Systems and methods for three-dimensional fabrication of nanostructures

Abstract

Systems and methods for three-dimensional fabrication of nanoscale products via triplet-triplet annihilation photon upconversion are provided. Generally, an optical system can be utilized to impinge patterned light onto a resin. The resin can comprise components triplet-triplet annihilation photon upconversion and components for polymerization. The patterned light provided by the optical system can induce triplet-triplet annihilation photon upconversion to stimulate polymerization and thus curing the resin.

Description

SYSTEMS AND METHODS FOR THREE-DIMENSIONAL FABRICATION OF NANOSTRUCTURESCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit of U.S. Provisional Patent Application No. 63 / 586,918, filed November 7, 2023, entitled “Systems and Methods for Three- Dimensional Fabrication of Nanostructures,” the disclosure of which is hereby incorporated by reference in its entirety for all purposes.TECHNICAL FIELD

[0002] The disclosure is generally directed to systems and methods for three- dimensional fabrication of a nanostructure via triplet-triplet annihilation upconversion of photons.BACKGROUND

[0003] Additive manufacturing (also referred to as three-dimensional printing or three- dimensional fabrication) is the construction of a three-dimensional object using a process of adding and / or joining material, as opposed to traditional means that remove material through milling, machining, carving, cutting, shaving, or shaping. Generally, additive manufacturing is performed by utilizing a computational three-dimensional design as a reference to instruct a three-dimensional fabrication system to add material in bottom-up process. One common process is to utilize an ink (also referred to as a resin) that is capable of being distributed via a dispenser (e.g., nozzle) in a pattern in accordance with the three-dimensional design. As the ink is deposited, it can be cured or otherwise solidified to form the object.

[0004] Photon upconversion is a process in which the sequential absorption of two or more photons leads to the emission of light at a shorter wavelength. One mechanism of photon upconversion is triplet-triplet annihilation upconversion (TTA-UC), which is an energy transfer mechanism between a sensitizer and an annihilator to yield an upconverted photon of higher energy.SUMMARY

[0005] Several embodiments are directed to systems and methods for three- dimensional (3D) fabrication on a nanoscale via triplet-triplet annihilation upconversion (TTA-UC). Generally, an optical system is utilized to serially impinge planar images of patterned light onto a resin in accordance with a three-dimensional design. The serial impingement of patterned light onto the light results in the resin curing to form a 3D nanostructure.

[0006] In accordance with many embodiments, the resin can comprise components for performing TTA-UC, including a sensitizer and annihilator pair. The resin can further comprise components for polymerization, including a photoinitiator and polymerizable compounds. The sensitizer and annihilator pair can be configured to upconvert a wavelength of light of lower energy into a wavelength of light of higher energy, which can stimulate the photoinitiator to induce polymerization of the polymerizable compounds.

[0007] In accordance with several embodiments, an optical system can comprise a light source, a means for generating a pattern of light, and a means for directing the light onto the resin. To generate a pattern of light a digital micromirror device (DMD) or a spatial light modulator (SLM) can be utilized selectively impinge pixels of light in accordance with a planar image. A series of planar images of patterned light is projected onto the resin to cure the resin via TTA-UC such that a 3D nanostructure is formed. A computational process can be utilized to instruct the optical system to project the series of planar images of patterned light, which can include deconvolution processes to determine the illumination pattern for each plane such that light energy is distributed in a manner reduce uneven curing of the resin.

[0008] In some aspects, the techniques described herein relate to a resin for three- dimensional fabrication via triplet-triplet annihilation photon upconversion, including: a sensitizer, an annihilator, and polymerizable compounds, wherein the sensitizer is paired with the annihilator such that the sensitizer-annihilator pair is configured to upconvert a lower energy wavelength of light into a higher energy wavelength of light capable of stimulating polymerization the polymerizable compounds.

[0009] In some aspects, the techniques described herein relate to a resin, wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n-octyldiisopropyl)silylethynyl-anthracene (NODIPS-an).

[0010] In some aspects, the techniques described herein relate to a resin, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

[0011] In some aspects, the techniques described herein relate to a resin, wherein the annihilator has a concentration that is at least 100-fold higher than the sensitizer.

[0012] In some aspects, the techniques described herein relate to a resin, wherein the polymerizable compounds include acrylic based monomers.

[0013] In some aspects, the techniques described herein relate to a resin, wherein the acrylic based monomers include acrylic acid, acrylamide, vinyl chloride, styrene, epoxide, methacrylate, N-vinyl-2-pyrrolidone, 2-hydroxyethyl, methacrylate pentaerythritol tetraacrylate, trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate, or tetra(ethylene glycol) diacrylate.

[0014] In some aspects, the techniques described herein relate to a resin further including a metal salt.

[0015] In some aspects, the techniques described herein relate to a resin, wherein the metal salt includes a gold salt or a silver salt.

[0016] In some aspects, the techniques described herein relate to a resin, wherein the polymerizable compounds include silsesquioxane.

[0017] In some aspects, the techniques described herein relate to a resin, wherein the polymerizable compounds include N,N-dimethylacrylamide (DMAA).

[0018] In some aspects, the techniques described herein relate to a resin further including a photoinitiator.

[0019] In some aspects, the techniques described herein relate to a resin, wherein the photoinitiator includes bis-(4-methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

[0020] In some aspects, the techniques described herein relate to a resin further including an inhibitor of polymerization.

[0021] In some aspects, the techniques described herein relate to a resin, wherein the inhibitor of polymerization includes: 2,2,6,6-tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

[0022] In some aspects, the techniques described herein relate to a resin further including a light blocker.

[0023] In some aspects, the techniques described herein relate to a resin, wherein the light blocker includes Sudan I, 3,3'-Diethyloxacarbocyanine iodide, or Coumarin 334.

[0024] In some aspects, the techniques described herein relate to a resin, wherein the resin is aqueous.

[0025] In some aspects, the techniques described herein relate to a resin, wherein the resin is hydrocarbon-based.

[0026] In some aspects, the techniques described herein relate to a resin, wherein the resin is not an emulsion.

[0027] In some aspects, the techniques described herein relate to a resin, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.

[0028] In some aspects, the techniques described herein relate to a system for performing three-dimensional fabrication via triplet-triplet annihilation photon upconversion, including: a resin including: a sensitizer, an annihilator and polymerizable compounds; and an optical system configured to serially impinge patterned light onto the resin such that the resin is cured to form a three-dimensional product.

[0029] In some aspects, the techniques described herein relate to a system, wherein the resin and the optical system are configured to yield a nanoscale three-dimensional product.

[0030] In some aspects, the techniques described herein relate to a system, wherein the optical system includes a light source, a means for patterning light, and a means for relaying and focusing light emitted by the light source onto the resin.

[0031] In some aspects, the techniques described herein relate to a system, wherein the means for patterning light includes an array of pixels, wherein each pixel of the array can individually relay light in a binary manner or modify light intensity such that the pattern of light is formed by the array of pixels.

[0032] In some aspects, the techniques described herein relate to a system, wherein the means for patterning light is a digital micromirror device or spatial light modulator.

[0033] In some aspects, the techniques described herein relate to a system, wherein the optical system is in digital connection with a computational processor with a memory including instructions that directs the means for patterning light to generate patterned light in accordance with the three-dimensional product to be formed.

[0034] In some aspects, the techniques described herein relate to a system, wherein the instructions that directs the means for patterning light accounts for adjacency, proximity, or density of light voxels to be relayed and impinged.

[0035] In some aspects, the techniques described herein relate to a system, wherein the instructions that directs the means for patterning includes a deconvolution method to account for adjacency, proximity, or density of light voxels to be relayed and impinged.

[0036] In some aspects, the techniques described herein relate to a system, wherein the light source is a low-powered light-emitting diode or a continuous-wave laser.

[0037] In some aspects, the techniques described herein relate to a system, wherein the light source is divergent and the optical system further includes a collimator.

[0038] In some aspects, the techniques described herein relate to a system, wherein the optical system is configured to serially impinge red patterned light.

[0039] In some aspects, the techniques described herein relate to a system, wherein the optical system includes a stage or an objective lens configured to move in the z- direction to serially impinge focal planes of patterned light along the z-axis of the resin.

[0040] In some aspects, the techniques described herein relate to a system, wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n-octyldiisopropyl)silylethynyl-anthracene (NODIPS-an).

[0041] In some aspects, the techniques described herein relate to a system, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

[0042] In some aspects, the techniques described herein relate to a system, wherein the polymerizable compounds include acrylic based monomers.

[0043] In some aspects, the techniques described herein relate to a system, wherein the polymerizable compounds include N,N-dimethylacrylamide (DMAA).

[0044] In some aspects, the techniques described herein relate to a system, wherein the resin further includes a photoinitiator, wherein the photoinitiator includes bis-(4- methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

[0045] In some aspects, the techniques described herein relate to a system, wherein the resin further includes an inhibitor of polymerization, wherein the inhibitor of polymerization includes 2,2,6,6-tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

[0046] In some aspects, the techniques described herein relate to a system, wherein the resin further includes a light blocker, wherein the light blocker includes Sudan I, 3,3'- Diethyloxacarbocyanine iodide, or Coumarin 334.

[0047] In some aspects, the techniques described herein relate to a system, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.

[0048] In some aspects, the techniques described herein relate to a method for three- dimensional fabrication, including: providing a resin on a stage, wherein the resin includes a sensitizer, an annihilator, and polymerizable compounds; and serially performing curing cycles to yield a three-dimensional product, wherein each curing cycle cures a layer of the resin and includes: impinging, utilizing an optical system, patterned light onto the resin to cure a layer of the resin via energy yielded by triplet-triplet annihilation photon upconversion.

[0049] In some aspects, the techniques described herein relate to a method, wherein each curing cycle further includes: emitting light from a light source; relaying, utilizing the optical system, the emitted light to a means for patterning light; generating the patterned light utilizing the emitted light via the means for patterning light; and relaying and focusing, utilizing the optical system, the patterned onto the resin.

[0050] In some aspects, the techniques described herein relate to a method, wherein the means for patterning light includes an array of pixels, wherein each pixel of the array can individually relay light in a binary manner or modify light intensity such that the pattern of light is formed by the array of pixels.

[0051] In some aspects, the techniques described herein relate to a method, wherein the means for patterning light is a digital micromirror device or spatial light modulator.

[0052] In some aspects, the techniques described herein relate to a method, wherein the optical system is in digital connection with a computational processor with a memory including instructions that directs the means for patterning light to generate patterned light in accordance with the three-dimensional product to be formed.

[0053] In some aspects, the techniques described herein relate to a method, wherein the instructions that directs the means for patterning light accounts for adjacency, proximity, or density of light voxels to be relayed and impinged.

[0054] In some aspects, the techniques described herein relate to a method, wherein the instructions that directs the means for patterning includes a deconvolution method to account for adjacency, proximity, or density of light voxels to be relayed and impinged.

[0055] In some aspects, the techniques described herein relate to a method, wherein the light source is a low-powered light-emitting diode or a continuous-wave laser.

[0056] In some aspects, the techniques described herein relate to a method, wherein the light source is divergent, each curing cycle further includes: passing the emitted light or the patterned though a collimator.

[0057] In some aspects, the techniques described herein relate to a method, wherein the patterned light is red light.

[0058] In some aspects, the techniques described herein relate to a method, wherein the optical system includes a stage or an objective lens configured to move in the z- direction to serially performing curing cycles along the z-axis of the resin.

[0059] In some aspects, the techniques described herein relate to a method, wherein the three-dimensional product is of nanoscale.

[0060] In some aspects, the techniques described herein relate to a method, wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n-octyldiisopropyl)silylethynyl-anthracene (NODIPS-an).

[0061] In some aspects, the techniques described herein relate to a method, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

[0062] In some aspects, the techniques described herein relate to a method, wherein the polymerizable compounds include acrylic based monomers.

[0063] In some aspects, the techniques described herein relate to a method, wherein the polymerizable compounds include N,N-dimethylacrylamide (DMAA).

[0064] In some aspects, the techniques described herein relate to a method, wherein the resin further includes a photoinitiator, wherein the photoinitiator includes bis-(4- methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

[0065] In some aspects, the techniques described herein relate to a method, wherein the resin further includes an inhibitor of polymerization, wherein the inhibitor of polymerization includes 2,2,6,6-tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

[0066] In some aspects, the techniques described herein relate to a method, wherein the resin further includes a light blocker, wherein the light blocker includes Sudan I, 3,3'- Diethyloxacarbocyanine iodide, or Coumarin 334.

[0067] In some aspects, the techniques described herein relate to a method, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The description and claims will be more fully understood with reference to the following figures and data graphs, which are presented as exemplary embodiments of the invention and should not be construed as a complete recitation of the scope of the invention.

[0069] Figure 1 provides a schematic of triplet-triplet annihilation photon upconversion.

[0070] Figures 2A-2E provide structural formulae of examples of and a schematic of resin components. Figure 2A provides structural formulae of examples of photoinitiators. Figure 2B provides structural formulae of examples of a sensitizer and an annihilator. Figure 2C provides structural formulae of examples of inhibitors of polymerization. Figure 2D provides structural formulae of examples of light blockers. Figure 2E provides aschematic of an example of a resin that can be cured via triplet-triplet annihilation photon upconversion.

[0071] Figures 3A-3D each provides a schematic of an example of an optical system for providing patterned light for curing resin.

[0072] Figure 4 provides a schematic of overlapping TTA-UC Chemistry.

[0073] Figure 5 provides an example of a computational system for directing an optical system for three-dimensional fabrication.

[0074] Figure 6A provides a schematic comparing one-photon absorption and two- photon absorption. Figure 6B provides a schematic comparing monovoxel excitation printing and parallel excitation printing.

[0075] Figure 7 provides a schematic of an optics setup and printing workflow.

[0076] Figure 8 provides simulated and acquired data visualization of the Point Spread Function (PSF) for the projections of different number of pixels, demonstrating the light intensity distribution in the x-z plane.

[0077] Figure 9 provides a schematic of a process of 3D convolution to simulate the light-intensity distribution in TTA-UC printing and subsequent deconvolution to correct light dosage.

[0078] Figure 10 provides visualization of 3D-deconvolved Benchy of different deconvolution algorithms with various constraints.

[0079] Figure 11 provides data describing losses over iterations of different deconvolution algorithms with various constraints.

[0080] Figures 12A-12B provide examples of nanoscale products yielded by a three- dimensional fabrication process utilizing TTA-UC.DETAILED DESCRIPTION

[0081] Turning now to the drawings and data, systems and methods of three- dimensional (3D) nanoscale fabrication via triplet-triplet annihilation photon upconversion (TTA-UC) are described. In several embodiments, TTA-UC sensitizers and annihilators are utilized within a resin, which can be cured in accordance with a 3D design in a scale of nanometers to yield nanoscale products, such as nanostructures or nano-objects. In many embodiments, the resin is cured using light energy that is upconverted via TTA-UC.In several embodiments, an optical system can provide a planar image of patterned light to cure of a layer of resin. In many embodiments, the patterned light stimulates localized TTA-UC and subsequent polymerization of the resin such that the resin is cured in accordance with the planar image. In many embodiments, the curing of resin is serially performed along a z-axis such that a 3D nanostructure is fabricated. A computational system can be utilized in conjunction with the optical system to determine a pattern of light to be illuminated onto the resin and / or to govern the fabrication process by controlling the optical system, including a means for patterning light. A computational process can also be utilized to mitigate uneven curing of the resin by determining a series of pattern of light to be illuminated that account for various factors that affect uniformity of resin curing by TTA-UC chemistry.

[0082] Prior efforts to perform nanoscale 3D fabrication generally relied on two-photon polymerization, which has several limitations. The process of two-photon polymerization is inefficient as it requires the use of very high-powered lasers (e.g., femtosecond pulsed lasers), which are expensive and are limited to monovoxel printing per light source that is difficult to parallelize due to the required high-power densities for curing. Here, several of the systems and methods of the disclosure utilize TTA-UC chemistry, which provides several benefits over traditional two-photon technique. Photon upconversion is a process in which the sequential absorption of two or more photons leads to the emission of light at a shorter wavelength. Various organic and inorganic materials can upconvert photons via triplet-triplet annihilation (TTA-UC), which is an energy transfer mechanism between two molecules in their triplet state (Fig. 1 ). To achieve photon upconversion, low energy light is impinged upon a cooperative sensitizer and annihilator. The sensitizer absorbs the low energy photon and populates its first excited triplet state (T1 ) through intersystem crossing. The sensitizer then transfers the excitation energy to the annihilator, resulting in a triplet excited emitter and a ground state sensitizer. Two triplet excited emitters then can undergo triplet-triplet annihilation, and if a singlet excited state (S1 ) of the emitter is populated fluorescence results in an upconverted photon.

[0083] By utilizing TTA-UC chemistry, many of the various embodiments of the disclosure provide a means for accelerated and scaled-up fabrication of nanostructures. To facilitate the use of TTA-UC chemistry, several compounds and functionalconcentrations of compounds have been identified that can be utilized as sensitizers and annihilators within a resin for printing. Further, an optical system has been designed that permits parallelized curing of resin such that a layer of printed resin to be cured simultaneously, while controlling for light uniformity to mitigate overcuring and / or undercuring. Another advantage of utilizing TTA-UC for curing is that the light source is not required to be high powered, allowing for more affordable light sources to be used such as continuous-wave lasers or light-emitting diodes (LEDs). These advances of nanoscale manufacturing have numerous applications and improve the ability to fabricate various nanotools, such as (for example) nanolenses for optical imaging and nanoscale cell scaffolds for tissue engineering.Compositions and Compounds

[0084] Many embodiments are directed to compositions and compounds which can be utilized as a resin for 3D fabrication. In several embodiments, a resin comprises components for performing TTA-UC and components for polymerization. Accordingly, the TTA-UC components provide the requisite photon energy to polymerize polymerizable compounds such that the resin can be cured.

[0085] Components that are useful within a resin have good solubility within the resin and provide efficient TTA-UC. Various solvents and / or buffers can be utilized and can be selected based on the solubility properties of the resin components. In some embodiments, an aqueous resin is utilized. In some embodiments, a hydrocarbon-based resin is utilized. N,N-dimethylacrylamide (DMAA) can also act as a cosolvent for a resin (aqueous or hydrocarbon), which can improve solubility of various other compounds. In some embodiments, the resin is a dispersion. In several embodiments, the resin is not an emulsion, and does not comprise nanocapsules, micelles, or liposomes. In some embodiments, the sensitizer and the annihilator is not solubilized within nanocapsules, micelles, or liposomes. The use of nanocapsules, micelles, or liposomes to solubilize TTA-UC compounds limits the 3D printing resolution to a microscale product, and thus is not desired when greater resolution is desired (e.g., nanoscale resolution).

[0086] A resin will components for polymerization, including polymerizable compounds that are photoreactive or otherwise polymerize in the presence of aphotoinitiator. Accordingly, in some embodiments a resin will comprises polymerizable compounds and photoinitiators. Various compounds can be utilized as polymerizable compounds for polymerization, such as (for example) acrylic-based monomers. Examples of acrylic-based monomers that have been found to work well within a resin include (but are not limited to) acrylic acid, acrylamide, vinyl chloride, styrene, epoxide, methacrylate, N-vinyl-2-pyrrolidone, 2-hydroxyethyl, methacrylate pentaerythritol tetraacrylate, trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate, and tetra(ethylene glycol) diacrylate. Other polymerizable compounds (especially acrylic-based monomers) that can polymerize via radicalization to form a 3D object can be utilized. In some embodiments, acrylic-based monomers are utilized to form hydrogel (e.g., tetra(ethylene glycol) diacrylate), which may include a crosslinking step (e.g., UV-treatment).

[0087] Other types of materials can also be printed to yield nanoscale product utilizing the light energy of TTA-UC. For example, nanoscale silica glass can be printed via TTA- UC polymerization using silsesquioxane oligomers. In addition, nanoscale metal composites can be printed via TTA-UC by concurrent acrylate monomer polymerization and metal salt reduction. Examples metal composites that can be printed include composites of silver (Ag) and gold (Au).

[0088] In some implementations, polymerizable compounds are photoreactive and will polymerize without a photoinitiator. And in some implementations, a photoinitiator is utilized to promote polymerization. Examples of a photoinitiators that can be utilized include (but not limited to) bis-(4-methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), and 2,2-dimethoxy-2-phenylacetophenone (DMPA) (Fig. 2A). Generally, any photoreactive monomer and / or photoinitiator capable of utilizing photon energy provided by an annihilator to initiate radical polymerization can be utilized.

[0089] In some implementations, a comonomer is utilized as a component for polymerization. A comonomer can help adjust various properties of the resin to enhance TTA-UC chemistry and / or polymerization. In one example, DMAA can be utilized as a comonomer in acrylic polymerization, helping improve polymerization and polymerproduct properties. As noted, DMAA can also improve solubility of other resin components.

[0090] To provide the requisite energy for polymerization, a resin will generally comprise components for performing TTA-UC, including a sensitizer and an annihilator. The sensitizer and the annihilator can be a cooperative pair of compounds to upconvert low energy light photons. The sensitizer and annihilator pair should be selected based on compatible properties, such as solubility within the resin and ability to efficiently upconvert light photons. Various compounds have been found to be useful as sensitizers and annihilators within a resin for 3D fabrication. One example of a sensitizer that works well within a resin is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) which has strong absorption at multiple band of light and can generate triplets efficiently upon light excitation (Fig. 2B). One example of an annihilator that works well is 9,10- bis((diisopropyl(octyl)silyl)ethynyl)anthracene (NODIPS-an), which has good solubility within a resin and does not have a substantial negative effect on the efficiency of upconversion (Fig. 2B. PdTPTBP and NODIPS-an can be paired to perform red to green / blue upconversion. Other pairs of sensitizers and annihilators having good resin solubility can be utilized.

[0091] In some implementations, a resin comprises a polymerization inhibitor, which can be included for increasing the threshold of polymerization reaction. It has been found that including an inhibitor enhances the spatial resolution of printing. Examples of inhibitors that can be utilized within a resin include (2,2,6,6-tetramethylpiperidin-1 - yl)oxidanyl (TEMPO) and bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS), but any polymerization inhibitor can be utilized (Fig. 2C).

[0092] In some implementations, a resin comprises a light blocker for stabilizing the resin by absorbing scattered light and / or background light. Examples of light blockers are Sudan I, 3,3'-Diethyloxacarbocyanine iodide and Coumarin 334, but any compound capable of absorbing scattered light and / or background light can be utilized and can be adjusted based on input light and emitted light of the TTA-UC reaction (Fig. 2D). Other compounds also can be utilized as filler within a resin. A filler should be inert to the TTA- UC and polymerization chemistries such that it does not interfere with the curing process.

[0093] An example of a resin having various components with the energy path is provided in Fig. 2E. In this example, the resin comprises PdTPTBP as a sensitizer, NODIPS-an as an annihilator, ivocerin as a photoinitiator, di(trimethylolpropane) tetraacrylate as a monomer, N,N-Dimethylacrylamide (DMAA) as a co-monomer for improving overall solubility of the resin components, TEMPO as an inhibitor, and Sudan I as a light blocker. The resin can be cured via TTA-UC and polymerization. Accordingly, two photons of red light can be impinged on the resin to stimulate PdTPTBP. The energy simulated within PdTPTBP is upconverted to a photon of blue light via NODIPS-an. The photon blue light can stimulate local polymerization of monomers of di(trimethylolpropane) tetraacrylate via the photoiniator ivocerin. Although Fig. 2E depicts a specific combination of compounds to yield a resin, any of the other components can be substituted for alternative compounds as described herein.

[0094] It has been found that functional curing of the resin can require relatively low concentrations of sensitizer and high concentrations of annihilator. In various embodiments, the annihilator has concentration relative to the sensitizer that is at least 5- fold higher, at least 10-fold higher, at least 20-fold higher, at least 50-fold higher, or at least 100-fold higher. This helps ensure that triplets from the sensitizer are utilized in the triplet-triplet annihilation transfer, utilizing the nonlinearity of TTA-UC. Accordingly, in some embodiments, the sensitizer PdTPTBP is provided within a resin at a concentration between 10 pM and 500 pM. And in some embodiments, the annihilator NODIPS-an is provided within a resin at a concentration between 500 pM and 5.00 mM.Optical Systems

[0095] Several embodiments of the disclosure are directed towards optical systems for parallelized 3D fabrication of nanostructures. In many embodiments, an optical system comprises a light source, a series of mirrors and / or lenses for directing the light, a means for providing a patterned image, and an objective lens for focusing the patterned light onto the resin. In some implementations, the means for providing a patterned image is a DMD. In some implementations, the means for providing a patterned image is an SLM. A stage and / or objective lens can move in the z-axis such that the optical system can sequentially project a stack of patterned planar images to fabricate a nanoscale 3D object.

[0096] A light source can be any emitter for providing light, such as (for example) a light-emitting diode (LED), laser, a mercury arc-lamp, a xenon-arc lamp, or a tungstenhalogen lamp. In some implementations, a filter is utilized in conjunction with an emitter to provide a particular wavelength (or band of wavelengths). In some implementations, the light source is a low power light source, such as a continuous-wave laser or a lightemitting diodes. In some implementations, the light source provides visible light or infrared light. In some implementations, the provided light has a wavelength of between 400 nm and 1000 nm. In some implementations, the provided light is red light. In some embodiments, the provided light is a particular wavelength, a narrowband, a broadband, or a multiband. The selection of light wavelength is determined by the compatibility of the sensitizer and / or the desired light emission. In some embodiments, when a divergent light source is utilized (e.g., LED), the light beam is collimated (or pseudo-collimated). The light can be collimated by any means, such as by lenses, mirrors, reflectors, pinholes, or any other collimator for generating collimated (or pseudo-collimated) light. The collimator can be located at various locations along the beam path, and can be before or after the means for generating patterned light. In some embodiments, the light is passed through a phase change material (PCM).

[0097] A DMD, SLM, or other pattern generator can be utilized for generating and relaying a pattern of light for curing a layer of the resin. Generally, any pattern generator can be utilized that comprises an array of pixels that are individually capable of selectively relaying light such that the cumulative relaying of light by the array yields a pattern of light. For example, a DMD comprises an array of micromirrors in which each mirror represents a pixel. Each mirror can be individually selected to reflect and relay light to yield a spatial pattern. In some implementations, a micromirror reflects light in a binary capacity (e.g., on or off) to yield a pattern of light to be projected. In some implementations, a micromirror can utilize grayscale to modulate the intensity of the light reflected onto a resin. In some implementations, a micromirror can operate with multiple wavelengths of the light. Likewise, an SLM comprises an array liquid-crystal modulators that can modulate intensity, phase and / or polarization of light to yield a pattern. Accordingly, light can be impinged upon a resin with spatially different intensities and / or phase to control spatial resin curing.

[0098] Provided in Fig. 3A is an example of an optical system for 3D fabrication of nanoscale products. In this example, a light source provides light of a particular wavelength (or band of wavelengths) that can be upconverted via a sensitizer and annihilator combination. In this example, the light is directed to a DMD, which selectively relays pixels of light in a patterned manner. Any other means of patterning light, such as an SLM can be utilized instead of (or in addition to) the DMD. The patterned light is directed to an objective lens and focused onto the resin to cure the resin in accordance with the planar image.

[0099] Provided in Figs 3B to 3D are alternative examples of optical systems for 3D fabrication of nanoscale products, which are based Fourier optics. Fourier optical systems provide high resolution projection with the light intensity well confined to the focal plane, yielding light fields well suited for nanoscale 3D fabrication. Fig. 3B provides an example of a 4f optical system and Fig. 3C provides an example of 8f optical system, which can utilize a divergent light source. Fig. 3D provides an example of 6f system, which may be preferred when using a collimated light source. This system diverges the collimated light to illuminate the means for patterning light, which can project a phase mask with the objective lens performing a Fourier transformation to project the image onto the focal plane.

[0100] To fabricate a 3D product, a series of curing cycles is performed, each curing cycle resulting in formation of a layer of the structure. Accordingly, light is sequentially pulsed, patterned, and relayed along focal planes of the z-axis to yield a 3D curing process. Each curing cycle can comprise the light source emitting one or more pulses of light that are relayed towards a patterned generator and then relayed and focused upon the resin. The patterned light is impinged upon a focal plane of the resin for a period of time to form a layer of the 3D object. Each subsequent curing cycles are performed on adjacent focal planes along the z axis. A series of curing cycles are performed along the z-axis to form the 3D product.

[0101] In some implementations, a plurality of discrete products is fabricated concurrently. The number of objects that can be fabricated concurrently depends on the generated light pattern and the area of x-y plane of the focused light.

[0102] In some embodiments, the optical system comprises or is in connection with a computational processing system, in which a computational process can govern the fabrication process and / or determine a series of patterns of light that mitigate uneven curing. In some embodiments, a computational process can direct and control the light source, a means for patterning light, lenses, and / or other components of the optical system. The computational process can further adjust the focal plane of the light along the z-axis (e.g., by adjusting the stage and / or objective lens along the z-axis). Accordingly, a computational process can supervise and instruct the optical system to sequentially perform curing cycles of the resin along the z-axis. For each curing cycle, a computational process can instruct the light source to emit one or more pulses of light, instruct a means for patterning light to generate and relay pattern of light voxels, and instruct an objective lens to relay and the patterned light onto a focal plane of the resin.

[0103] A computational process can also be utilized to govern the patterning of light. In some embodiments, the computational process instructs a DMD, an SLM, or other means of light patterning to generate a pattern of light during each curing cycle. For example, when instructing a DMD, the computational process can instruct each individual micromirror to be in a reflective or unreflective state, and / or the duration of time the micromirror is to be in the reflective or unreflective state during a curing cycle. In another example, when instructing an SLM, the computational process can instruct each pixel of the SLM can be modulate its mirrors and liquid crystals to modulate light intensity.

[0104] It has been discovered that non-uniform curing can be an issue when fabricating of a nanoscale product in which portions may be overcured and other portions may be undercured upon completion of a curing cycle. This issue arises due to uneven density of voxels illuminated, where voxels within regions of high adjacency, proximity, or density of illuminated voxels receive excessive light energy and voxels within regions of high density of illuminated voxels receive insufficient light energy. This results in uneven curing across an x-y field and along the z-direction. Thus, controlling for voxel illumination density can be important in order to reliably fabricate a nanoscale product.

[0105] Generally, if the light pattern impinges light onto a voxel of the resin, that voxel is cured by local TTA-UC chemistry (i.e. , light energy is upconverted to higher light energy resulting in polymerization within the voxel). And if the light pattern is dark upon voxel ofthe resin (i.e., no projection of light), then that voxel remains uncured. Although the combination of light pattern illumination with TTA-UC chemistry has been found to be a great option to fabricate nanostructures due to its nonlinear property, the TTA-UC reaction process results in light energy extending beyond border of an illuminated voxel. And thus, dark voxels that are adjacent to illuminated voxels will also receive upconverted light energy that extends beyond the border of the illuminated voxel. And when two adjacent voxels are both illuminated (in the x-, y-, or z-direction), both voxels receive an excess of upconverted light energy due to the upconverted light energy extending across the shared voxel border. Because of the overlapping upconverting light energy phenomenon, regions of the resin that have a high density of illuminated voxels adjacent and / or proximal to other illuminated voxels will be sensitive to overcuring, whereas regions of the resin that have a low density of voxels adjacent and / or proximal to other voxels receiving light illumination will be sensitive to undercuring.

[0106] The overlapping upconverting light energy phenomenon is illustrated in the example of Fig. 4, which depicts three examples of a pattern of illumination to be projected onto a focal plane of resin. As can be seen in these examples, voxels that are adjacent to illuminated voxels receive overlapping light energy from the TTA-UC chemistry. The top left example has only one central voxel illuminated, which renders this region of resin that receives this pattern prone to undercuring. The central voxel of the top right example is illuminated and is surrounded by adjacent and proximal illuminated voxels, which makes this region prone to overcuring. And the central voxel bottom left example has four illuminated pixels that are proximal but not adjacent. This pattern has less overlapping light energy provided by TTA-UC chemistry and results in a more even curing within that region. And although these examples are illustrated in only two dimensions (i.e., the x-y plane), voxels of resin adjacent and / or proximal voxels along the z-axis are also sensitive (and potentially more sensitive) to the overlapping upconverting light energy phenomenon in a similar manner.

[0107] Non-uniform curing can be mitigated by spatially controlling the amount of light energy projected onto the resin, which can be dictated by the pattern of light relayed to the resin. Accordingly, the means for patterning light can be utilized to promote even curing. Whether using a DMD, SLM, or other means for patterning light, curing uniformitycan be enhanced by relaying and projecting select voxels of light to impinge upon the resin. The amount of light energy projected within each select voxel can be further modulated by regulating the intensity and / or pulse duration of that voxel of light.

[0108] To determine the pattern of spatial light to be projected to mitigate curing unevenness, the localized number of voxels or resin illuminated during a curing cycle can be adjusted based on adjacent and proximal voxel curing density. The projected light pattern the can be adjusted such that certain voxels of resin are not illuminated when adjacent and / or proximal voxels are also to be cured. Accordingly, in some implementations, in areas of dense additive fabrication, the means for patterning is regulated to reduce the density of voxels of light that is relayed and projected onto resin in those regions. In some implementations, the pattern of voxels of light that are relayed and projected can be based on by the number of adjacent and / or proximal voxels of resin to be cured. For example, in some situations, if a voxel of resin to be cured is adjacent and / or proximal to one or more voxels to be cured, then the light pattern that is relayed and projected might not need to illuminate light onto that voxel of resin, which can be cured by the overlapping TTA-UC chemistry of adjacent and / or proximal voxels of illuminated resin. And conversely, in some situations, if a voxel of resin to be cured is not adjacent and / or proximal to any other voxels of resin to be cured, then the light pattern that is relayed and projected may need to illuminate light onto one or more proximal and / or adjacent voxels of resin in addition to the voxel of resin to be cured, which can increase the amount TTA-UC chemistry in that voxel.

[0109] Because of the overlapping TTA-UC chemistry, it may not be ideal for a pattern of light voxels to exactly match the pattern of voxels of resin to be cured. Accordingly, in many embodiments, a pattern of voxels of light to be relayed and projected onto a focal plane of resin is not equivalent to the pattern of voxels of resin to be cured. And in many embodiments, the pattern of voxels of light to be relayed and projected onto a focal plane of resin is at least partially based on adjacency, proximity, and density of voxels of resin to be cured. In some embodiments, a pattern of voxels of light to be relayed and projected onto a focal plane of resin has fewer voxels of light than the number of voxels of resin to be cured in areas of that have a high adjacency, high proximity, and / or high density of voxels of resin to be cured. And, in some embodiments, a pattern of voxels of light to berelayed and projected onto a focal plane of resin has more voxels of light than the number of voxels of resin to be cured in areas of that have a low adjacency, low proximity, and / or low density of voxels of resin to be cured.

[0110] In addition to spatial patterning of light within the focal plane, the amount light energy impinged upon each voxel of resin can be modulated, which can provide greater resolution of the amount of light energy provided by TTA-UC chemistry. The amount of light energy that is impinged can be modulated by regulating the amount light intensity projected and / or the duration of light illumination within a voxel of light energy. For example, when utilizing a DMD, the duration that light is projected onto a voxel of resin can be regulated by the the duration of time a micromirror is in a reflective state during a curing cycle. In another example, when utilizing an SLM, the intensity of light that is projected onto a voxel of resin can be modulated by the SLM. Accordingly, in some embodiments, the amount of light energy impinged upon a voxel of resin is partially based on adjacency, proximity, and density of voxels of resin to be cured. In some embodiments, during a curing cycle, the amount light energy relayed and illuminated upon a voxel of resin is different than at least one other voxel of resin. In some embodiments, during a cycle, an amount light energy relayed and illuminated upon a first voxel of resin is lesser a second voxel of resin when the first voxel of resin is within a region having higher density of voxels of resin to be cured.

[0111] In some optical systems, the light that is relayed and projected onto the resin is pseudo-collimated. Because a pseudo-collimated light source provides greater light intensity in the middle of its field of projection, curing within the center of an optical field can occur faster than curing towards the edge. To mitigate overcuring in the center of the field and / or undercuring along the edge of the field, the amount of light energy projected within these regions during a curing cycle is modulated to account for the variation of light intensity projected by pseudo-collimated light. The modulation of light impinged upon can be achieved by the various methodologies described herein, including modulating the spatial density of voxels of light, the intensity of voxels of light, and / or the duration of voxels of light projected onto the resin. For example, voxels of light that is relayed and projected onto the resin at or near the outer edges of an optical field can have greater spatial density than voxels of light that is relayed and projected onto the resin within thecenter of the optical field, which can be determined relative to the spatial density of voxels of resin to be cured. Likewise, light intensity of voxels of light that is relayed and projected onto the resin at or near the outer edges of an optical field can be greater than light intensity of voxels of light that is relayed and projected onto the resin at or near the center of the optical field. And, the duration that voxels of light projected onto the resin at or near the outer edges of an optical field can be greater than the duration of voxels of light that is projected onto the resin at or near the center of the optical field.

[0112] A pattern of light that is relayed and projected onto the resin can be at least partially based on on or more parameters that have an effect on curing uniformity, many of which have been described herein. Various methodologies can be utilized to determine a series of sequential patterns of light to be relayed and projected upon resin for fabricating a nanoscale product. In several embodiments, a series of sequential patterns of light for fabricating a nanoscale product is determined computationally.

[0113] A computational process can be utilized to determine to mitigate uneven curing that arises due to TTA-UC chemistry. In some embodiments, the computational process for mitigating uneven curing determines a series of sequential patterns of light to be projected onto the resin. In some embodiments, the computational process for mitigating uneven curing determines the series of sequential patterns at least partially based on the adjacency, proximity, and / or density of voxels of resin to be cured. Accordingly, for each curing cycle, a computational process can simulate a curing process to determine which voxels of resin would be overcured and / or undercured due to adjacency, proximity, and / or density to other voxels of resin to be cured. The computational model can generate alternative permutations of light patterns to assess and determine which pattern yields that improves the curing process by reducing the amount of curing unevenness.

[0114] A computational process can be utilized predict a 3D product, which can be further deconvoluted determine which parameters can be adjusted to improve image outcome. In some embodiments, the computational process for mitigating uneven curing utilizes a deconvolution method on a 3D image of product to fabricated utilizing light energy produced by TTA-UC, which can be utilized to correct for optical aberrations related to uneven curing arising from effects of TTA-UC chemistry. Various deconvolution methods can be utilized, but generally any deconvolution method for image restorationcan be utilized. In some embodiments, the deconvolution method utilizes Richardson- Lucy deconvolution. In some embodiments, the deconvolution method utilizes an alternative direction method of multipliers (ADMM). In some embodiments, the deconvolution method utilizes half quadratic splitting (HQS). In some embodiments, the deconvolution method utilizes nonnegativity regularization, which ensures the solutions of parameters have no negative values. In some embodiments, the deconvolution method utilizes a total variation prior term, which can promote sparsity to enhance edge definition and reduce noise within the image.

[0115] In some embodiments, a computational process is utilized to predict a predicted 3D image of the product by simulating the additive fabrication process via TTA-UC. In some embodiments, this predicted 3D image of the product is utilized within the deconvolution methods described herein. In some embodiments, the computational process for simulating the additive fabrication process via TTA-UC utilizes an optical kernel to simulate the series of sequential spatial patterns of light illuminated on the resin. In some embodiments, the computational process for simulating the additive fabrication process via TTA-UC utilizes a diffusion kernel to model the polymerization of the resin that is stimulated by the energy provided by TTA-UC chemistry.

[0116] A computational process can also be utilized to govern the patterning of light. The computational process can instruct a DMD, a SLM, or other means of light patterning to perform a series of curing reactions to yield a 3D nanostructure. For each curing cycle, the computational process can instruct each micromirror to be in a reflective or unreflective state, and / or the duration of time the micromirror is to be in the reflective or unreflective state during a curing cycle. Accordingly, for each curing cycle, a computational process can be utilized to direct a micromirror of the DMD to reflect an amount of light onto a voxel of resin as determined by voxel adjacency, local voxel density, local light intensity received, voxel position within the field, prior curing cycle patterns, subsequent curing cycle patterns, or any other parameter that would affect localized TTA-UC chemistry. For example, a computational process can instruct a spatial and temporal pattern of curing for a curing cycle in which every other micromirror is in the reflective state (e.g., checkered pattern) and / or limit the duration of time each micromirror is in the reflective state in areas of high voxel density. The computational process canfurther adjust the spatial and temporal pattern of curing in adjacent curing cycles by offsetting the pattern in areas of high voxel density to prevent overcuring of adjacent voxels in the z-axis.Computational Systems

[0117] The systems and methods of the current disclosure can be utilized in conjunction with a computational system. The computational system can optionally be in digital connection with or is comprised within the optical system such that it can instruct various functions to be performed by the optical system. The computational system can also perform processes to determine patterns on light to be project on the resin. The process can be utilized to improve curing uniformity. Provided in Fig. 5 is an example of a computational system 500 that can be utilized to perform functions related to 3D fabrication via an optical system 520.

[0118] Computational system 500 comprises a processor system 402 and I / O interface 504 for input and output of data, such as data communicated between computational system 500, optical system 520, and a user interface. As can readily be appreciated, the processor system 502, I / O interface 504, and memory system 506 can be implemented using any of a variety of components appropriate to the requirements of specific applications including (but not limited to) CPUs, GPUs, ISPs, DSPs, wireless modems (e.g., Wi-Fi, Bluetooth modems), serial interfaces, volatile memory (e.g., DRAM) and / or non-volatile memory (e.g., SRAM, and / or NAND Flash). The computational system can optionally be a local computer, remote server, tablet, smart phone, or any other computational device capable of digitally connecting with the optical system, which can be a wireless connection. The computational can optionally be integrated within or otherwise dedicated for the optical system.

[0119] Memory system 506 is capable of storing various data and applications. It is to be understood that the listed data and applications are a representative sample of what can be stored in memory and that various memory systems may store some or all of the various data and applications listed. Further, any combination of data and applications can be stored, and in some implementations, various data and applications can be stored temporarily.

[0120] Computational system 500 can utilize a number of applications stored within memory system 506 to be executed by processor system 502 to perform a set of instructions, which can perform various computational methods as described herein. Applications that can optionally be stored within a memory system 506 include an application for controlling the optical system 510, an application for simulating 3D fabrication 512, and an application for determining light patterning 514. Memory system 506 can further store three-dimensional nanostructure images that can optionally be generated via the application for simulating 3D fabrication 512 and can be utilized by the application for controlling the optical system 510 to fabricate 3D nanoscale products via optical system 520. The application can direct the optical system 520 to emit a light, direct the patterning of light, and focus the light onto a resin to cure the resin to form the nanoscale product. The application for determining light patterning 514 can comprise instructions for determining light patterning that mitigates uneven curing. The application for controlling the optical system 510 can comprise instructions for mitigating overcuring of voxels of resin to be cured that are adjacent to and nearby to voxels of resin to be cured. The various applications can be provided as individual processes or as an ensemble of processes. Real-time data and / or resulting data of fabrication process can also optionally be stored on memory system 506 and / or displayed on a display screen via the I / O interface 504.EXAMPLES

[0121] The various embodiments of the disclosure will be better understood with the several examples described below. Systems and methods for fabricating 3D nanoscale products via TTA-UC are described. In particular, the many examples and results show that parallelized printing of nanoscale products with high resolution can be achieved using an optical system configured to serially impinge planar images of patterned light onto a resin comprising components for performing TTA-UC and components for polymerization.Enhancing Nanofabrication at Scale via 3D Deconvolution Optimization1 1ntroduction

[0122] There is demand for fabricating complex three-dimensional (3D) structures with micro- and nanoscale features in a plethora of fields, ranging from nanooptics, nanophotonics, microfluidics, to biomedicine (see J. Bauer, et al., Science, vol. 380, no. 6648, pp. 960-966, 2023; A. K. Nguyen and R. J. Narayan, Materials Today, vol. 20, pp. 314-322, 2017; and J. L. Sanchez Noriega, et al., Nature Communications, vol. 12, no. 1 , pp. 1-13, 2021 ; the disclosure of which are hereby incorporated by reference). Some promising next-generation micro- and nanoprinting technologies for realizing such applications include dual-color polymerization and light-sheet 3D laser microprinting (M. Regehly, et al., Nature, vol. 588, no. 7839, pp. 620-624, 2020; and V. Hahn, et al., Nature Photonics, pp. 1-8, 2022; the disclosures of which are hereby incorporated by reference). These technologies leverage relatively low powered, continuous-wave lasers as the light source to parallelize the printing of millions of voxels (volume element in 3D) at one time. Nevertheless, these technologies rely on one-photon absorption (1 PA) processes (Fig. 6A, on the left) and require the creation of precise light sheet optically, making them difficult to print structures with nanoscale resolution, and the scalability is really limited by the optics. Resultantly, one of the most well-established techniques for making nanoscale objects with arbitrary architectures is a volumetric 3D printing process with two-photon polymerization (2PP) (see S. Koo, Applied Sciences, vol. 10, p. 8563, 2020; Q. Geng, et al., Nature Communications, vol. 10, no. 1 , pp. 1-7, 2019; L. Zheng, et al., Nanoscale Res Lett, vol. 14, pp. 1-9, 2019; Z. Faraji Rad, et al., Microsystems & Nanoengineering, vol. 7, no. 1 , pp. 1-17, 2021 ; the disclosures of which are hereby incorporated by reference). 2PP has been widely commercialized as a laboratory fabrication tool. The quadratic nature of the two-photon absorption (2PA) (Fig. 6A, on the right) process enables precise spatial control of the polymerization process at a focal point down to nanoscale resolution in all dimensions. However, 2PA has a high threshold requirement; therefore, expensive, high-powered femtosecond pulsed lasers are required for 2PP, resulting in increased cost and reduced print speed to avoid undesired local heating effects. More importantly, it is practically impossible to parallelize the printing process(Fig. 6B) using 2PP due to the requisite high-power densities, making it extremely challenging to use this technology for mass production of 3D nanostructures.

[0123] Triplet-triplet annihilation upconversion (TTA-UC) (Fig. 1 ) is a potential solution to this challenge as a net nonlinear process that can be triggered by low input powers S. N. Sanders, et al., Nature, vol. 604, no. 7906, pp. 474-478, 2022; D. K. Limberg, et al., J Am Chem Soc, vol. 144, pp. 5226-5232, 2022; Z. Wang, et al., Science China Chemistry, vol. 65, no. 11 , pp. 2283-2289, 2022; Z. Wang, et al., Chemical Communications, vol. 57, no. 72, pp. 9044-9047, 2021 ; Z. Luo, et al., The Journal of Physical Chemistry Letters, vol. 14, no. 3, pp. 709-715, 2023; and V. Hahn, et al. ACS Photonics, vol. 10, no. 1 , pp. 24-33, 2022; the disclosures of which are hereby incorporated by reference). Materials that can facilitate TTA-UC convert two low energy photons into one higher energy photon by manipulating excitonic states in molecules. More specifically, sensitizers absorb low- energy photons, generate triplets via spin-orbit coupling, and transfer the triplet states to annihilators through triplet energy transfer. Two annihilator triplet states can then undergo triplet-triplet annihilation to generate one high-energy singlet excited state, which can radiatively decay and emit light at a higher energy than the incident photon energy. Intriguingly, the absorption steps involved in TTA-UC is linear, while the overall process is nonlinear (two photons in, one photon out). Thus, TTA-UC can be triggered by low power light sources, such as continuous-wave lasers or light-emitting diodes (LEDs). At the same time, it displays a quadratic nature / threshold behavior. Therefore, TTA-UC facilitated volumetric 3D printing can theoretically access nanoscale resolution (similar to 2PP in terms of resolution), while the printing process can be easily parallelized and accelerated because of the low-power requirement (similar to dual-color polymerization and light-sheet 3D laser in terms of printing speed). Taken together, TTA-UC can provide exclusive possibilities for rapid, parallelized next-generation nanofabrication for wide- spanning applications.2 Challenges

[0124] In order to parallelize the printing, a digital micromirror device (DMD) (1920 x 1080 pixels, 7.56 pm micromirror pitch) is coupled to a high numerical aperture objective to project millions of voxels simultaneously. The magnification of the objective waschosen to be 20* so that the size of each pixel is already at the diffraction limit, while the projection image size is maximized to ensure the scalability of the technology. Meanwhile, a microstage, in sync with the DMD, is used to move the sample holder of the resin to achieve 3D printing. The setup of the optics and printing schema is summarized in Fig. 7. As an initial estimation, nanofabrication via TTA-UC is about two orders of magnitude faster than 2PP.

[0125] A TTA-UC chemistry nanofabrication method holds the promise of printing intricate 3D structures with complexity. However, when projecting images that feature non-periodic and intricate shapes, the distribution of light across the focal plane becomes non-uniform due to the proximity effects of neighboring pixels. This phenomenon results in varying light intensity across the focal plane, with areas containing more activated pixels experiencing more intense light exposure while others receive less. This issue becomes particularly pronounced in the z-direction, leading to inconsistencies such as over-curing and under-curing within different regions of the printed objects. Algorithms can be employed to correct the projected image, ensuring a nearly uniform distribution of light after optical processing. Previous attempts have utilized the Richardson-Lucy deconvolution method with notable improvements in feature fidelity (A. Orth, et al., Nature Communications, vol. 14, no. 1 , p. 4412, 2023, the disclosure of which is hereby incorporated by reference), although these attempts were for products at microscale and it was unknown whether this deconvolution method would work at nanoscale fabrication. Furthermore, exploring more advanced deconvolution algorithms, such as half quadratic splitting (HQS) and the alternating direction method of multipliers (ADMM), each with unique constraints, presents a promising avenue for improving nanoscale printing.3 Methods3.1 3D Simulation

[0126] Before diving into deconvolution, an optical kernel based on optics setup and a diffusion kernel based on materials properties were simulated as follows.3.1.1 Optical Kernel

[0127] The optical kernel considers the spatial distribution of light intensity as a function of position, which is described by the equation:where / is the light intensity at coordinates (x,y, z), Io is the initial light intensity at the focal point, wo is the beam waist radius in the transverse plane, wzis the axial spread of the beam along the z-axis, a is the absorption coefficient of the medium, and c is the concentration of the absorbing species.

[0128] The optical kernel simulation provides the basis for understanding how light behaves when focused through the nanofabrication system’s optics. The intensity Hx, y z) of light at any point is governed by the initial light intensity Io at the focal point, attenuating as it moves away from the center. The spread of the beam in the transverse plane is given by wo and along the axial direction by wz, respectively. Additionally, the absorption of the medium, characterized by the absorption coefficient a and the concentration c of the absorbing species, also affects the intensity. The exponential terms describe the Gaussian nature of the beam profile in both the lateral and axial dimensions, while the term exp(- c ) accounts for the absorption of light by the medium. At last, I2is used to mimic the generation of the upconverted light triggered by the incident light. This simulation is helpful for predicting the actual light distribution within the resin during the printing process, which directly impacts the resolution and quality of the nanofabricated structures.

[0129] Fig. 8 provides visualization data representing the Point Spread Function (PSF) for a singular pixel both simulated and captured through actual data measurements. The upper diagram depicts the theoretical intensity distribution of light as it interacts with the photopolymer, whereas the lower charts provide an empirical analysis across corresponding axes.3.1.2 Diffusion Kernel

[0130] The diffusion kernel models radical diffusion within the material with respect to the incident light and is given by the equation:where Tfis the diffusion kernel, rd is the radial distance for diffusion, t is the time step in the diffusion process, and D is the diffusion coefficient in the material.

[0131] The diffusion kernel captures the dynamics of the radicals generated by photoinitiator molecules and the resultant polymerization that occurs within the resin during the 3D printing process. Here, D represents the diffusion coefficient, dt is the time step over which diffusion occurs, and rd denotes the radial distance from the source of diffusion. The equation models the diffusion as a continuous process, described by a time-dependent Gaussian distribution. Theterm normalizes the distribution, ensuring the conservation of mass as the radicals spread out. The exp(-.n / 7( Z ))termdescribes how the radicals spread through the resin, affecting the curing process’s uniformity and the eventual resolution of the printed structures.3.1.2 3D Convolution

[0132] This sequential approach— starting with the optical kernel then incorporating diffusion effects — provides a relatively comprehensive simulation of the 3D printing process. It can have precise adjustments based on the actual printing parameters to counteract uneven light distribution and diffusion-induced variations, ensuring the fabrication of high-fidelity nanostructures.

[0133] The Final Kernel, integrating both optical and diffusion effects previously modeled, is applied to the Benchy structure. Benchy is a benchmark structure in the field of 3D printing, since it features various challenging geometries such as overhangs, small details, curves, and flat surfaces. This step is aimed to simulate the intricate interplay of light with the material, mapped across Benchy’s unique geometry. Through this convolution of the composite kernel with Benchy, it becomes possible to forecast how light scattering and molecule diffusion impact the nanoscale print. This predictive insightallows for adjusting printing parameters to achieve precise outcomes, highlighting the importance of the kernel in refining the printing process for accuracy and detail.3.2 3D Deconvolution3.2.1 Richardson-Lucy Deconvolution

[0134] The Richardson-Lucy (RL) deconvolution is an iterative algorithm designed for image restoration, particularly effective in scenarios where the point spread function (PSF) (the final kernel in this case) is known. The essence of RL deconvolution lies in its iterative process, aiming to recover the original image by minimizing the differences between observed images and the convolution of the estimated images with the PSF.

[0135] By applying RL deconvolution, it is possible to correct optical aberrations and improve the precision of the fabrication process. This adjustment can mitigate uneven curing, resulting in high-resolution and high-fidelity nanostructures, which is useful in fields such as in photonics and biomedicine, where even minor inaccuracies can significantly impact the functionality and efficiency of the fabricated devices.

[0136] The implementation of RL deconvolution in the context of 3D nanofabrication involves adjusting the light intensity distribution to achieve uniform polymerization across the printing plane. This correction process mitigates uneven light distribution, improving the likelihood of each voxel within the printed structure is appropriately cured, and avoiding issues like overcuring or undercuring. The ability of RL deconvolution to iteratively refine the light intensity map makes it an invaluable tool in the pursuit of high- precision nanofabrication.3.2.2 Alternative Direction Method of Multiplier

[0137] The Alternative Direction Method of Multipliers (ADMM)

[0017] is a powerful optimization algorithm that breaks down complex problems into simpler subproblems, solving them iteratively to find an optimal solution efficiently (S. Boyd, et al., Foundations and Trends in Machine learning, vol. 3, no. 1 , pp. 1-122, 2011 , the disclosure of which ishereby incorporated by reference). This method is particularly effective in scenarios involving constraints, as it alternates between optimizing different components of the objective function while ensuring that these components adhere to a set of constraints.

[0138] The deconvolution problem can be defined as follows:

[0139] The objective function described,underscores the dual nature of the problem ADMM addresses. Here, (A) represents one aspect of the objective, such as the fidelity of the reconstruction to the observed data, encapsulated bywhere A is a linear operator, i.e., convolution operation in this case, x is the variable representing the estimated image, and b is the observed (blurred and noisy) image.On the other hand, g z) embodies regularization terms that impose certain desired properties on the solution, like sparsity or non-negativity or total variation. The inclusion of g z) = IR+ Z) introduces nonnegativity (Nn) regularization terms to the optimization.

[0140] The Total Variation (TV) prior, denoted in the context of ADMM as TV , is instrumental in promoting sparsity in the gradient of the image. This means it encourages the image to have fewer and simpler transitions, which is especially beneficial in enhancing edge definition and reducing noise. In the realm of nanofabrication, applying the TV prior helps in preserving the sharpness and clarity of nanostructures’ boundaries, ensuring that even at the nanoscale, fabricated structures are defined accurately.

[0141] The Nonnegativity prior Nn ensures that the solution z, and by extension the estimated image x, contains no negative values. This constraint aligns with physical realities in nanofabrication, where negative values for parameters such as light intensity or material density do not make sense. Enforcing nonnegativity helps in maintaining the physical plausibility of the deconvolved image, which is beneficial for accurately guiding the fabrication process.

[0142] The constraints, .? ■■■• s ---- 0 , facilitate the coupling of the two parts of the objective function, allowing ADMM to efficiently find a balance between them. This balance is crucial in nanofabrication, where the goal is to achieve high-fidelity fabrication that accurately reflects the intended design. Fig. 9 summarizes the methodology of the process from simulation to deconvolution.4 Experimental Results

[0143] The results of 3D deconvolution using different algorithms and constraints are presented in Figs. 10 and 11. It is evident that half quadratic splitting (HQS) with TV and ADMM with TV yielded similar solutions. Utilizing ADMM with non-negativity constraints yielded the lowest loss in this example, as defined by the mean square error of Ax- b. This result can be attributed to the advantages of the ADMM algorithm in finding optimal solutions, and the non-negativity constraint that mimics the physical process of 3D printing well because light intensity and material deposition cannot be negative (Y. Xu, et al., Optics & Laser Technology, vol. 169, p. 110119, 2024; and J. M. Long, et al., Applied Optics, vol. 60, no. 27, pp. 8485-8492, 2021 ; the disclosures of which are hereby incorporated by reference). By enforcing non-negativity, the deconvolution process prohibits the generation of physically implausible corrections to the light intensity map.

[0144] When simultaneously adding TV and non-negativity constraints, competing objectives arise. TV constraints aim to minimize variation between adjacent elements (e.g., pixels in image processing), promoting smoothness or sparsity. Non-negativity constraints, on the other hand, ensure that parameters do not drop below zero. When an algorithm attempts to satisfy both constraints, especially in regions where the optimalsolution requires fine balance, it can lead to large updates as the optimizer oscillates between meeting one constraint and then the other.5 Conclusions

[0145] The implementation of ADMM in nanofabrication marks a significant stride towards achieving scalable, high-fidelity manufacturing of nanostructures. By harnessing ADMM, researchers and engineers can transcend traditional limitations, opening pathways for advanced applications across diverse fields, from photonics to biomedicine, where precise and scalable fabrication of nanostructures are desired. For instance, in photonics, a TTA-UC chemistry fabrication technique can be utilized to manufacture more efficient light-manipulating metasurfaces, while in biomedicine, it could facilitate the creation of more precise microfluidic devices.

[0146] Looking forward, 3D micro- and nanoscale fabrication using TTA-UC along with deconcolution optimization holds the promise to revolutionize fabrication in terms of both speed and resolution, rendering it suitable for the industrial production of large-scale, precisely tailored micro- and nanopatterned materials. Moreover, the printing resin can be further developed to accommodate other materials such as glass and ceramics, and can be fine-tuned to incorporate additional desired functionalities, including biocompatibility for chemical and biological applications. In essence, this technology harbors immense potential for applications ranging from constructing metasurfaces for AR / VR purposes to fabricating cell scaffolds fortissue engineering, large-scale production of hydrophobic surfaces, and even the development of photonic integrated circuits, among others.

[0147] The accurateness and precision of the TTA-UC additive fabrication was assessed by attempting to fabricate nanoscale Benchy products. Through trial and error experimentation, a resin comprising Palladium (II) meso-TetraphenylTetrabenzoporphine (PdTPTBP) as sensitizer, 9,10- bis((diisopropyl(octyl)silyl)ethynyl)anthracene (NODIPS-an)annihilator, di(trimethylolpropane) tetraacrylate as polymerizable compound, N,N- dimethylacrylamide (DMAA) as comonomer and cosolvent, bis-(4- methoxybenzoyl)diethylgermanium (ivocerin) as photoinitiator, bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS) as inhibitor of polymerization, and Sudan I as light blocker was found to be able to synthesize nanoscale products. Computational deconvolution of a 3D Benchy image that was generated by computational simulation of the curing process was utilized to set parameters and generate a series of light patterns for fabrication of Benchy.

[0148] Six nanoscale Benchies were fabricated in parallel, highlighting the resolution and scalability of TTA-UC process. The fabrication process was completed in under two minutes, highlighting the speed that that nanoscale products can be manufactured. Provided in Fig. 12A is a field view of the six Benchies. Fig. 12B provides a close-up view of one of the Benchies.

Claims

WHAT IS CLAIMED IS:

1. A resin for three-dimensional fabrication via triplet-triplet annihilation photon upconversion, comprising: a sensitizer, an annihilator, and polymerizable compounds, wherein the sensitizer is paired with the annihilator such that the sensitizer-annihilator pair is configured to upconvert a lower energy wavelength of light into a higher energy wavelength of light capable of stimulating polymerization the polymerizable compounds.

2. The resin of claim 1 , wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n-octyldiisopropyl)silylethynyl- anthracene (NODIPS-an).

3. The resin of claim 1 or 2, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

4. The resin of claim 3, wherein the annihilator has a concentration that is at least 100-fold higher than the sensitizer.

5. The resin of any one of claims 1-4, wherein the polymerizable compounds comprise acrylic based monomers.

6. The resin of claim 5, wherein the acrylic based monomers comprise acrylic acid, acrylamide, vinyl chloride, styrene, epoxide, methacrylate, N-vinyl-2-pyrrolidone, 2- hydroxyethyl, methacrylate pentaerythritol tetraacrylate, trimethylolpropane triacrylate, di(trimethylolpropane) tetraacrylate, dipentaerythritol hexaacrylate, or tetra(ethylene glycol) diacrylate.

7. The resin of any one of claims 1-6 further comprising a metal salt.

8. The resin of claim 7, wherein the metal salt comprises a gold salt or a silver salt.

9. The resin of any one of claims 1-8, wherein the polymerizable compounds comprise silsesquioxane.

10. The resin of any one of claims 1-9, wherein the polymerizable compounds comprise N,N-dimethylacrylamide (DMAA).

11. The resin of any one of claims 1 -10 further comprising a photoinitiator.

12. The resin of claim 11 , wherein the photoinitiator comprises bis-(4- methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

13. The resin of any one of claims 1 -12 further comprising an inhibitor of polymerization.

14. The resin of claim 13, wherein the inhibitor of polymerization comprises: 2, 2,6,6- tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

15. The resin of any one of claims 1 -14 further comprising a light blocker.

16. The resin of claim 15, wherein the light blocker comprises Sudan I, 3,3'- Diethyloxacarbocyanine iodide, or Coumarin 334.

17. The resin of any one of claims 1 -16, wherein the resin is aqueous.

18. The resin of any one of claim 1 -16, wherein the resin is hydrocarbon-based.

19. The resin of any one of claim 1 -18, wherein the resin is not an emulsion.

20. The resin of any one of claim 1 -19, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.

21. A system for performing three-dimensional fabrication via triplet-triplet annihilation photon upconversion, comprising: a resin comprising: a sensitizer, an annihilator and polymerizable compounds; and an optical system configured to serially impinge patterned light onto the resin such that the resin is cured to form a three-dimensional product.

22. The system of claim 21 , wherein the resin and the optical system are configured to yield a nanoscale three-dimensional product.

23. The system of claims 21 or 22, wherein the optical system comprises a light source, a means for patterning light, and a means for relaying and focusing light emitted by the light source onto the resin.

24. The system of claim 23, wherein the means for patterning light comprises an array of pixels, wherein each pixel of the array can individually relay light in a binary manner or modify light intensity such that the pattern of light is formed by the array of pixels.

25. The system of claim 23 or 24, wherein the means for patterning light is a digital micromirror device or spatial light modulator.

26. The system of any one of claims 23-25, wherein the optical system is in digital connection with a computational processor with a memory comprising instructions that directs the means for patterning light to generate patterned light in accordance with the three-dimensional product to be formed.

27. The system of claim 26, wherein the instructions that directs the means for patterning light accounts for adjacency, proximity, or density of light voxels to be relayed and impinged.

28. The system of claim 27, wherein the instructions that directs the means for patterning comprises a deconvolution method to account for adjacency, proximity, or density of light voxels to be relayed and impinged.

29. The system of any one of claims 23-28, wherein the light source is a low-powered light-emitting diode or a continuous-wave laser.

30. The system of any one of claims 23-29, wherein the light source is divergent and the optical system further comprises a collimator.

31. The system of any one of claims 21 -30, wherein the optical system is configured to serially impinge red patterned light.

32. The system of any one of claims 21-30, wherein the optical system comprises a stage or an objective lens configured to move in the z-direction to serially impinge focal planes of patterned light along the z-axis of the resin.

33. The system of any one of claims 21 -32, wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n- octyldiisopropyl)silylethynyl-anthracene (NODIPS-an).

34. The system of any one of claims 21 -33, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

35. The system of any one of claims 21 -34, wherein the polymerizable compounds comprise acrylic based monomers.

36. The system of any one of claims 21 -35, wherein the polymerizable compounds comprise N,N-dimethylacrylamide (DMAA).

37. The system of any one of claims 21-36, wherein the resin further comprises a photoinitiator, wherein the photoinitiator comprises bis-(4- methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

38. The system of any one of claims 21 -37, wherein the resin further comprises an inhibitor of polymerization, wherein the inhibitor of polymerization comprises 2, 2,6,6- tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

39. The system of any one of claims 21-38, wherein the resin further comprises a light blocker, wherein the light blocker comprises Sudan I, 3,3'-Diethyloxacarbocyanine iodide, or Coumarin 334.

40. The system of any one of claims 21 -39, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.

41. A method for three-dimensional fabrication, comprising: providing a resin on a stage, wherein the resin comprises a sensitizer, an annihilator, and polymerizable compounds; and serially performing curing cycles to yield a three-dimensional product, wherein each curing cycle cures a layer of the resin and comprises: impinging, utilizing an optical system, patterned light onto the resin to cure a layer of the resin via energy yielded by triplet-triplet annihilation photon upconversion.

42. The method of claim 41 , wherein each curing cycle further comprises: emitting light from a light source; relaying, utilizing the optical system, the emitted light to a means for patterning light; generating the patterned light utilizing the emitted light via the means for patterning light; and relaying and focusing, utilizing the optical system, the patterned onto the resin.

43. The method of claim 42, wherein the means for patterning light comprises an array of pixels, wherein each pixel of the array can individually relay light in a binary manner or modify light intensity such that the pattern of light is formed by the array of pixels.

44. The method of claim 42 or 43, wherein the means for patterning light is a digital micromirror device or spatial light modulator.

45. The method of any one of claims 42-44, wherein the optical system is in digital connection with a computational processor with a memory comprising instructions that directs the means for patterning light to generate patterned light in accordance with the three-dimensional product to be formed.

46. The method of claim 45, wherein the instructions that directs the means for patterning light accounts for adjacency, proximity, or density of light voxels to be relayed and impinged.

47. The method of claim 46, wherein the instructions that directs the means for patterning comprises a deconvolution method to account for adjacency, proximity, or density of light voxels to be relayed and impinged.

48. The method of any one of claims 42-47, wherein the light source is a low-powered light-emitting diode or a continuous-wave laser.

49. The method of any one of claims 42-48, wherein the light source is divergent, each curing cycle further comprises: passing the emitted light or the patterned though a collimator.

50. The method of any one of claims 41 -49, wherein the patterned light is red light.

51. The method of any one of claims 41-50, wherein the optical system comprises a stage or an objective lens configured to move in the z-direction to serially performing curing cycles along the z-axis of the resin.

52. The method of any one of claims 41 -51 , wherein the three-dimensional product is of nanoscale.

53. The method of any one of claims 41 -52, wherein the sensitizer is Palladium (II) meso-Tetraphenyl Tetrabenzoporphine (PdTPTBP) and the annihilator is (n- octyldiisopropyl)silylethynyl-anthracene (NODIPS-an).

54. The method of any one of claims 41 -53, wherein the annihilator has a concentration that is at least 10-fold higher than the sensitizer.

55. The method of any one of claims 41-54, wherein the polymerizable compounds comprise acrylic based monomers.

56. The method of any one of claims 41 -55, wherein the polymerizable compounds comprise N,N-dimethylacrylamide (DMAA).

57. The method of any one of claims 41 -56, wherein the resin further comprises a photoinitiator, wherein the photoinitiator comprises bis-(4- methoxybenzoyl)diethylgermanium (ivocerin), phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide (BAPO), ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (TPO-L), or 2,2-dimethoxy-2-phenylacetophenone (DMPA).

58. The method of any one of claims 41 -57, wherein the resin further comprises an inhibitor of polymerization, wherein the inhibitor of polymerization comprises 2, 2,6,6- tetramethylpiperidin-1 -yl)oxidanyl (TEMPO) or bis(2,2,6,6-tetramethyl-4-piperidyl-1 -oxyl) sebacate (BTPOS).

59. The method of any one of claims 41 -58, wherein the resin further comprises a light blocker, wherein the light blocker comprises Sudan I, 3,3'-Diethyloxacarbocyanine iodide, or Coumarin 334.

60. The method of any one of claims 41 -59, wherein the sensitizer and the annihilator are not solubilized within nanocapsules, micelles, or liposomes.

Images