Self-assembled nanoparticle monolayer formation via ultrasonic spray coating

Abstract

A method for forming a structure may include atomizing a colloidal suspension of functionalized particles suspended in a solvent to create a plurality of droplets, each droplet comprising one or more of the functionalized particles and directing the droplets to an injection site present on a liquid surface of a liquid contained within a reservoir to form a self-assembled particle monolayer on the liquid surface, wherein each functionalized particle comprises a particle functionalized with one or more molecules in order to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto the particles.

Description

[0001]

[0002] SELF-ASSEMBLED NANOPARTICLE MONOLAYER FORMATION VIA ULTRASONIC SPRAY COATING

[0003] FEDERALLY-SPONSORED RESEARCH This invention was made with government support under Grant numbers

[0004] DMR1720595, EEC1540028, ECCS2025227, DMR2308817, ECCS1542159 awarded by the National Science Foundation. The government has certain rights in the invention. RELATED APPLICATION

[0005] This application claims priority to United States Patent Application Serial No. 63 / 595,139, filed November 1, 2023, which is incorporated by reference herein in its entirety. FIELD OF DISCLOSURE

[0006] The present disclosure relates in general to methods and systems for the selfassembly of ordered particle monolayers using an atomized beam of colloidal particles.

[0007]

[0008] BACKGROUND

[0009] The ability to engineer matter at the nanometer and sub-micron scales has become increasingly important for the development of next generation nanophotonic, biomedical, renewable energy, and semiconductor technologies. Many developing technologies require periodic two-dimensional submicron patterning. Currently, the two-dimensional submicron nanostructures enabling these technologies are made utilizing nanoimprint lithography, electron beam lithography, or photolithography. While these platforms offer high repeatability, precision, and pattern fidelity, they require massive capital investments preventing their use for the manufacturing of low- cost technologies.

[0010] Two-dimensional arrays of colloidal polymeric micro and nanoparticles have been extensively investigated for use as low-cost submicron lithographic templates. Leveraging nanoparticles as lithographic masks can enable extremely low cost nanopatteming due to its parallelized self-assembled nature, wide particle size availability (e.g., tens to thousands of nanometers), and the extremely low-cost synthesis of colloidal nanoparticles.

[0011] While colloidal lithography has seen broad use since its development, with only a few exceptions it has been plagued by poor scaling which has limited its use to research-scale devices with cm2footprints or smaller. The inability to scale colloidal lithography has greatly constrained the usefulness of the technique and limited its application to academic research and device prototyping.

[0012] Over the years, vanous techniques have been developed to increase the throughput of colloidal lithography, including spin coating, convective assembly and blade coating, and Langmuir-Blodgett based methods. While many of these techniques have been leveraged to self-assemble high quality and large-area nanoparticle monolayers, they suffer from either complex implementation or slow monolayer growth rates (mm2 / min), which has prevented their use in any commercial scale manufacturing. In order to unlock colloidal lithography’s potential for low-cost submicron lithography, a new self-assembly method must be developed that can rapidly create high quality and large-area nanoparticle monolayers and that easily integrates into existing manufacturing processes.

[0013]

[0014] SUMMARY

[0015] In accordance with the teachings of the present disclosure, the disadvantages and problems associated with existing approaches for forming nano- to micro-scale solid or soft material structures may be reduced or eliminated.

[0016] In accordance with embodiments of the present disclosure, a method for forming a structure may include atomizing a colloidal suspension of functionalized particles suspended in a solvent to create a plurality of droplets, each droplet comprising one or more of the functionalized particles and directing the droplets to an injection site present on a liquid surface of a liquid contained within a reservoir to form a self-assembled particle monolayer on the liquid surface, wherein each functionalized particle comprises a particle functionalized with one or more molecules in order to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto the particles.

[0017] In accordance with these and other embodiments of the present disclosure, a system for forming a structure may include an atomization nozzle configured to atomize a colloidal suspension of functionalized particles suspended in a solvent to create a plurality of droplets, each droplet comprising one or more of the functionalized particles and direct the droplets to an injection site present on a liquid surface of a liquid contained within a reserv oir to form the self-assembled particle monolayer on the liquid surface, wherein each functionalized particle comprises a particle functionalized with one or more molecules in order to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto the particles.

[0018] Technical advantages of the present disclosure may be readily apparent to one having ordinary skill in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims.

[0019] It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure.

[0020] BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein:

[0022] FIGURE 1 illustrates a system for forming self-assembled nanoparticle monolayers onto a liquid surface, in accordance with embodiments of the present disclosure;

[0023] FIGURE 2A illustrates an atomization nozzle of the system of FIGURE 1 generating an atomized aerosol of droplets, in accordance with embodiments of the present disclosure;

[0024] FIGURE 2B illustrates detail of a droplet of FIGURE 2A, in accordance with embodiments of the present disclosure;

[0025] FIGURE 3 illustrates a process of self-assembly of nanoparticles at an airwater interface as a function of injection time, in accordance with embodiments of the present disclosure;

[0026] FIGURES 4A-4D illustrate a schematic process flow of self-assembled monolayer grow th processes from high magnitude zeta-potential colloidal particles, in accordance with embodiments of the present disclosure;

[0027] FIGURES 5A-5D illustrate a schematic process flow of self-assembled monolayer growth processes from low magnitude zeta-potential colloidal particles, in accordance with embodiments of the present disclosure;

[0028] FIGURE 6 illustrates a reservoir filled with a high surface tension liquid having added thereto an aqueous droplet of a lower surface tension liquid, in accordance with embodiments of the present disclosure;

[0029] FIGURES 7A-7C illustrate the effect of a Marangoni force on colloidal particles when the Marangoni force is created via asymmetric addition of a low surface tension liquid, in accordance with embodiments of the present disclosure;

[0030] FIGURE 8 illustrates a reservoir filled with a high surface tension liquid having added thereto aqueous droplets of a low er surface tension liquid in a symmetric pattern, in accordance with embodiments of the present disclosure;

[0031] FIGURES 9A-9C illustrate the effect of a Marangoni force on colloidal particles when a Marangoni force is created via symmetric addition of a low surface tension liquid, in accordance with embodiments of the present disclosure; and

[0032] FIGURES 10A-10F illustrate non-limiting examples of nanostructures and microstructures which may be created by leveraging the previously described selfassembled colloidal monolayer.

[0033]

[0034] DETAILED DESCRIPTION

[0035] The description below sets forth example embodiments according to this disclosure. Further example embodiments and implementations will be apparent to those having ordinary skill in the art. Further, those having ordinary skill in the art will recognize that various equivalent techniques may be applied in lieu of, or in conjunction with, the embodiment discussed below, and all such equivalents should be deemed as being encompassed by the present disclosure.

[0036] FIGURE 1 illustrates a system 100 for forming self-assembled nanoparticle monolayers onto a liquid surface, in accordance with embodiments of the present disclosure. Such system 100 may be used to form nano- to micro-scale solid or soft- material structures, and systems similar to system 100 may be used to form nano- to micro-scale solid or soft-material structures.

[0037] As shown in FIGURE 1, system 100 may include a computer-controlled pump 102 (e.g., a syringe pump, a peristaltic pump, or another liquid delivery' system) configured to continuously pump to an atomization nozzle 104 fluidically coupled to computer-controlled pump 102 a colloidal suspension 106 of nanoparticles suspended in a liquid solvent. Atomization nozzle 104 may also receive a supply of pressurized air 108 to enable atomization nozzle 104 to generate a finely atomized, collimated, focused, or shaped aerosol 110 of droplets, as described in greater detail below. As also shown in FIGURE 1, atomization nozzle 104 may direct finely atomized aerosol 110 of droplets onto a liquid surface 112 of a liquid 114 (e.g., deionized water) held within an appropriate reservoir 116. Although not explicitly shown in FIGURE 1, a substrate which is to be coated with a monolayer may be submerged in liquid 114.

[0038] The liquid solvent may comprise any suitable solvent that has a lower surface tension than liquid 114. For example, in embodiments in which liquid 114 is deionized water, an alcohol (e.g., ethanol, isopropanol, butanol, etc.), or alcohol-containing solution may be used for the liquid solvent.

[0039] The nanoparticles suspended in the solvent may be made from any suitable inorganic or organic material (e.g., polysty rene, silicon dioxide, titanium dioxide, gold, silver, silicon, polymethylmethacrylate (PMMA), or from a combination of materials). The nano / microparticles can be made of any geometry' such as, for example, spheres, rods, core-shell particles, stars, cubes, platelets, bipyramids, multilayered particles, hierarchically-shaped particles, hierarchically-textured particles, etc.

[0040] FIGURE 2A illustrates atomization nozzle 104 of the system of FIGURE 1 generating finely atomized aerosol 110 of droplets 200, in accordance with embodiments of the present disclosure. As shown in FIGURE 2B, each droplet 200 may comprise one or more nanoparticles 202. Although any suitable approaches may be used to generate an atomized aerosol, in some embodiments, in order to generate finely atomized aerosol 1 10 of droplets 200, atomization nozzle 104 may' oscillate at an ultrasonic frequency (e.g., 120 kHz) to generate droplets 200, which in some embodiments may be 15pm to 25pm in diameter. Via pressurized air 108 shown in FIGURE 1, atomization nozzle 104 may focus droplets 200 into a collimated beam.

[0041] FIGURE 3 illustrates a process of self-assembly of nanoparticles 202 at an airwater interface as a function of injection time, in accordance with embodiments of the present disclosure. In operation, as droplets 200 strike the air-liquid interface at liquid surface 112, a surface tension gradient may be formed between the solvent (e.g., which may have a low surface tension) and liquid 114 (which may have a high surface tension) via the Marangoni force. Thus, as shown in FIGURE 3, the Marangoni force may propel nanoparticles 202 radially away from the atomized beam of droplets 200, which may prevent aggregation of nanoparticles 202 at the site of injection. The radially symmetnc spreading of nanoparticles 202 away from the atomized beam may enable the self-assembly and uniform growth of a nanoparticle structure, which may take on the shape of an annulus if a cylindrical reservoir is used. The continuous introduction of nanoparticles 202 via the atomized beam may add new nanoparticles to the established structure, causing it to grow inwards from the outside perimeter of reservoir 116 towards the injection site. Further, due to solvent evaporation, micron- scale aqueous ethanol droplets may shrink during free fall. This decrease in size of droplets 200 from evaporation may further increase the transfer efficiency of nanoparticles to the air-water interface.

[0042] To optimize ordering of monolayers formed on the air-liquid interface at liquid surface 112. nanoparticles 202 suspended in the solvent may be functionalized with different surface modifiers such as surfactants, proteins, polymers, fluorescent molecules, stabilizing molecules, and / or any other suitable molecules to engineer surface chemistry of nanoparticles 202 to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto nanoparticles 202.

[0043] For example, in embodiments in which nanoparticles 202 comprise polystyrene, if left unmodified and not functionalized with other molecules, polystyrene nanoparticles may aggregate to one another instead of forming an ordered two-dimensional array due to the hydrophobic nature of polystyrene polymer. Left unmodified, hydrophobic polystyrene nanoparticles may lower their free energy by aggregation with other hydrophobic particles instead of assembling on the aqueous / hydrophilic water surface. Accordingly, a surfactant, for example sodium dodecyl sulfate (SDS), may be added to the polystyrene nanoparticles to impart a negative charge to the nanoparticles to increase their hydrophilicity and minimize particle aggregation on the liquid surface. Thus, polystyrene nanoparticles modified with SDS may be added in a very high concentration (e.g., 1 x 109to 1 x 1013and in some embodiments 1 x 1011to 1 x 1013particles / mL) to droplets 200 created by atomization nozzle 104. However, desired concentrations and functionalizing molecules may vary based on particle material type and / or solvent / reservoir liquid used.

[0044] The use of functionalization in combination with a high nanoparticle concentration may alter attractive van der Waals forces which may be needed to promote the ordered self-assembly. However, if these attractive forces are too high, nanoparticles may aggregate and the monolayer may be disordered. Accordingly, functionalization of nanoparticles with another molecule may enable the effective modification of a zeta potential for the nanoparticles (the magnitude of which correlates to a magnitude of electrical repulsion between nanoparticles) to be in a range where the van der Waals forces are high enough to allow particles to coordinate but not so high to cause the particles to aggregate. Such functionalization, in the case of polystyrene nanoparticles, may result in electrostatic repulsion between the nanoparticles, as the addition of SDS may cause the negatively-charged polystyrene nanoparticles to be more negatively charged.

[0045] However, different stabilizing / functionalizing molecules may need to be chosen for nanoparticles with different surface properties. For example, in the case of polystyrene particles with positive surface charge, the polystyrene particles may be functionalized using 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AIBA) as a stabilizing molecule because AIBA is positively charged.

[0046] Further, nanoparticles that are naturally hydrophilic (e.g.. SiCh and TiOz) may be functionalized with molecules that are hydrophobic or uncharged high molecular weight surfactants for steric repulsion. This is because when nanoparticles are hydrophilic, they may mix into the bulk volume of liquid 114 instead of remaining suspended on liquid surface 112. In this case, imparting some hydrophobicity' or steric repulsion to such nanoparticles enables them to stay suspended on liquid surface 112.

[0047] To further demonstrate the benefit of stabilizing / functionalizing molecules, FIGURES 4A-4D illustrate a schematic process flow of self-assembled monolayer growth processes from colloidal particles with favorable surface functionalization (e.g., colloidal particles with high magnitude zeta-potential), in accordance with embodiments of the present disclosure, while FIGURES 5A-5D illustrate a schematic process flow of self-assembled monolayer growth processes from colloidal particles with unfavorable surface functionalization (e.g., low' magnitude zeta-potential colloidal particles), in accordance w ith embodiments of the present disclosure.

[0048] In FIGURE 4A. a new nanoparticle 202a may obtain kinetic energy from the Marangoni force and may be introduced to a newly -formed array of nanoparticles (not explicitly labeled, for purposes of clarity and exposition). As shown in FIGURE 4B, new nanoparticle 202a may collide with the crystal structure of nanoparticles and may transfer energy and momentum to neighboring nanoparticles introducing disorder and fragmentation of the crystal. In FIGURE 4C, the impinging and neighboring nanoparticles may reach a new dynamic equilibrium. As the Marangoni force dissipates, the liquid surface 112 may contract to bring the particles into a new crystalline arrangement. As depicted in FIGURE 4D, the high magnitude zeta potential of the nanoparticles may prevent their aggregation and may promote ordered growth of the nanoparticles in successive colloidal crystal fragmentation and regrowth.

[0049] In FIGURE 5 A, a new nanoparticle 202b may obtain kinetic energy from the Marangoni force and may be introduced to a newly formed array of nanoparticles (not explicitly labeled, for purposes of clarity and exposition). As shown in FIGURE 5B, new nanoparticle 202b may collide with the cry stal though its low colloidal stability (due to its low magnitude zeta potential) may cause it to stick to other particles in the collision. Similarly, neighboring nanoparticles which were in other scattering events may form aggregations with adjacent particles. In FIGURE 5C, as liquid surface 112 contracts, new scattering events may be created and form additional aggregations. As depicted in FIGURE 5D, a final larger array may be fonned with decreased order and amorphous packing and large particle aggregations.

[0050] The foregoing systems and methods may be used for fabrication of a two- dimensional self-assembled nanoparticle monolayer upon a substrate. For example, in a first step, nanoparticles 202 may be incorporated into a volume of solvent. In a second step, a substrate to be coated with the monolayer may be submerged in liquid 114 within reservoir 116. In a third step, pump 102 may pump the colloidal suspension 106 of nanoparticles 202 in the solvent to atomization nozzle 104. In a fourth step, the nanoparticle suspension may be accumulated at atomization nozzle 104 and atomization nozzle 104 (e.g., a nozzle head of atomization nozzle 104) may atomize the suspension into droplets 200 via ultrasonic vibration of atomization nozzle 104, with the addition of pressurized air 108 directed over atomization nozzle 104 providing a directional atomized beam of droplets. In a fifth step, droplets 200 may decrease in size as they evaporate through the air and may impact upon the air-liquid interface at liquid surface 112. In a sixth step, the solvent from each droplet 200 may cause the surface tension to locally decrease in an area 300 of the air-liquid interface where such droplet 200 was introduced, creating a gradient in the surface tension between the solvent droplet site and liquid surface 112 in areas where no droplets were introduced. In a seventh step, due to the surface tension gradient, a Marangoni force may be established which carries the nanoparticles 202 radially away from the impact site of droplets 200. In an eighth step, continued atomized spray deposition of the colloidal nanoparticle solution may accumulate more nanoparticles 202 at the air-liquid interface until the air-liquid interface is saturated with nanoparticles.

[0051] It is at this stage in which the previously-described particle functionalization may be beneficial. The particle functionalization may act to prevent mixing and subsequent loss of the colloidal particles to the bulk volume of liquid 114 while being propelled by the Marangoni force. As mentioned, the particle functionalization may also lower attractive van der Waals forces between adjacent particles to prevent aggregation and loss of long-range order in the growing colloidal particle monolayer. Further, the particle functionalization may lower attractive van der Waals forces between subsequently added, higher kinetic energy colloidal particles propelled by the Marangoni force, and the growing particle monolayer so as to allow- highly energetic particles to come to kinetic equilibrium without destroying long range order of the growing colloidal particle monolay er. In addition, the particle functionalization may increase attractive van der Waals forces between adjacent particles to allow adjacent particles to lower their free energy by arranging to a close-packed arrangement or other desired geometry.

[0052] In a ninth step, in some embodiments, a surfactant may be added to liquid surface 112 to further compress the nanoparticle monolayer into a close-packed array. In a tenth step, reservoir 116 may then be drained so that the self-assembled nanoparticle monolayer may be deposited onto the surface of the substrate. Alternatively to draining the reservoir, the substrate may be raised or lifted from liquid 114. Other approaches that enable formation of similarly -sized droplets comprising nanoparticle suspensions that can be distributed onto a suitable air-liquid interface may also be employed.

[0053] FIGURES 6, 7A-7C, 8, and 9A-9C depict the addition of surfactant to liquid surface 112 to further compress the nanoparticle monolayer into a close-packed array. FIGURE 6 illustrates reservoir 116 filled with a high surface tension liquid (e.g., water) having added thereto an aqueous droplet of a lower surface tension liquid (e.g., an aqueous surfactant), in accordance with embodiments of the present disclosure. After adding the aqueous droplet of the low surface tension liquid, the surface tension of the liquid mixture may rapidly decrease at an impact point 602 of the aqueous droplet. A surface tension gradient may form between the local surface tension area at impact point 602 and the high surface tension at surface 112 opposite the impact point. A Marangoni force may be created due to the surface tension gradient. The magnitude and direction of the Marangoni force is depicted in FIGURE 6 by the size and orientation of arrows. Over time the Marangoni force may propel the low surface tension liquid from its original impact point 602 to the areas of reservoir 116 which maintain a high surface tension. Dotted lines in the figure denote contours of constant surface tension. At a first time after introduction of the droplet, the low surface tension liquid may be propelled by the Marangoni force to the region bounded by large, dashed lines 604. At later times, the low surface tension liquid may travel to regions bounded by medium sized dashed lines 606 and smaller dashed lines 608.

[0054] If the low surface tension liquid is introduced to any position on surface 112 that is not centered to reservoir 116, there may be an asymmetric force pushing the low surface tension liquid which can be found by the vector sum of the Marangoni force field. In FIGURE 6, the introduction of the low surface tension liquid to the right side of surface 112 may cause a net force pushing to the leftmost extent of surface 112 and to the upper-left and lower-left regions of surface 112.

[0055] FIGURES 7A-7C illustrate the effect of a Marangoni force on nanoparticles 202 when a Marangoni force is created via asymmetric addition of a low surface tension liquid, in accordance with embodiments of the present disclosure. In FIGURE

[0056] 7 A, a non-close packed arrangement of nanoparticles 202 suspended on surface 112 may be subject to a net force to the left of the water surface when a low surface tension liquid is added to the right side of surface 112 at impact point 602. In FIGURE 7B, as the Marangoni force continues to travel across surface 112. it acts in a manner that locally compresses nanoparticles 202 with their neighboring nanoparticles 202. Due to the asymmetric force, nanoparticles 202 may be pushed into the leftmost, upperleft, and lower-left regions of surface 112. In FIGURE 7C, after the Marangoni force has reached the leftmost extent of surface 112, the nanoparticle monolayer may be maximally compressed and the compressive force generated by the Marangoni force may causes the monolayer to break into distinct regions on surface 112.

[0057] FIGURE 8 illustrates reservoir 116 filled with a high surface tension liquid having added thereto aqueous droplets of a lower surface tension liquid in a symmetric pattern, in accordance with embodiments of the present disclosure. As shown in FIGURE 8, when the low surface tension liquid is introduced to a high surface tension symmetrically across the liquid surface at impact points 802, various instances of the Marangoni force are excited and the forces decay radially away from impact points 802. The radial symmetry of the excited forces and the radial symmetry of reservoir 116 may cause the radial compression of surface 112 centered at the center of reservoir 116.

[0058] FIGURES 9A-9C illustrate the effect of a Marangoni force on nanoparticles 202 when a Marangoni force is created via symmetric addition of a low surface tension liquid, in accordance with embodiments of the present disclosure. In FIGURE 9A, after alow surface tension liquid is symmetrically introduced to various impact points 802 on surface 112 which has non-close packed nanoparticles 202 suspended on surface 112, the Marangoni force may push nanoparticles 202 radially away from impact points 802. In FIGURE 9B, the Marangoni force may continue to compress surface 112 towards the center of resen' oir 116, thereby compressing nanoparticles 202 into a symmetric area. In FIGURE 9C, further compression of the liquid interface and colloidal particles by the Marangoni force may cause the nanoparticle monolay er to reach its highest density. Using this scheme, cracks in the monolayer may be prevented because the symmetric Marangoni forces may produce no net force (e.g., for every' force pushing a nanoparticle 202 to the leftmost area of reservoir 116 there may an equal and opposite force opposing such motion resulting in no net force on the nanoparticle 202 after the Marangoni force dissipates).

[0059] Accordingly, to obtain the desired shape of surfactant droplets used to pack nanoparticles 202 into a desired density, a suitable system may control the timing, power, force, and / or other parameters for dispensing the surfactant droplets.

[0060] Although the foregoing describes forming structures of nanoparticle monolayers, it is understood that the systems and methods described herein may be applied to forming any suitable nano- to micro-scale solid or soft-material structures.

[0061] For example, FIGURES 10A-10F illustrate non-limiting examples of nanostructures and microstructures which may be created by leveraging the previously described self-assembled colloidal monolayer.

[0062] In some embodiments, a self-assembled colloidal monolayer 1000 of nanoparticles 202 may be leveraged as an inexpensive patterning mask which may be compatible with top-down and subtractive lithographic processing, as shown in FIGURE 10B, as well as bottom-up and additive lithographic processing, as shown in FIGURE 10C.

[0063] Self-assembled colloidal monolayer 1000 of nanoparticles 202 may also be used in applications in which engineered optical, chemical, or mechanical properties of the colloidal monolayer may impart new and enhanced material properties for a such applications. For example, as a photonic metasurface from the self-assembly of core-shell colloidal particles 1102, as shown in FIGURE 10D, for enhanced biosensing, cryptography, or detection applications.

[0064] Self-assembled colloidal monolayer 1000 of nanoparticles 202 may also be used to create multilayered structures from iterative deposition of multiple colloidal particle layers 1010, as shown in FIGURE 10E. In some embodiments, multiple of these nanopatteming techniques may be used together to create more complex structures, for example such shown in FIGURE 10F in which a multi-layered colloidal particle assembly may be combined with an additive assembly process to create an “inverse-opal” structure 1020 - known to have advanced catalytic and sensing properties.

[0065] The various geometries described above may be used in various applications such as anti-fouling, photonics, biomedical engineering, chemical engineering, and other applications.

[0066] As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electrical, mechanical, or electromechanical communication, whether connected indirectly or directly, with or without intervening elements.

[0067] This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set.

[0068] Although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary' implementations and techniques illustrated in the drawings and described above.

[0069] Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale.

[0070] All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure.

[0071] Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the foregoing figures and description.

[0072] To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. § 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.

Claims

WHAT IS CLAIMED IS:

1. A method for forming a structure, comprising: atomizing a colloidal suspension of functionalized particles suspended in a solvent to create a plurality of droplets, each droplet comprising one or more of the functionalized particles; and directing the droplets to an injection site present on a liquid surface of a liquid contained within a reservoir to form a self-assembled particle monolayer on the liquid surface; wherein each functionalized particle comprises a particle functionalized with one or more molecules in order to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto the particles.

2. The method of Claim 1, wherein the liquid contained in the reservoir has a first surface tension substantially higher than a second surface tension of the solvent.

3. The method of Claim 1, wherein the liquid contained in the reservoir comprises water.

4. The method of Claim 1, wherein the solvent comprises an alcohol or alcohol-containing solution.

5. The method of Claim 1, wherein atomizing the colloidal suspension comprises atomizing the colloidal suspension via ultrasonic vibration.

6. The method of Claim 1 , further comprising draining the liquid from the reservoir to deposit the self-assembled particle monolayer onto a substrate submerged in the liquid.

7. The method of Claim 1, further comprising raising a substrate submerged in the liquid to deposit the self-assembled particle monolayer onto the substrate.

8. The method of Claim 1, wherein the one or more molecules comprise a surfactant, a protein, a polymer, a fluorescent molecule, or a stabilizing molecule.

9. The method of Claim 1. further comprising adding a surfactant to the liquid surface to compress the self-assembled particle monolayer into a close-packed array.

10. The method of Claim 1, wherein each of the functionalized particles is a nano- to micro-scale particle.

11. The method of Claim 1 , wherein each of the functionalized particles is in the geometric shape of one of a sphere, a rod, a core-shell particle, a star, a cube, a platelet, a bipyramid, a multilayered particle, a hierarchically-shaped particle, and a hierarchically-textured particle.

12. A system for forming a structure, comprising: an atomization nozzle configured to: atomize a colloidal suspension of functionalized particles suspended in a solvent to create a plurality of droplets, each droplet comprising one or more of the functionalized particles; and direct the droplets to an injection site present on a liquid surface of a liquid contained within a reservoir to form the self-assembled particle monolayer on the liquid surface; wherein each functionalized particle comprises a particle functionalized with one or more molecules in order to impart desired hydrophobic, hydrophilic, electrostatic, and / or chemical properties onto the particles.

13. The system of Claim 12, wherein the liquid contained in the reservoir has a first surface tension substantially higher than a second surface tension of the solvent.

14. The system of Claim 12, wherein the liquid contained in the reservoir comprises water.

15. The system of Claim 12, wherein the solvent comprises an alcohol or alcohol-containing solution.

16. The system of Claim 12, wherein atomizing the colloidal suspension comprises atomizing the colloidal suspension via ultrasonic vibration.

17. The system of Claim 12, the system further configured to drain the liquid from the reservoir to deposit the self-assembled nanoparticle monolayer onto a substrate submerged in the liquid.

18. The system of Claim 12, the system further configured to raise a substrate submerged in the liquid to deposit the self-assembled particle monolayer onto the substrate.

19. The system of Claim 12, wherein the one or more molecules comprise a surfactant, a protein, a polymer, a fluorescent molecule, or a stabilizing molecule.

20. The system of Claim 12, further comprising adding a surfactant to the liquid surface to compress the self-assembled nanoparticle monolayer into a close- packed array.

21. The system of Claim 12. wherein each of the functionalized particles is a nano- to micro-scale particle.

22. The system of Claim 12, wherein each of the functionalized particles is in the geometric shape of one of a sphere, a rod, a core-shell particle, a star, a cube, a platelet, a bipyramid, a multilayered particle, a hierarchically-shaped particle, and a hierarchically-textured particle.

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