# US 11,440,225 B2 · Layerless bioprinting via dynamic optical projection and uses thereof

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- Number: US 11,440,225 B2
- Document ID: US11440225B2
- Status: Granted
- Kind: B2
- Application number: 16/669,248
- Filed: 2019-10-30
- Published: 2020-05-07
- Granted: 2022-09-13
- Earliest claimed: 2014-05-20
- Assignees: The Regents of the University of California
- Applicants: The Regents of the University of California
- Inventors: Peter Chung; Shaochen Chen
- Web page: https://patentgrep.com/patent/US11440225B2

## CPC

- B29C 35/0894: {provided with masks or diaphragms}
- B29C 35/0805: {using electromagnetic radiation}
- B29C 64/129: characterised by the energy source therefor, e.g. by global irradiation combined with a mask
- B29C 64/277: using multiple radiation means, e.g. micromirrors or multiple light-emitting diodes [LED]
- B29C 64/386: Data acquisition or data processing for additive manufacturing
- B29C 64/40: Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
- B33Y 10/00: Processes of additive manufacturing
- B33Y 30/00: Apparatus for additive manufacturing; Details thereof or accessories therefor
- B33Y 50/02: for controlling or regulating additive manufacturing processes
- B33Y 70/00: Materials specially adapted for additive manufacturing
- B33Y 80/00: Products made by additive manufacturing
- G01N 33/502: {for testing non-proliferative effects}
- G01N 33/5058: {Neurological cells}
- B29C 2035/0827: {using UV radiation}
- B29C 2035/0838: {using laser}
- B29K 2995/0005: Conductive
- B29K 2995/0056: Biocompatible, e.g. biopolymers or bioelastomers
- B29L 2031/752: {Measuring equipment}
- B29L 2031/7532: {Artificial members, protheses}
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- 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
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

A system and method for 3D microfabrication projects light capable of initiating photopolymerization toward a spatial light modulator that modulates light responsive to digital masks corresponding to layers of the structure. Projection optics focus the modulated light onto an optical plane within a photopolymerizable material supported on a stage. A computer controller causes the spatial light modulator to project a sequences of images corresponding to the digital masks while coordinating movement of the stage to move a position of the optical plane within the photopolymerizable material to sequentially project each image of the sequence to generate the structure by progressively photopolymerizing the photopolymerizable material.

## Claims

### Claim 1

A system for 3D microfabrication of a structure, comprising:
a light source configured for projecting light within an optical path, the light source emitting light at a wavelength configured for initiating photopolymerization of one or more photopolymerizable material disposed in a container;
a digital micromirror device disposed within the optical path and configured for modulating light from the light source responsive to a set of digital masks corresponding to layers of the structure;
projection optics configured to focus the modulated light to an optical plane, the projection optics comprising an optical tube having a window disposed at an end thereof, the window configured to prevent adhesion of the one or more photopolymerizable material when the window is immersed therein, wherein the optical plane is substantially coincident with a printing interface between the window and the one or more photopolymerizable material;
a stage configured to support the container within the optical path, wherein the stage is configured for movement along at least one axis; and
a computer processor operable for:
controlling the digital micromirror device to project a sequence of images corresponding to the set of digital masks;
coordinating movement of the stage to immerse the window within the one or more photopolymerizable material and sequentially project each image of the sequence to generate the structure by progressively photopolymerizing the one or more photopolymerizable material along the at least one axis to progressively define the structure starting at a target substrate in a bottom of the container.

### Claim 2 (depends on 1)

The system of claim 1, wherein the target substrate comprises a glass bottom within the container or a glass slide disposed on the bottom of the container.

### Claim 3 (depends on 1)

The system of claim 1, further comprising an image acquisition device disposed to detect light within the optical path, the image acquisition device configured to facilitate alignment of projected images with the target substrate.

### Claim 4 (depends on 3)

The system of claim 3, wherein the target substrate comprises one or more electrodes.

### Claim 5 (depends on 4)

The system of claim 4, wherein the one or more photopolymerizable material comprises a conductive polymer and at least a portion of the sequence of images corresponds to interconnecting structures aligned with one or more electrodes disposed within the container.

### Claim 6 (depends on 1)

The system of claim 1, wherein the container comprises a well in a multi-well plate, and wherein the stage is further configured to translate the multi-well plate within an X,Y plane to access a plurality of wells in the multi-well plate.

### Claim 7 (depends on 1)

The system of claim 1, wherein the computer processor is further operable for activating and deactivating individual pixels within the digital micromirror device for effecting localized changes in the structure.

### Claim 8 (depends on 7)

The system of claim 7, wherein localized changes comprise one or more of porosity and stiffness.

### Claim 9 (depends on 1)

The system of claim 1, wherein the container comprises a well in a multi-well plate and wherein at least a portion of wells within the multi-well plate contain different photopolymerizable materials.

### Claim 10 (depends on 1)

The system of claim 1, further comprising a second light source disposed within the optical path, the second light source emitting light at a wavelength configured to stimulate a photo-active biological material.

### Claim 11 (depends on 1)

The system of claim 1, wherein at least a portion of the digital masks cause the spatial light modulator to generate subpatterns within selected layers of the structure.

### Claim 12 (depends on 1)

The system of claim 1, wherein the target substrate is chemically modified to promote bonding of the structure to the target substrate.

### Claim 13 (depends on 12)

The system of claim 12, wherein the chemical modification is methacrylation.

### Claim 14 (depends on 1)

The system of claim 1, wherein the window is formed from a material selected from silica, sapphire, polydimethysiloxane (PDMS), transparent ceramic, and transparent plastic.

### Claim 15 (depends on 14)

The system of claim 14, wherein the window is surface-treated to render it hydrophobic.

### Claim 16 (depends on 1)

The system of claim 1, wherein the one or more photopolymerizable material comprises a photo-crosslinkable hydrogel.

### Claim 17 (depends on 16)

The system of claim 16, wherein the photo-crosslinkable hydrogel comprises one or more of a gelatin methacrylate [GelMA], a methacrylated hyaluronic acid [MeHA] and a polyethylene glycol diacrylate [PEGDA].

### Claim 18 (depends on 1)

A method for 3D microfabrication of a structure, comprising:
controlling the system of claim 1 using the computer processor to position the stage to immerse the window into the one or more photopolymerizable material within the container and to project an image of the sequence of images toward the optical plane; and
simultaneously and continuously controlling, via the computer processor, the sequence of images and the stage movement to generate the structure by progressively photopolymerizing the photopolymerizable material along the at least one axis starting at the target substrate at the bottom of the container and progressing upward.

### Claim 19 (depends on 18)

The method of claim 18, wherein the container comprises a well within a multi-well plate.

### Claim 20 (depends on 19)

The method of claim 19, wherein at least of portion of a plurality of wells within the multi-well plate contain different pre-polymer solutions.

### Claim 21 (depends on 19)

The method of claim 19, further comprising controlling the stage to translate the multi-well plate within an X,Y plane to access a plurality of wells in the multi-well plate.

### Claim 22 (depends on 18)

The method of claim 18, wherein the target substrate comprises a glass bottom within the container or a glass slide disposed on the bottom of the container.

### Claim 23 (depends on 18)

The method of claim 18, wherein the one or more photopolymerizable material comprises a photo-crosslinkable hydrogel.

### Claim 24 (depends on 23)

The method of claim 23, wherein the photo-crosslinkable hydrogel comprises one or more of a gelatin methacrylate [GelMA], a methacrylated hyaluronic acid [MeHA] and a polyethylene glycol diacrylate [PEGDA].

### Claim 25 (depends on 18)

The method of claim 18, wherein the container has an electrode or a multi-electrode array disposed therein.

### Claim 26 (depends on 25)

The method of claim 25, wherein the one or more photopolymerizable material comprises a conductive polymer and at least a portion of the sequence of patterns corresponds to interconnecting structures aligned with one or more electrodes.

### Claim 27 (depends on 18)

The method of claim 18, further comprising:
disposing an image acquisition device within the optical path; and
aligning projected images with the target substrate.

### Claim 28 (depends on 18)

The method of claim 18, further comprising controlling the spatial light modulator to generate subpatterns within selected layers of the structure.

### Claim 29 (depends on 18)

The method of claim 18, further comprising selectively activating and deactivating individual pixels within the digital micromirror device to effect localized changes in the structure.

### Claim 30 (depends on 29)

The method of claim 29, wherein the localized changes comprise one or more of porosity and stiffness.

### Claim 31 (depends on 18)

The method of claim 18, further comprising controlling scaffold structural parameters by selectively controlling one or a combination of pre-polymer solution concentration, UV intensity, and UV exposure time.

### Claim 32 (depends on 31)

The method of claim 31, wherein the scaffold structural parameters comprise one or more of spacing and height.

### Claim 33 (depends on 18)

The method of claim 18, further comprising chemically modifying the target substrate to promote bonding of the structure to the target substrate.