{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/18431"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/18431","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Direct ink writing of microvascular networks","abstract":"Nature is replete with examples of embedded microvascular systems that enable efficient fluid flow and distribution for autonomic healing, cooling, and energy harvesting. The ability to incorporate microvascular networks in functional materials systems is therefore both scientifically and technologically important. In this PhD thesis, the direct-write assembly of planar and 3D biomimetic microvascular networks within polymer and hydrogel matrices is demonstrated. In addition, the influence of network design of fluid transport efficiency is characterized. Planar microvascular networks composed of periodic lattices of uniformal microchannels and hierarchical, branching architectures are constructed by direct-write assembly of a fugitive organic ink. Several advancements are required to facilitate their patterning, including pressure valving, dual ink printing, and dynamic pressure variation to allow tunable control of ink deposition. The hydraulic conductance is measured using a high pressure flow meter as a function of network design. For a constant vascular volume and areal coverage, 2- and 4-generation branched architectures that obey Murray's Law exhibited the highest hydraulic conductivity. These experimental observations are in good agreement with predictions made by analytic models. 3D microvascular networks are fabricated by omnidirectional printing a fugitive organic ink into a photopolymerizable hydrogel matrix that is capped with fluid filler of nearly identical composition. Using this approach, 3D networks of arbitrary design can be patterned. After ink deposition is complete, the matrix and fluid filler are chemically cross-linked via UV irradiation, and the ink is removed by liquefication. Aqueous solutions composed of a triblock copolymer of polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO constitute the materials system of choice due to their thermal- and concentration-dependent phase behavior. Specifically, the fugitive ink consists of a 23 w/w% PEO-PPO-PEO (Pluronic F127) solution, while matrix (25 w/w%) and fluid filler (20 w/w%) are composed of an acrylate-modified form of the Pluronic F127 that can be subsequently photopolymerized. The ink and matrix concentrations exceed the critical micelle concentration (CMC) of 22 w/w% and thus reside in a physical gel state. At their respective concentrations, they possess an elastic plateau modulus G' > 104 Pa needed for ink filament formation, shape retention, and support during the printing process. By contrast, the fluid filler is formulated below the CMC to facilitate its flow into void spaces created as the nozzle translates through the matrix during printing. After printing is completed, photopolymerization is carried out to yield a chemically cross-linked matrix from which the fugitive ink is removed leaving behind the desired 3D microvascular network. Due to the potential application of 3D microvasularized hydrogels in tissue engineering, dye diffusion through the cured Pluronic F127-diacrylate matrix is investigated via fluorescent microscopy. Image analysis is used to extract diffusion profiles of the dye as a function of time. Extraction of the 1-D Gaussian fitting parameters is used to determine the spatial peak variance 2 and plotted as a function of time to determine the dye diffusivity.","abstract_html":"Nature is replete with examples of embedded microvascular systems that enable efficient fluid flow and distribution for autonomic healing, cooling, and energy harvesting. The ability to incorporate microvascular networks in functional materials systems is therefore both scientifically and technologically important. In this PhD thesis, the direct-write assembly of planar and 3D biomimetic microvascular networks within polymer and hydrogel matrices is demonstrated. In addition, the influence of network design of fluid transport efficiency is characterized. Planar microvascular networks composed of periodic lattices of uniformal microchannels and hierarchical, branching architectures are constructed by direct-write assembly of a fugitive organic ink. Several advancements are required to facilitate their patterning, including pressure valving, dual ink printing, and dynamic pressure variation to allow tunable control of ink deposition. The hydraulic conductance is measured using a high pressure flow meter as a function of network design. For a constant vascular volume and areal coverage, 2- and 4-generation branched architectures that obey Murray's Law exhibited the highest hydraulic conductivity. These experimental observations are in good agreement with predictions made by analytic models. 3D microvascular networks are fabricated by omnidirectional printing a fugitive organic ink into a photopolymerizable hydrogel matrix that is capped with fluid filler of nearly identical composition. Using this approach, 3D networks of arbitrary design can be patterned. After ink deposition is complete, the matrix and fluid filler are chemically cross-linked via UV irradiation, and the ink is removed by liquefication. Aqueous solutions composed of a triblock copolymer of polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO constitute the materials system of choice due to their thermal- and concentration-dependent phase behavior. Specifically, the fugitive ink consists of a 23 w/w% PEO-PPO-PEO (Pluronic F127) solution, while matrix (25 w/w%) and fluid filler (20 w/w%) are composed of an acrylate-modified form of the Pluronic F127 that can be subsequently photopolymerized. The ink and matrix concentrations exceed the critical micelle concentration (CMC) of 22 w/w% and thus reside in a physical gel state. At their respective concentrations, they possess an elastic plateau modulus G' > 104 Pa needed for ink filament formation, shape retention, and support during the printing process. By contrast, the fluid filler is formulated below the CMC to facilitate its flow into void spaces created as the nozzle translates through the matrix during printing. After printing is completed, photopolymerization is carried out to yield a chemically cross-linked matrix from which the fugitive ink is removed leaving behind the desired 3D microvascular network. Due to the potential application of 3D microvasularized hydrogels in tissue engineering, dye diffusion through the cured Pluronic F127-diacrylate matrix is investigated via fluorescent microscopy. Image analysis is used to extract diffusion profiles of the dye as a function of time. Extraction of the 1-D Gaussian fitting parameters is used to determine the spatial peak variance 2 and plotted as a function of time to determine the dye diffusivity.","abstract_has_math":false,"creators":["Wu, Willie"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science & Engr","degree_department":null,"school":null,"contributors":["Lewis, Jennifer A.","White, Scott R.","Sottos, Nancy R.","Braun, Paul V."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-01-14T22:50:40Z","date_published":"2011-01-14T22:50:40Z","updated_at":"2026-07-22T22:25:11Z","subjects":["Microvascular Networks","Direct Ink Writing","Biomimetic"],"languages":["en"],"rights":["Copyright 2010 Willie Wu"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/18431","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lewis, Jennifer A.","White, Scott R.","Sottos, Nancy R.","Braun, Paul V."]},{"key":"dc:creator","label":"Author","values":["Wu, Willie"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-01-14T22:50:40Z","2010-12"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science & Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Microvascular Networks","Direct Ink Writing","Biomimetic"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2010 Willie Wu"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/18431"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Nature is replete with examples of embedded microvascular systems that enable efficient fluid flow and distribution for autonomic healing, cooling, and energy harvesting. The ability to incorporate microvascular networks in functional materials systems is therefore both scientifically and technologically important. In this PhD thesis, the direct-write assembly of planar and 3D biomimetic microvascular networks within polymer and hydrogel matrices is demonstrated. In addition, the influence of network design of fluid transport efficiency is characterized. Planar microvascular networks composed of periodic lattices of uniformal microchannels and hierarchical, branching architectures are constructed by direct-write assembly of a fugitive organic ink. Several advancements are required to facilitate their patterning, including pressure valving, dual ink printing, and dynamic pressure variation to allow tunable control of ink deposition. The hydraulic conductance is measured using a high pressure flow meter as a function of network design. For a constant vascular volume and areal coverage, 2- and 4-generation branched architectures that obey Murray's Law exhibited the highest hydraulic conductivity. These experimental observations are in good agreement with predictions made by analytic models. 3D microvascular networks are fabricated by omnidirectional printing a fugitive organic ink into a photopolymerizable hydrogel matrix that is capped with fluid filler of nearly identical composition. Using this approach, 3D networks of arbitrary design can be patterned. After ink deposition is complete, the matrix and fluid filler are chemically cross-linked via UV irradiation, and the ink is removed by liquefication. Aqueous solutions composed of a triblock copolymer of polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO constitute the materials system of choice due to their thermal- and concentration-dependent phase behavior. Specifically, the fugitive ink consists of a 23 w/w% PEO-PPO-PEO (Pluronic F127) solution, while matrix (25 w/w%) and fluid filler (20 w/w%) are composed of an acrylate-modified form of the Pluronic F127 that can be subsequently photopolymerized. The ink and matrix concentrations exceed the critical micelle concentration (CMC) of 22 w/w% and thus reside in a physical gel state. At their respective concentrations, they possess an elastic plateau modulus G' > 104 Pa needed for ink filament formation, shape retention, and support during the printing process. By contrast, the fluid filler is formulated below the CMC to facilitate its flow into void spaces created as the nozzle translates through the matrix during printing. After printing is completed, photopolymerization is carried out to yield a chemically cross-linked matrix from which the fugitive ink is removed leaving behind the desired 3D microvascular network. Due to the potential application of 3D microvasularized hydrogels in tissue engineering, dye diffusion through the cured Pluronic F127-diacrylate matrix is investigated via fluorescent microscopy. Image analysis is used to extract diffusion profiles of the dye as a function of time. Extraction of the 1-D Gaussian fitting parameters is used to determine the spatial peak variance 2 and plotted as a function of time to determine the dye diffusivity.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2010-11-05T18:02:43Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Wu_Willie.docx: 39948033 bytes, checksum: c119d2a82c5e9863e53c5812a68b9297 (MD5) Wu_Willie.pdf: 4391072 bytes, checksum: 419056bf6e73593cf304557f155b1237 (MD5)","Made available in DSpace on 2011-01-14T22:50:40Z (GMT). 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In this PhD thesis, the direct-write assembly of planar and 3D biomimetic microvascular networks within polymer and hydrogel matrices is demonstrated. In addition, the influence of network design of fluid transport efficiency is characterized. Planar microvascular networks composed of periodic lattices of uniformal microchannels and hierarchical, branching architectures are constructed by direct-write assembly of a fugitive organic ink. Several advancements are required to facilitate their patterning, including pressure valving, dual ink printing, and dynamic pressure variation to allow tunable control of ink deposition. The hydraulic conductance is measured using a high pressure flow meter as a function of network design. For a constant vascular volume and areal coverage, 2- and 4-generation branched architectures that obey Murray's Law exhibited the highest hydraulic conductivity. These experimental observations are in good agreement with predictions made by analytic models. 3D microvascular networks are fabricated by omnidirectional printing a fugitive organic ink into a photopolymerizable hydrogel matrix that is capped with fluid filler of nearly identical composition. Using this approach, 3D networks of arbitrary design can be patterned. After ink deposition is complete, the matrix and fluid filler are chemically cross-linked via UV irradiation, and the ink is removed by liquefication. Aqueous solutions composed of a triblock copolymer of polyethylene oxide (PEO)-polypropylene oxide (PPO)-PEO constitute the materials system of choice due to their thermal- and concentration-dependent phase behavior. Specifically, the fugitive ink consists of a 23 w/w% PEO-PPO-PEO (Pluronic F127) solution, while matrix (25 w/w%) and fluid filler (20 w/w%) are composed of an acrylate-modified form of the Pluronic F127 that can be subsequently photopolymerized. The ink and matrix concentrations exceed the critical micelle concentration (CMC) of 22 w/w% and thus reside in a physical gel state. At their respective concentrations, they possess an elastic plateau modulus G' > 104 Pa needed for ink filament formation, shape retention, and support during the printing process. By contrast, the fluid filler is formulated below the CMC to facilitate its flow into void spaces created as the nozzle translates through the matrix during printing. After printing is completed, photopolymerization is carried out to yield a chemically cross-linked matrix from which the fugitive ink is removed leaving behind the desired 3D microvascular network. Due to the potential application of 3D microvasularized hydrogels in tissue engineering, dye diffusion through the cured Pluronic F127-diacrylate matrix is investigated via fluorescent microscopy. Image analysis is used to extract diffusion profiles of the dye as a function of time. Extraction of the 1-D Gaussian fitting parameters is used to determine the spatial peak variance 2 and plotted as a function of time to determine the dye diffusivity.","Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2010-11-05T18:02:43Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Wu_Willie.docx: 39948033 bytes, checksum: c119d2a82c5e9863e53c5812a68b9297 (MD5) Wu_Willie.pdf: 4391072 bytes, checksum: 419056bf6e73593cf304557f155b1237 (MD5)","Made available in DSpace on 2011-01-14T22:50:40Z (GMT). No. of bitstreams: 4 Wu_Willie.pdf: 4391391 bytes, checksum: a586b8594c79e7c5bd60beca41a40cfa (MD5) license.txt: 4059 bytes, checksum: 179536d7d1934ead485180d341e1fc3a (MD5) Wu_Willie.docx: 39948316 bytes, checksum: 151008e8063b6de3526ec35f13b337b9 (MD5) 1_Wu_Willie.docx: 39948316 bytes, checksum: 151008e8063b6de3526ec35f13b337b9 (MD5)"],"dc:identifier":["http://hdl.handle.net/2142/18431"],"dc:language":["en"],"dc:rights":["Copyright 2010 Willie Wu"],"dc:subject":["Microvascular Networks","Direct Ink Writing","Biomimetic"],"dc:title":["Direct ink writing of microvascular networks"],"thesis:degree_discipline":["Materials Science & Engr"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:11Z"}