Systems and methods for high-resolution 3D nanofabrication

Abstract

A system and method for nanofabrication that may enable complex three-dimensional nanostructures, comprising: curing a gel scaffold; patterning the gel scaffold with a photosensitive patterning material, using light to pattern the photosensitive patterning material into the gel scaffold to create the shape of a desired construct (i.e., create a latent pattern of the shape of the desired construct); depositing a build material onto the latent pattern, thereby creating a construct; and reducing the construct to a desired size. The system and method exploit the photosensitivity of photosensitive molecules and high-precision optical positioning for the fabrication of high-resolution constructs. The system and method may enable the fabrication of nanoconstructs of simple and complex material designs, where the constructs can implement multiple distinct build materials and gradients of build materials.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 193,321, filed May 26, 2021, which is incorporated by reference herein in its entirety.

[0002] FIELD OF THEINVENTION The present invention relates generally to the field of nanofabrication, and more specifically to new and useful systems and methods for three-dimensional nanofabrication. [Background technology]

[0003] Nanofabrication is a technique that has become an important part of our technology in the last century. It has become particularly important in the fields of photonics, microprocessor development, microelectromechanical systems, and is accelerating other aspects of modern technology such as biotechnology and microfluidics.

[0004] Current nanofabrication techniques are primarily derived from planar processes, which build two-dimensional layers on top of each other to produce three-dimensional objects. While this method may work for some constructs, planar processes do not work well as strictly three-dimensional fabrication techniques in many aspects (e.g., for constructs that lack a support to build on), and for this reason are considered 2.5D fabrication techniques. Additionally, current nanofabrication techniques have difficulty producing objects made of multiple materials or that incorporate construction gradients. Finally, methods derived from planar processes suffer from registration errors resulting from imperfectly aligned successive steps.

[0005] Thus, there is a need in the field of nanofabrication to create new and useful systems and methods for rigorous three-dimensional nanofabrication capable of implementing multiple materials and gradients. The present invention provides such new and useful systems and methods. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of an exemplary system. [Diagram 2] 1 is a list of exemplary monomers that make up the gel scaffold. [Diagram 3] This is a depiction of the xanthene core. [Figure 4] This is the general formula for the polymethine core. [Diagram 5] This is the general formula for the cyanine structure. [Figure 6] This is the general formula for the sulfonated dole-squaraine structure. [Figure 7] This is the general formula for benzothiazole squaraines. [Figure 8] 1 is a list of general formulas for exemplary chromophores. [Figure 9] 1 is a flow chart of an exemplary method. [Figure 10] 4 is a flowchart of a second exemplary method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The following description of embodiments of the invention is not intended to limit the invention to those embodiments, but rather to enable any person skilled in the art to make and use the invention.

[0008] 1. Overview The systems and methods for nanofabrication may enable complex three-dimensional nanostructures using a variety of materials. The systems and methods may employ a process of patterning a gel scaffold with photosensitive molecules, using light to pattern the photosensitive molecules into the gel scaffold to create a desired construct shape, thereby creating a latent pattern of the desired construct shape, binding a build material to the latent pattern, thereby creating the construct, and shrinking the construct to a desired size. The systems and methods exploit the photosensitivity of the photosensitive molecules and high-precision optical positioning for the fabrication of high-resolution constructs. The systems and methods may enable the fabrication of nanoconstructs of simple and complex material designs, where the constructs can implement multiple distinct build materials and gradients of build materials.

[0009] The systems and methods offer a wide range of use cases in diverse fields that can benefit from nanofabrication. The systems and methods can be implemented to build simple and complex tools in many general fields such as electronics, optics, and mechanics. The systems and methods can be used in the production of nanofabricated electrical, optical, and / or mechanical components and combinations thereof.

[0010] Because the systems and methods enable the construction of nanoarchitectures using gradients and multiple materials, the systems and methods may be particularly useful in the fields of optics and photonics. The systems and methods may be implemented for the construction of waveguides, prisms, diffraction gratings, conventional lenses, Fresnel lenses, GRIN lenses, metalenses, lens arrays, zone plates, inverse design structures, photonic crystals, linear and circular polarizers, optical isolators, reflective optical elements (such as parabolic reflectors), optical resonators, lasers, and many other tools and objects, as well as integrated combinations thereof.

[0011] The systems and methods may provide many potential benefits. The systems and methods are not limited to always providing such benefits, and are presented only as exemplary representations of how the systems and methods may be useful. The list of benefits is not intended to be exhaustive, and other benefits may additionally or alternatively exist.

[0012] The systems and methods offer the benefits of rigorous three-dimensional nanofabrication, without the need for two-dimensional layering for fabrication.

[0013] The systems and methods may utilize high precision light beams to enable equally precise positioning of build materials for the creation of high resolution constructs.

[0014] Additionally, the systems and methods allow for the initial building of "larger" structures before reducing the structures, providing even better building accuracy.

[0015] The system and method provide the additional benefit of enabling multi-material construction. Through the use of ligand-binding latent patterning, the system and method enable the use of multiple materials for fabrication.

[0016] The systems and methods allow for the implementation of concentration gradients of materials within a construct, i.e., the density of a material can be varied throughout the construct by implementing light positioning directed throughout the material.

[0017] 2. System 1, the system for the nanofabrication platform includes a gel scaffold 110 that provides a framework for constructing the nanofabrication, a latent patterning material 120 that is photosensitive and selectively binds to the gel scaffold, thereby providing the architecture of the nanofabrication, and a build material 130 that binds to the latent patterning material, thereby providing the compositional material for the nanofabrication. The system functions as a nanofabrication assembly that enables the fabrication of desired constructs (i.e., nanofabrication) composed of the desired build materials, potentially with nanometer precision.

[0018] The system has many use cases and implementations. In certain embodiments, the system may further comprise a light-based nanofabrication platform, and a light source may be incorporated to guide / enable the nanofabrication. In this manner, the system may function as an enhanced photonic lithography device, allowing the system to build high precision film structures in addition to building complex three-dimensional structures (unconstrained on any side). In these embodiments, the system may further comprise a light source (e.g., a laser), which may be directed with high precision onto any region of the gel scaffold 110. In variations in which the system functions as an enhanced photolithography device, the system may further comprise a mask, which may be positioned to allow, block, or redirect light to reach certain portions of the gel scaffold 110, depending on the desired nanofabrication implementation.

[0019] As used herein, component names may be used to refer to components at any level of scale. For example, gel scaffold 110 may be used to refer to a single molecule of the gel scaffold, some set of molecules that make up all or part of the gel scaffold, or the entire gel scaffold. Thus, any reference to gel scaffold 110 may refer to any of these scales of the gel scaffold. The particular scale of the components is provided by the context, as appropriate.

[0020] The system may include a gel scaffold 110. The gel scaffold 110 functions as a multi-dimensional scaffold for nanofabrication. The gel scaffold 110 provides a scaffold network for attachment of a latent patterning material 120. As used herein, the term gel scaffold 110 may be used to refer to each individual gel scaffold molecule, a group of gel scaffold molecules, all of the gel scaffold molecules, or any subset therein.

[0021] The gel scaffold 110 may include any known or future "gel" material. As used herein, a gel material may refer to any colloidal solid (or semi-solid) polymer network, including gel materials that allow for the diffusion (active or passive) of other system components throughout the gel scaffold. Depending on the embodiment, the gel scaffold 110 may be composed of one or more gel materials. Examples of possible gel materials include agarose, acrylates (e.g., polyacrylates), methacrylates, acrylamides, and silicones.

[0022] In many variations, the gel scaffold 110 is non-reactive with other system components other than the latent patterning material 120. Alternatively, the gel scaffold 110 can be reactive to other components. For example, in one variation, the system can further include a masking component, to which the gel scaffold can selectively bind. This selective binding (e.g., to the masking component) can block the gel scaffold and prevent binding of the latent patterning material 120.

[0023] In many variations, the gel scaffold 110 may include a cross-linked (i.e., cross-linked) polymer network. The gel scaffold 110 may have inherent or implemented physical or covalent cross-links as part of the multi-dimensional gel scaffold. For example, a polyacrylate gel may have an N,N'-methylene-bis(acrylamide) cross-linker. In some variations, the polymer network is generated from one or more vinyl monomers. The vinyl monomers may be acrylic or acrylamide monomers bearing side groups that may or may not be inert to reaction with other system components other than the latent patterning material 120. In some variations, the gel scaffold 110 is covalently cross-linked via radical polymerization with diacrylamide monomers. In other variations, dimethacrylamides, diacrylates, dimethacrylates, divinyl ethers, and suitable hydrophobic or hydrophilic divinyl monomers may be used to generate the covalent cross-links.

[0024] In some variations, the gel scaffold 110 may be composed of hydrophobic or hydrophilic vinyl monomers. As used herein, the term "hydrophilic monomer" describes a monomer that, upon polymerization, results in a polymer that is soluble in water or capable of absorbing at least 10% by weight of water under ambient (i.e., 20° C.) conditions. Similarly, as used herein, the term "hydrophobic monomer" describes a monomer that, upon polymerization, results in a polymer that is not soluble in water or capable of absorbing at least 10% by weight of water under ambient conditions. As shown in FIG. 2, examples of suitable monomers may include methacrylates, acrylates, styrenes, methacrylamides, acrylamides, and silyl-containing monomers.

[0025] The gel scaffold 110 may include side groups. More specifically, a gel scaffold molecule or group of gel scaffold molecules may have one side group or multiple side groups. The side groups function to provide attachment sites for the latent patterning material 120. The side groups may be any desired side group that can be used for attachment of the latent patterning molecules 120. Potential examples of side groups include, but are not limited to, carboxylic acids, sulfonic acids, phosphates, primary amines, quaternary amines, amides, hydroxides, and / or sulfonates. Depending on the embodiment, the gel scaffold 110 may incorporate one or multiple side groups. Multiple side groups may allow attachment of multiple types of latent patterning materials 120, other components (e.g., masking components), and / or may provide for binding with different binding strengths (e.g., to allow for gradient effect binding).

[0026] In some variations where the gel scaffold 110 includes a vinyl monomer, the vinyl monomer may have a side group. Examples of side groups include carboxylic acid, sulfonic acid, phosphate, primary, secondary, tertiary, and quaternary amines, hydroxyl, thiol and thioesters, amides, and acetates. As used herein, side groups such as "carboxylic acid," "sulfonic acid," or "phosphate" include free acid moieties and the corresponding metal salts of the acid moiety, as well as ester derivatives of the acid moiety, including but not limited to alkyl esters, aryl esters, and acyloxyalkyl esters. In some variations, the gel may be composed of naturally occurring polymers such as agarose, alginates, or other polysaccharides. In some variations, the gel may be composed of charged monomers such as acrylic acid, 2-(dimethylamino)ethyl methacrylate, sulfonated monomers, or others.

[0027] In some variations, the gel scaffold 110 may contain functional groups that allow for the attachment of the latent patterning material 120. The functional groups may be incorporated as part of the backbone of the gel scaffold 110 or as side groups of the gel scaffold. The functional groups may be susceptible to radical oxidation. In some variations, the functional groups may be introduced into the gel scaffold 110 by radical polymerization of suitable vinyl monomers. The polymerization may be conventional (e.g., no control over the polymer molecular weight) or may be controlled, where the molecular weight of the resulting polymer that constitutes the gel scaffold 110 is narrow and well-defined. Examples of controlled free radical polymerizations (cFRP) include reversible addition-fragmentation chain-transfer (RAFT) polymerization, nitroxide-mediated polymerization (NMP), and atom transfer radical polymerization (ATRP). In other variations, the functional groups may be introduced by chemical modification of the gel scaffold 110. Examples of functional groups that may be incorporated into the gel scaffold 110 include carboxylic acid, amide, or primary amine, or hydroxyl groups introduced by polymerization of acrylic acid and acrylamide monomers. Other examples of functional groups that the gel scaffold 110 may contain include phosphate, quaternary amine, amide, hydroxide, cyclic anhydride, and succinimide, and / or sulfonate.

[0028] The system may include a latent patterning material 120. The latent patterning material 120 serves as a "latent pattern" for nanofabrication, i.e., a temporary construct that provides the architecture of the nanofabrication. In some variations, it may be desirable to retain the latent patterning material 120, so it can be performed for a longer period of time if necessary. Additionally, the latent patterning material 120 may function to bind the build material 130 in place, providing a function similar to a mold. The latent patterning material 120 (also referred to as a chromophore) may include latent patterning molecules, each molecule may be composed of any desired type or subgroups of types. As used herein, the term latent patterning material 120 may be used to refer to each individual latent patterning molecule, a group of latent patterning molecules, all of the latent pattern molecules, or any subset thereof. Thus, each latent patterning molecule 120 or group of latent patterning molecules may have a gel binding region that binds to the gel scaffold 110, and a material binding region that binds to the build material 130. Additionally, latent patterning molecules 120 can be photosensitive such that latent patterning activity (e.g., gel binding) can be turned on or off by light. Each latent patterning molecule or group of latent patterning molecules can include other components as desired according to the embodiment.

[0029] In some variations, the system may include multiple latent patterning materials 120. Different latent patterning materials 120 may be distinguished by the base molecule itself or by their specific regions (e.g., building material binding regions). For example, different latent patterning materials may bind to different types of building materials 130 (e.g., a first latent patterning material binds to diamond and a second latent patterning material binds to azide). In another example, different latent patterning materials 120 may have different activations. For example, two photosensitive latent patterning materials 120 may have different photosensitive regions. In one embodiment, a first latent patterning material absorbs blue light and a second latent patterning material binds to yellow light. In another photosensitive embodiment, a first latent patterning material 120 that is bound to a first building material 130 may be capable of binding to a gel scaffold 110 upon photoactivation, and a second latent patterning material that is bound to a second building material may lose its ability to bind to the gel scaffold upon photoactivation.

[0030] The latent patterning material 120 can be photosensitive. That is, the latent patterning material 120 can include photosensitive molecules and / or photosensitive regions that allow the latent patterning material to absorb certain wavelengths of the electromagnetic spectrum. In some variations, the photosensitivity of the latent patterning material 120 is connected to the conjugation chemistry of the latent patterning material. The photosensitive regions act as photosensitive regions of the latent patterning material 120, and light of the appropriate wavelength can be used on the photosensitive segments to activate or deactivate the gel bonds of the latent patterning material. Depending on the embodiment, each latent patterning molecule can have one or multiple photosensitive regions, with each photosensitive region allowing for different activation (e.g., one light bandwidth can allow the molecules to gel bond and another bandwidth can allow the molecules to release the gel).

[0031] The photosensitive regions that are cured by the chemicals can be sensitive to any desired wavelength or bandwidth of electromagnetic radiation. In some variations, the photosensitive regions can have sensitivity to bandwidths at or near the visible spectrum (e.g., blue light, UV light, red light, infrared light, etc.). The photosensitive regions can have broad or narrow bandwidths as needed and cured by the chemicals. The photosensitive regions can include any photochemical. In many variations, the type of latent patterning material 120 can cure the chemicals of the photosensitive regions. Examples of latent patterning materials include derivatives of xanthene dyes (e.g., fluorescein, rhodamine, eosin), BODIPY, cyanine, phthalocyanine, anthracene, coumarin, porphyrin, squaraine, squarylium, and azobenzene. Depending on the embodiment, the latent patterning material 120 can include any one or combination of these or other photochemicals.

[0032] The latent patterning material 120 may include one or more gel-binding regions. The gel-binding regions may function to enable binding of the latent patterning material to the gel scaffold 110. In many variations, the gel-binding regions may bind to side groups of the gel scaffold 110. In other variations, the gel-binding regions may non-specifically bind the gel scaffold 110 (e.g., a charged / polar gel-binding region binds to a charged gel scaffold), i.e., gel-binding regions (or gel-binding sites). The gel-binding regions may include photosensitive regions, which may include any molecule that may enable or disable gel binding. Depending on the type of latent patterning material 120, light activation may enable activation or deactivation of the latent patterning material bonds.

[0033] The latent patterning material 120 may include a material binding region. The material binding region may function to enable binding of the building material 130. In some variations, the material binding region may include a conjugated chemical (or conjugated moiety) that serves to enable binding of the building material 130, and the conjugated chemical may enable binding of the building material at the building material coordination site. Alternatively, the latent patterning material 120 may not have a conjugated chemical segment. In one example, the building material 130 or the building material coordination site may directly bind to the latent patterning material 120.

[0034] In some variations, the material binding region may be considered to be "activated" at all times. Alternatively, the material binding region may have active and inactive structures, such that the binding of the building material 130 may be activated or deactivated. In one example, the building material binding region may be linked to a photosensitive region of the latent patterning material 120, such that the binding of the building material 130 may be turned on or off by a band of light at or near the appropriate wavelength. In another example, the material binding region may have an allosteric site, such that binding of a compound to the allosteric site may turn the building material binding on or off. The material binding region may include any molecule that may enable or improve the binding of the building material 130 to the latent patterning material 120. Examples of chemicals that may be incorporated into the material binding region include primary amines, N-hydrosuccimide (NHS) and NHS esters, carboxylic acids including their free acids and corresponding metal salts, thiols / sulfhydryls, cyclic anhydrides such as succinic anhydride and maleimide anhydride, alkenes, alkynes, azides, tetrazines, tetrazoles, nitrones, isocyanides, isocyanates, dibenzocyclooctyne (DBCO), biarylazacyclooctynone (BARAC), dimethoxyazacyclooctyne (DIMAC), monofluorinated isopropyl alcohols, and the like. Examples include cyclooctynes, including cyclooctyne (MOFO) and difluorinated (DIFO) cyclooctytin, biotin, avidin / streptavidin, proteins / antibodies / enzymes, oligonucleotides and nucleic acids, including deoxyribonucleic acid (DNA), ribonucleic acid (RNA), locked nucleic acid (LNA), peptide nucleic acid (PNA), lipids / hydrocarbons / fluorocarbons, and dendrimers.

[0035] In some variations, the latent patterning material 120 may include non-xanthene chromophores. As shown in FIG. 3, xanthene chromophores have a basic structure of two benzene rings connected with an internal ring between them with an oxygen. In these variations, the latent patterning material 120 may include structures that do not include a xanthene base structure. Examples of classes of non-xanthene chromophores include polymethines (e.g., cyanines, squaraines), naphthalenes, coumarins, oxadiazoles, anthracenes, pyrenes, phenoxazines, acridines, tetrapyrroles, and dipyrromethenes (e.g., BODIPY), and azadipyrromethenes (Aza-BODIPY), as shown in FIG. 4-8, and derivatives thereof (shown in FIG. 8).

[0036] Polymethine dyes and their derivatives include polymethine dyes in which the chromophore units are conjugated C=C systems (either open or in a ring) with an odd number of methine groups with functional groups at each end of the chain with the general formula shown in Figure 4. Examples of polymethine dyes and their derivatives include cyanines (hemicyanines, streptocyanines, Cy3, Cy3.5, Cy5, Cy5.5, Cy7, Cy7.5, merocyanines) and their derivatives (e.g., sulfonated derivatives). Cyanines are characterized by a conjugated π system bridged by two nitrogen atoms with delocalized charges and have the general cyanine structure shown in Figure 5.

[0037] Squaraine dyes and their derivatives include symmetrical and asymmetrical indole-based squaraines bearing a sulfonate group at the 5-position of the indole ring, where X1, X2=O, S, or a combination of the two, and having the general formula shown in Figure 6; symmetrical and asymmetrical benzothiazole-based squaraines bearing a sulfonate group at the 5-position of the indole ring, where X1, X2=O, S, or a combination of the two, and having the general formula shown in Figure 7. Here, the reactive substituent of the benzothiazole-based squaraines, e.g., NHS, amine, -COOH, azide, alkyne, epoxide, etc., is attached to the 1-position of the benzothiazole ring (R8 or R9) via an alkyl spacer of length (CH2)n (n≧5). The term "symmetrical" means that each pair of R9 and R8 groups (see structure) is the same, such that the pattern of substituents on each benzothiazole ring in the compound is the same. The term "asymmetric" means that at least one of R8 and R9 is different from their corresponding substituents on the other benzothiazole groups, such that the pattern of substituents on each benzothiazole ring is different. The term "symmetric" for symmetric and asymmetric benzothiazole-based squaraines means that each pair of R8, R10, and R11 groups (structure below) is the same, such that the pattern of substituents on each indole ring in the compound is the same. The term "asymmetric" means that at least one of R8, R10, and R11 is different from their corresponding substituents on the other indole ring, such that the pattern of substituents on each indole ring is different.

[0038] In some variations, the latent patterning material 120 includes reactive groups, which may include any one or combination of latent patterning material moiety components. For example, the reactive groups may comprise gel-binding regions and photosensitive regions of the latent patterning material. The reactive groups may function by selectively binding the gel scaffold 110 through photoreaction of the latent patterning material and a reactive intermediate. In this manner, the reactive groups function to provide an additional step of control over how the latent patterning material 120 may be patterned on the gel scaffold 110 by leveraging interactions between the reactive groups and the reactive intermediates. In many instances, the reactive intermediates include small molecules capable of radical generation (e.g., oxygen). In these variations, the nanofabrication system may have additional components that allow for control of thermodynamic variables during operation of the system. Examples of these additional system components include enclosed volumes (e.g., controlled volumes that restrict the flow of solids, liquids, and / or gases into and out of the nanofabrication platform), heating elements (e.g., to control reaction temperatures), and controlled inlet / outlet of reactive intermediates (e.g., to control the concentration of reactive intermediates within the system).

[0039] The building material 130 can function as the material from which the nanofabrication constructs are made. The building material 130 can be bonded to the latent patterning material 120. In some variations, the building material 130 bonds directly to the latent patterning material 120. In other variations, the building material 130 bonds to material binding regions of the latent patterning material 120. In other variations, the building material 130 bonds directly to the latent patterning material 130 through coordination chemistry of the building material coordination sites. In other variations, the building material 130 bonds to material binding regions of the latent patterning material 120 through coordination chemistry.

[0040] The particular type of build material 130 may be implementation specific. In some variations, the build material 130 may include multiple distinct types of build materials (e.g., titanium dioxide and gallium phosphide). The only requirement for the build material 130 is a coordinating chemistry that allows for bonding of the latent patterning material 120. Since the build material 130 is the material composition of the final product, the bonding requirements of the build material 130 can typically be addressed by selection of a latent patterning material 120 with material bonding regions with appropriate chemistries. Examples of types of build materials 130 include metal chalcogenides, where the metal is Ge, Al, Sn, Pb, Sb, Bi, Ga, In, Tl, Cu, or combinations thereof, and chalcogens, such as S, Se, Te, or combinations thereof; pnictides, and the resulting pnictide polymorphs of Group XIII elements, such as B, Al, Ga, In, and Tl, or combinations thereof, and pnictogens, such as N, P, As, and Sn; metal oxides having an empirical formula MxOy, where M is a metal, such as Bi, Sn, Cr, Co, Mn, Mo, Ti, Zn, Zr, Cu, Fe, Ni, Eu, Dy, Pr, Ce, Sm, or La; and carbon and its allotropes, silicon, germanium, tin, silicon carbide (3C, 4H, 6H, -SiC), silicon germanium, and silicon tin.

[0041] The build material 130 may include coordination sites. The coordination sites serve as regions that bind to the latent patterning material 120 (i.e., appropriate coordination chemistry that binds to the latent patterning material). In many variations, the coordination site binding is highly selective, allowing for binding of only certain atoms or molecules. Alternatively, the coordination sites may be more general, allowing for binding of families of molecules (e.g., chalcogenides). Examples of possible coordination chemistries include, but are not limited to, silyl, sulfhydryl / thiolamine / ammonia, carboxylic acid, iodide, bromide, chloride, fluoride, thiocyanate, nitrate, azide, oxalate, water, nitrite, isothiocyanate, acetonitrile, pyridine, ethylenediamine, 2,2'-bipyridine, 1,10-phenathroline, nitrile, triphenylphosphine, cyanide, and carbon monoxide. Since the purpose of the coordination sites is to bind to the latent patterning material 120, the coordination sites may additionally or alternatively have other chemical compositions. In variations in which multiple building materials 130 or multiple latent patterning materials 120 are incorporated, each building material 130 may have one or more separate coordination sites (comprising different chemistries), with each separate coordination site potentially binding to a particular separate latent patterning material. In some variations, the coordination chemistry may be incorporated directly onto the latent patterning material 120. In these variations, the building material 130 may then bind to the latent patterning material 120 using the coordination chemistry incorporated onto the latent patterning material.

[0042] In some variations, the system may further include a light source. The type of light source may vary depending on the embodiment. The light source functions to photoactivate / deactivate photosensitive regions of the latent patterning material 120. Depending on the embodiment, this may allow for binding (or release) of the latent patterning material 120 to the gel scaffold 110 and / or binding of the latent patterning material to the build material 130.

[0043] The light source may include one (or more) light emitters (e.g., one, two, three diodes) of the same or different types (e.g., incandescent, halogen, fluorescent, laser, LED, etc.). The light source preferably has sufficient precision so that the light emission from the light source can be directed with sufficient precision to precisely photoactivate / deactivate the latent patterning material 120 to pattern the desired structures. In variations involving a mask, a broad scattering light source may be sufficient for the desired implementation, while in non-masked nanofabrication the light source may require nanometer precision.

[0044] Depending on the embodiment, the light source may emit EM waves of any desired wavelength, bandwidth, etc. Additionally, depending on the embodiment, the light source may comprise a single or multiple optical emitters such that each emitter can emit EM waves at a desired wavelength with a desired bandwidth.

[0045] The light source may further enable high throughput patterning. This may be part of the basic operation of the nanofabrication platform and / or part of the lithography implementation. In high throughput patterning, the light source may have a separate mode of operation that allows for fast and complex light pulsing modes. For example, the light source may be capable of emitting light pulses in a rapid manner such that the time between pulses is shorter than the excited triplet state lifetime of the latent patterning material 120. Depending on the implementation, the triplet excited state lifetime may range from milliseconds (ms) to picoseconds. Thus, depending on the implementation, it is preferable that the light source is capable of emitting light pulses with an appropriate separation between each light pulse. In one example, the latent patterning material 120 includes Cy5, which has been reported to have an excited triplet state lifetime of approximately 10 μs. In this example, the light source may emit pulses with a separation between each pulse of less than 10 μs.

[0046] As part of an enhanced photon lithography embodiment, the light source may include a suitable light source for the embodiment. For example, in a single photon lithography embodiment, the light source may include a single laser (e.g., a diode). In another example, in a two-photon lithography embodiment, the light source may include two lasers (e.g., gas lasers). That is, depending on the embodiment, single photon or multi-photon lithography techniques may be incorporated for gel bonding. Depending on the embodiment, the light source may enable any type of single photon lithography, such as contact lithography, projection lithography, interference lithography, or phase mask lithography, tomographic lithography, and / or the light source may enable any type of multi-photon lithography, such as point-scanning multi-photon lithography, multi-focus multi-photon lithography, holographic multi-photon lithography, or temporally focused multi-photon lithography.

[0047] As part of an enhanced photonic lithography embodiment, the system may further include a mask. The mask functions to define the boundaries of the areas requiring photoactivation. That is, the mask may be located between the gel scaffold 110 and the light source such that the mask can selectively block and reflect (or in some variations change its phase) the light emitted from the light source, thereby preventing or reducing the light source from photoactivating the latent patterning material 120 in certain areas of the gel scaffold 110. In some variations, a mask equivalent may be implemented. For example, in some variations (e.g., projection lithography or holographic lithography), a digital equivalent of a mask may be incorporated, where the digital equivalent mask may induce partial or complete blocking, reflection, or phase change of the light passing through it. Examples of digital mask equivalents include a digital mirror device (DMD), a spatial light modulator (SLM), and a phase mask (e.g., a hologram). Additionally, exposure time or number of mask elements can be used to control the light dose, thus allowing more or less patterning in a given area. In another variation, the system can be used in lithography implementations where the light source can illuminate from more than one angle, using one or more masks.

[0048] In many variations, light intensity can also be incorporated for patterning, particularly pattern gradients. Light intensity can be modified either directly at the light source or through the implementation of a mask. In this manner, a mask can be incorporated to create a gradient pattern. In one example, a physical mask with varying density (e.g., increasing density along one axis) can be incorporated. A spatial pattern gradient can then be created in which less irradiated areas bind less potential patterning material. In another example, a digital mask can be incorporated. In the same manner, a gradient pattern can be created by allowing a reduction in the transmission of light through a digital mask.

[0049] In some variations, the nanofabrication platform, and more specifically, the gel scaffold 110, may be attached to a surface. In these variations, the system further comprises binding groups that allow the gel scaffold 110 to be attached to a surface.

[0050] In many variations, the binding group is comprised of a silane, which serves to functionalize the surface. This may include silanization of the substrate (e.g., glass) using a monosilane coupling agent to form a stable siloxane film to which the polymer adheres via covalent or electrostatic bonds. Examples of silanes that may include binding groups include alkylsilanes and aminosilanes, such as (3-aminopropyl)triethoxysilane (APTES), (3-aminopropyl)trimethoxysilane (APTMS). Through the implementation of the binding group, the system can adhere to a vast number of surfaces of relatively any shape or roughness (e.g., flat surfaces, curved surfaces, uneven surfaces, etc.). Examples of surfaces to which the gel scaffold 110 can adhere include glass, silicon, metals / alloys, and hard plastics (e.g., HDPE, polypropylene, acrylic).

[0051] In one example of a silane linking group, the linking group can be a monosilane (e.g., a trialkoxysilane), having the general formula R'-(CH2) n Monosilanes with -Si(OR)3, where R' is a functional group capable of binding to the gel scaffold 110, n > 1, and R is an alkyl group. Examples of R include Me, Et, or propyl. Examples of R' include protonated amines, either primary, secondary, tertiary, or quaternary (with permanent charge) for electrostatic attachment of acrylic gels.

[0052] In another example of a silane linking group, the linking group can be a silane reagent having the general formula R'-Ln-Si(OR)3, where R is an alkyl group (methyl, ethyl, etc.), L is a stable organic linker of length n made from a stable bond such as CC, CO, or CN, and R' is a functional group capable of step-wise or chain-growth polymerization, such that it is capable of forming a covalent bond to the gel scaffold 110 in the presence of a radical initiator or polymerization catalyst.

[0053] In another variation, the binding group is a functional group having an opposite charge to the gel scaffold 110. The functional group having an opposite charge to the gel scaffold 110 may allow for the formation of hydrogen bonds with the gel scaffold or may be polymerized or covalently incorporated into the gel scaffold. For example, the desired surface may be coated with a synthetic or natural cationic macromolecule / polymer that carries an opposite charge to the gel scaffold 110 to facilitate electrostatic binding of the gel scaffold to the functionalized surface. Examples of such macromolecules include polycations such as poly-l-lysine, polyethyleneimine (PEI), polymers containing quaternary amine salts, polymers of dimethylaminoethylmethacrylate (DMAEMA), and the like.

[0054] In another variation, the binding groups may constitute the entire polymer network, i.e., referred to herein as a surface-bound polymer network. The surface-bound polymer network may be embedded within and / or around the gel scaffold 110. In some variations, the surface-bound polymer network may include an alkene. The surface-bound polymer network may be incorporated on or into the gel scaffold 110 by washing the monomeric components of the polymer network with appropriate thermodynamic conditions to allow polymerization of the monomeric components. In some variations, the surface-bound polymer network may already be capable of binding to the desired surface (e.g., when a charged surface-bound polymer network is incorporated to bind to a surface with an opposite charge). Alternatively, the surface-bound polymer network may be further functionalized (e.g., treated with silane or plasma) to bind to the desired surface.

[0055] Since the system can encompass a wide range of embodiments, a set of exemplary system variations that are illustrative of the scope of the invention are presented below.

[0056] In system variant A1, a system for a nanofabrication platform includes a gel scaffold 110, a latent patterning material 120 that selectively binds the gel scaffold and includes a non-xanthene-based chromophore, and a build material that includes a coordination site that binds to the latent patterning material. In one example, the non-xanthene chromophore includes a compound from the list consisting of polymethine dyes, polymethine dye derivatives, squaraine dyes, squaraine dye derivatives, BODIPY-based dyes, and BODIPY-based dye derivatives. Examples of polymethine dyes and polymethine dye derivatives include cyanines (hemicyanines, streptocyanines, Cy3, Cy5, Cy5.5, Cy7, Cy7.5, merocyanines) and their derivatives (e.g., sulfonated derivatives). Examples of squaraine dyes and squaraine dye derivatives include symmetrical and asymmetrical indole-based squaraines, and symmetrical and asymmetrical benzothiazole-based squaraines bearing sulfonate groups. Other examples of non-xanthene dyes include naphthalenes, coumarins, oxadiazoles, anthracenes, pyrenes, phenoxazines, acridines, tetrapyrroles (eg, ring-open or cyclic tetrapyrroles), and dipyrromethenes (eg, BODIPY), and azadipyrromethenes (Aza-BODIPY).

[0057] As part of system variant A1, the gel scaffold 110 is selected from the group consisting of agarose, acrylate, methacrylate, acrylamide, and silicone.

[0058] As part of the system variant A1, the building material 130 is selected from the group consisting of metal chalcogenides, where the metal is Ge, Al, Sn, Pb, Sb, Bi, Ga, In, Tl, Cu, or a combination thereof, and chalcogens, such as S, Se, Te, or a combination thereof. Pnictides, and the resulting pnictide polymorphs of Group XIII elements, such as B, Al, Ga, In, and Tl, or a combination thereof, and pnictogens, such as N, P, As, and Sn. Metal oxides having an empirical formula MxOy, where M is a metal, such as Bi, Sn, Cr, Co, Mn, Mo, Ti, Zn, Zr, Cu, Fe, Ni, Eu, Dy, Pr, Ce, Sm, or La; and carbon and its allotropes, silicon, germanium, tin, silicon carbide (3C, 4H, 6H, -SiC), silicon germanium, and silicon tin.

[0059] In system variant A2, a system for a nanofabrication platform includes a gel scaffold 110, a photosensitive latent patterning material 120 that includes reactive groups, and a build material 130 that includes coordination sites that bind to the latent patterning material. The reactive groups selectively bind the gel scaffold through photoreaction of the latent patterning material and the reactive intermediate. The system functions to enable improved gel binding by exploiting interactions between the reactive groups and the reactive intermediate. In this A2 variant, the system may further include a control volume, the control volume functions to contain the gel scaffold, the control volume being sufficiently enclosed to enable control of the reactive intermediate concentration. In many examples, the reactive intermediate includes a small molecule capable of radical generation. In some examples, the reactive intermediate includes oxygen. In this example embodiment that includes a control volume, the control volume may further include a controlled inlet (e.g., to enable oxygen to be pumped in) and a controlled outlet (e.g., to maintain internal pressure). In some embodiments of system A1, the latent patterning material comprises a polymethine dye or a polymethine dye derivative. In other embodiments of system A1, the latent patterning material comprises a squaraine or a squaraine derivative. In other embodiments of system A1, the latent patterning material comprises a BODIPY-based dye or a BODIPY-based dye derivative.

[0060] In system variant A3, the system comprises an enhanced lithographic fabrication platform and includes a gel scaffold 110, a photosensitive latent patterning material 120, a build material that includes coordination sites that bind to the latent patterning material, and a light source capable of providing extremely short light pulses. More specifically, the light source is capable of providing short light pulses (of an appropriate wavelength), the light pulses being separated by an amount of time that is shorter than the excited triplet state lifetime of the latent patterning material 120. System variant A3 functions to exploit the excited triplet state of the latent patterning material 130 to provide a high throughput fabrication system.

[0061] That is, the light source is preferably operable to provide light pulses on the order of milliseconds to picoseconds depending on the excited triplet state of the latent patterning material. As part of the system's functionality, the system may have an implosion fabrication mode of operation in which the light source provides light pulses separated by a time shorter than the excited triplet state lifetime of the latent patterning material 120. In one example, the latent patterning material includes sulfo-Cy5, which has a triplet excited state lifetime on the order of about 10 μs. In this example, in the implosion fabrication operating mode, the light source provides pulses spaced apart by less than 10 μs. As part of an enhanced lithographic fabrication platform, system variant A3 may include a pulsed light source (e.g., a titanium sapphire or erbium doped fiber laser source) and / or components that allow for the creation of bursts of multiple pulses. In a second example, the latent patterning material may include a squaraine or squaraine derivative with a triplet excited state lifetime in the range of approximately 1 ps to 250 ps. In this example, in the implosion fabrication mode of operation, the light source provides pulses having a pulse separation on the order of about 0.1 ps to 100 ps, ​​i.e., the light source provides pulses having a pulse separation less than the triplet excited state lifetime of the squaraine or squaraine derivative.

[0062] In system variant A4, a system for a nanofabrication platform includes a gel scaffold 110, a photosensitive latent patterning material, a build material that includes coordination sites that bind to the latent patterning material, and binding groups that allow the gel to be attached to a surface. The A4 system variant functions to allow nanofabrication on a surface; that is, through the binding groups, the gel scaffold 110 can be attached to a surface during the nanofabrication process.

[0063] In many variants of the A4 system, the linking group consists of a silane and / or siloxane. The silane and / or siloxane may allow for silanization of the surface. In one embodiment of the A4 system, the linking group is of the general formula R'-(CH2) n The A4 system includes a monosilane having the formula Si(OR)3, where R' is a functional group capable of binding to the gel scaffold, R is an alkyl group, and n > 1. In another example of the A4 system, the binding group includes a silane reagent having the general formula R'-(Ln)-Si(OR)3, where R is an alkyl group, L is a stable organic linker having length n consisting of CC, CO, or CN bonds, and R' is a functional group capable of step- or chain-growth polymerization such that it is capable of forming a covalent bond with the gel scaffold.

[0064] In another variation of the A4 system, the binding group comprises a functional group that has an opposite charge to the gel scaffold 110 .

[0065] As part of some embodiments, such as system variants A2, A3, and A4, the latent patterning material 120 may include a non-xanthene chromophore. In a first embodiment of these variants, the non-xanthene chromophore includes a polymethine dye. In a second embodiment of these variants, the non-xanthene chromophore includes a polymethine dye or a polymethine dye derivative. Alternatively, in system variants A2, A3, and A4, the latent patterning material 120 may consist of at least one compound from the group of polymethines (e.g., cyanines, squaraines, naphthalenes, coumarins, oxadiazoles, anthracenes, pyrenes, phenoxazines, acridines, tetrapyrroles, and dipyrromethenes (e.g., BODIPY, and azadipyrromethenes (Aza-BODIPY)).

[0066] As part of some embodiments, such as system variants A1, A3, and A4, the latent patterning material 120 can include reactive groups that selectively bind the gel scaffold 110 through photoreaction of the latent patterning material and a reactive intermediate. The reactive intermediate can include a small molecule capable of radical generation. In one embodiment of system variants A1, A3, and A4, the reactive intermediate includes oxygen.

[0067] As part of some embodiments, such as system variants A1, A2, A3, and A4, the gel scaffold may include a hydrated gel (i.e., a swollen gel). In these embodiments, the system may further include a mechanical spacer or may be spin-coated under controlled conditions to set the thickness of the gel scaffold 110. These embodiments may be particularly useful for photolithography and may further be incorporated as part of an enhanced lithography embodiment. In one embodiment, the swollen gel is implemented as part of a photolithography process. In a second embodiment, the swollen gel is implemented as part of a multiphoton lithography process.

[0068] As part of some embodiments, such as system variants A1, A2, and A3, the system may further include a binding group that allows the gel scaffold 110 to adhere to a surface. In one example of these system variants, the binding group comprises a silane or siloxane.

[0069] As part of some embodiments, such as system variants A1, A2, A3, and A4, the system may further include a lithography mask. The mask can function to block or reduce light on designated areas of the gel scaffold. The mask can be a physical mask or a digital mask made up of pixels that blocks or reduces light. In one embodiment of systems A1, A2, A3, and A4, the mask includes a digital micromirror device. In a second embodiment of systems A1, A2, A3, and A4, the mask includes a spatial light modulator. In a third embodiment of systems A1, A2, A3, and A4, the mask includes a phase mask.

[0070] 3. Method As shown in Figure 9, a method for three-dimensional nanofabrication includes patterning a gel S120, dispersing a patterning material throughout the gel, binding a build material to the patterning material, thereby building a three-dimensional creation, and reducing the three-dimensional nanofabrication. Patterning the gel S120 further includes dispersing a patterning material throughout the gel S122, and photoactivating the patterning material at discrete locations within the gel S124, thereby causing selective binding of the patterning material to the gel at the discrete locations. In some variations, patterning the gel S120 may further include removing unbound patterning material. The method functions in creating a desired composition / object comprised of a desired build material within a desired gel matrix. More specifically, the method provides a means for building the scaled-up version of the desired fabrication onto a light-sensitive patterning material (through photoactivation) and then assembling the build material onto the photoactivated patterning material. Furthermore, the method allows the entire structure to be scaled down to the appropriate size. In some variations, as shown in FIG. 10, the method further includes curing the gel S110. The hardening of the gel matrix provides a scaffold network for the patterning process. Depending on the embodiment, the method may include any one, multiple, or all steps of the method described above. The method may be performed using the system described above, but may also be performed using any general system that meets the appropriate system criteria.

[0071] The method can be implemented in a wide range of fields. Numerous compositions / objects with a wide range of functionalities and building materials can be fabricated incorporating the method. The method can be particularly useful in fields requiring high precision nano-sized materials (i.e., nanotechnology). Examples include the fields of fabrication of advanced and basic electronic primitives (e.g., resistors, capacitors, inductors, solenoids, transformers, diodes, antennas, resonators, electromagnets, memristors, etc.), the fields of manufacturing optical and basic optical devices (e.g., waveguides, prisms, diffraction gratings, Fresnel lenses, GRIN lenses, metalenses, lens arrays, zone plates, inverse design structures, gain media, photonic crystals, linear polarizers, circular polarizers, optical isolators, reflective optics, optical resonators), and the fabrication of advanced and basic mechanical devices (e.g., gears, ratchets, springs, linear motors, rotary motors, structural gratings, mechanical metamaterials, ball and socket joints, hinges, chains, mechanical switches). Additionally, the method can be implemented for the fabrication of more complex objects such as complex motors, microchips, lasers, LEDs, diffractive neural networks, and the like.

[0072] In some variations, the method includes curing the gel S110. Curing the gel S110 functions in creating a multidimensional scaffold for nanofabrication. Alternatively, the method may utilize an existing gel or other multidimensional scaffold for nanofabrication. The gel may be of any desired type that is non-reactive with the other components. In many variations, the gel type may depend on the embodiment. Examples of gels include agarose, acrylates (e.g., polyacrylates), methacrylates, acrylamides, and silicones.

[0073] In some variations, curing the gel may include adhering the gel to a surface. Adhering the gel to a surface may function to enable the functionality of the method on the surface. That is, all method steps (e.g., irradiating the gel, patterning the gel, shrinking the gel, etc.) may be performed while the gel is attached to the surface. Additionally, the surface may have a unique shape that may affect construct construction. Adhering the gel to a surface may include incorporating binding groups (e.g., silane, siloxane) that bond to the desired surface, bond with the gel matrix, or are incorporated into the gel matrix.

[0074] In some variations, the additional polymer network may be cured. Curing the additional polymer network may occur at any time after the initial curing of gel 110 (e.g., before, during, or after patterning gel 120), before, during, or after depositing build material 130, or before, during, or after shrinking material 140. Curing the secondary polymer network may function to help stabilize the patterning material and / or the build material.

[0075] In some embodiments, the additional polymer network may be incorporated as a binding group. In these embodiments, curing the additional polymer network may incorporate a polymer network (i.e., a surface-bound polymer network) into and / or on the gel that may enable the gel to bond to a surface. Curing the surface-bound polymer network may include washing the gel with the monomeric components under suitable thermodynamic conditions so that the monomeric components polymerize to form the surface-bound polymer network. Alternatively, any other method of polymer incorporation to harden the surface-bound polymer network may be performed. Depending on the embodiment, the surface-bound polymer network may already be cured and bonded to the desired surface (e.g., complementary polarity or charge of the surface-bound polymer network and the surface). Additionally or alternatively, the surface-bound polymer network needs to be prepared for surface bonding. In one example, the surface-bound polymer network is functionalized with silane to enable glass bonding. Alternatively, the surface-bound polymer network is functionalized with plasma.

[0076] Block S120, which includes patterning the gel, functions to pattern (i.e., map out) the desired fabrication by binding a patterning material to the gel. Patterning the gel S120 includes dispersing the patterning material throughout the gel S122 and photoactivating the patterning material S124. The patterning material is preferably a photosensitive material such that photoactivating the patterning material allows for a change in the interaction between the gel and the patterning material (e.g., binding, debinding). In its simplest form, areas of the gel with the photoactivated patterning material can become fixed in place or bound to the gel. By specifically photoactivating the patterning material in a manner that traces the shape of the desired fabrication, a mapping of the desired fabrication can be created with the bound patterning material. The unbound latent patterning material can then be washed away, leaving behind the desired patterning of the fabrication. For complex structures, patterning the gel S120 and its sub-steps may be repeated multiple times until the final desired mapping of the fabrication is produced.

[0077] The patterning material (also referred to as a chromophore, conjugated material, or dye) used in patterning the gel S120 can be of any desired type or types of material. That is, the patterning material can be a single compound or multiple distinct compounds that are patterned onto the gel. The compound or compounds can be patterned or dispersed throughout distinct regions of the gel. The type or types of patterning material and their dispersion can be embodiment specific.

[0078] The patterning material may include single or multiple functional molecules or molecular segments, where each single or multiple molecules provides the patterning material with a functional desired property (e.g., phosphorescence, photosensitivity, binding sites, increased / decreased solubility, etc.) As used herein, any functional property may be referred to as a "segment," where a segment enables a particular functional property and may equally refer to a portion of a molecule, a single molecule, or multiple molecules without loss of generality.

[0079] The patterning material may include a reactive group segment. The reactive group segment includes a reactive group that is utilized to enable the binding of the building material. The reactive group segment may include any molecule that may enable the binding of the patterning material to the building material. In some variations, the reactive group segment may be turned on or off (e.g., by allosteric binding or photoactivation). In some variations, the reactive group segment is always active. In some variations, the reactive group segment bond may only be activatable such that binding occurs only after the reactive group segment is activated (e.g., by photoactivation). In an alternative variation, the reactive group segment may be active from the start such that the building material can directly bind to the patterning material. Activating the reactive group segment (e.g., through photoactivation) may then release the building material so that it can be washed away, allowing the building material to be patterned by "erasing".

[0080] In some variations, the number of reactive groups can be amplified by depositing a material containing multiple reactive groups. In these variations, the method can further include amplifying the reactive groups by depositing a reactive group rich compound. Amplifying the reactive groups can function to increase the rate and / or ability of the patterning material to bond to the gel. In some examples, depositing the reactive group rich compound includes depositing a poly(amido)amine.

[0081] In some variations, the patterning material does not include reactive group segments or includes suboptimal reactive group segments (i.e., reactive group segments that do not allow sufficient binding with the desired building material). In these variations, the method may further include priming the patterning material. Priming the patterning material serves to add or modify reactive group segments to the patterning material so that the building material can better bind to the patterning material. Priming the latent patterning material may include creating or obtaining the desired molecular sequence and binding it to the patterning material. Alternatively, priming the patterning material may include using molecular techniques to modify current reactive group segments into the desired sequence. Alternatively, priming the patterning material may include using recombinant techniques to create DNA precursors of the desired molecular sequence prior to producing the protein.

[0082] The reactive group segment may include any molecule that allows for building material attachment. Examples of conjugation segments include primary amines, NHS, carboxylic acids, sulfhydryls, maleimides, alkenes, alkynes, azides, tetrazines, tetrazoles, difluorinated cycloocytne (DIFO), DIBO, BARAC, DBCO, biotin, avidin / streptavidin, proteins (e.g., antibodies / enzymes), nucleic acids (e.g., DNA, RNA, LNA, PNA), lipids (e.g., hydrocarbons, fluorocarbons), and dendrimers.

[0083] The patterning material may include a photosensitive segment. The photosensitive segment may be operatively connected to the gel-bonded segment. The photosensitive segment serves as a photosensitive region of the patterning material, and light of an appropriate wavelength may be used to activate or deactivate the bonds of the gel-bonded segments. Thus, the photosensitive segment allows for patterning the gel S120 by photoactivating the patterning material. In some alternative variations, the photosensitive segment may allow for the bonding or debonding of reactive group segments.

[0084] In some variations, multiple distinct types of latent patterning materials (e.g., two distinct patterning material types, each one associating with a different build material through a distinct coordination site) may be incorporated. These variations may have patterning materials with photosensitive segments where each type of patterning material is sensitive to a distinct light bandwidth, such that patterning of a first patterning material by photoactivation with a first light bandwidth will not affect patterning of a second patterning material by photoactivation with a second light bandwidth. This may allow for patterning the gel with distinct patterning materials S120, such that each material can later be bonded to a different build material.

[0085] The photosensitive segment may be "photo" sensitive to any desired bandwidth of electromagnetic radiation that will cure with the chemicals of the photosensitive segment. In some variations, the photosensitive region may have sensitivity to optical bandwidths at or near the visible spectrum (e.g., blue light, UV light, red light, infrared light, etc.). The sensitivity may have a broad or narrow bandwidth as desired and cured with the chemicals. In variations where the gel bonded segment may be both activated and deactivated, the photosensitive segment may be photosensitive to multiple distinct regions of the visible spectrum. For example, red light may be used to activate the gel bond and green light may be used to prevent or reverse the gel bond.

[0086] The photosensitive segment may include any chemical that allows photosensitivity, i.e., photochemicals. Examples of possible photochemical molecules that may constitute the photosensitive segment include, but are not limited to, fluorescein, rhodamine, cyanine, squaraine, naphthalene, coumarin, oxadiazole, anthracene, pyrene, phenoxazine, acridine, tetrapyrrole, and dipyrromethene (e.g., BODIPY), and azadipyrromethene (Aza-BODIPY). Depending on the embodiment, the photosensitive segment may include any one or combination of these or other photochemicals.

[0087] The patterning material may include a gel-binding segment. The gel-binding segment may function in binding the gel. The gel-binding segment may include any molecule that may bind to the gel or allow for the binding of the gel. In some variations, the gel-binding segment may be always active, such that the gel-binding segment of the patterning material always binds to the gel. In one variation, the gel-binding segment may be turned on or off (e.g., by allosteric binding or photoactivation). In some variations, the gel-binding segment may be "positively activatable", such that binding occurs only if the gel-binding segment is activated. In a second variation, the gel-binding segment may be "negatively activatable", such that the latent patterning material can initially bind to the gel, but through activation (e.g., photoactivation), the patterning material becomes unable to bind to the gel and is decoupled from the gel. In a third variation, the gel-binding segment may be both positively and negatively activatable, such that the patterning material may be able to change conformation so that it can bind to and be decoupled from the gel. For example, the gel-bonded segment may be connected to one or more photosensitive segments that are sensitive to different bands of light. In this example, photoactivation with a first band of light (e.g., blue light) can activate the gel-bonded segment such that it can bond to the gel, and photoactivation with a second band of light (e.g., red light) can deactivate the gel-bonded segment such that it cannot bond to the gel.

[0088] In some variations, the method may include utilizing a reaction for gel attachment with the patterning material. Depending on the reactive group segment, photoreaction of the patterning material (e.g., chromophore) and a reactive intermediate promotes gel attachment via a radical reaction. By controlling the concentration of the reactive intermediate, the rate at which the patterning material attaches to the gel can be manipulated.

[0089] Block S122, which includes dispersing the patterning material throughout the gel, can be a component of patterning the gel S120. Dispersing the patterning material throughout the gel S122 functions to provide a foundation for creating nanofabrication. In some variations, dispersing the patterning material throughout the gel S122 deposits the patterning material homogenously throughout the gel. This can be done by flowing the patterning material throughout the gel until the gel is saturated with the patterning material. In negatively activatable variations, the gel-binding segments of the patterning material bind to the gel up to the saturation level. In positively activatable variations, the gel-binding segments need to be activated for gel binding and can therefore freely diffuse throughout the gel.

[0090] Alternatively, dispersing the patterning material throughout the gel S122 may allow for a non-homogeneous deposition of the patterning material. For example, unidirectional flow (e.g., using microfluidics) may allow for a higher concentration of deposition on the side of the gel where the material enters the gel and a lower concentration on the side where the material exits, creating a gradient of the patterning material. Through the use of directed flow, any desired gradient deposition may be implemented depending on the gel geometry. By restricting the flow for a certain period of time, a latent patterning material concentration gradient may be created throughout the gel. Gradient deposition of the patterning material may allow for the formation of gradients in the final nanofabrication (e.g., in the construction of basic optical devices such as lenses).

[0091] Block S124, which includes photoactivating the patterning material, can be a component of patterning the gel S120. Photoactivating the patterning material s124 functions in mapping the shape of the structure of the fabrication with the bound patterning material. That is, the bound patterning material can thus define the boundaries of the shape and structure of the desired fabrication within the diffused unbound latent patterning material. Additionally, the different concentrations of the patterning material can also define the boundaries of a gradient in the desired fabrication. Depending on the embodiment, the boundary definition can include the general shape / structure of the desired fabrication, or a negative (e.g., mold) of the general shape / structure of the desired fabrication. In a preferred variation, the unbound patterning material can be washed away. Photoactivating the patterning material S124 includes irradiating with a focused light or light beam of an appropriate wavelength such that the desired photosensitive segments of the patterning material are activated. Photoactivating the patterning material S124 can include both the spatial focus of the light beam and the exposure time. The spatial focus of the light beam can be used to physically shape the desired artifact (or its shadow volume). The exposure time of the light beam (i.e., the length of time the beam is focused on a given area) can be used to "shape" the concentration of material in a given area, i.e., to allow deposition (or removal) of different concentrations of patterning material in a given area.

[0092] The effectiveness of photoactivating a patterning material can depend greatly on how the light is focused on the patterning material. By taking advantage of the triplet excited state lifetime of the patterning material, the efficiency of photoactivating the patterning material can be significantly improved. In some variations, photoactivating the patterning material includes providing a pulse of light separated by an amount of time shorter than the triplet excited state of the patterning material. Depending on the patterning material being implemented, this pulse rate can vary. For chromophores, the lifetime of the triplet excited state is typically between microseconds and picoseconds.

[0093] In a first, positively activatable variation, photoactivating the patterning material S124 may enable bonding of the patterning material to the gel (e.g., at the gel-bonded segment). In a second, negatively activatable variation, photoactivating the latent patterning material S124 may enable release of the latent patterning material from the gel (e.g., at the gel-bonded segment).

[0094] As part of a first variation, photoactivating the patterning material S124 can be performed simultaneously with dispersing the patterning material throughout the gel S122 such that the photoactivated regions containing the latent patterning material bond to the gel (e.g., at activated gel-bonding segments) and other non-activated patterning material flows or is washed away.

[0095] In a first embodiment of the first variant (the positively activatable variant), block S124 is performed such that the regions that correspond to the actual design of the fabrication are photoactivated, i.e., only the regions that define the boundaries of the fabrication's shapes and structures are photoactivated, and thus the patterning material remains bound only to the regions that define the boundaries of the fabrication's shapes and structures.

[0096] In a second negative embodiment of the first variant (positively activatable variant), block S124 is performed such that the areas that do not match the actual design of the production are photoactivated. That is, only the negative areas, i.e., the areas that do not match the production, are photoactivated. In this second embodiment, the latent patterning material bonds to the negative form of the desired production, thus defining the boundaries of the production's mold.

[0097] As part of the second negatively activatable transformation, the patterning material may be initially dispersed throughout the gel such that the gel is fully or partially saturated and bound. Photoactivating the patterning material S124 may then be performed to release unwanted patterning material, which may then be washed away, if desired.

[0098] In a first implementation of the second variant (negatively activatable variant), block S124 is performed such that the regions that do not match the actual design of the fabrication are photoactivated. That is, only the negative regions, i.e., the regions that do not match the fabrication, are photoactivated, thereby releasing the patterning material from the negative regions. In this first implementation, the patterning material remains bound to the regions that define the boundaries of the desired fabrication, and the negatively photoactivated latent patterning material is washed away.

[0099] In a second negative embodiment of the second variant (negatively activatable variant), block S124 is performed such that the areas that correspond to the actual design of the fabrication are photoactivated. That is, only the areas that define the boundaries of the fabrication's shape and structure are photoactivated, thereby releasing the latent patterning material that defines the boundaries of the fabrication's shape and structure. In this second embodiment, the patterning material remains bound to the negative areas, i.e., areas that do not correspond to the fabrication, thus defining the boundaries of the fabrication's mold.

[0100] In "simpler" fabrication embodiments, block S124 may be performed only once, such that the fabrication structure is fully mapped onto the patterning material. Depending on the complexity of the fabrication (e.g., multiple material fabrications, complex 3D structures, gradients, etc.), photoactivating the patterning material S124 may include a series of photoactivation steps, where certain regions of the latent patterning material are bond-activated / bond-deactivated multiple times to form both positive and / or negative regions of the fabrication. In some variations, patterning the gel S120 may additionally include alternating steps of depositing the build material S130.

[0101] Photoactivating the patterning material S124 may additionally be used to provide a framework for creating gradients in the fabrication. Photoactivating the patterning material S124 preferably includes both spatial and temporal activation of the patterning material. By irradiating a particular region of the patterning material with a light beam for a longer period of time and / or with a greater intensity, a higher concentration of the latent patterning material is photoactivated in a given region, thereby allowing a higher concentration of the patterning material to bind to one region of the gel. Gradient implementations may be particularly useful for the fabrication of lenses and prisms. By implementing increasing / decreasing periods of photoactivation over a given spatial region, a concentration gradient of bound patterning material can be created.

[0102] In some variations, patterning the gel S120 may include incorporating lithography techniques. Incorporating lithography techniques may serve to provide a more precise and tailored method for photoactivating the patterning material S124, where the lithography techniques help determine how and where the patterning material is photoactivated. Incorporating lithography techniques may provide precision up to nanometers in patterning the gel with the patterning material. Depending on the embodiment, incorporating this lithography technique may include photolithography techniques (also referred to as one-photon lithography), multi-photon lithography (also referred to as two-, three-, four-photon lithography, etc.), or some combination of lithography techniques for photoactivating the latent patterning material S124. Additionally, depending on the desired embodiment, the incorporated lithography techniques may be used to create either positive or negative patterning or both. Depending on the implementation, incorporating lithographic techniques may include the use of pre-fabricated "masks."

[0103] In some variations, incorporating a lithography technique may include incorporating a single-photon lithography technique. A single-photon lithography technique may include using a photon emitter (i.e., a single light source such as an LED) to photoactivate S124 the latent patterning material. Depending on the embodiment, any single-photon lithography technique or techniques may be incorporated. Examples include contact lithography, projection lithography (e.g., direct light projection or tomographic lithography), interference / holographic lithography, and phase mask lithography.

[0104] In one embodiment, incorporating lithography techniques includes incorporating contact lithography. In this embodiment, a prefabricated mask is implemented (the mask can be fabricated prior to implementation or as part of the embodiment). The mask can then be placed in contact with or in close proximity to the photosensitive substrate such that light passing through the light pattern passes through the mask and is transferred onto the photosensitive substrate. This can be accomplished by illumination from either a point source, a focused source, a diffuse source, or a parallel source. Depending on the embodiment, the light source can be incorporated from any desired angle.

[0105] In another embodiment, incorporating lithography techniques may include incorporating projection lithography. In this embodiment, a prefabricated mask may be implemented (the mask may be fabricated prior to implementation or as part of the embodiment). Alternatively, a digital equivalent mask (e.g., maskless lithography, micromirror device, spatial light modulator, or phase mask) may be incorporated. A mask may be used to create a 2D or 3D pattern of light that is projected onto a photosensitive substrate through the use of refractive, diffractive, or reflective optical elements. The optical elements may magnify, reduce, or directly transfer the light pattern. Projection may be accomplished either by illuminating the mask completely at once, or by gradually scanning the illuminated area (e.g., a line) on the mask and / or on the photosensitive substrate. Examples of projection lithography include extreme ultraviolet lithography, immersion lithography, and direct light projection and projection tomography (methods for creating 3D patterns by projecting light from multiple angles).

[0106] In some variations, incorporating lithographic techniques includes incorporating interference lithography (also referred to as holographic lithography). These variations involve the interference of two or more coherent light beams to generate periodic patterns in 2D or 3D. This interference can be generated by splitting and recombining the beams through the use of reflective, refractive, or diffractive optical elements.

[0107] In some variations, incorporating lithographic techniques includes incorporating phase mask lithography. In this embodiment, a prefabricated mask (the mask can be fabricated prior to implementation or as part of the embodiment) or other structure can be implemented. The use of a mask or other structure can be used to modulate the phase of light using 2D or 3D structures to project a holographic image that is patterned into a photosensitive substrate.

[0108] In some variations, incorporating a lithography technique may include incorporating a multiphoton lithography technique (also referred to as a direct laser writing technique). A multiphoton lithography technique may include using light to photoactivate (or deactivate) S124 a patterning material, utilizing two (or more) photon absorption to excite a photosensitive segment. Depending on the embodiment, any number of photons may be used in multiphoton lithography to pattern a photosensitive substrate, i.e., two-photon, three-photon, or n-photon excitation. Depending on the embodiment, any multiphoton lithography technique or techniques may be incorporated. Examples include point-scanning multiphoton lithography, multifocal multiphoton lithography, holographic multiphoton lithography, and time-focused multiphoton lithography.

[0109] In some variations, incorporating lithographic techniques includes incorporating point-scanning multiphoton lithography, which may include mechanically, electro-optically, or acousto-optically scanning a single point of multiphoton excitation into a photosensitive substrate.

[0110] In some variations, incorporating lithographic techniques includes incorporating multifocal multiphoton lithography, which may include using a diffractive optical element or lens array to generate multiple foci of multiphoton excitation, which are then projected onto a photosensitive substrate and scanned mechanically, holographically, electro-optically, or acousto-optically to generate a pattern.

[0111] In some variations, incorporating lithographic techniques includes incorporating holographic multiphoton lithography. Holographic multiphoton lithography may include using digital elements such as DMD or SLM located at the Fourier plane of an optical element to enable the projection of multiphoton excitation patterns (i.e., holograms) onto a photosensitive substrate. These projected holograms can be mechanically, electro-optically, or acousto-optically scanned within the substrate, as well as modified to generate arbitrary patterns.

[0112] In some variations, incorporating lithography techniques includes incorporating time-focused multiphoton lithography. Time-focused multiphoton lithography may include using light pulses to create a pattern, which are defocused and then refocused in time within a photosensitive substrate. The light pattern is generated by using either a mask or a digital mirror device, which may be fully or partially illuminated for a complete frame pattern, such as with a line / point of light scanned across the surface to transfer the pattern to the photosensitive material.

[0113] In some variations, hardening the gel can include hardening a swollen gel (i.e., a hydrated gel). In these variations, the method can further include mechanically deforming (e.g., compressing) the swollen gel prior to and during photoactivating the gel S124. Mechanical deformation of the swollen material concurrent with photoactivation can serve to provide higher resolution patterning on uncompressed surfaces.

[0114] Block S130, which includes depositing a build material, functions to create the physical structure of the fabrication. Depositing a build material S130 includes flowing a desired build material throughout the gel. As the build material flows / disperses throughout the patterning material, it bonds to the latent patterning material, thereby creating the physical structure of the fabrication. Depending on the build material, the positional concentration of the patterning material, and the implemented flow of the build material throughout the latent patterning material, the build material can be deposited homogeneously or heterogeneously on the patterning material. In one variation, the build material bonds directly to the patterning material. In a second variation, the build material bonds to reactive group segments on the patterning material. In a third variation, the coordination segments on the build material bond directly to the patterning material. In a fourth variation, the coordination segments on the build material bond to reactive group segments on the patterning material.

[0115] The building materials may include coordination segments. The coordination segments may function as molecules that can bind to one or more desired building materials. In preferred variations, the coordination segment bonds are highly selective, allowing for binding of only specific molecules. In some variations, the coordination segment bonds may be activatable. That is, the binding ability of the coordination segment may be turned on or off (e.g., by allosteric binding or photoactivation). In some variations, the coordination segment bonds may be activatable, such that binding occurs only if the coordination segment is activated.

[0116] The coordination segments may include any desired chemical composition. In many variations, the coordination segments may include embodiment-specific chemical compositions so that the coordination segments can bind to specific building materials. Examples of coordination segment compositions include, but are not limited to, silane / siloxane, sulfhydryl / sulfur, amine / ammonia, carboxylic acid, iodide, bromide, chloride, fluoride, thiocyanate, nitrate, azide, oxalate, water, nitrite, isothiocyanate, acetonitrile, pyridine, ethylenediamine, 2,2′-bipyridine, 1,10-phenanthroline, nitrile, triphenylphosphine, cyanide, and carbon monoxide. Since the purpose of the coordination segments is to bind to building materials, the coordination segments may additionally or alternatively have other chemical compositions. In variations in which multiple building materials are incorporated, each type of building material may have one or more separate coordination segments, with each coordination segment type potentially binding to a separate patterning material or a separate reactive group segment of a patterning material.

[0117] In some variations, the building material does not initially include a coordination segment. In these variations, depositing the building material S130 can include attaching a coordination segment to the building material. Attaching the coordination segment to the building material functions to enable or improve ligand attachment to the patterning material.

[0118] In some variations, depositing the build material may further include adding or modifying the chemical of the reactive group segment of the patterning molecule. Adding or modifying the chemical of the reactive group segment of the patterning molecule may function to improve build material bonding. If deemed necessary, adding or modifying the reactive group segment may be performed multiple times until a reactive group segment with the desired bonding capability is obtained.

[0119] In some variations, bonding the build material to the patterning material includes depositing a non-metal enhancer. The non-metal enhancer can function to allow the build material to grow on the patterning material. In this manner, the build material can grow outward, allowing the build material sites to grow outward and connect to one another. In some implementations, this can allow the build material to form and solidify before, during, or after shrinking the gel. Depending on the implementation, the method can further include depositing the build material until it bridges adjacent patterning material bond sites. Depositing the build material can include depositing metallic and / or non-metallic build materials, allowing either type to grow until the build material bridges adjacent patterning material bond sites. In some variations, the build material, metallic and / or non-metallic, can be allowed to grow over adjacent patterning material bond sites. In one example, the non-metallic enhancer includes a chalcogenide.

[0120] Depositing the build material S130 may be in a manner in which the build material is deposited as a concentration gradient. That is, certain areas may have a higher concentration of build material compared to different areas of the fabrication. The concentration gradient of the build material may be implemented through a non-uniform distribution of the patterning material throughout the gel, and therefore a non-uniform distribution of the build material that binds to the patterning material. The concentration of the build material throughout the fabrication may be modified as desired through the patterning material concentration, the activated patterning material concentration, or the flow of the build material.

[0121] Depending on the embodiment, depositing the build material S130 may include depositing a single type or multiple types of build materials. Depending on the embodiment, depositing the build material S130 may occur simultaneously with or after patterning the gel S120. In some embodiments, depositing the build material S130 may occur multiple times (e.g., each different build material separately or to create a layered fabrication).

[0122] Depositing a build material S130 may include depositing any type or types of build materials as desired according to the embodiment. The desired build material may be limited only by the selection of coordination segments of the build material that are capable of binding to the patterning material. Examples of possible build materials include, but are not limited to, metal chalcogenides, where the metal is Ge, Al, Sn, Pb, Sb, Bi, Ga, In, Tl, Cu, or combinations thereof, and chalcogens, such as S, Se, Te, or combinations thereof. Pnictides, and resulting pnictide polymorphs of Group XIII elements, such as B, Al, Ga, In, and Tl, or combinations thereof, and pnictogens, such as N, P, As, and Sn. Metal oxides having the empirical formula MxOy, where M is a metal such as Bi, Sn, Cr, Co, Mn, Mo, Ti, Zn, Zr, Cu, Fe, Ni, Eu, Dy, Pr, Ce, Sm, or La; and carbon and its allotropes, silicon, germanium, tin, silicon carbide (3C, 4H, 6H, -SiC), silicon germanium, and silicon tin.

[0123] Through blocks S120 and S130, complex structures using multiple types of building materials can be created, potentially in any desired geometric shape. For example, in the fabrication of layered blocks made from two different types of building materials, each layer is completely surrounded by an outer layer: a first patterning material for a first material (e.g., including reactive group segments that bond to the first material) is dispersed throughout the gel while the area of ​​the desired deposition of the first layer is photoactivated, thereby causing the first patterning material to bond to the "first layer" area of ​​the gel and allowing the remainder of the patterning material to be washed away. Then, a second patterning material for a second building material (e.g., including reactive group segments that bond to the second material) is dispersed throughout the gel while the area of ​​the second material is photoactivated, thereby causing the second patterning material to bond to the "second layer" of the gel and allowing the remainder of the patterning material to be washed away. Additional layers of patterning materials may be added in the same manner. Once the patterning of the gel S120 is complete, first and second build materials may be flowed simultaneously or sequentially throughout the gel. The first build material may then bond to and fill the first layer region (i.e., bond to the conjugated segments of the first material), and then a second build material may be flowed throughout the gel to bond to and fill the second layer region, etc.

[0124] In an alternative variation to construct the previous example (for multi-layered blocks), the patterning materials can be implemented with separate photosensitive segments associated with separate gel-bonding segments. That is, the first patterning material can additionally include a first gel-bonding segment (e.g., activated by blue light), and the second patterning material can additionally include a second gel-bonding segment (e.g., activated by yellow light). All patterning materials can be patterned simultaneously by simultaneously photoactivating with both blue and yellow light (on appropriate desired areas). To prevent unbonded second material from being accidentally trapped within the first layer, depositing a building material S120 can be performed once so that the first building material completely bonds and fills the first layer, and then depositing a second material to completely bond and fill the second layer of the multi-layered block.

[0125] Block S140, which includes shrinking the material, functions to enable high resolution patterning and fabrication and then reduce the size of the fabrication to an appropriate size to enable high precision fabrication. Shrinking the material S140 may include adding acids, salts, and / or different solvents to cause shrinkage of the gel, thereby causing shrinkage of the fabrication bonded to the patterning material embedded in the gel. In a preferred variation, shrinking the material may reduce the size of the fabrication by more than a factor of 20. For example, an object may be fabricated with a resolution of 5 micrometers and then shrink down to 500 nanometers. Examples of other shrinkage methods that may be used to shrink the material S140 include chemical reactions that modify the polymer (e.g., converting charged groups on the backbone to hydrophobic uncharged groups or creating additional crosslinks), photoisomerization or photoreactions that change the solubility or charge of the polymer backbone, incorporating electrochemical changes that modify the charge or solubility of the polymer backbone, changing the gel temperature, drying in air or creating N2, vacuum, or another non-solvent environment, or adding additives to an external solvent that change the chemical potential of the solvent.

[0126] In some variations, the method may further include post-processing the build material. Post-processing of the build material serves to modify the build material closer to a functional form for use. Depending on the embodiment, this may occur at any time after deposition of the build material begins. In one variation, the post-processing may occur simultaneously with depositing 130 the build material. In another variation, the post-processing may occur after a single deposition of the build material (e.g., one layer of build material may be deposited, post-processed, and then another layer of build material may be deposited). Examples of post-processing steps that may be performed include metal conversion (i.e., converting the build material metal), removing the gel scaffold, coating the build material, quenching the build material, etc.).

[0127] In some variations where the build material includes a metal, post-processing the build material includes converting the metal build material. In a first example, converting the metal converts the metal build material to a metal chalcogen (e.g., a sulfide, selenide, telluride). Depending on the embodiment, the metal chalcogen may then be converted to a second metal (e.g., cadmium, zinc, lead, tin, copper, or mixtures thereof). In a second example, converting the metal converts the metal build material to a metal oxide.

[0128] In one embodiment of the first example of converting the building metal material, silver is converted to silver chalcogen and then converted to a second metal (e.g., zinc sulfide, cadmium sulfide, etc.), and the conversion is carried out in a range of solvents.

[0129] In some variations, post-processing the build material may include desolvating the gel. Desolvating the gel may include freeze-drying or supercritical drying the gel while it is in a fully swollen or partially swollen state. Supercritically drying the gel may include drying the gel using a solvent. Examples of solvents for supercritical drying include ethanol, acetone, acetic acid, formic acid, and the like. Depending on the embodiment, freeze-drying the gel may be performed in the presence of a cryoprotectant. Alternatively, freeze-drying the gel may be performed without a cryoprotectant.

[0130] In some variations, post-processing can include removing the polymer network (e.g., the gel or an additional polymer network). In particular, in variations involving adding an additional polymer network, removing the polymer network can include removing the first and / or any additional polymer networks. Removing the polymer network can serve to provide a new "environment" for the construct, potentially for further processing or construction. Depending on the embodiment, removing the polymer network can occur before, during, or after patterning the gel, before, during, or after depositing a build material, and / or before, during, or after shrinking the gel. In one example involving embedding an additional polymer network in the gel, removing the polymer network can remove the gel. In another example involving embedding an additional polymer network in the gel, removing the polymer network can remove the additional polymer network.

[0131] The method may be particularly useful for fabricating simple and complex optical components such as GRIN elements, diffractive elements, refractive surface geometries, meta-optical elements, magneto-optical elements, electro-optical elements, etc. This may be particularly the case with the use of lithographic embodiments and / or pulsed fabrication techniques. The optical components may be constructed from any build material. Depending on the desired embodiment, the build material may preferably be sufficiently translucent and / or reflective. In one optical component fabrication embodiment, bonding the build material to the patterning material may include creating a refractive index (RI) contrast. In this manner, a refractive index contrast may be created by deposition of an appropriate build material. In another optical component fabrication embodiment, the refractive index may be created through ion exchange between materials. In some variations, the method may allow multiple components to be fabricated together.

[0132] For example, the method may allow the construction of optical structures having both refractive and diffractive lenses. In one example, an optical structure having both refractive and diffractive lenses is fabricated using one-photon lithography with a mask. In another example, the optical structure is a metasurface on the curved surface of a conventional refractive lens (e.g., a metasurface that corrects the spherical aberration of a spherical lens). In one embodiment, the optical structure metasurface is fabricated using two-photon lithography (with or without a mask) inside a molded hydrogel. In some examples of metasurface optical structures, the optical structure includes multiple layers of optical metasurfaces (e.g., patterned with two-photon lithography). In another example, the optical structure comprises a thermal Mach-Zehnder interferometer with an integrated electrical resistive heating element (e.g., patterned with two-photon lithography). In another example, the optical structure comprises an optical isolator formed by combining an integrated magneto-optical Faraday rotator and an optical polarizer.

[0133] As part of constructing optical components with refractive index contrast, the method can further generate a spatially dependent refractive index, i.e., refractive index contrast. Thus, the method can enable the construction of components with large refractive index contrast (e.g., >0.05n). In one example, a spatially dependent refractive index with large refractive index contrast is constructed by converting the build material to a metal chalcogenide. In another example, a spatially dependent refractive index with large refractive index contrast is achieved by amplifying the patterning material reactive groups (e.g., by addition / amplification of poly(amido)amine).

[0134] Herein, an example is provided for the fabrication of a multi-layer diamond prism block, where each layer has a different refractive index (due to a diamond concentration gradient), thus creating an object with different light propagation speeds in different directions. Starting with a pre-fabricated gel, a patterning material is dispersed throughout the gel with conjugated segments that bond to diamond. A light beam (tuned to activate the gel-bonded segments of the latent patterning material) is directed for a short amount of time to the region consisting of the desired top layer of the prism. The light beam is then directed to each layer for successively longer times, going down the layers of the desired prism shape. Upon completion, the patterning material is present throughout the desired prism region, decreasing in concentration from the top layer of the prism to the bottom of the prism. Any additional unbound patterning material is washed away. Diamond material is then deposited throughout the gel, bonding to the patterning material and creating the desired prism shape. In accordance with the patterning material, a lower concentration of diamond building material is deposited on the top of the prism, with an increasing concentration of diamond toward the bottom. Excess diamond material is washed away. Acid is then added to shrink the gel, reducing the size of the prisms by an order of magnitude. Once complete, a solvent is added to wash away the gel and latent patterning material, leaving behind the diamond prisms.

[0135] A sample build for integrated refractive and meta-optical lenses is presented herein as a second example. Curing the gel S110 includes curing the swollen gel and adhering the gel to a surface (e.g., glass). Patterning the gel S120 then includes patterning the appropriate shape of the gel using a chromophore (e.g., sulfo-Cy5). Patterning using two-photon lithography can be performed to create a metasurface pattern inside the gel. When the unpatterned (unbound) chromophore is washed away, the patterned chromophore then reacts with the seed nanoparticles (e.g., nanogold). Depositing the build material S130 then includes depositing the build material (e.g., silver) on the seed particles. Through an ion exchange process, the silver can be converted to a HRID material (e.g., CdS or ZnS). Shrinking the material S140 is then performed to shrink and dehydrate the gel. An embodiment-specific post-processing can then be used to prepare the lenses, which in this embodiment can include first dehydrating the gel, then grinding and polishing the construct to form a refractive lens with the desired metasurface embedded therein.

[0136] In method variant B1, a method for three-dimensional nanofabrication includes patterning a gel, bonding a build material to the patterning material, and reducing the three-dimensional nanofabrication. Patterning the gel may further include dispersing a patterning material throughout the gel at distinct locations within the gel, photoactivating the patterning material, thereby causing selective bonding of the patterning material to the gel at the distinct locations, and removing unbound patterning material. Photoactivating the patterning material may further include activating a reactive intermediate that promotes bonding of the patterning material to the gel via the reactive group. This method variant may function to allow for tuning the reactive intermediate to modify the method output. In some examples, activating the reactive intermediate includes radical generation. Depending on the desired embodiment, the method may further include tuning the reactive intermediate concentration. For example, in one embodiment, the reactive intermediate is oxygen. Tuning of the reactive intermediate concentration (e.g., by pumping oxygen into the enclosed nanofabrication platform) can be incorporated to improve the efficiency of the method. In one embodiment of Method Variant B1, the patterning material can include a polymethine dye that contains a donor-acceptor bridge that interacts with the reactive intermediate.

[0137] In method variant B2, a method for three-dimensional nanofabrication includes patterning a gel, bonding a build material to the patterning material, and reducing the three-dimensional nanofabrication. Patterning the gel may further include dispersing the patterning material throughout the gel at distinct locations within the gel, photoactivating the patterning material including directing light pulses separated by an amount of time shorter than the excited triplet state lifetime of the patterning material, causing selective bonding of the patterning material to the gel at the distinct locations, and removing unbound patterning material. By exploiting the excited triplet state lifetime of the patterning material, the method functions to provide high throughput fabrication by efficiently bonding the patterning material to the gel. This method may be particularly useful for enabling enhanced photonic lithography techniques.

[0138] In method variant B3, the method for three-dimensional nanofabrication includes curing the gel, patterning the gel, bonding a build material to the patterning material, and shrinking the three-dimensional nanofabrication. Curing the gel may further include adhering the gel to a surface via a binding group. This method functions to enable nanofabrication on a fixed surface, and all other method steps may be performed while the gel is adhering to the surface (including shrinking the material S140). In one example of system variant B3, adhering the gel to a surface includes functionalizing the surface using a binding group comprised of a silane or siloxane. In a second example, adhering of system variant B3, adhering includes adhering the gel using a binding group having an opposite charge to that of the gel, thereby incorporating the binding group into the gel.

[0139] As part of some embodiments, such as method variants B2 and B3, the method can include photoactivating the patterning material to activate a reactive intermediate that facilitates binding of the patterning material to the gel via a reactive group of the patterning material. In some examples, the patterning material includes a polymethine dye that contains a donor-acceptor bridge that interacts with the reactive intermediate.

[0140] As part of some embodiments, such as method variants B1, B2, and B3, the method further includes amplifying the reactive groups by depositing a reactive group rich compound. Amplifying the reactive groups can function to increase the speed and ability of the patterning material to bond to the gel. In one example, depositing the reactive group rich compound includes depositing a poly(amido)amine.

[0141] As part of some embodiments, such as method variants B1, B2, and B3, bonding the build material to the patterning material includes depositing a non-metallic enhancer. The non-metallic enhancer may allow the build material to grow on the patterning material. Depending on the embodiment, each method variant may further include depositing the build material until it bridges adjacent patterning material bond sites. In one embodiment of each method variant, depositing the non-metallic enhancer includes depositing a chalcogenide and allowing the build material to grow. The deposited build material may be metallic or non-metallic, and the build material is then deposited until it bridges adjacent patterning bond sites.

[0142] As part of some embodiments, such as method variants B1 and B3, photoactivating the patterning material can include directing light pulses to distinct locations within the gel. Directing the light pulses can exploit the lifetime of the triplet excited state of the patterning material to enable high throughput patterning of the gel. In some examples, directing the light pulses includes directing light pulses separated by an amount of time less than the excited triplet state lifetime of the patterning material. In some embodiments, the patterning material can include a cyanine, and directing the light pulses includes directing light pulses separated by less than 10 microseconds.

[0143] As part of some embodiments, such as method variants B1, B2, and B3, in which the build material includes a semi-transparent material, bonding the build material to the patterning material can include generating a refractive index. In one example, generating a refractive index includes generating a spatially dependent refractive index. More specifically, in some embodiments, generating a spatially dependent refractive index using a dielectric material. Depending on the embodiment, generating a spatially dependent refractive index can include generating a refractive index contrast of greater than 0.050. In another example, generating a spatially dependent refractive index can include generating a spatially dependent refractive index by converting the build material to a chalcogenide. Additionally or alternatively, generating a spatially dependent refractive index can include amplifying reactive groups by depositing a poly(amido)amine.

[0144] As part of some embodiments, such as method variants B1, B2, and B3, where the gel comprises a hydrated gel (i.e., a swollen gel), patterning the gel may include mechanically compressing the gel in one plane. Compressing the gel in one plane can serve to improve the patterned resolution in the uncompressed plane. Mechanically compressing the gel may be very useful for lithography techniques. In one example, the method may further include using one-photon lithography while compressing the gel in one plane. In an alternative example, the method may further include using two-photon lithography while compressing the gel in one plane.

[0145] As part of some embodiments, such as method variants B1 and B1, the method may include curing the gel, where curing the gel further includes adhering the gel to the surface via the binding groups. In one of these variants, adhering the gel to the surface includes functionalizing the surface with binding groups comprised of silanes and / or siloxanes. Alternatively, adhering the gel to the surface may include using binding groups that have an opposite charge to the gel, thereby incorporating the binding groups into the gel.

[0146] As part of some embodiments, such as method variants B2 and B3, where the build material includes a first metal, the method may further include converting the first metal to a metal chalcogen on the patterning material. Additionally, in some embodiments, the method may further include converting the metal chalcogen to a second metal.

[0147] As used herein, first, second, third, etc. are used to characterize and distinguish various elements, components, regions, layers, and / or sections. These elements, components, regions, layers, and / or sections should not be limited by these terms. The use of numerical terms may be used to distinguish one element, component, region, layer, and / or section from another element, component, region, layer, and / or section. The use of such numerical terms does not imply a sequence or order unless clearly indicated by the context. Such numerical measures may be used interchangeably without departing from the teachings of the embodiments and variations herein.

[0148] As those skilled in the art will recognize from the foregoing detailed description, and the drawings and claims, modifications and variations can be made to the embodiments of the invention without departing from the scope of the invention, which is defined in the following claims.

Claims

1. 1. A system for a nanofabrication platform, comprising: A gel scaffold; a latent patterning material that selectively binds to the gel scaffold and comprises a non-xanthene based chromophore; A build material comprising a conjugated chemical that binds to the latent patterning material.

2. 10. The system of claim 1, wherein the latent patterning material further comprises a reactive group, the reactive group selectively bonding to the gel scaffold through photoreaction of the latent patterning material and a reactive intermediate.

3. The system of claim 2 , wherein the reactive intermediate comprises a small molecule capable of radical generation.

4. The system of claim 3 , wherein the reactive intermediate comprises oxygen.

5. The system of claim 4 , wherein the latent patterning material is a polymethine dye.

6. The system of claim 5 , wherein the polymethine dye comprises squaraine or a squaraine derivative.

7. The system of claim 5 , wherein the latent patterning material further comprises a donor-acceptor bridge.

8. The system of claim 11 , wherein the gel scaffold comprises a hydrated gel (i.e., a swollen gel), and the system further comprises a mechanical spacer that sets a thickness of the gel scaffold.

9. The system of claim 1 , further comprising a binding group that enables the gel scaffold to adhere to a surface.

10. The system of claim 9 , wherein the binding group comprises a silane or a siloxane.

11. 10. The system of claim 1, further comprising a mask, said mask blocking, reducing or redirecting light onto designated areas of said gel scaffold.

12. The system of claim 11 , wherein the mask comprises a digital mask made up of pixels that block or reduce light.

13. The system of claim 12 , wherein the mask is a digital micromirror device.

14. The system of claim 12 , wherein the mask is a spatial light modulator.

15. The system of claim 12 , wherein the mask is a phase mask.

16. The system of claim 1 , wherein the latent patterning material is selected from the group consisting of polymethine or dipyrromethene.

17. The system of claim 16 , wherein the latent patterning material comprises a cyanine.

18. 20. The system of claim 17, wherein the latent patterning materials include hemicyanines, streptocyanines, Cy3, Cy3.5, Cy5, Cy5.5, Cy7, Cy7.5, merocyanines, and sulfonated derivatives thereof.

19. The system of claim 16 , wherein the latent patterning materials include squaraines and their derivatives (e.g., sulfonated derivatives).

20. 20. The system of claim 19, wherein the latent patterning materials include symmetrical and asymmetrical indole-based squaraines, symmetrical and asymmetrical benzothiazole-based squaraines, squaryliums, and sulfonated derivatives thereof.

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