US-12623408-B2 - Stereolithography with micron scale control of properties

US12623408B2US 12623408 B2US12623408 B2US 12623408B2US-12623408-B2

Abstract

Stereolithography with micron scale control of properties is described herein. In one aspect, a computer-implemented method for 3-D printing of a material can include generating a functional relation predicting one or more physical properties of the material resulting from printing parameters; algebraically or numerically solving the functional relation to generate a second functional relation predicting expected printing parameters resulting in the one or more physical properties; and printing the material via a photopolymerization printer according to the set of printing parameters determined by the second functional relation.

Inventors

Robert R. McLeod
Asais Camila Uzcategui
John Elliott Hergert
Archish Muralidharan

Assignees

THE REGENTS OF THE UNIVERSITY OF COLORADO, A BODY CORPORATE

Dates

Publication Date: 20260512
Application Date: 20210114

Claims (12)

1 . A computer-implemented method for 3-dimensional (3-D) printing of a material, the method comprising: generating a functional relation predicting one or more physical properties of the material resulting from printing parameters, wherein the one or more physical properties of the material is selected from the group consisting of a cross link density, a swellability, a Young's modulus, a diffusivity coefficient, a shear modulus, a stiffness factor, a viscoelasticity factor, and a coefficient of friction; algebraically or numerically inverting the functional relation to generate a second functional relation; determining a set of printing parameters from the second functional relation; and printing the material having the one or more physical properties via a vat photopolymerization printer according to the set of determined printing parameters.
2 . The computer-implemented method of claim 1 , wherein the printing is further implemented according to a printing pattern on the micron scale.
3 . The computer-implemented method of claim 1 , wherein generating the functional relation further comprises: measuring or calculating a physical property of the material as a function of exposure time, post-exposure time, and light intensity; identifying an equation to model the measurements or calculations which include a number of unknown parameters; and fitting the measurements or calculations to the model to estimate values of the unknown parameters.
4 . The computer-implemented method of claim 3 , wherein the equation for modeling the physical property of the material comprises: C p = x 3 + ax + b x 3 + cx + d where a, b, c, and d are fitting parameters, and x is a variable of the exposure time, post-exposure time, and light intensity.
5 . The computer-implemented method of claim 1 , wherein the set of printing parameters comprises at least one of a layer thickness, an energy dose, an optical intensity, an exposure time, and a cure depth.
6 . The computer-implemented method of claim 1 , wherein the vat photopolymerization printer is a stereolithography (SLA) printer or a digital light processing (DLP) printer.
7 . The computer-implemented method of claim 1 , wherein printing the material comprises printing multiple layers of the material.
8 . The computer-implemented method of claim 1 , wherein the material originates from a single vat of precursor solution or resin of the printer.
9 . The computer-implemented method of claim 1 , wherein printing the material results in a functionally graded material (FGM).
10 . A non-transitory computer-readable medium including instructions executable by a processor for printing a material, the instructions comprising: generating a functional relation predicting one or more physical properties of the material resulting from printing parameters, wherein the one or more physical properties of the material is selected from the group consisting of a cross link density, a swellability, a Young's modulus, a diffusivity coefficient, a shear modulus, a stiffness factor, a viscoelasticity factor, and a coefficient of friction; algebraically or numerically inverting the functional relation to generate a second functional relation; determining a set of printing parameters from the second functional relation; and printing the material having the one or more physical properties via a vat photopolymerization printer according to the set of determined printing parameters.
11 . The non-transitory computer-readable medium of claim 10 , wherein the printing is further implemented according to a printing pattern on the micron scale.
12 . The non-transitory computer-readable medium of claim 10 , wherein generating the functional relation further comprises: measuring or calculating a physical property of the material as a function of exposure time, post-exposure time, and light intensity; identifying an equation to model the measurements or calculations which include a number of unknown parameters; and fitting the measurements or calculations to the model to estimate values of the unknown parameters.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 U.S.C. § 119 (e) to U.S. Provisional Patent Application No. 62/960,956, filed Jan. 14, 2020, the contents of which is incorporated herein by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made with government support under 1R01AR069060 and 1R21HD090696 awarded by the National Institutes of Health and under 1826454 awarded by the National Science Foundation. The government has certain rights in the invention. BACKGROUND OF THE INVENTION 3D printing is transforming traditional processing methods for applications ranging from tissue engineering to optics. To fulfill its maximum potential, 3D printing requires a robust technique for producing structures with precise three-dimensional (x, y, and z) control of mechanical properties. Previous efforts to realize such spatial control of modulus within 3D printed parts have largely focused on low-resolution (mm to cm scale) multi-material processes and grayscale approaches that spatially vary the modulus in the x-y plane and energy dose-based (E)=I0 texp) models that do not account for the resin's sub-linear response to irradiation intensity. 3D printing creates complex, highly customized architectures with applications in tissue engineering, soft robotics, optics and metamaterials. Today, the elastic moduli of materials used for 3D printing vary from 10 s of kPa in polymers to 100 s of GPa in metals. However, the material properties resulting from most 3D printing methods are limited to a single property value or multiple discrete property values with limited control of spatial gradients. One of the pitfalls in the adoption of 3D printing for operational part fabrication is the lack of mechanical performance and the susceptibility of the structures to fail as compared to traditionally-manufactured analogues. There is a need in the art for precise control of the mechanical, electrical, and/or biological properties of a 3D printed material. The present disclosure addresses this unmet need. BRIEF SUMMARY Stereolithography with micron scale control of properties is described herein. In one aspect, a computer-implemented method for 3-D printing of a material can include generating a functional relation predicting one or more physical properties of the material resulting from printing parameters; algebraically or numerically solving the functional relation to generate a second functional relation predicting expected printing parameters resulting in the one or more physical properties; and printing the material via a photopolymerization printer according to the set of printing parameters determined by the second functional relation. This aspect can include a variety of embodiments. In certain embodiments, the printing is further implemented according to a printing pattern on the micronscale. In some cases, the printing pattern includes a smooth gradation in modulus of 30 MPa change over 75 μm, a step change in modulus of 30 MPa change over 5 μm, and/or both. In other embodiments, the generating the functional relation includes measuring or calculating a physical property of the material as a function of exposure time, post-exposure time, and light intensity; identifying an equation to model the measurements or calculations which include a number of unknown parameters; and fitting the measurements or calculations to the model to estimate values of the unknown parameters. In some cases, the equation for characterizing the material property can include Cp=x3+ax+bx3+cx+d,where a, b, c, and d are fitting parameters, and x is a variable of scaled light intensity, time, and effective exposure. In other embodiments, the one or more physical properties of the material includes at least one of a monomer-to-polymer conversion, a cross link density, a swellability, a Young's modulus, a diffusivity coefficient, a shear modulus, a stiffness factor, a viscoelasticity factor, a coefficient of friction, or a combination thereof. In other embodiments, the set of printing parameters includes at least one of a layer thickness, an energy dose, an exposure time, an optical intensity, a cure depth, or a combination thereof. In other embodiments, the polymerization printer comprises a stereolithography (SLA) printer or a digital light processing (DLP) printer. In other embodiments, the printing the material comprises printing multiple layers of the material. In other embodiments, the printing the material results in a functionally graded material (FGM). Another aspect of the present disclosure includes a composition produced by the steps of printing a plurality of layers of a 3-D printed material via a photopolymerization printer according to a gradient design on the micronscale. Another aspect of the present disclosure is a photopolymerized 3-D printed material comprising a preselected gradient design on the micronscale. These aspects can include a variety of embodime