An integrated injection mold and molding method for multilayer microfluidic chips

Abstract

This invention relates to the field of microfluidic chip technology, and more particularly to an integrated injection molding mold and molding method for multilayer microfluidic chips. The method includes: determining whether injection molding is complete based on the cavity pressure curve and melt temperature distribution during the injection molding process; determining whether the alignment process can proceed based on the real-time included angle and curvature difference between the upper and lower chips; determining whether there is a risk of relative slippage during bonding based on the pressure loading offset coefficient, and if so, extending the pressure rise time and switching the loading mode by adjusting the coefficient; and determining whether the control effect meets the standard based on the bonding alignment deviation increment, and if not, optimizing the adjustment coefficient by an optimization coefficient. This invention solves the technical problem that in the thermocompression bonding process of multilayer microfluidic chips, the horizontal component force generated during bonding pressure loading due to the indenter not being completely parallel to the chip contact surface causes micron-level relative slippage between the precisely aligned upper chip and the lower chip.

Description

Technical Field

[0001] This invention relates to the field of microfluidic chip technology, and in particular to an integrated injection mold and molding method for multilayer microfluidic chips. Background Technology

[0002] The manufacturing of multilayer microfluidic chips typically involves three main processes: injection molding, interlayer alignment, and thermoforming. Currently, these processes are mostly completed step-by-step on independent equipment, with data and parameters between processes being uncorrelated and lacking closed-loop quality control throughout the entire process. In the injection molding process, uneven melt filling or uneven temperature distribution can easily lead to chip warping. Existing methods can only detect the amount of warping afterward, and cannot quantitatively assess the degree of chip deformation after injection molding and before the alignment process. This results in chips with excessive warping still entering the alignment stage, causing alignment failure or exceeding accuracy tolerances. The alignment process relies on a vision system to align the microchannels of the upper and lower layers of the chip. However, current technologies usually assume that the chip is an ideal plane, ignoring the differences in interlayer angles and curvature caused by injection molding warping, making it impossible to adaptively adjust alignment parameters according to actual deformation. During the bonding process, the imbalance between the pressure head and the chip contact surface during hot pressing can cause micron-level relative slippage of the aligned chips. However, existing equipment lacks online sensing methods for the risk of micro-displacement during pressure loading. Channel misalignment can only be detected by microscope or leak test after bonding is completed, at which point the entire batch of chips may have been scrapped.

[0003] Therefore, how to achieve data connectivity throughout the entire process from injection molding to bonding, and how to establish a closed-loop control mechanism for real-time detection, hierarchical regulation, and effect verification for micro-displacement risks during the bonding process, are technical problems that urgently need to be solved in this field.

[0004] Chinese Patent Publication No. CN118322551A discloses a rapid fabrication method for multilayer microfluidic chips based on photopolymerization technology. The method includes: forming holes on a top substrate, a middle spacer substrate, and a bottom substrate; depositing a photosensitive material on the bottom substrate; covering the bottom surface of the middle spacer substrate onto the photosensitive material; projecting a binary pattern onto the photosensitive material, causing the photosensitive material selected by the light source to solidify and bond with the bottom substrate and the middle spacer substrate; and removing uncured photosensitive material to form a first layer of microfluidic channel sandwich structure; depositing photosensitive material on the top surface of the middle spacer substrate and repeating the above steps to form a second layer of microfluidic channel sandwich structure; and finally obtaining a multilayer microfluidic chip by stacking the middle spacer substrate and photosensitive material layer by layer. This invention eliminates the need for expensive equipment, harsh environments, cumbersome processing procedures, and specialized technicians, enabling rapid, simple, and low-cost fabrication of multilayer composite microfluidic chips.

[0005] However, the aforementioned method for rapid fabrication of multilayer microfluidic chips based on photopolymerization technology has the following problems: This scheme lacks real-time monitoring of dynamic parameters such as horizontal force component, contact point eccentricity, and rising rate during pressure loading. It also cannot quantify the increase in actual deviation between the upper and lower channels after bonding and the initial alignment deviation. Therefore, it is difficult to identify specific defects such as micron-level slippage, channel misalignment, and sealing failure caused by uneven resin shrinkage, film creep, or substrate warping. Furthermore, it lacks adaptive verification and parameter optimization methods for the control effect. As a result, the interlayer alignment accuracy of multilayer composite structure chips cannot be guaranteed in actual production, and the leakage risk caused by misalignment is difficult to suppress, ultimately affecting the functional reliability and yield of the chip. Summary of the Invention

[0006] To address this issue, the present invention provides an integrated injection molding mold and molding method for multilayer microfluidic chips, which overcomes the problem in the prior art where the bonding pressure is not perfectly parallel to the chip contact surface, resulting in a horizontal component force and causing micron-level relative slippage between the precisely aligned upper chip and the lower chip during bonding pressure loading.

[0007] To achieve the above objectives, the present invention provides a method for molding multilayer microfluidic chips. It includes: Based on the cavity pressure curve and melt temperature distribution during the injection molding process, the injection filling quality evaluation coefficient is determined to determine whether the injection of the multilayer microfluidic chip in the current mold is complete, and demolding is performed after completion. Based on the real-time angle and curvature difference between the upper and lower layer chips after entering the alignment station, it is determined whether the multilayer microfluidic chip after injection molding can enter the alignment process, and the alignment process is performed if the conditions for entering the alignment process are met. Based on the pressure loading offset coefficient between the pressure head and the chip contact surface during the pressure loading process, it is determined whether there is a relative slippage risk in the multilayer microfluidic chip during the current bonding process. If a relative slip risk is identified, the pressure generation time is extended by adjusting the coefficient based on the pressure loading offset coefficient and the preset pressure loading offset coefficient, and the loading mode is switched. Based on the incremental bonding alignment deviation of the upper and lower channels after bonding control, it is determined whether the control effect of bonding parameters meets the standard. If the effect of adjusting the bonding parameters is not satisfactory, the adjustment coefficient is optimized by determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment.

[0008] Furthermore, the process of determining whether there is a risk of relative slippage in the multilayer microfluidic chip during the current bonding process includes, Acquire the state parameters and process parameters of the contact surface between the pressure head and the chip during the bonding process, where; The state parameters and process parameters include horizontal force component, vertical bonding pressure, distance of the initial contact point from the geometric center of the chip, chip feature length, rise time of pressure from zero to the set pressure, and total holding time. The pressure loading offset coefficient is calculated and determined based on the state parameters and the process parameters; Based on the fact that the pressure loading offset coefficient is greater than the preset pressure loading offset coefficient, it is determined that there is a relative slippage risk in the multilayer microfluidic chip during the current bonding process.

[0009] Furthermore, the process of determining an adjustment coefficient to extend the pressure generation time based on the pressure loading offset coefficient and a preset pressure loading offset coefficient, and switching the loading mode, includes: Calculate the ratio of the pressure loading offset coefficient to the preset pressure loading offset coefficient; If the ratio is less than or equal to a preset ratio, then a first control strategy is determined; The first control strategy is to obtain the adjusted pressure rise time by multiplying the first adjustment coefficient by the rise time of the current pressure from zero to the set pressure.

[0010] Furthermore, the process of determining an adjustment coefficient to extend the pressure generation time based on the pressure loading offset coefficient and a preset pressure loading offset coefficient, and switching the loading mode, also includes: Based on the fact that the ratio is greater than a preset ratio, a second control strategy is determined; The second control strategy for book search is to obtain the adjusted pressure rise time by multiplying the second adjustment coefficient by the rise time of the current pressure from zero to the set pressure, and at the same time change the single-stage pressure loading mode to a two-stage stepped loading mode.

[0011] Furthermore, the process of determining whether the effect of regulating the bonding parameters meets the standard includes, Obtain the actual deviation of the upper and lower channels after adjustment, the initial deviation at the time of alignment completion, and the angular deviation before and after adjustment; The bonding alignment deviation increment is calculated and determined based on the actual deviation, the initial deviation, and the angular deviation. The control effect is deemed unsatisfactory if the increment of the bonding alignment deviation is greater than the preset increment of the bonding alignment deviation.

[0012] Furthermore, the process of determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment includes, The incremental deviation coefficient is calculated and determined based on the interval alignment deviation increment and the preset bonding alignment deviation increment. Based on the fact that the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient, a first optimization strategy is determined; The first optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient based on the first optimization coefficient.

[0013] Furthermore, the process of determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment includes, Based on the fact that the incremental deviation coefficient is greater than the preset incremental deviation coefficient, a second optimization strategy is determined; The second optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient based on the second optimization coefficient, and switch the loading mode.

[0014] Furthermore, the process of optimizing the first adjustment coefficient or the second adjustment coefficient based on the first optimization coefficient includes, The first optimization coefficient is determined by calculating the actual incremental deviation coefficient under the condition that the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient. Based on the current execution of the first control strategy, the first optimization coefficient is multiplied by the first adjustment coefficient to obtain the optimized value of the first adjustment coefficient; Based on the current implementation of the second control strategy, the first optimization coefficient is multiplied by the second adjustment coefficient to obtain the second adjustment coefficient optimization value.

[0015] Furthermore, the process of optimizing the first adjustment coefficient or the second adjustment coefficient based on the second optimization coefficient and switching the loading mode includes, The second optimization coefficient is determined based on the actual incremental deviation coefficient under the condition that the incremental deviation coefficient is greater than the preset incremental deviation coefficient. Based on the current execution of the first control strategy, the second optimization coefficient is multiplied by the first adjustment coefficient to obtain the third adjustment coefficient optimization value; Based on the current implementation of the second control strategy, the second optimization coefficient is multiplied by the second adjustment coefficient to obtain the fourth adjustment coefficient optimization value, and the two-stage step loading mode is switched to a three-stage step loading mode.

[0016] On the other hand, the present invention also provides an integrated injection mold for multilayer microfluidic chips, comprising: The injection nozzle layer has a first circular through hole and an injection nozzle for injecting molten plastic into the mold. The observation layer has several second circular through holes, third circular through holes, and first octagonal rectangular holes on its surface. The cavity layer has a plurality of second octagonal rectangular holes on its surface, and also has a fourth circular through hole aligned with the first circular through hole, a fifth circular through hole aligned with the third circular through hole, and a third octagonal rectangular hole aligned with the first octagonal rectangular hole. The laminar flow microchannel layer has microflow channels on its surface and also has several fourth octagonal rectangular holes aligned with several second octagonal rectangular holes. A thin film sealing layer, the surface of which is provided with a sixth circular through hole aligned with the first circular through hole and the fourth circular through hole.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: By acquiring key parameters such as the horizontal component force, vertical bonding pressure, contact point eccentricity distance, and pressure rise time during the pressure loading process in real time, and calculating the pressure loading offset coefficient, this invention achieves online quantitative perception of micro-displacement risks during the bonding stage. It can determine the relative slippage risk at the moment of pressure loading and adjust the pressure rise time and loading mode according to the degree of risk. This can effectively suppress the slippage of upper and lower layer chips caused by the horizontal component force during the bonding process. By acquiring the actual deviation of the upper and lower layer channels after bonding and calculating the bonding alignment deviation increment, it can promptly verify whether the control strategy is qualified. When the control effect is not up to standard, the adjustment coefficient is optimized based on the incremental deviation coefficient or upgraded to three-stage loading. This can ensure the stability of the channel alignment deviation after bonding of each chip, effectively solving the problem of micron-level slippage of aligned chips caused by unbalanced pressure loading, which ultimately leads to channel misalignment and leakage. This significantly improves the bonding yield and production consistency of multilayer microfluidic chips.

[0018] Furthermore, this invention, by real-time monitoring of the cavity pressure curve and melt temperature distribution and calculating the injection filling quality evaluation coefficient, can accurately determine the timing of injection completion, avoiding microchannel replication defects caused by insufficient filling or uneven temperature, thus ensuring molding quality from the source. By acquiring the real-time angle and curvature difference between upper and lower layer chips through a laser displacement sensor, a comprehensive alignment difficulty evaluation value is calculated, and the degree of warpage deformation is quantitatively assessed. Only chips with a difficulty evaluation value less than or equal to the preset value are allowed to enter the alignment process, effectively avoiding alignment failures or precision deviations. During the bonding pressure loading process, by real-time acquisition of parameters such as horizontal force component, contact point eccentricity distance, and pressure rise time, a pressure loading offset coefficient is calculated, achieving precise perception of micro-displacement risks. This significantly suppresses the incremental channel alignment deviation caused by unbalanced pressure loading, improving channel alignment accuracy after bonding. It solves the interlayer misalignment problem caused by warpage deformation and unbalanced pressure loading throughout the entire process from injection molding to bonding, greatly improving the bonding yield and production consistency of multilayer microfluidic chips.

[0019] Furthermore, this invention achieves dynamic control of relative slippage risk during bonding by calculating the ratio of the pressure loading offset coefficient to the preset value in real time. When the ratio is less than or equal to the preset value, a first control strategy is adopted, which appropriately extends the pressure rise time according to the first adjustment coefficient, thereby reducing the horizontal impact force by indirectly reducing the loading rate and suppressing the occurrence of micro-displacement. When the ratio is greater than the preset value, a second control strategy is activated, which further extends the rise time with the second adjustment coefficient and changes the single-stage loading to a two-stage stepped loading. First, the pressure is loaded to 40% of the set pressure and held for 0.8s, and then loaded to 100%. This allows the pressure head to gradually adhere to the chip, effectively eliminating the horizontal component force generated by the initial contact eccentricity. The bonding process parameters can be adaptively adjusted according to the intensity of slippage risk, avoiding chip slippage caused by excessively fast pressure loading or contact imbalance, and significantly improving the bonding yield and process stability of multilayer microfluidic chips.

[0020] Furthermore, this invention obtains the actual spatial coordinates of the upper and lower channels after bonding and compares them with the initial deviation at the alignment completion time to calculate and determine the bonding alignment deviation increment. This achieves objective, timely, and effective verification of the control effect. When the bonding alignment deviation increment exceeds the preset value, it indicates that the existing control strategy has failed to effectively suppress slippage. The system further calculates the incremental deviation coefficient and implements optimization based on the comparison result between the incremental deviation coefficient and the preset value: for slight non-compliance, the first optimization strategy is adopted, and the adjustment coefficient in the current control strategy is optimized according to the first optimization coefficient to enhance the extension of the pressure rise time. For severe non-compliance, the second optimization strategy is initiated, and the adjustment coefficient in the current control strategy is further optimized according to the second optimization coefficient. The two-stage step loading is upgraded to a three-stage process, which significantly improves the consistency and long-term reliability of multilayer microfluidic chip bonding and avoids the batch scrapping of multilayer chips due to insufficient long-term control. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the steps of a molding method for a multilayer microfluidic chip according to an embodiment of the present invention; Figure 2 This is a logic block diagram of an embodiment of the present invention for determining whether there is a risk of relative slippage in the multilayer microfluidic chip during the current bonding process based on the pressure loading offset coefficient; Figure 3 This is a schematic diagram of the axial side structure of the integrated injection mold according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the axial side structure of the integrated injection mold according to an embodiment of the present invention; In the figure, 1 - injection nozzle injection layer; 101 - injection nozzle; 102 - first circular through hole; 2 - observation layer; 201 - second circular through hole; 202 - third circular through hole; 203 - first octagonal rectangular hole; 3 - cavity layer; 301 - second octagonal rectangular hole; 302 - fourth circular through hole; 303 - fifth circular through hole; 304 - third octagonal rectangular hole; 4 - laminar flow microchannel layer; 401 - fourth octagonal rectangular hole; 402 - microfluidic channel; 5 - thin film sealing layer; 501 - sixth circular through hole; 6 - seventh circular through hole. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0025] Please see Figure 1 As shown, it is a schematic diagram of the steps of the molding method for multilayer microfluidic chips according to an embodiment of the present invention.

[0026] The present invention provides a method for molding multilayer microfluidic chips, comprising: Step S1: Analyze the cavity pressure curve and melt temperature distribution during the injection molding process, extract the pressure peak response time and temperature uniformity index, calculate the injection filling quality evaluation coefficient based on the pressure peak response time and temperature uniformity index, in order to determine whether the injection of the multilayer microfluidic chip in the current mold is completed, and perform demolding process after completion; Step S2: Under the condition that the injection molding of the multilayer microfluidic chip in the current mold is completed, the comprehensive alignment difficulty evaluation value is calculated based on the real-time angle and curvature difference between the upper and lower layers of the chip after entering the alignment station, so as to determine whether the multilayer microfluidic chip after injection molding can enter the alignment process, and the alignment process is executed under the condition of entering the alignment process. Step S3: Under the condition that the alignment is completed, the pressure loading offset coefficient is calculated based on the horizontal component of the pressure head and the chip contact surface, the vertical bonding pressure, the distance of the initial contact point from the geometric center of the chip, the chip feature length, the rise time of the pressure from zero to the set pressure, and the total holding time during the pressure loading process, in order to determine whether there is a relative slip risk of the multilayer microfluidic chip in the current bonding process. Step S4: Under the condition that there is a risk of relative slippage of the multilayer microfluidic chip during the current bonding process, the bonding parameters are adjusted according to the ratio of the pressure loading offset coefficient to the preset pressure loading offset coefficient. Step S5: Under the condition of adjusting the bonding parameters, calculate the bonding alignment deviation increment based on the actual deviation of the upper and lower channels after bonding adjustment, the initial deviation at the alignment completion time, and the angle deviation before and after bonding adjustment, so as to determine whether the effect of adjusting the bonding parameters meets the standard. Step S6: If it is determined that the effect of adjusting the bonding parameters is not up to standard, the bonding parameters are optimized based on the bonding alignment deviation increment and the preset bonding alignment deviation increment.

[0027] Specifically, this invention achieves online quantitative perception of micro-displacement risks during the bonding stage by acquiring key parameters such as horizontal force component, vertical bonding pressure, contact point eccentricity distance, and pressure rise time in real time during the pressure loading process, and calculating the pressure loading offset coefficient. It can determine the relative slippage risk at the moment of pressure loading and adjust the pressure rise time and loading mode according to the risk level. It can effectively suppress the slippage of upper and lower layer chips caused by horizontal force during the bonding process. By acquiring the actual deviation of upper and lower layer channels after bonding and calculating the bonding alignment deviation increment, it can promptly verify whether the control strategy is qualified. When the control effect is not up to standard, the adjustment coefficient is optimized based on the incremental deviation coefficient or upgraded to three-stage loading. This can ensure the stability of the channel alignment deviation after bonding of each chip, effectively solving the problem of micron-level slippage of aligned chips caused by unbalanced pressure loading, which ultimately leads to channel misalignment and leakage. It significantly improves the bonding yield and production consistency of multilayer microfluidic chips.

[0028] In this embodiment of the invention, the cavity pressure curve and the melt temperature distribution are obtained by a pressure sensor installed in the cavity of the injection molding machine mold with a sampling frequency of 1kHz and a thermocouple with a sampling frequency of 10Hz.

[0029] In this embodiment of the invention, the real-time included angle and the curvature difference are obtained by a laser displacement sensor installed between the upper chip clamping mechanism and the lower chip carrying platform.

[0030] In this embodiment of the invention, the horizontal component force and the vertical bonding pressure are obtained by a torque sensor installed between the bonding head and the head drive mechanism, with a sampling frequency of 2kHz; the distance is obtained by an eddy current displacement sensor installed at the center of the head; and the rise time and the total holding time are obtained by an encoder.

[0031] Specifically, the injection filling quality evaluation coefficient is compared with the preset injection filling quality evaluation coefficient to determine whether the injection of the multilayer microfluidic chip in the current mold is complete, and demolding is performed after completion. If the injection filling quality evaluation coefficient is less than or equal to the preset injection filling quality evaluation coefficient, it is determined that the injection of the multilayer microfluidic chip in the current mold has been completed, and demolding is performed. If the injection filling quality evaluation coefficient is greater than the preset injection filling quality evaluation coefficient, it is determined that the injection is not completed and the injection process continues.

[0032] In this embodiment of the invention, the injection molding filling quality evaluation coefficient is calculated according to the following formula:

[0033] In the formula, This is the evaluation coefficient for injection molding filler quality; This refers to the peak pressure response time. The preset standard pressure peak response time is set to a value ranging from 0.7s to 1.0s, preferably 0.8s. This is an indicator of temperature uniformity. , These are the weighting coefficients. It is 0.6. It is 0.4; among which, The pressure peak response time is extracted from the cavity pressure curve, that is, the time interval from the start of injection to the pressure reaching the first peak. The temperature uniformity index is obtained by dividing the mold cavity into a 3×3 grid and using the ratio of the standard deviation to the average value of the melt temperature in each grid as the temperature uniformity index.

[0034] In this embodiment of the invention, the preset injection filling quality evaluation coefficient ranges from 0.12 to 0.18, preferably 0.15. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0035] Specifically, given that the injection molding of the multilayer microfluidic chip within the current mold is complete, the system determines whether the currently injection-molded multilayer microfluidic chip meets the requirements for entering the alignment process based on the comparison between the comprehensive alignment difficulty evaluation value and the preset difficulty evaluation value. If the chip meets the requirements for entering the alignment process, the system performs an alignment process. If the overall alignment difficulty evaluation value is less than or equal to the preset difficulty evaluation value, then it is determined that the alignment process can proceed and alignment can be performed. If the overall alignment difficulty evaluation value is greater than the preset difficulty evaluation value, it is determined that the alignment process cannot be entered and alignment will not be performed.

[0036] In this embodiment of the invention, the comprehensive alignment difficulty evaluation value is calculated according to the following formula:

[0037] In the formula, To comprehensively assess the difficulty level; This refers to the real-time angle between the upper and lower layer chips after they enter the alignment station. The reference angle is taken in the range of 0.005 rad to 0.015 rad, preferably 0.01 rad; The curvature difference between the upper and lower layer chips after they enter the alignment station; For reference curvature differences, the value range is 0.01mm. -1 ~0.04mm -1 0.02mm is preferred. -1 ; , These are the weighting coefficients. It is 0.6. It is 0.4, where, The curvature difference is obtained as follows: a laser displacement sensor is used to perform a full-area scan of the surfaces of the upper and lower chips to obtain the three-dimensional coordinate data of each sampling point on the chip surface; the warped surfaces of the upper and lower chips are fitted based on the least squares method to obtain the global warped surface equations of the upper and lower chips; the geometric center of the chip is selected as the center point, and a square region with a side length of 1 / 3 of the chip feature length is defined as the central region. The three-dimensional coordinate data of all sampling points in the central region are extracted, substituted into the corresponding chip warped surface equation, and the upper average curvature of the upper chip in the central region and the lower average curvature of the lower chip in the central region are calculated. The absolute difference between the upper average curvature and the lower average curvature is calculated to obtain the curvature difference.

[0038] In this embodiment of the invention, the general form of the global warped surface equation is z = ax² + by² + cxy + dx + ey + f, where a, b, c, d, e, and f are fitting coefficients, which are calculated from the three-dimensional coordinate sampling data of the chip surface using the least squares method.

[0039] In this embodiment of the invention, the preset difficulty evaluation value ranges from 0.6 to 0.9, preferably 0.8. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0040] Please see Figure 2 As shown, it is a logic block diagram of an embodiment of the present invention for determining whether there is a risk of relative slippage in the multilayer microfluidic chip during the current bonding process based on the pressure loading offset coefficient.

[0041] Specifically, assuming alignment is complete, the risk of relative slippage of the multilayer microfluidic chip during the current bonding process is determined based on the comparison between the pressure loading offset coefficient and the preset pressure loading offset coefficient. If the pressure loading offset coefficient is less than or equal to the preset pressure loading offset coefficient, it is determined that there is no risk of relative slippage of the multilayer microfluidic chip during the current bonding process; If the pressure loading offset coefficient is greater than the preset pressure loading offset coefficient, it is determined that there is a risk of relative slippage of the multilayer microfluidic chip during the current bonding process.

[0042] In this embodiment of the invention, the pressure loading offset coefficient is calculated according to the following formula:

[0043] In the formula, This is the pressure loading offset coefficient; The horizontal component of the force; For vertical bonding pressure; The distance between the initial contact point and the geometric center of the chip; The chip feature length; The rise time for the pressure to rise from zero to the set pressure; This refers to the total holding time.

[0044] In this embodiment of the invention, the preset pressure loading offset coefficient ranges from 0.05 to 0.15, preferably 0.10. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0045] Specifically, this invention, by real-time monitoring of the cavity pressure curve and melt temperature distribution and calculating the injection filling quality evaluation coefficient, can accurately determine the timing of injection completion, avoiding microchannel replication defects caused by insufficient filling or uneven temperature, thus ensuring molding quality from the source. By acquiring the real-time angle and curvature difference between upper and lower layer chips through a laser displacement sensor, a comprehensive alignment difficulty evaluation value is calculated, and the degree of warpage deformation is quantitatively assessed. Only chips with a difficulty evaluation value less than or equal to the preset value are allowed to enter the alignment process, effectively avoiding alignment failures or precision deviations. During the bonding pressure loading process, by real-time acquisition of parameters such as horizontal force component, contact point eccentricity distance, and pressure rise time, a pressure loading offset coefficient is calculated, achieving precise perception of micro-displacement risks. This significantly suppresses the incremental channel alignment deviation caused by unbalanced pressure loading, improving the channel alignment accuracy after bonding. It solves the interlayer misalignment problem caused by warpage deformation and unbalanced pressure loading throughout the entire process from injection molding to bonding, greatly improving the bonding yield and production consistency of multilayer microfluidic chips.

[0046] Specifically, given that the multilayer microfluidic chip is at risk of relative slippage during the current bonding process, a strategy for adjusting the bonding parameters is determined based on a comparison between the ratio of the pressure loading offset coefficient to a preset pressure loading offset coefficient and a preset ratio. If the ratio is less than or equal to a preset ratio, then the first control strategy is determined; If the ratio is greater than the preset ratio, then the second control strategy is determined.

[0047] In this embodiment of the invention, the preset ratio ranges from 1.2 to 1.6, preferably 1.4. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0048] In this embodiment of the invention, the first control strategy is to extend the rise time of the pressure from zero to the set pressure based on a first adjustment coefficient. Specifically, the first adjustment coefficient is multiplied by the rise time of the current pressure from zero to the set pressure to obtain the adjusted pressure rise time.

[0049] The first adjustment coefficient is calculated according to the following formula.

[0050] In the formula, This is the first adjustment factor; This refers to the actual ratio under the condition that the ratio is less than or equal to the preset ratio.

[0051] In this embodiment of the invention, the second control strategy is to extend the rise time of the pressure from zero to the set pressure based on the second adjustment coefficient. Specifically, the second adjustment coefficient is multiplied by the rise time of the current pressure from zero to the set pressure to obtain the adjusted pressure rise time. At the same time, the single-stage pressure loading mode is changed to a two-stage stepped loading mode, that is, the first stage is loaded to 30% to 50% of the set pressure, preferably 40%, and held for 0.3s to 1.0s, preferably 0.8s, and the second stage is loaded to 100% of the preset pressure.

[0052] The second adjustment coefficient is calculated according to the following formula:

[0053] In the formula, This is the second adjustment factor; This is the actual ratio under the condition that the ratio is greater than the preset ratio.

[0054] In this embodiment of the invention, the set pressure is a preset target pressure value in the bonding process, that is, the rated bonding pressure that the pressure head needs to reach and maintain. For microfluidic chips made of PMMA material, the set pressure is preferably 1.0 Bar.

[0055] Specifically, this invention achieves dynamic control of relative slippage risk during bonding by calculating the ratio of the pressure loading offset coefficient to a preset value in real time. When the ratio is less than or equal to the preset value, a first control strategy is adopted, which appropriately extends the pressure rise time according to the first adjustment coefficient. This indirectly reduces the horizontal impact force by decreasing the loading rate, thereby suppressing the occurrence of micro-displacement. When the ratio is greater than the preset value, a second control strategy is activated, which further extends the rise time with the second adjustment coefficient and changes the single-stage loading to a two-stage stepped loading. The pressure is first loaded to 40% of the set pressure and held for 0.8s, and then loaded to 100%. This allows the pressure head to gradually adhere to the chip, effectively eliminating the horizontal component force generated by the initial contact eccentricity. The bonding process parameters can be adaptively adjusted according to the intensity of slippage risk, avoiding chip slippage caused by excessively fast pressure loading or contact imbalance. This significantly improves the bonding yield and process stability of multilayer microfluidic chips.

[0056] Specifically, under the condition of adjusting the bonding parameters, based on the actual deviation of the upper and lower channels after bonding adjustment, the initial deviation at the alignment completion time, and the angular deviation before and after bonding adjustment, the bonding alignment deviation increment is calculated. The comparison between the bond alignment deviation increment and the preset bond alignment deviation increment determines whether the adjustment effect of the bonding parameters meets the standard. If the bonding alignment deviation increment is less than or equal to the preset bonding alignment deviation increment, then the control effect is determined to be satisfactory. If the increment of the bonding alignment deviation is greater than the preset increment of the bonding alignment deviation, then the control effect is determined to be unsatisfactory.

[0057] In this embodiment of the invention, the specific process for obtaining the bonding alignment deviation increment is as follows: Step S51: After bonding is completed, the chip is transferred to the inspection station, and the optical coherence tomography (OCT) device is started to perform tomographic imaging on the bonding interface. The spatial coordinates (X1, Y1) of the upper channel centerline and the spatial coordinates (X2, Y2) of the lower channel centerline are extracted from the OCT image. Step S52: Calculate the absolute difference between the spatial coordinates of X1 and X2 of the center line of the upper channel and the lower channel, and obtain the actual X-axis deviation of the upper and lower channels after adjustment. Calculate the absolute difference between the spatial coordinates Y1 of the upper channel centerline and Y2 of the lower channel centerline to obtain the actual Y-axis deviation of the upper and lower channels after adjustment. Continue to calculate the absolute difference in the angle between the center lines of the upper and lower channels to obtain the actual angle deviation of the upper and lower channels after adjustment; Step S53: Calculate the bonding alignment deviation increment according to the following formula.

[0058] In the formula, This represents the actual deviation along the X-axis. This represents the actual deviation along the Y-axis. This refers to the actual deviation of the angle. The X-axis deviation at the time of alignment completion; The Y-axis deviation at the alignment completion time; To account for the angular deviation at the time of completion; The conversion factor from angular deviation to linear displacement is taken as half the feature length of the chip, i.e. = / 2 (unit: μm) In this embodiment of the invention, the preset bonding alignment deviation increment ranges from 2μm to 4μm, preferably 3μm. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0059] Specifically, when it is determined that the effect of adjusting the bonding parameters is not up to standard, the bonding parameters are optimized based on the comparison between the incremental deviation coefficient of the bonding alignment deviation increment and the preset incremental deviation coefficient. If the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient, then the first optimization strategy is determined; If the incremental deviation coefficient is greater than the preset incremental deviation coefficient, then the second optimization strategy is determined.

[0060] In this embodiment of the invention, the incremental deviation coefficient is the ratio of the bonding alignment deviation increment to the preset bonding alignment deviation increment.

[0061] In this embodiment of the invention, the first optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient in the control strategy based on the first optimization coefficient, specifically; If the first control strategy is currently implemented, the first optimization coefficient is multiplied by the first adjustment coefficient to obtain the optimized value of the first adjustment coefficient; If the second control strategy is currently implemented, the first optimization coefficient is multiplied by the second adjustment coefficient to obtain the second adjustment coefficient optimization value.

[0062] The first optimization coefficient is calculated according to the following formula.

[0063] In the formula, The first optimization coefficient; The actual incremental deviation coefficient is the condition that the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient.

[0064] In this embodiment of the invention, the second optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient in the control strategy based on the second optimization coefficient, specifically; If the first control strategy is currently implemented, the second optimization coefficient is multiplied by the first adjustment coefficient to obtain the third adjustment coefficient optimization value; If the second control strategy is currently implemented, the second optimization coefficient is multiplied by the second adjustment coefficient to obtain the fourth adjustment coefficient optimization value. At the same time, the two-stage stepped loading mode is switched to a three-stage stepped loading mode, that is, the first stage is loaded to 20% to 30% of the set pressure, preferably 25%, and held for 0.2s to 0.7s, preferably 0.5s; the second stage is loaded to 50% to 70% of the set pressure, preferably 60%, and held for 0.2s to 0.7s, preferably 0.5s; and the third stage is loaded to 100% of the set pressure.

[0065] The second optimization coefficient is calculated according to the following formula:

[0066] In the formula, This is the second optimization coefficient; This is the actual incremental deviation coefficient under the condition that the incremental deviation coefficient is greater than the preset incremental deviation coefficient.

[0067] Specifically, this invention obtains the actual spatial coordinates of the upper and lower channels after bonding and compares them with the initial deviation at the alignment completion time to calculate and determine the bonding alignment deviation increment. This enables objective, timely, and effective verification of the control effect. When the bonding alignment deviation increment exceeds the preset value, it indicates that the existing control strategy has failed to effectively suppress slippage. The system further calculates the incremental deviation coefficient and implements optimization based on the comparison result between the incremental deviation coefficient and the preset value: for slight non-compliance, a first optimization strategy is adopted, which optimizes the adjustment coefficient in the current control strategy according to the first optimization coefficient to enhance the extension of the pressure rise time; for severe non-compliance, a second optimization strategy is initiated, which further optimizes the adjustment coefficient in the current control strategy according to the second optimization coefficient, and upgrades the two-stage step-by-step loading to a three-stage process. This significantly improves the consistency and long-term reliability of multilayer microfluidic chip bonding and avoids the batch scrapping of multilayer chips due to insufficient long-term control.

[0068] Specifically, embodiments of the present invention also provide an integrated injection mold for multilayer microfluidic chips, comprising, The injection nozzle injection layer 1 is the first layer of the integrated injection mold. One end of the injection nozzle injection layer is circular and has a first circular through hole 102 on its surface. The other end is rectangular and has an injection nozzle 101 on its surface for injecting molten plastic into the mold.

[0069] The observation layer 2 is located below the injection nozzle injection layer 1 and is the second layer of the integrated injection mold. One end of the observation layer is circular and has several second circular through holes 201 on the outer circular side of its surface. The other end is rectangular and has a third circular through hole 202 on one side of its surface and a first octagonal rectangular hole 203 on the other side.

[0070] The cavity layer 3 is located below the observation layer 2 and is the third layer of the integrated injection mold. One end of the cavity layer is circular, and a plurality of second octagonal rectangular holes 301 are provided on the outer circular side of the surface. A fourth circular through hole 302 is provided in the middle of the inner circle. The fourth circular through hole 302 is aligned with the first circular through hole 102. The other end is rectangular, and a fifth circular through hole 303 is provided on one side of the surface. A third octagonal rectangular hole 304 is provided on the other side. The fifth circular through hole 303 is aligned with the third circular through hole 202, and the third octagonal rectangular hole 304 is aligned with the first octagonal rectangular hole 203.

[0071] The laminar flow microchannel layer 4 is disposed at the lower part of the cavity layer and is the fourth layer of the integrated injection mold. One end of the laminar flow microchannel layer is circular, and the outer circular side of the surface is provided with a plurality of fourth octagonal rectangular holes 401 aligned with a plurality of second octagonal rectangular holes 301. The other end is rectangular, and the surface is provided with microflow channels 402.

[0072] A thin film sealing layer 5 is disposed in the laminar flow microchannel layer and is the fifth layer of the integrated injection mold. One end of the thin film sealing layer is circular, and a sixth circular through hole 501 is provided on its surface. The sixth circular through hole 501 is aligned with the first circular through hole 102 and the fourth circular through hole 302.

[0073] The injection nozzle injection layer 1, the layer observation layer 2, the layer cavity layer 3, the laminar flow microchannel layer 4, and the layer film sealing layer 5 are all provided with a pair of seventh circular through holes 6 at one bottom for interlayer alignment.

[0074] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for molding multilayer microfluidic chips, characterized in that, include, Based on the cavity pressure curve and melt temperature distribution during the injection molding process, the injection filling quality evaluation coefficient is determined to determine whether the injection of the multilayer microfluidic chip in the current mold is completed, and demolding is performed after completion. Based on the real-time angle and curvature difference between the upper and lower layer chips after entering the alignment station, it is determined whether the multilayer microfluidic chip after injection molding can enter the alignment process, and the alignment process is performed if the conditions for entering the alignment process are met. Based on the pressure loading offset coefficient between the pressure head and the chip contact surface during the pressure loading process, it is determined whether there is a relative slippage risk in the multilayer microfluidic chip during the current bonding process. If a relative slip risk is identified, the pressure generation time is extended by adjusting the coefficient based on the pressure loading offset coefficient and the preset pressure loading offset coefficient, and the loading mode is switched. Based on the incremental bonding alignment deviation of the upper and lower channels after bonding control, it is determined whether the control effect of bonding parameters meets the standard. If the effect of adjusting the bonding parameters is not satisfactory, the adjustment coefficient is optimized by determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment.

2. The molding method for multilayer microfluidic chips according to claim 1, characterized in that, The process of determining whether there is a risk of relative slippage in the multilayer microfluidic chip during the current bonding process includes: Acquire the state parameters and process parameters of the contact surface between the pressure head and the chip during the bonding process, where; The state parameters and process parameters include horizontal force component, vertical bonding pressure, distance of the initial contact point from the geometric center of the chip, chip feature length, rise time of pressure from zero to the set pressure, and total holding time. The pressure loading offset coefficient is calculated and determined based on the state parameters and the process parameters; Based on the fact that the pressure loading offset coefficient is greater than the preset pressure loading offset coefficient, it is determined that there is a relative slippage risk in the multilayer microfluidic chip during the current bonding process.

3. The molding method for multilayer microfluidic chips according to claim 2, characterized in that, The process of determining an adjustment coefficient to extend the pressure generation time based on the pressure loading offset coefficient and a preset pressure loading offset coefficient, and switching the loading mode. include, Calculate the ratio of the pressure loading offset coefficient to the preset pressure loading offset coefficient; If the ratio is less than or equal to a preset ratio, then a first control strategy is determined; The first control strategy is to obtain the adjusted pressure rise time by multiplying the first adjustment coefficient by the rise time of the current pressure from zero to the set pressure.

4. The molding method for multilayer microfluidic chips according to claim 3, characterized in that, The process of determining the adjustment coefficient to extend the pressure generation time based on the pressure loading offset coefficient and the preset pressure loading offset coefficient, and switching the loading mode, also includes: Based on the fact that the ratio is greater than a preset ratio, a second control strategy is determined; The second control strategy for book search is to obtain the adjusted pressure rise time by multiplying the second adjustment coefficient by the rise time of the current pressure from zero to the set pressure, and at the same time change the single-stage pressure loading mode to a two-stage stepped loading mode.

5. The molding method for multilayer microfluidic chips according to claim 4, characterized in that, The process of determining whether the effect of regulating the bonding parameters meets the standard includes, Obtain the actual deviation of the upper and lower channels after adjustment, the initial deviation at the time of alignment completion, and the angular deviation before and after adjustment; The bonding alignment deviation increment is calculated and determined based on the actual deviation, the initial deviation, and the angular deviation. The control effect is determined to be substandard if the increment of the bonding alignment deviation is greater than the preset increment of the bonding alignment deviation.

6. The molding method for multilayer microfluidic chips according to claim 5, characterized in that, The process of determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment includes the following steps: The incremental deviation coefficient is calculated and determined based on the bonding alignment deviation increment and the preset bonding alignment deviation increment. Based on the fact that the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient, a first optimization strategy is determined; The first optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient based on the first optimization coefficient.

7. The molding method for multilayer microfluidic chips according to claim 6, characterized in that, The process of determining the optimization coefficient based on the bonding alignment deviation increment and the preset bonding alignment deviation increment includes the following steps: Based on the fact that the incremental deviation coefficient is greater than the preset incremental deviation coefficient, a second optimization strategy is determined; The second optimization strategy is to optimize the first adjustment coefficient or the second adjustment coefficient based on the second optimization coefficient, and switch the loading mode.

8. The molding method for multilayer microfluidic chips according to claim 7, characterized in that, The process of optimizing the first adjustment coefficient or the second adjustment coefficient based on the first optimization coefficient includes: The first optimization coefficient is determined by calculating the actual incremental deviation coefficient under the condition that the incremental deviation coefficient is less than or equal to the preset incremental deviation coefficient. Based on the current execution of the first control strategy, the first optimization coefficient is multiplied by the first adjustment coefficient to obtain the optimized value of the first adjustment coefficient; Based on the current implementation of the second control strategy, the first optimization coefficient is multiplied by the second adjustment coefficient to obtain the second adjustment coefficient optimization value.

9. The molding method for multilayer microfluidic chips according to claim 8, characterized in that, The process of optimizing the first adjustment coefficient or the second adjustment coefficient based on the second optimization coefficient and switching the loading mode includes, The second optimization coefficient is determined based on the actual incremental deviation coefficient under the condition that the incremental deviation coefficient is greater than the preset incremental deviation coefficient. Based on the current execution of the first control strategy, the second optimization coefficient is multiplied by the first adjustment coefficient to obtain the third adjustment coefficient optimization value; Based on the current implementation of the second control strategy, the second optimization coefficient is multiplied by the second adjustment coefficient to obtain the fourth adjustment coefficient optimization value, and the two-stage step loading mode is switched to a three-stage step loading mode.

10. An integrated injection mold suitable for the molding method of multilayer microfluidic chips according to any one of claims 1-9, characterized in that, include, The injection nozzle layer has a first circular through hole and an injection nozzle for injecting molten plastic into the mold. The observation layer has several second circular through holes, third circular through holes, and first octagonal rectangular holes on its surface. The cavity layer has a plurality of second octagonal rectangular holes on its surface, and also has a fourth circular through hole aligned with the first circular through hole, a fifth circular through hole aligned with the third circular through hole, and a third octagonal rectangular hole aligned with the first octagonal rectangular hole. The laminar flow microchannel layer has microflow channels on its surface and also has several fourth octagonal rectangular holes aligned with several second octagonal rectangular holes. A thin film sealing layer, the surface of which is provided with a sixth circular through hole aligned with the first circular through hole and the fourth circular through hole.

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