaped mirror comprising four fan-shaped sections: a reflecting mirror, a transmitting mirror, and two backgrounds, wherein the backgrounds neither transmit nor reflect; the reflecting mirror and the transmitting mirror are separated by the backgrounds.

[0022] Furthermore, the rotating sector mirror is divided into four sector-shaped sections of equal area.

[0023] Furthermore, the sample carrier is a turntable, which rotates under the control of the controller, and the ports are distributed on the turntable in a circular array; the sample carrier is positioned at a certain position on the sample optical path as a test position, and the sample tube is switched to the test position of the sample carrier by the rotation of the sample carrier.

[0024] Furthermore, the second focusing lens is fixed at a 45-degree angle to the sample light path.

[0025] Furthermore, the laser source is a pulsed source, and the incident light generated is blue light with a wavelength of 445nm and a power of 5-50 milliwatts; or green light with a wavelength of 532nm and a power of 5-50 milliwatts.

[0026] Furthermore, the photosensor is a photomultiplier tube.

[0027] According to a first aspect of the present invention, a method for determining gelation time based on light scattering effect is provided, using a gelation time measuring instrument based on light scattering effect as described above, comprising the following steps:

[0028] Run the test software on the host computer and set the laser pulse period, the constant illumination time of each laser pulse period, the signal ratio threshold, and the rate of change threshold.

[0029] Control the laser source to emit pulsed laser light at a set period;

[0030] The system receives data from the photosensor and records the average intensity of the scattered light and the average intensity of the reference light in each cycle. It calculates the signal ratio for each cycle and determines whether gelation is complete according to the gelation time criterion. If complete, the test stops, and the time of the previous cycle is recorded as the gelation time. Otherwise, the test continues until complete gelation or a condition for forced termination of the test is triggered, and the test results are displayed on the terminal. The signal ratio is the ratio of the average intensity of the scattered light to the average intensity of the reference light in each laser pulse cycle. The gelation time criterion is: the signal ratio exceeds the signal ratio threshold, and the rate of change of the signal ratio is within the rate of change threshold. The condition for forced termination of the test is: the test duration exceeds the maximum test time, but the signal ratio is still less than the signal ratio threshold.

[0031] Furthermore, it also includes a sample carrier control step: controlling the rotation speed of the sample carrier's turntable so that the laser source is always on when any sample tube passes through the test position.

[0032] By adopting the above technical solution, the present invention achieves the following beneficial effects:

[0033] In one specific embodiment, a reference light design is employed to effectively prevent measurement errors caused by fluctuations in the light source signal itself.

[0034] In one specific embodiment, the sample carrier adopts a turntable design, which can test multiple samples at once, realizing batch sample determination and improving efficiency.

[0035] In one specific embodiment, the laser source adopts a pulsed laser design, which can significantly increase the lifespan of the source and reduce energy consumption. Attached Figure Description

[0036] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0037] Figure 1 This is a functional block diagram of the gelation time tester of the present invention;

[0038] Figure 2 This is a schematic diagram of the cutter of the present invention;

[0039] Figure 3 This is a 3D rendering of the sample carrier of the present invention;

[0040] Figure 4 Theoretical criteria for determining gelation time;

[0041] Figure 5 The actual standard for judging gelation time;

[0042] Figure 6 This is a schematic diagram of the full cycle and the duration of constant illumination. Detailed Implementation

[0043] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0044] When light passes through a sample, the scattered light intensifies due to the increased degree of gelation. When the gel stops growing, the intensity of the scattered light remains essentially unchanged. This invention utilizes this principle to design a gelation time measuring instrument.

[0045] like Figure 1 As shown, the present invention provides an embodiment of a gelation time measuring instrument based on light scattering effect, which mainly consists of a laser light source 1, a cutter 2, a condenser lens 4, a sample carrier 3, a photosensor 5, a condenser lens 6, a controller 7, and a computer 8.

[0046] In this embodiment, the laser source 1 can use a common laser pointer light source to reduce costs. It preferentially uses blue light with a wavelength of 445nm (power 5-50 mW) or green light with a wavelength of 532nm (power 5-50 mW). The wavelength order of the laser is blue light < green light < red light. According to Rayleigh's light scattering formula, the intensity of scattered light is inversely proportional to the fourth power of the wavelength. To improve signal strength, the laser color priority is blue light > green light > red light. The light source adopts a pulsed design, and the pulse period and the irradiation time of each period can be adjusted by the controller 7 to reduce energy consumption and improve the lifespan of the light source.

[0047] like Figure 2 As shown, in this embodiment, the chopper 2 is a rotating fan-shaped mirror, divided into four parts: 1 / 4 is a reflecting mirror (marked R in the figure), 1 / 4 is a transmitting mirror (marked T in the figure), and the remainder is a background that neither transmits nor reflects (marked B in the figure). When the fan-shaped mirror rotates, when the reflecting mirror enters the optical path, the incident light S1 is reflected, generating the reference light S3; when the transmitting mirror enters the optical path, the incident light S1 is transmitted, generating the sample light S2; when the background portion enters the optical path, the incident light S1 is almost completely absorbed. Through rotation, the chopper 2 converts the incident light S1 from the laser source 1 into two alternating beams: the reference light S3 and the sample light S2, which travel through different paths and finally arrive at the photosensor 5 at different times. Even if the light source fluctuates or the background noise changes, the reference light and the sample light change synchronously, and their ratio remains stable, effectively offsetting the negative effects of light source fluctuations, stray light, and background noise.

[0048] Converging lenses 4 and 6 are used to converge the sample light S2 and reference light S3, respectively, to increase the intensity of light entering the photosensor 5. Converging lens 6 is fixed in the direction of the reference light S3, and converging lens 4 is fixed at a 45-degree angle to the sample light S2. According to Rayleigh's light scattering formula, the intensity of scattered light is related to the scattering angle. The intensity is highest at 0 degrees or 180 degrees and lowest at 90 degrees. However, if the angle is designed to be 0 degrees or 180 degrees, the transmitted light (i.e., sample light S2) will produce strong interference. Therefore, preferably, a scattering angle of 45 degrees is used to avoid interference from the transmitted light while maintaining a moderate intensity of scattered signal.

[0049] like Figure 3 As shown, an embodiment of a sample carrier 3 is provided. In this embodiment, the sample carrier 3 includes a turntable with sockets and a motor. The turntable is connected to the motor, and the surface of the turntable has 8 sockets, which can hold up to 8 sample tubes at a time. Under the action of the motor, the sample tubes loaded on the turntable can be transferred to the testing position. At the testing position, the sample light S2 will irradiate the sol in the sample tube, forming scattered light S4. The turntable has a diameter of 10cm. To prevent corrosion by the sample, the turntable is preferably made of polytetrafluoroethylene (PTFE). The motor can be controlled by a controller to drive the turntable to rotate at a specified speed. The sample tubes are used to hold the sample solution. To maximize the intensity of the scattered light S4 while meeting mechanical strength requirements, high-transmittance materials such as glass or quartz are used. In this embodiment, the sample tubes have a diameter of 1cm, a wall thickness of 0.5mm, and a height of 5cm. The sample tubes are loaded onto the sockets of the turntable, and 1 to 8 tubes can be loaded as needed. Figure 3 The effect of loading four sample tubes is depicted. The sample carrier 3 of this embodiment allows for batch sample testing, with the sample light and scattered light at a 45-degree angle, forming a plane parallel to the horizontal plane.

[0050] The photosensor 5 is used to receive signals from the reference light S3 and the sample light S2. Through optical path design, focusing lenses 4 and 6 are placed in the optical paths of the reference light S3 and the scattered light S13, so that the reference light S3 and the scattered light S4 can be focused onto the same photosensor 5. The photosensor 5 preferably uses a photomultiplier tube, which can greatly improve the signal strength.

[0051] In this embodiment, the computer 8 is a desktop or laptop computer with a Windows operating system. It needs to be connected to the measuring instrument via a data cable and have the corresponding program installed. The program has functions such as adjusting sample testing parameters, controlling the testing process, and outputting test results. In specific applications, the computer is also integrated into the measuring instrument via a board and the corresponding testing program is written into it, thereby realizing stand-alone operation.

[0052] The controller 7 is an embedded design using a single-chip microcomputer. It can receive instructions from the computer and control the light source parameters of the laser source, the rotation frequency of the cutter, the rotation of the sample carrier, and the position of the sample tube.

[0053] Working principle:

[0054] This gelation time tester is based on the Rayleigh scattering principle. It judges the degree of gelation by the change in the intensity of scattered light. During the gelation process, the particle size increases and the scattered light intensifies. When the gel stops growing, the intensity of the scattered light remains basically unchanged. The gelation time is obtained by the inflection point of the scattered light signal from change to no change.

[0055] Rayleigh light scattering formula:

[0056]

[0057] I, I0: Intensities of scattered light and incident light

[0058] λ: wavelength of incident light

[0059] V: Volume of a single particle

[0060] c: Particle concentration (number of colloidal particles per unit volume of sol)

[0061] n0, n: Refractive indices of the dispersion medium and the dispersed phase, respectively.

[0062] This gelation time tester can perform single-sample testing and batch sample testing, as shown below:

[0063] Example 1: Single Sample Testing

[0064] 1. Criteria for judging gelation time

[0065] When the sample is in solution, the intensity of scattered light is very low. The ratio of the average intensity of scattered light to the average intensity of the reference light (referred to as the signal-to-weight ratio, denoted by C) within each laser pulse cycle is almost 0. As the gelation reaction proceeds, the number and size of gel particles gradually increase, the scattered light gradually intensifies, while the reference light remains constant, so C gradually increases. When the gelation reaction is complete, the number and size of gel particles remain stable, the scattered light also remains stable, and C also remains stable. Therefore, the time corresponding to the inflection point where C changes from change to constancy is the gelation time. Figure 4 As shown. In actual operation, when the gelation reaction is complete, C will fluctuate within a certain range. Therefore, the criterion for judging the gelation time is that C is strong enough, that is, it exceeds the signal-to-weight ratio threshold (using C). m (represented by) and the rate of change of the signal ratio is within the rate of change threshold (using B) m (Indicated) such as Figure 5 As shown, points a and b represent two consecutive signal ratios, each of which is greater than the signal ratio threshold C.m And |ΔC / Ca|≤B m Then the time at point a is the gelation time.

[0066] 2. Set test parameters

[0067] Set the test parameters within the software, including the full cycle of the pulsed laser (default 1s), the duration of constant illumination in each cycle (default 0.1s), the rotary table rotation speed (represented by r, default 0), and the maximum test time (represented by t). m (This indicates a default value of 60 minutes) and a signal-to-weight ratio threshold C. m (Default value 0.05) and the rate of change threshold B m (Default value 5%), etc. The above parameters can be adjusted according to actual needs. For example, if the predicted gel time exceeds 30 minutes, the pulse cycle time can be increased; if the gel time is less than 5 minutes, the pulse cycle time can be decreased. For details on the relationship between the pulse cycle and the constant illumination duration, please refer to [link to relevant documentation]. Figure 6 For a single sample, the turntable speed should be set to 0. Maximum test time t m Used to limit the test duration; if the test duration exceeds t m But C is still less than C. m If the gelation time of the sample is too long, the test should be terminated abruptly to protect the instrument.

[0068] 3. Sample preparation

[0069] Testable gels include any inorganic gel and organic gel resin, as long as the resulting gel particle size is between 10 nm and 100 nm. The test solution should be mixed thoroughly beforehand, and the time recorded is the starting point of the gel reaction. The solution is then poured into a sample tube, filling it to half to three-quarters of its capacity. As long as this range is within which the amount poured does not affect the test results, the sample tube is then placed in the test position. Figure 1 Position 1 in the middle.

[0070] 4. Sample Testing

[0071] The test begins with the light source emitting pulsed laser light at a specified cycle. The average intensity of the scattered light and the average intensity of the reference light are recorded for each cycle. The value C for each cycle is calculated, and the gelation time is used to determine if gelation is complete. If complete, the test stops, and the time of the previous cycle is recorded as the gelation time. Otherwise, the test continues until complete gelation or the condition for forcibly ending the test is triggered (test duration exceeds t). m But C is still less than C. m The test results are displayed on the terminal.

[0072] Example 2: Batch Sample Testing

[0073] 1. Criteria for judging gelation time

[0074] Completely the same as Example 1

[0075] 2. Set test parameters

[0076] In this embodiment, the turntable speed is set to rotate once per second, and the sample tubes on the turntable will continuously circulate and pass through the test positions in sequence. By reasonably setting the full cycle and the constant-on duration (compared to Embodiment 1, the constant-on duration should be appropriately increased, and the full cycle should be appropriately shortened), the light source is kept constantly lit when any sample tube passes through the test position. Other test parameters are the same as in Embodiment 1.

[0077] 3. Sample preparation

[0078] In this embodiment, the turntable has 8 slots, meaning it can hold up to 8 sample tubes. Preferably, the sample tubes can be arranged continuously or evenly to match the constant illumination duration and full cycle of the test parameters, ensuring that the light source remains constantly lit when the sample tubes pass the test position. Everything else is the same as in embodiment one.

[0079] 4. Sample Testing

[0080] According to Experimental Scheme 1, determine the gelation time of each sample tube until all sample tubes have been tested or the condition for forcibly terminating the test is triggered (test duration exceeds t). m But C is still less than C. m The test results for each sample tube are displayed on the terminal.

[0081] The gelation time measuring instrument in this embodiment adopts a reference light design, which can effectively prevent measurement errors caused by fluctuations in the light source signal itself; the sample carrier adopts a turntable design, which can perform single sample and batch sample measurements, resulting in higher efficiency; the laser light source adopts a pulsed light source design, which can significantly increase the lifespan of the light source.

[0082] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A gelation time measuring instrument based on light scattering effect, characterized in that: It includes a laser source, a beam cutter, a first condenser lens, a second condenser lens, a sample carrier, a photosensor, and a controller; The laser source is used to generate incident light; The chopper is used to convert the incident light into alternating sample light and reference light in different directions; The reference light is projected onto the photosensor through a first focusing lens; The sample carrier is provided with at least one socket for placing a sample tube; the sample light is projected onto the sol loaded in a sample tube of the sample carrier and forms scattered light. The second condenser lens is fixed on the path that forms a certain angle with the sample light, and the scattered light is projected into the photosensor through the second condenser lens; The photosensor is connected to the host computer. The controller is connected to the laser source and the host computer; The light cutter is a rotating sector mirror comprising four sector sections: a reflecting mirror, a transmitting mirror, and two backgrounds, wherein the backgrounds neither transmit nor reflect; the reflecting mirror and the transmitting mirror are separated by the backgrounds. The sample carrier is a turntable, and the ports are distributed on the turntable in a ring array. The sample carrier is positioned at a certain position on the sample optical path as a test position, and the sample tube is switched to the test position of the sample carrier by rotating the sample carrier. The first condenser lens is fixed in the direction of the reference light, and the second condenser lens is fixed in the path at a 45-degree angle to the sample light. The light scattering-based gelation time measuring instrument performs a gelation time measurement method, including the following steps: Run the test software on the host computer and set the laser pulse period, the constant illumination time of each laser pulse period, the signal ratio threshold, and the rate of change threshold. Control the laser source to emit pulsed laser light at a set period; The system receives data from the photosensor and records the average intensity of the scattered light and the average intensity of the reference light in each cycle. It calculates the signal ratio for each cycle and determines whether gelation is complete according to the gelation time criterion. If complete, the test stops, and the time of the previous cycle is recorded as the gelation time. Otherwise, the test continues until complete gelation or a condition for forced termination of the test is triggered, and the test results are displayed on the terminal. The signal ratio is the ratio of the average intensity of the scattered light to the average intensity of the reference light in each laser pulse cycle. The gelation time criterion is: the signal ratio exceeds the signal ratio threshold, and the rate of change of the signal ratio is within the rate of change threshold. The condition for forced termination of the test is: the test duration exceeds the maximum test time, but the signal ratio is still less than the signal ratio threshold.

2. The gelation time measuring instrument based on light scattering effect as described in claim 1, characterized in that: The incident light is a pulsed laser.

3. The gelation time measuring instrument based on light scattering effect as described in claim 2, characterized in that: The rotating sector mirror is divided into four sector sections of equal area.

4. The gelation time measuring instrument based on light scattering effect as described in claim 1, characterized in that: The laser source is a pulsed source, and the incident light produced is blue light with a wavelength of 445nm and a power of 5-50 milliwatts; or green light with a wavelength of 532nm and a power of 5-50 milliwatts.

5. The gelation time measuring instrument based on light scattering effect as described in claim 1, characterized in that: The light sensor is a photomultiplier tube.

6. The gelation time measuring instrument based on light scattering effect as described in claim 5, characterized in that, It also includes a sample carrier control step: controlling the rotation speed of the sample carrier's turntable so that the laser source is always on when any sample tube passes the test position.

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