Microstructure biomaterials and fabrication methods therefor

{
  "publication_number": "US9631171B2",
  "country": "US",
  "kind": "B2",
  "title": "Microstructure biomaterials and fabrication methods therefor",
  "abstract": "Methods and systems for fabricating a micro-structured biomaterial include printing a three-dimensional structure using polymerizing radiation modulated by a digital micromirror array to project microstructure patterns into a pre-polymer material to form one or more porous scaffold sheets. The microstructure patterns have a unit-cell geometry that exhibits a negative Poisson ratio that is tunable in magnitude.",
  "claims": [
    "1. A method of fabricating a microstructure biomaterial scaffold comprising: (a) designing two-dimensional graphics models of scaffold layers; (b) generating virtual photomasks of the scaffold layers using the designed two-dimensional graphics model; and (c) patterning and fabricating each of the scaffold layers using the generated virtual photomasks, wherein at least one of the scaffold layers is a microstructure hybrid layer with a first portion of the microstructure hybrid layer comprising a unit-cell geometry having a negative Poisson ratio and a second portion of the microstructure hybrid layer comprising a unit-cell geometry having a positive Poisson ratio.",
    "2. The method of claim 1, wherein the scaffold layers comprise porous layers.",
    "3. The method of claim 2, wherein the Poisson ratio is tuned by controlling pore geometry of each scaffold layer.",
    "4. The method of claim 2, wherein each scaffold layer is stacked above or below each other and connected by vertical connecting posts.",
    "5. The method of claim 1, wherein each scaffold layer is stacked above or below each other and connected by vertical connecting posts.",
    "6. A method for fabricating a microstructure biomaterial scaffold comprising: disposing a transparent plate above a servo stage to define a gap; injecting a photo-curable polymer into the gap; modulating light having a wavelength suitable for curing the photo-curable polymer using a digital micro-mirror array, wherein the digital micro-mirror array is controlled by a plurality of virtual software masks for defining a microstructure pattern; focusing modulated light onto a plane below the transparent plate to cure the photo-curable polymer within the plane with the microstructure pattern; and removing uncured polymer to reveal a microstructure hybrid layer having the microstructure pattern, wherein at least a first portion of the microstructure hybrid layer comprises a unit-cell geometry having a negative Poisson ratio, and wherein a second portion of the microstructure hybrid layer comprises a second unit-cell geometry having a positive Poisson ratio.",
    "7. The method of claim 6, wherein the unit-cell geometry comprises a reentrant honeycomb model.",
    "8. The method of claim 6, wherein the unit-cell geometry comprises a cut missing rib model.",
    "9. The method of claim 6, further comprising; after removing uncured polymer: lowering the servo stage to define a second gap; repeating the steps of injecting, modulating, focusing, and removing and thereby defining a second microstructure hybrid layer having a second microstructure pattern on top of the microstructure hybrid layer.",
    "10. The method of claim 9, wherein the second microstructure layer comprises a plurality of vertical posts, and further comprising repeating the steps of injecting, modulating, focusing, and removing to define a third microstructure layer having a third microstructure pattern on top of the vertical posts.",
    "11. The method of claim 10, further comprising: injecting a sacrificial material into the second gap before repeating the steps of injecting, modulating, focusing, and removing; and after the removing step, removing the sacrificial material to reveal a multi-layered microstructure.",
    "12. The method of claim 9, wherein the step of focusing further comprises translating the servo stage in an x-y direction to cure with the microstructure pattern the photo-curable polymer within one or more adjacent areas, whereby a plurality of areas are stitched together to produce a scaffold.",
    "13. The method of claim 9, further comprising: injecting a sacrificial material into the second gap before repeating the steps of injecting, modulating, focusing, and removing; and after the removing step, removing the sacrificial material to reveal a multi-layered microstructure.",
    "14. The method of claim 6, wherein the second unit-cell geometry comprises an intact rib model.",
    "15. The method of claim 12, wherein the scaffold has a Poisson ratio tuned by controlling unit-cell geometry of each area.",
    "16. The method of claim 6, wherein the unit-cell geometry is a reentrant six-sided honeycomb having four side angles between ribs, and wherein the negative Poisson ratio is tuned by changing one or more of the side angles and lengths of the ribs.",
    "17. The method of claim 6, wherein the unit-cell geometry is a reentrant honeycomb having four side angles between ribs, and wherein the negative Poisson ratio is tuned by changing a direction of loading relative to an orientation of the unit-cell."
  ],
  "description_excerpt": "This invention relates to devices, techniques and material related to micro-structured biomaterials, and more particularly relates to auxetic micro-structured biomaterials, methods to fabricate these biomaterials and uses of these materials.\n\nTissue engineering has been defined as an interdisciplinary field that applies the principles of engineering and life sciences toward the development of biological substitutes that restore, maintain, or improve tissue function. Three general strategies are employed in tissue engineering: use of isolated cells or cell substitutes, use of tissue-inducing substances, and use of cells placed on or within matrices.\n\nCells are often implanted or ‘seeded’ into an artificial structure capable of supporting three-dimensional tissue formation. These structures, typically called “scaffolds”, are often critical, both ex vivo as well as in vivo, to allowing cells to influence their own microenvironments. Scaffolds serve one or more of the following purposes: allow cell attachment and migration; deliver and retain cells and biochemical factors; enable diffusion of vital cell nutrients and expressed products; and exert certain mechanical and biological influences to modify the behavior of the cell phase.\n\nTo achieve the goal of tissue reconstruction, scaffolds must meet some specific requirements. A high porosity and an adequate pore size are necessary to facilitate cell seeding and diffusion throughout the whole structure of both cells and nutrients.",
  "cpc": [
    "C12N 5/00",
    "A61L 2400/08",
    "A61L 2400/12",
    "A61L 2400/18",
    "A61L 27/14",
    "A61L 27/40",
    "A61L 27/52",
    "A61L 27/56",
    "B29C 64/165",
    "B29C 67/0081",
    "B33Y 80/00"
  ],
  "ipc": [
    "B29C 67/00",
    "C12N 5/00",
    "A61L 27/14",
    "A61L 27/40",
    "A61L 27/52",
    "A61L 27/56"
  ],
  "assignees": [
    "University of California San Diego UCSD"
  ],
  "inventors": [
    "Pranav Soman",
    "Shaochen Chen",
    "David Fozdar"
  ],
  "filing_date": "2011-11-22",
  "publication_date": "2017-04-25",
  "grant_date": "2017-04-25",
  "priority_date": "2010-11-22",
  "application_number": "US-201113989024-A",
  "family_id": "46146409",
  "cited_by_count": 13,
  "citations": [
    "US20070031667A1",
    "US8034103B2",
    "US20090041978A1"
  ]
}