# US 12,109,329 B2 · Digital light four-dimensional printing of programmable morphology and motion structures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,109,329 B2 - Document ID: US12109329B2 - Status: Granted - Kind: B2 - Application number: 17/055,798 - Filed: 2019-05-23 - Published: 2021-07-29 - Granted: 2024-10-08 - Earliest claimed: 2018-05-23 - Assignees: Board of Regents, The University of Texas System - Applicants: Board of Regents, The University of Texas System - Inventors: Kyung Suk Yum; Amirali Nojoomi - Web page: https://patentgrep.com/patent/US12109329B2 ## CPC - A61L 27/52: Hydrogels or hydrocolloids - C08J 3/075: Macromolecular gels - B33Y 10/00: Processes of additive manufacturing - B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor - B33Y 40/20: Post-treatment, e.g. curing, coating or polishing - C08J 3/24: Crosslinking, e.g. vulcanising, of macromolecules (mechanical aspects B29C35/00; crosslinking agents C08K) - C08J 3/28: Treatment by wave energy or particle radiation - B33Y 70/10: Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials - C08J 2333/26: Homopolymers or copolymers of acrylamide or methacrylamide - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING ## Abstract The approach described herein uses the spatially and temporally controlled growth for programming 3D shapes and their motions, possibly with an unlimited number of degrees of freedom, could thus create dynamic 3D structures. The ability to program growth-induced 3D shapes and motions could transform the way engineering systems, such as robots, actuators, and artificial muscles, are designed. The concept is applicable to other programmable materials. The 2D printing approach for 3D material programming represents a scalable and customizable 3D manufacturing technology, which can potentially be integrated with biological systems and existing 2D fabrication methods and devices for broader applications. ## Claims ### Claim 1 A method of forming hydrogel structures with programmed 3D shapes, comprising: preparing a precursor solution; introducing the precursor solution into a cell; exposing the precursor solution in the cell with light; spatially and temporally controlling the exposure of the precursor solution using dynamic light projection grayscale lithography and a growth function or a growth pattern that can induce a target 3D structure and motion to form a hydrogel structure from the precursor solution that comprises continuously varying, spatially controlled compositions and material properties; and shape-morphing the hydrogel structure to form a prescribed shape by heating or cooling the hydrogel structure. ### Claim 2 (depends on 1) The method of claim 1, wherein the precursor solution comprises a solution comprising monomers, two or more cross linkers with different chain lengths, at least one photoinitiator, and at least one solvent. ### Claim 3 (depends on 1) The method of claim 1, wherein the precursor solution comprises a solution of N-isopropylacrylamide (NIPAm), N,N′-methylene bisacrylamide (BIS), poly(ethylene glycol) diacrylate (PEGDA), diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, water, and acetone. ### Claim 4 (depends on 1) The method of claim 1, wherein spatially and temporally controlling exposure of the precursor solution using the dynamic light projection grayscale lithography forms the hydrogel structure with spatially controlled material properties, including degrees and rates of swelling and shrinking, described by a growth function or a growth pattern. ### Claim 5 (depends on 1) The method of claim 1, wherein: the precursor solution comprises a solution of N-isopropylacrylamide (NIPAm), N,N′-methylene bisacrylamide (BIS), and poly(ethylene glycol) diacrylate (PEGDA); and spatially and temporally controlling exposure of the precursor solution using the dynamic light projection grayscale lithography forms a hydrogel structure with continuously varying, spatially controlled compositions and material properties, including degrees and rates of swelling and shrinking, using a growth function or a growth pattern. ### Claim 6 (depends on 1) The method of claim 1, further comprising generating calibration curves of areal swelling and shrinking ratios versus light exposure time to convert a growth function or a growth pattern into a spatially controlled light exposure time. ### Claim 7 (depends on 1) The method of claim 1, wherein the cell comprises a substrate with a spacer formed of polydimethylsiloxane (PDMS). ### Claim 8 (depends on 1) The method of claim 1, further comprising, before introducing the precursor solution into the cell, purging the solution with nitrogen to reduce the effect of oxygen on photopolymerization of the precursor solution. ### Claim 9 A method of forming hydrogel structures with programmed 3D shapes, comprising: generating calibration curves of areal swelling and shrinking ratios versus light exposure time to convert a growth function or a growth pattern into a spatially controlled light exposure time; preparing a precursor solution; introducing the precursor solution into a cell; exposing the precursor solution in the cell with light; spatially and temporally controlling the exposure of the precursor solution using the generated calibration curves to form a hydrogel structure from the precursor solution that comprises continuously varying, spatially controlled compositions and material properties; and shape-morphing the hydrogel structure to form a prescribed shape by heating or cooling the hydrogel structure. ### Claim 10 A method of forming hydrogel structures with programmed 3D shapes, comprising: preparing a precursor solution; introducing the precursor solution into a cell; exposing the precursor solution in the cell with light; and spatially and temporally controlling the exposure of the precursor solution using dynamic light projection grayscale lithography and a growth function or a growth pattern that can induce a target 3D structure to form a hydrogel structure from the precursor solution that comprises continuously varying, spatially controlled compositions and material properties. ### Claim 11 (depends on 10) The method of claim 10, wherein the growth function or growth pattern can further induce a target motion. ### Claim 12 (depends on 11) The method of claim 11, wherein the hydrogel structure can morph to form prescribed shapes when heated or cooled. ### Claim 13 (depends on 10) The method of claim 10, wherein the precursor solution comprises a solution comprising monomers, two or more cross linkers with different chain lengths, at least one photoinitiator, and at least one solvent. ### Claim 14 (depends on 10) The method of claim 10, wherein the precursor solution comprises a solution of N-isopropylacrylamide (NIPAm), N,N′-methylene bisacrylamide (BIS), and poly(ethylene glycol) diacrylate (PEGDA). ### Claim 15 (depends on 10) The method of claim 10, wherein spatially and temporally controlling exposure of the precursor solution provides the hydrogel structure with spatially controlled degrees and rates of swelling and shrinking, described by the growth function or growth pattern.