Method for predicting single-layer curing thickness of DLP biological 3D printing ink

Abstract

The invention discloses a method for predicting the single-layer curing thickness of DLP biological 3D printing ink. The single-layer curing thickness is obtained through calculation according to the formula (1). By adopting the technical scheme of the invention, the predictability and repeatability of the curing process are improved, and a theoretical basis and a technical means are provided for optimizing a biological printing process. According to the technical scheme provided by the invention, the mathematical model of which the characteristic penetration depth dynamically changes along with the exposure time is introduced, so that the actual light response behavior of the bio-ink in the exposure process is more accurately reflected. Meanwhile, key process parameters such as exposure time and light source intensity serve as input variables, and the guiding capacity of the model for printing parameter selection is remarkably improved. In addition, parameters such as light absorption stability and bio-ink gel points are further introduced, the material characteristics of bio-ink are visually described, and the adaptability and prediction accuracy of the model to inks of different formulas are enhanced.

Description

Technical Field

[0001] This invention relates to the field of bio-additive manufacturing technology, and in particular to a method for predicting the single-layer curing thickness of DLP bio-3D printing ink. Background Technology

[0002] The Jacobs work curve is a classic mathematical model widely used in the field of photopolymerization additive manufacturing. Based on the kinetics of photopolymerization, this model describes the exponential relationship between the curing depth and the cumulative exposure energy. Its core formula is:

[0003]

[0004] Where C d D represents the thickness of a single-layer cured layer, measured in μm, indicating the thickness of one cured layer formed by the resin in a single exposure. p The characteristic penetration depth, in μm, represents the distance light travels after entering the resin and its intensity decays to 1 / e of its initial value; E is the incident light energy, in mJ / cm². 2 The actual energy transferred from the light source to the resin can be considered as the product of the incident light intensity I and the exposure time t; E c Critical energy, unit mJ / cm 2 This refers to the minimum energy required for the resin to begin curing. This model is applicable to traditional photocurable resin systems and has significant guiding value in process prediction and parameter optimization. However, in DLP (Digital Light Processing) bio-3D printing, this model has obvious limitations:

[0005] First, in DLP bio-3D printing, the types and concentrations of light absorbers are strictly limited to ensure cell viability, making them more susceptible to decomposition or structural changes under light irradiation. This results in a dynamic decrease in light absorption capacity over time, producing a significant photobleaching effect. However, the Jacobs model, based on traditional photocuring systems, assumes that the light absorption characteristics of the material remain constant throughout the curing process, failing to reflect this dynamic change in bio-inks.

[0006] Second, the prediction accuracy is insufficient. Photobleaching increases the light transmittance of the ink, allowing more light to penetrate deeper and cause over-curing. This results in the actual cured thickness being significantly greater than the theoretical value, leading to problems such as dimensional errors in the printed structure and excessive interlayer bonding, thus affecting the forming accuracy.

[0007] Third, the model only uses cumulative exposure energy as an input variable and does not explicitly include key parameters that can be directly controlled, such as exposure time and light intensity, making it difficult to deduce a reasonable combination of printing parameters and limiting its practical operability.

[0008] Fourth, it cannot guide ink formulation selection. The model lacks key parameters related to the curing behavior of bio-inks, making it difficult to reflect the impact of formulation changes on curing performance and failing to meet the application needs of diverse bio-ink systems.

[0009] In summary, Jacobs' working curves in DLP bioprinting scenarios not only lack direct guidance for the selection of key printing parameters and bio-ink formulations, but also fail to consider the dynamic changes in material response characteristics, making it difficult to meet the needs of high-precision and controllable bioprinting processes. Summary of the Invention

[0010] To address the above technical problems, this invention discloses a method for predicting the single-layer curing thickness of DLP bio-3D printing ink.

[0011] The technical solution adopted by this invention is as follows:

[0012] A method for predicting the single-layer curing thickness of DLP bio-3D printing ink, wherein the single-layer curing thickness of the DLP bio-3D printing ink is calculated using equation (1):

[0013]

[0014] Among them, C d I represents the solidified thickness of a single layer of bio-ink for DLP bio-3D printing, in μm; I represents the initial light intensity, in mW / cm². 2 t represents exposure time in seconds; S represents light absorption stability, which is the reciprocal of the rate of change of the characteristic penetration depth in the DLP bio-3D printing ink over time, and is dimensionless; H represents the initial characteristic penetration depth in μm, which is the penetration depth corresponding to when the light intensity at the beginning of exposure decays along the depth direction of the material to 1 / e (approximately 36.8%) of the initial value; G represents the gel point in mJ / cm. 2 ;

[0015] The gel point is calculated using equation (2):

[0016] G = It T (2);

[0017] In the formula, I represents the initial light intensity, in mW / cm². 2 ;t T The critical curing time of the bio-ink, expressed in seconds (s), is the time from the start of irradiation to the beginning of curing. The critical curing time of the bio-ink was determined experimentally as follows: after determining the light intensity, the ink transitions from a liquid to a solid state after irradiation time t. The minimum time t required for the bio-ink to cure is the critical curing time t. T .

[0018] As a further improvement of the present invention, the light absorption stability is obtained by linear fitting based on experimental data of characteristic penetration depth measurement of bio-ink. This light absorption stability S is used to measure the rate of change of characteristic penetration depth.

[0019] As a further improvement of the present invention, the initial characteristic penetration depth is the intersection of the characteristic penetration depth-time line of the bio-ink and the y-axis; that is, the initial value of the linear relationship line of characteristic penetration depth-time of the bio-ink, which is used to measure the light absorption capacity of the bio-ink when it is not exposed to light.

[0020] The Beer-Lambert law measures the attenuation of light intensity in a homogeneous medium, where the optical path length corresponding to the attenuation of light intensity to 1 / e of the incident light intensity is called the characteristic penetration depth. Jacobs' working curves assume the characteristic penetration depth is constant, which is suitable for commercial resin printing. However, experiments have shown that the characteristic penetration depth of bio-inks is a variable that changes linearly with time; based on this linear change, the initial characteristic penetration depth can be obtained.

[0021] As a further improvement of the present invention, the bio-ink comprises the following components and concentrations: 10-20 w / v% of polyethylene glycol diacrylate with a molecular weight of 1 kDa, 0.1-0.5 w / v% of lithium phenyl-2,4,6-trimethylbenzoyl phosphate, and 0.05-0.2 w / v% of tartrazine.

[0022] As a further improvement of the present invention, the bio-ink comprises the following components and concentrations: 15 w / v% polyethylene glycol diacrylate with a molecular weight of 1 kDa, 0.25 w / v% lithium phenyl-2,4,6-trimethylbenzoyl phosphate, and 0.1 w / v% tartrazine.

[0023] As a further improvement of the present invention, the initial characteristic penetration depth H is 300 μm, the light absorption stability S is 100, and the gel point G is 160 mJ / cm. 2 .

[0024] The single-layer curing thickness prediction method for DLP bio-3D printing ink of this invention is mainly applied in the field of bio-additive manufacturing. The following are the known and potential application areas and methods of this technology:

[0025] 1. Known application areas

[0026] Biomimetic tissue vascular channel fabrication: By predicting the single-layer curing thickness under key printing parameters (such as exposure time, light source intensity, etc.), the forming accuracy and structural consistency of the vascular channel are optimized, effectively avoiding channel blockage problems and realizing high-precision manufacturing of complex microvascular channels.

[0027] Bio-ink formulation development and evaluation: Provides a rapid verification method for the printability of novel photosensitive bio-inks, and assists in screening material combinations suitable for specific printing needs.

[0028] DLP bioprinter process optimization module: can be integrated into the control system of existing DLP bioprinting equipment as a pre-printing simulation and prediction tool to improve printing success rate and consistency.

[0029] 2. Potential application areas

[0030] Personalized artificial organ / tissue printing: In the process of printing customized artificial organs or tissues, the model is used to achieve adaptive prediction and dynamic adjustment of the layer-by-layer curing thickness, improve the geometric accuracy and detail resolution of the three-dimensional structure, and promote the controllable fabrication of high-precision organs.

[0031] Multi-material composite printing control: For printing scenarios involving combinations of various bio-inks with different photoresponse characteristics, the curing behavior of each material is predicted uniformly to ensure structural integrity.

[0032] Intelligent manufacturing and online quality monitoring system: As the predictive engine of the intelligent bioprinting system, it supports real-time feedback adjustment, improving the automation level and stability of the printing process.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The technical solution of this invention not only improves the predictability and repeatability of the curing process but also provides a theoretical basis and technical means for optimizing bioprinting processes. Based on traditional models, this method introduces a mathematical model of the dynamic change of feature penetration depth with exposure time, more accurately reflecting the actual photoresponse behavior of bio-inks during exposure. Simultaneously, by using key process parameters such as exposure time and light source intensity as input variables, the model's ability to guide the selection of printing parameters is significantly enhanced. Furthermore, by introducing parameters such as light absorption stability and the gel point of the bio-ink, the material properties of the bio-ink are intuitively characterized, enhancing the model's adaptability and predictive accuracy for different ink formulations.

[0035] Secondly, the technical solution of this invention can not only effectively compensate for the influence of photobleaching effect on curing thickness, but also provide a unified prediction framework for the curing behavior of bio-inks with different process parameters and different formulations. It has good versatility and practicality and is suitable for parameter optimization and quality control of high-precision and controllable bioprinting processes. Attached Figure Description

[0036] Figure 1 This is a comparison chart showing the trend of the single-layer curing thickness prediction curve in an embodiment of the present invention.

[0037] Figure 2 This is a graph showing the attenuation trend of light intensity with penetration depth according to an embodiment of the present invention.

[0038] Figure 3 This is an analysis diagram of the intersection of light dose and gel point at different times in an embodiment of the present invention.

[0039] Figure 4 This is a graph showing the change of feature penetration depth over time in an embodiment of the present invention.

[0040] Figure 5 This is a diagram showing the effect of the initial light intensity on the prediction curve in an embodiment of the present invention.

[0041] Figure 6 This is a diagram showing the influence of the initial feature penetration depth on the prediction curve in an embodiment of the present invention.

[0042] Figure 7 This is a graph showing the effect of light absorption stability on the prediction curve in an embodiment of the present invention.

[0043] Figure 8 This is a graph showing the effect of the gel point on the prediction curve in an embodiment of the present invention.

[0044] Figure 9 This is a curing analysis of the comparative example of the present invention.

[0045] Figure 10 These are the various blockage scenarios in the comparative examples of this invention.

[0046] Figure 11 These are printing effects of microchannels of different sizes in embodiments of the present invention; wherein, (a) is a printing effect image of a 1000μm square hole, (b) is a printing effect image of a 200μm square hole, and (c) is a printing effect image of a 150*100μm rectangular hole. Detailed Implementation

[0047] The preferred embodiments of the present invention will be described in further detail below.

[0048] A method for predicting the single-layer curing thickness of DLP bio-3D printing ink. The specific formula is as follows:

[0049]

[0050] In the formula C d Single-layer cured thickness, in μm; I is the initial light intensity, in mW / cm². 2 t is the exposure time in seconds; S is the light absorption stability (dimensionless); H is the initial characteristic penetration depth in micrometers (μm); G is the gel point in mJ / cm³. 2 .

[0051] The bio-ink composition consists of polyethylene glycol diacrylate (PEGDA) with a molecular weight of 1 kDa, lithium phenyl-2,4,6-trimethylbenzoyl phosphate (LAP), and tartrazine. The concentrations of PEGDA, LAP, and tartrazine were set at 15% (w / v), LAP at 0.25% (w / v), and tartrazine at 0.1% (w / v). Under the same printing parameters, a curve predicting the curing thickness was plotted with the curing thickness on the vertical axis and exposure time on the horizontal axis, and compared with the Jacobs working curve under the same parameters. Figure 1 As shown.

[0052] The core component of DLP bioprinting equipment is the DMD chip. Based on a two-dimensional image generated from a model slice, the DMD chip controls the deflection of a micromirror array, modulating an incident light beam to form a specific pattern. This patterned light field induces selective photopolymerization and curing of the bio-ink, forming the desired structural layers. By repeatedly exposing each layer and ensuring interlayer bonding, a three-dimensional structure with complex morphology and functional partitions is constructed.

[0053] During exposure, the initial light intensity *I* and exposure time *t* need to be preset; these two parameters are key factors directly affecting printing accuracy. The distance light travels in the bio-ink medium is defined as the penetration depth *z*. Due to the presence of light-absorbing substances in bio-inks, light continuously attenuates during propagation; therefore, the actual light intensity decreases as *z* increases. According to Beer-Lambert's law, this attenuation trend is similar to exponential decay, such as... Figure 2 As shown.

[0054] The Beer-Lambert law states that when light passes through a uniform light-absorbing medium, its intensity decreases exponentially with increasing penetration depth α, as expressed by:

[0055] I d (z)=Ie -αz

[0056] In the formula, z is the penetration depth, in μm; I d The light intensity at the penetration depth z is expressed in mW / cm. 2 I represents the initial light intensity, in mW / cm². 2 α is the solution absorption coefficient. From the mathematical expression of the exponential decay curve, the characteristic penetration depth h is defined as the depth at which the light intensity decays to 1 / e of the initial light intensity. That is, I... d (h) = I / e, which simplifies to α = 1 / h. The reciprocal of the extinction coefficient α, characteristic of the penetration depth h, can also measure the light attenuation rate; the smaller h is, the stronger the light absorption capacity. Its expression is:

[0057] I d (z)=Ie -z / h

[0058] In the formula, z is the penetration depth, in μm; I d The light intensity at the penetration depth z is expressed in mW / cm. 2 I represents the initial light intensity, in mW / cm². 2 h represents the characteristic penetration depth (μm).

[0059] Fixing the viewing angle at the ink penetration depth z, the light intensity I at that point... d The product of (z) and exposure time t is called the light dose E(z,t) at that point. Light dose represents the energy transferred from the light field to the bio-ink. A higher light dose results in a higher concentration of free radicals and a faster polymerization rate. (The last sentence appears to be incomplete and possibly refers to a different topic.) d Multiplying (z) by t yields the light dose E(z,t), which can be expressed in the following form:

[0060] E(z,t)=I d (z)·t

[0061] =Ie -z / h ·t

[0062] In the formula, E is the light dose, in mJ / cm². 2 ;I d The light intensity at the penetration depth z is expressed in mJ / cm. 2 z is the penetration depth in μm; t is the exposure time in seconds; I is the initial light intensity in mW / cm². 2 h represents the characteristic penetration depth, in μm.

[0063] When the free radical concentration in bio-ink reaches a certain critical value, its polymerization rate suddenly increases, thus completing the discontinuous transition from liquid to solid state. This light dose threshold is called the gel point G of the bio-ink. After determining the initial light intensity I, the time from the start of irradiation to the start of curing of the bio-ink is called the critical curing time t. T According to the definition of light dose, the gel point can be expressed as:

[0064] G = It T

[0065] In the formula, G represents the gel point of the bio-ink, with units of mJ / cm. 2 I represents the initial light intensity, in mW / cm². 2 ;t T The critical curing time of the bio-ink is expressed in seconds (s). The critical curing time is the minimum time t required for the bio-ink to solidify after irradiation for a given light intensity, after which it transitions from a liquid to a solid state. T .

[0066] Assuming that after an exposure time t, the light dose at the penetration depth z = d exactly reaches the gel point G, causing the material to transition from a liquid to a solid state. The portion below the penetration depth d has already received a light dose exceeding G and is therefore considered to have solidified. Therefore, d is considered the thickness of a single layer that has solidified. The light dose at d equals the gel point, i.e., satisfying E(d,t) = G. Substituting this relationship into the light dose expression and simplifying, we get:

[0067]

[0068] In the formula, d is the single-layer curing thickness in μm; h is the characteristic penetration depth in μm; t is the exposure time in s; t T This is the critical curing time, in seconds. For example... Figure 3 To obtain the intersection of light dose and gel point at different exposure time points, the x-coordinate of each intersection point is the theoretical single-layer curing thickness at the current time point.

[0069] The feature penetration depth h gradually increases with exposure time t, and its rate of increase is positively correlated with the initial light intensity I, accelerating gradually during printing, resembling a gentle quadratic curve. Considering engineering applications, a straight line is used to fit it. The experimental data and the fitting function are as follows: Figure 4 As shown.

[0070] The initial characteristic penetration depth H is defined as the starting point of characteristic penetration depth growth (the intersection of the line representing the characteristic penetration depth of the bio-ink and time with the y-axis). Light absorption stability S is introduced to quantify the growth rate of characteristic penetration depth, obtained by linear fitting based on experimental data of characteristic penetration depth measurements of bio-inks. By fitting the characteristic penetration depth versus time curve, the light absorption characteristics of different bio-inks can be analyzed and compared more accurately. The equation can be expressed as:

[0071]

[0072] In the formula, h is the characteristic penetration depth in μm; I is the initial light intensity in mW / cm². 2 S represents light absorption stability, dimensionless; H represents initial characteristic penetration depth, in μm; t represents exposure time, in s.

[0073] Using h(t) instead of h, in Multiplying both the upper and lower parts of the equation by the initial light intensity I, the critical curing time at the bottom of the fraction can be converted into the ink's gel point G. Finally, the single-layer curing thickness is calculated using C. d This means that the predicted curve for the curing thickness of a single layer is obtained:

[0074]

[0075] In the formula C d I represents the thickness of a single-layer cured layer, in μm; I represents the initial light intensity, in mW / cm². 2 t is the exposure time in seconds; S is the light absorption stability (dimensionless); H is the initial characteristic penetration depth in micrometers (μm); G is the gel point in mJ / cm³. 2 .

[0076] Initial light intensity I and exposure time t are used as process parameters affecting the printing effect of the device. Three key photoresponse parameters are also introduced to evaluate the performance of the bio-ink: initial feature penetration depth H, light absorption stability S, and gel point G. By accurately measuring these parameters experimentally, effective control of the cured thickness of the bio-ink can be achieved.

[0077] In the process of demonstrating the process parameters, generally speaking, the longer the exposure time, the thicker the cured layer formed by the photocurable material. Therefore, choosing exposure time as the independent variable in the printing process is beneficial for achieving precise control of the printed layer thickness. The other four parameters are studied as key fixed parameters affecting printing quality. To further analyze the influence of each parameter on the molding effect, in the subsequent experimental design, other parameters will be kept constant, and only the effect of the change of a single variable on the predicted molding curve will be examined. The initial light intensity I is set to 10 mW / cm². 2 The initial characteristic penetration depth H is 300 μm, the light absorption stability S is 100, and the gel point G is 160 mJ / cm. 2 When analyzing the various process parameters, except for the variable under study, all other parameters were kept at the initial set values ​​mentioned above to ensure the consistency and comparability of the experimental conditions.

[0078] The effect of initial light intensity on the predicted curve exhibits a holistic characteristic and shows a decreasing marginal effect. As light intensity increases, the critical curing time gradually decreases, and the curvature of the predicted curve increases accordingly, generally shifting towards the upper left. However, the magnitude of this shift gradually slows down with increasing light intensity. Therefore, under lower light intensity conditions, changes in light intensity have a significant impact on the curing state; while under higher light intensity conditions, its impact on the curing effect tends to be gradual, with limited regulatory effect. At the same exposure time, a linear increase in initial light intensity does not lead to a linear change in the single-layer cured thickness; this theoretical performance of the predicted curve aligns with practical printing experience.

[0079] Furthermore, since the initial light intensity affects curing behavior throughout the entire molding process, achieving precise control of the cured thickness solely by adjusting the initial light intensity is quite difficult and may lead to unpredictable process deviations, thus affecting the final print quality. Therefore, in actual printing, the synergistic effect between the initial light intensity and other process parameters should be comprehensively considered to achieve more stable and controllable printing results. The influence of initial light intensity on the predicted curve is as follows: Figure 5 As shown.

[0080] The initial characteristic penetration depth is the penetration depth corresponding to when the light intensity decays along the depth direction of the material to 1 / e (approximately 36.8%) of its initial value. It reflects the light absorption capacity of bio-inks before light attenuation occurs and is mainly determined by the concentration of the light absorber, making it an important indicator for evaluating the light absorption performance of inks. The initial characteristic penetration depth has good controllability over the single-layer cured thickness and has relatively little impact on the critical curing time and the curvature of the prediction curve. Under the same exposure time conditions, the initial characteristic penetration depth exhibits a linear trend, and the corresponding single-layer cured thickness also shows a basically linear trend.

[0081] The initial characteristic penetration depth is easy to measure and has a clear physical meaning. This parameter can be measured layer by layer along the sample depth direction using a light intensity detector. Experiments show that this parameter depends only on the composition of the bio-ink itself, particularly the concentration of the light absorber, and is not affected by the initial light intensity. Regardless of changes in the initial light intensity, the initial characteristic penetration depth remains constant, exhibiting good parameter stability. In practical applications, pre-calibrating the initial characteristic penetration depth of different ink formulations helps to achieve precise control of the curing depth, improving the geometric accuracy and consistency of the printed structure. The effect of the initial characteristic penetration depth on the prediction curve is as follows: Figure 6 As shown.

[0082] Light absorption stability is a dimensionless parameter used to describe the rate of change of the characteristic penetration depth of bio-inks during exposure. It aims to eliminate the influence of different initial light intensities, thereby achieving a unified characterization of material degradation behavior. A higher light absorption stability value indicates a stronger ability of the bio-ink to maintain its light absorption capacity under continuous illumination. Notably, the change in characteristic penetration depth during exposure exhibits an exponential trend.

[0083] As light absorption stability decreases, the curve of cured thickness versus exposure time gradually approaches a straight line, with an increasing slope. This printing phenomenon is very common in photopolymer bioprinting and is consistent with experience. Under higher light absorption stability conditions, the trend of the predicted curve gradually converges with the classic Jacobs working curve, indicating that the curing behavior at this point is close to the ideal photopolymerization model. This stage reflects the behavior exhibited by commercially available resin photopolymerization. Furthermore, light absorption stability primarily affects the overall shape and curvature of the predicted curve, without affecting the critical curing time; that is, it does not change the minimum energy threshold required for the material to begin forming a stable cured structure. The influence of light absorption stability on the predicted curve is as follows: Figure 7 As shown.

[0084] The gel point is the energy density required for bio-ink to transform from a liquid to a semi-solid gel state. This parameter reflects the minimum energy threshold for effective cross-linking and structure formation in the material. The gel point mainly depends on the chemical composition of the bio-ink, particularly the type and concentration of the photoinitiator and the reactivity of the prepolymer, and is not directly affected by external exposure conditions such as initial light intensity. Under the same material system, the gel point exhibits good repeatability and measurability.

[0085] As the gel point value increases, the cumulative exposure energy required for the material to complete gelation increases accordingly, leading to a prolonged critical curing time and a downward shift in the predicted curve to the right. This shift is approximately linearly related to the change in gel point. However, the change in gel point has a relatively small impact on the curve curvature, indicating that the gel point does not significantly alter the curing rate or nonlinear response behavior of the material after exceeding the gel point. Therefore, in process control, the gel point can be used as an effective parameter for adjusting the curing initiation conditions, but its impact on the dynamic trend of single-layer cured thickness increasing with exposure time is limited. The effect of gel point on the predicted curve is as follows: Figure 8 As shown.

[0086] In DLP-based photopolymerization bioprinting, mismatches between device parameters (such as excessively high initial light intensity I and excessively long exposure time t) and ink parameters (such as light absorption stability S, feature penetration depth H, and incorrect gel point estimation G) can lead to excessive or uncontrolled light energy input, causing premature or over-curing of non-target areas. This problem is particularly prominent in microchannels and fine structures, such as... Figure 9As shown. This clogging phenomenon can be categorized into slight, mild, moderate, and complete clogging based on severity: Slight clogging results in a slight distortion of the microchannel shape, exhibiting a noticeable arc-shaped contour; mild clogging manifests as dimensional inaccuracies in the microchannels, no longer meeting design requirements and increasing flow resistance; moderate clogging refers to the over-cured portion occupying half of the microchannel cavity, causing hydrogel structure distortion, impaired fluid flow, and severely affecting the geometric consistency of the printed structure; complete clogging occurs when the photocuring reaction continues to expand within the channel, ultimately leading to complete blockage of the microchannel, completely blocking the microchannel and causing printing failure. The various clogging scenarios are shown below. Figure 10 As shown.

[0087] By employing the method of this invention, non-target photopolymerization reactions are effectively suppressed, the over-curing clogging problem is significantly alleviated, and printing accuracy is greatly improved, such as... Figure 11 As shown. Figure 11 (a) The 1000μm flow channel printing results show that the micro-channels did not exhibit over-curing, had sharp edges, and maintained unobstructed flow, significantly improving the dimensional accuracy of the molded channels. Dimensional deviations were reduced from over 30% using traditional methods to less than 10%. Meanwhile, as shown in... Figure 11 (b) and Figure 11 As shown in (c), the minimum achievable stable printing square hole feature size is reduced to 200 μm, and the minimum achievable stable printing vertical height feature size is reduced to 100 μm. Using the method of the present invention, it is possible to reliably manufacture three-dimensional microscale flow channels with high resolution and structural fidelity.

[0088] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for predicting the single-layer curing thickness of DLP bio-3D printing ink, characterized in that: The single-layer curing thickness of the DLP bio-3D printing ink is calculated using formula (1): Among them, C d I represents the single-layer cured thickness of the DLP bio-3D printing ink, in μm; I represents the initial light intensity, in mW / cm². 2 t represents exposure time in seconds; S represents light absorption stability, which is the reciprocal of the rate of change of the characteristic penetration depth in the DLP bio-3D printing ink over time, and is dimensionless; H represents the initial characteristic penetration depth in μm, which is the penetration depth corresponding to when the light intensity at the beginning of exposure decays along the depth direction of the material to 1 / e (approximately 36.8%) of the initial value; G represents the gel point in mJ / cm. 2 ; The gel point is calculated using equation (2): G=It T (2); In the formula, I represents the initial light intensity, in mW / cm². 2 ;t T The critical curing time of DLP bio-3D printing ink, measured in seconds, is the time from the start of irradiation to the start of curing of the bio-ink.

2. The method for predicting the single-layer curing thickness of a DLP bio-3D printing ink according to claim 1, characterized in that: The light absorption stability was obtained by linear fitting based on experimental data of characteristic penetration depth measurements of bio-ink.

3. The method for predicting the single-layer curing thickness of a DLP bio-3D printing ink according to claim 1, characterized in that: The initial feature penetration depth is the value of the intersection of the line representing the feature penetration depth of the bio-ink versus time and the y-axis.

4. A method for predicting the single-layer curing thickness of a DLP bio-3D printing ink according to any one of claims 1 to 3, characterized in that: The bio-ink contains the following components and concentrations: 10-20 w / v of polyethylene glycol diacrylate with a molecular weight of 1 kDa, 0.1-0.5 w / v of lithium phenyl-2,4,6-trimethylbenzoyl phosphate, and 0.05-0.2 w / v of tartrazine.

5. The method for predicting the single-layer curing thickness of a DLP bio-3D printing ink according to claim 3, characterized in that: The bio-ink contains the following components and concentrations: 15 w / v of polyethylene glycol diacrylate with a molecular weight of 1 kDa, 0.25 w / v of lithium phenyl-2,4,6-trimethylbenzoyl phosphate, and 0.1 w / v of tartrazine.

6. The method for predicting the single-layer curing thickness of a DLP bio-3D printing ink according to claim 5, characterized in that: The initial characteristic penetration depth H is 300 μm, the light absorption stability S is 100, and the gel point G is 160 mJ / cm. 2 .

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