Electrophoretic display

Abstract

The present disclosure provides an electrophoretic display system, the electrophoretic display system including a first electrode disposed on a substrate and a three-dimensional (3D) carbon-based structure configured to direct the migration of charged electrophoretic ink particles dispersed therein, the charged electrophoretic ink particles being configured to respond to a voltage applied to the first electrode. The 3D carbon-based structure includes: a plurality of 3D aggregates defined by the morphology of graphene nanosheets orthogonally fused together and crosslinked by a polymer; and a plurality of channels dispersed throughout the 3D carbon-based structure defined by the morphology. The plurality of channels includes a plurality of inter-particle pathways and a plurality of intra-particle pathways. Each inter-particle pathway may have a smaller size than each inter-particle pathway. A second electrode is disposed on the 3D carbon-based structure. Each 3D aggregate may include any one or more of graphene, carbon nano-onions, carbon nanosheets, or carbon nanotubes.

Description

[0001] Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 866,464, filed Jun. 25, 2019, entitled “Electrophoretic Display”, and this application is a partial continuation of U.S. Patent Application No. 16 / 706,542, filed Dec. 6, 2019, entitled “Resonant Gas Sensor”, which claims priority to U.S. Provisional Patent Application No. 62 / 815,927, filed Mar. 8, 2019, entitled “Resonant Gas Sensor” and is a continuation of U.S. Patent Application No. 16 / 239,423, filed Jan. 3, 2019, entitled “Resonant Gas Sensor”, which claims priority to U.S. Provisional Patent Application No. 62 / 613,716, filed Jan. 4, 2018, entitled “Volatiles Sensor”; and this application is a partial continuation of and claims the priority benefit of U.S. Patent Application No. 16 / 282,895, filed Feb. 22, 2019, entitled “Antenna with Frequency-Selective Elements”, which is a continuation of U.S. Patent Application No. 15 / 944,482, filed Apr. 3, 2018, entitled “Antenna with Frequency-Selective Elements”, which claims priority to U.S. Provisional Patent Application No. 62 / 508,295, filed May 18, 2017, entitled “Carbon-Based Antenna” and claims priority to U.S. Provisional Patent Application No. 62 / 482,806, filed Apr. 7, 2017, entitled “Dynamic Energy Harvesting Power Architecture”, and claims priority to U.S. Provisional Patent Application No. 62 / 481,821, filed Apr. 5, 2017, entitled “Dynamic Energy Harvesting Power Architecture”; all of which are hereby incorporated by reference in their entireties for all purposes. Technical Field

[0003] The present disclosure generally relates to an electrophoretic display, and more particularly to an electrophoretic display device that includes carbon particles crosslinked to each other by a polymer and that mimics the appearance of traditional ink on paper when activated. Background Art

[0004] An electrophoretic display (EPD), also known as electronic paper, provides a low-power alternative to traditional flat-panel displays and has thus been widely used in a variety of consumer products, including e-reading devices, digital notebooks, shelf labels, signs, and simple displays suitable for packaging or use as digital tags. Unlike traditional backlit flat-panel displays that emit light, an EPD reflects light like traditional paper. This can make it more convenient to read and provide a wider viewing angle than most light-emitting displays. EPDs typically operate by using charged pigment particles held between a front substrate and a back substrate. When a voltage is applied across the two plates, the particles migrate to the plate with the charge opposite to that on the particles. Current EPD devices are limited in resolution and performance due to the use of conventional materials. There is a desire to incorporate highly structured and surface-functionalized carbon particles to enhance EPD resolution, reduce power consumption, extend the service life, and reduce production costs. SUMMARY OF THE INVENTION

[0005] The present invention content is provided to introduce in a simplified form a series of concepts further described below in the detailed description. The present invention content is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Additionally, each of the systems, methods, and devices of the present disclosure has several innovative aspects, and no single aspect alone is responsible for the desired attributes disclosed herein.

[0006] One innovative aspect of the subject matter described in the present disclosure can be implemented as a three-dimensional (3D) carbon-based structure configured to direct the migration of charged electrophoretic ink particles dispersed therein, the charged electrophoretic ink particles being configured to respond to the application of a voltage to a first electrode. The 3D carbon-based structure can include a plurality of 3D aggregates defined by the morphology of orthogonally fused graphene nanosheets and cross-linked by a polymer, and a plurality of channels defined by the morphology and dispersed throughout the 3D carbon-based structure. The plurality of channels can include a plurality of inter-particle pathways and a plurality of intra-particle pathways. Each inter-particle pathway can have a smaller size than each inter-particle pathway. A second electrode can be disposed on the 3D carbon-based structure.

[0007] In some implementations, the electrophoretic display system can include a plurality of recesses formed in any one or more of the plurality of 3D aggregates or the plurality of channels. Any one or more of the inter-particle pathways can have an average radial size of no greater than about 10 μm. Any one or more of the intra-particle pathways can have an average radial size greater than about 200 nm.

[0008] In some implementations, each 3D aggregate further includes any one or more of graphene, carbon nano-onions, carbon nanosheets, or carbon nanotubes. The polymer may include any one or more of cellulose, cellulose acetate butyrate, styrene butadiene, polyurethane, polyether-polyurethane, acrylate, epoxy resin, or vinyl resin.

[0009] Another innovative aspect of the subject matter described in this disclosure can be implemented as a method of preparing an electrophoretic display structure. The method may include causing self-nucleation of a 3D open porous structure defined by a plurality of 3D carbon-based aggregates from a carbon-containing vapor stream; functionalizing one or more exposed surfaces of the 3D open porous structure with a nucleophilic moiety; and crosslinking the plurality of 3D carbon-based aggregates in the 3D open porous structure. The crosslinking may include transforming the nucleophilic moiety; and defining the porosity in the 3D open porous structure.

[0010] In some implementations, the self-nucleation of the 3D open porous structure may further include defining a porosity with an average pore size greater than about 200 nm. The self-nucleation of the 3D open porous structure may include forming a plurality of passageways therein defined by the plurality of 3D carbon-based aggregates. The plurality of passageways may be configured to direct a plurality of charged movable titanium dioxide particles toward a charged electrode disposed on the electrophoretic display structure. Any one or more of the plurality of charged movable titanium dioxide particles may be configured to be non-reactively dragged into or out of the 3D open porous structure.

[0011] Another innovative aspect of the subject matter described in this disclosure can be implemented as a display device, which includes a pair of electrodes disposed on a substrate and a three-dimensional (3D) carbon-based structure disposed between the pair of electrodes. The 3D carbon-based structure may be configured to direct the migration of a plurality of charged electrophoretic ink particles dispersed therein based on a voltage difference applied to any one or more of the pair of electrodes. The 3D carbon-based structure may include: a plurality of 3D aggregates defined by the morphology of orthogonally fused graphene nanosheets and crosslinked by a polymer; and a plurality of channels dispersed throughout the 3D carbon-based structure defined by the morphology. The plurality of channels may include a plurality of inter-particle passageways and a plurality of intra-particle passageways. Each inter-particle passageway may have a smaller size than each inter-particle passageway.

[0012] In some implementations, the 3D carbon-based structure can be independent of any one or more of the microcups or microcapsules. The plurality of charged electrophoretic ink particles can include a plurality of negatively charged movable titanium dioxide particles. The negatively charged movable titanium dioxide particles can exhibit a substantially white color. The negatively charged movable titanium dioxide particles that exhibit a substantially white color can be configured to be attracted to any one of the pair of electrodes when that electrode is positively charged; or, to be repelled away from that electrode when that electrode is negatively charged.

[0013] In some implementations, the 3D carbon-based structure can be configured to be in a non-conductive state. The display device can include an antenna configured to provide power to the display device. The display device can include a contrast layer located between the 3D carbon-based structure and any one or more of the pair of electrodes. The contrast layer can be a first color. The plurality of charged electrophoretic ink particles can be a second color different from the first color. The 3D carbon-based structure is defined by a polydispersity index of less than about 0.5.

[0014] Details of one or more implementations of the subject matter described in this specification are set forth in the following drawings and description. Other features, aspects, and advantages will be apparent from the detailed description, drawings, and claims. It should be noted that the relative dimensions in the following drawings may not be drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Implementations of the subject matter disclosed herein are shown by way of example and are not intended to be limited by the figures in the drawings. Like numerals refer to like elements throughout the drawings and the specification. It should be noted that the relative dimensions in the following drawings may not be drawn to scale.

[0016] Figure 1A A side cross-sectional schematic 110A of an exemplary conventional EPD device 100A according to some implementations is shown.

[0017] Figure 1B A conventional microcapsule-based electrophoretic display according to some implementations is shown.

[0018] Figure 1C A conventional PMEPD 100C using microcup technology according to some implementations is shown.

[0019] Figure 1D A cross-sectional schematic diagram of an EPD device including a carbon-based structure according to some implementations is shown.

[0020] Figure 1E An exemplary EPD device including a carbon-containing structure according to some implementations is shown.

[0021] Figure 2Shows a schematic diagram illustrating the structure of an electrophoretic display (such as shown in FIG. 1) according to some implementations.

[0022] Figures 3A to 3B Shows a scanning electron micrograph of a structure (such as Figure 2 shown) according to some implementations.

[0023] Figures 4A to 4B Is a schematic diagram representing a method for manufacturing a structure (such as Figure 2 shown) for an electrophoretic visual display (such as shown in FIG. 1) according to some implementations.

[0024] Figure 5 Shows a cross-sectional view of an exemplary electrophoretic visual display according to some implementations.

[0025] Figure 6 Shows a cross-sectional view of an exemplary electrophoretic visual display according to some implementations.

[0026] Figure 7A Shows a schematic diagram representing a method for preparing carbon ink for an electrophoretic visual display according to some implementations.

[0027] Figure 7B Shows a schematic diagram representing another method for preparing carbon ink for an electrophoretic visual display according to some implementations.

[0028] Figure 8 Shows a cross-sectional schematic diagram of an exemplary display configuration for an electrophoretic visual display according to some implementations.

[0029] Figure 9 Shows a cross-sectional schematic diagram of an exemplary display configuration for an electrophoretic visual display according to some implementations.

[0030] Figure 10 Shows a cross-sectional schematic diagram of an exemplary display configuration for an electrophoretic visual display according to some implementations.

[0031] Figure 11 Shows a cross-sectional schematic diagram of an exemplary display configuration for an electrophoretic visual display according to some implementations.

[0032] Figure 12 Shows an image of an exemplary electrophoretic display cell according to some implementations.

[0033] Figure 13 Shows an image of an exemplary electrophoretic display cell according to some implementations.

[0034] Figure 14 Shows an image of an exemplary electrophoretic display cell according to some implementations.

[0035] Figure 15A Shows a cross-sectional schematic view of a multi-layer exemplary electrophoretic display according to some implementations.

[0036] Figure 15B Shows a list of features associated with a multi-layer electrophoretic display according to some implementations.

[0037] Figure 16A Shows an exemplary implementation of a multi-layer electrophoretic display according to some implementations.

[0038] Figure 16B Shows an exemplary implementation in which two multi-layer substrates include different sets of components according to some implementations. Detailed Description

[0039] Introduction

[0040] Various implementations of the subject matter disclosed herein generally relate to systems and methods for manufacturing electrophoretic displays (referred to herein as "EPDs" and commonly known as "electronic paper"). Electronic paper (electronic paper / e-paper), sometimes also electronic ink, and electrophoretic displays are display devices (or components or display devices) that substantially mimic the appearance of traditional ("ordinary") wet ink used on paper. However, unlike conventional backlit flat panel displays that emit light (referring to modern flat panel televisions and computer monitor displays), an electronic paper display reflects the emitted light onto it, similar to conventional paper. This can make the EPD relatively more natural for the eyes and more comfortable to read in well-lit environments (such as outdoors on a sunny day, or in an office conference room), while also providing a wider viewing angle than most conventional or currently available light-emitting displays. It is worth noting that the contrast ratio available in EPDs has reached a level similar to that of traditional printed media, including newspapers. Thus, manufacturers can now generally benchmark EPD performance based on whether they can read an image in direct sunlight without it appearing washed out (referring to becoming visually unclear or indistinguishable due to a lack of sufficient contrast between light and dark surfaces in the presence of significant external lighting).

[0041] Some EPD technologies can indefinitely maintain static text and images without electricity, thus providing a useful low-cost alternative to traditional digital displays for certain applications such as signs produced in grocery stores or disposable labels on goods and packaging. Flexible electronic paper can be configured to use plastic substrate materials and plastic electronics to provide structural rigidity in their respective display backplanes, and the lack of illumination can result in limited power consumption, translating into low operating costs. The applications of EPDs are numerous and can include electronic shelf labels and digital signage, schedules at airports, bus, regional rail, and subway (train) stations, ride-sharing service pick-up locations, electronic billboards (such as in stadiums), smartphone displays, and portable e-readers ("e-readers"), any one or more of which are capable of displaying digital versions of books and magazines that are conventionally available in print media with similar (or better) visual sensitivity and accuracy. Given that advancements in electronic devices and cloud-based computing have significantly increased the amount of data that can be processed and exchanged daily in various economic sectors ranging from higher education to corporate finance, the ability to visually present up-to-date information to users has become increasingly important.

[0042] Notably, the detailed display of text and graphical information is important for Internet of Things ("IoT") systems (which refer to systems of interconnected computing devices, machinery, and digital machines that have identifiers and the ability to transfer data over a network without human-to-human or human-to-computer interaction), where low cost and power requirements pose significant challenges to their widespread deployment and use. Modern display technologies, including organic light-emitting diode (OLED) technology, provide bright, detailed, and high-resolution displays (fully capable of accurately replicating true black representation), but these rich graphics typically require high operating costs, as reflected by continuous power consumption, and may not be particularly suitable for integration with self-powered or other alternative energy harvesting solutions. For many IoT applications, including electronic shelf or packaging labels, providing the basic necessary information at low power is more desirable than providing a rich graphical experience at high power. Although more energy-efficient electrophoretic display technologies have reduced continuous energy requirements, they still often require high voltage and energy to drive the display, thus negating the possibility of using ambient energy harvesting methods.

[0043] Unique 3D hierarchical open porous structure

[0044] The implementation disclosed by the present invention provides an EPD display device having a carbon-containing layer positioned between electrode layers with opposite charges. The carbon-containing layer serves as a physical barrier for electrophoretic ink migrating between the electrode layers to guide and control the migration, thereby achieving high image resolution while maintaining low power consumption. The EPD device provides improvements over conventional EPD displays by incorporating a three-dimensional (3D) carbon-based aggregate formed from graphene nanosheets (where graphene nanosheets refer to a relatively new class of carbon nanoparticles and / or nanopowders) in the carbon-containing layer with multifunctional characteristics. The graphene nanosheets can consist of small stacks (3 - 5 layers, or up to 15 layers) of substantially vertically aligned graphene sheets having a flake shape. Such graphene sheets can be nearly identical to those found in the walls of carbon nanotubes, but exist in a planar form. The graphene nanosheets can replace carbon fibers, carbon nanotubes, nanoclays, or other compounds in many composite applications, including those applicable to the EPD device provided herein.

[0045] The 3D carbon-based aggregate formed from graphene nanosheets can be synthesized (or otherwise "self-assembled", "self-nucleated", or formed) in a controlled and tunable chemical reaction chamber or reactor while flowing a carbon-containing gaseous substance therein, which optionally includes one or more inert carrier gases, etc. The 3D carbon-based aggregate inherently self-grows at defined positions orthogonal (at right angles) to each other in flight to define a 3D hierarchical open porous structure (the term "hierarchical" is used herein to refer to a plurality of open passageways of various widths or other dimensions scattered within or between larger 3D carbon aggregates). The self-growth or self-assembly method disclosed by the present invention provides significant procedural, synthetic, and technical differences from known and conventional carbon particle formation methods, such as annealing (which refers to a heat treatment that changes the physical properties and sometimes the chemical properties of a material to increase its ductility and reduce its hardness to make it more workable) and sintering (which refers to a method of compacting and forming a solid mass of a material by heat or pressure without melting it to the liquefaction point), to present unexpected favorable material and performance characteristics in the 3D hierarchical open porous structure.

[0046] Regarding the details of the carbon-containing layer of the proposed EPD device, an organized and tunable porous arrangement is formed in the 3D hierarchical open porous structure, which is configured to facilitate the electrophoretic migration of the carbon-based electronic ink therein. The porous arrangement can be substantially fixed such that the 3D carbon-based aggregates are cross-linked and can be held in place by an adhesive material or binder to promote flexibility, which is desirable for forming the porous arrangement on a flexible substrate (such as paper, plastic, or other materials), but still guides the electrophoretic ink migration as needed. The electrophoretic carbon-based ink can be prepared by using an ultrasonic treatment method, in which the carbon material is simultaneously fragmented and functionalized to prepare submicron ink particles in the range of about 100 nm to 200 nm that are effectively dispersed in a low dielectric solvent.

[0047] The EPD device, related structures, and electrophoretic carbon-based ink disclosed by the present invention can be 3D printed on flexible and disposable substrates, allowing for the development and economically viable production of low-cost devices suitable for daily use. Compared with traditional EPDs, the EPD device has relatively low power consumption requirements, and thus can operate with a relatively low amount of power, allowing devices that can be operated solely through energy harvesting, rather than operating on (for example) a portable battery power supply as occasionally found in traditional EPD devices. As previously discussed, the applications of the devices disclosed by the present invention are extensive and include (at least) shipping labels for packaging or price tags for store items, where the information to be displayed on the EPD can be wirelessly transmitted to the EPD. The low cost of the EPD allows it to be discarded after the item to which it is attached has been delivered or purchased, etc.

[0048] Conventional electrophoretic display (“EPD”) device

[0049] Unlike conventional backlit flat panel displays that emit light, electronic paper displays including the EPD device disclosed by the present invention reflect light like traditional paper, making them natural for human eye viewing and reading, and can also provide a wider viewing angle, thus achieving versatility in applications replacing traditional signage in alternative retail stores, etc. Moreover, many electronic paper technologies can indefinitely maintain (present) static text and images without power, thus reducing the continuous power consumption requirements for applications in various fields.

[0050] Figure 1AFIG. 110A shows a side cross-sectional schematic of an exemplary conventional EPD device 100A and FIG. 108A shows a top-down schematic of the EPD device 100A, which includes an upper (transparent) electrode layer 102A, a liquid polymer layer 104A containing electrophoretic ink capsules, and a lower electrode layer 106A. In conventional practice, titanium dioxide (“titania”) particles with a diameter of about one micrometer (μm) are dispersed in a hydrocarbon oil. A dark dye may also be added to the oil together with a surfactant (a substance that tends to reduce the surface tension of the liquid in which it is dissolved) and a charge agent that charges the titanium dioxide particles. The mixture is placed between two parallel conductive plates (shown as the upper electrode layer 102A and the lower electrode layer 106A, respectively) separated by a gap of 10 μm to 100 μm. When a voltage is applied across the two plates, the particles electrophoretically migrate (the movement of dispersed particles relative to a fluid under the influence of a spatially uniform electric field) to the plate with the opposite charge to the particles. When the particles are on the front (viewing) side of the display, the EPD 100A appears white because the titanium dioxide particles scatter light back to the viewer due to their refractive index (a dimensional value that describes how fast light travels through a given material). When the particles are on the back side of the display, that part of the EPD appears dark because the incident light is absorbed by the colored dye. If the rear electrode is divided into a plurality of small image elements (pixels), an image can be formed by applying an appropriate voltage to each area of the display to create a pattern of reflective and absorptive regions.

[0051] Conventional EPDs can be configured to be controlled by or utilize thin-film transistor (TFT) technology based on metal-oxide field-effect transistors (MOSFETs). TFTs may be required to form high-density images in EPDs. A common application of TFT-based EPDs is in e-readers. EPDs are considered a prime example of the electronic paper category because of their paper-like appearance and low power consumption. Examples of commercially available electrophoretic displays include the high-resolution active matrix displays used in Amazon Kindle, Barnes&Noble Nook, Sony Reader, and Kobo eReader.

[0052] A conventional microcapsule-based electrophoretic display 100B is shown in Figure 1Band includes a top electrode array 102B and a bottom electrode array 108B having alternating and opposite polarities or charges as shown, as well as white negatively charged particles 104B and black dyes 106B (collectively referred to as electronic ink). The EPD holds the microcapsules in a liquid polymer layer sandwiched between two electrode arrays 102B and 108B, where the upper part is transparent. The two electrode arrays 102B and 108B are aligned to divide the sheet into pixels, and each pixel corresponds to a pair of electrodes located on either side of the sheet. The sheet is laminated with a transparent plastic layer for protection, resulting in a total thickness of 80 microns, or twice that of ordinary paper. The network of electrode arrays (referring to the two electrode arrays 102B and 108B) is connected to a display circuit that "turns on" and "turns off" the electronic ink at specific pixels by applying a voltage to specific electrode pairs. The negative charge of the surface electrode repels the white negatively charged particles 106B to the bottom of the local capsule, forcing the black dye 106B to reach the surface to turn the pixel black. Reversing the voltage has the opposite effect. It attracts the white negatively charged particles 106B to the surface, turning the pixel white.

[0053] Ultra-thin plastic passive matrix EPD display (PMEPD)

[0054] A conventional PMEPD 100C using microcup technology is shown in Figure 1C and includes a top patterned conductor film 102C, charged particles 104C, a sealing or adhesive layer 106C, a bottom patterned conductor film 108C, and a dielectric solvent 110C. Exemplary microcups 114C (which may equally or alternatively refer to multiple microcups as microcups 114C) may have a cup size 112C (referring to width (w) or length (l)) in the range of 60 - 180 μm, and a microcup height 116C of 15 - 40 μm. The top patterned conductor film 102C and the bottom patterned conductor film 108C sandwich one or more microcups, each microcup filled with a dielectric solvent 110C, thereby allowing the migration of charged particles 104C to be guided according to the formation of the microcups 114C when exposed to a voltage.

[0055] PMEPDs have been prepared by a form-flexible roll-to-roll manufacturing method based on microcup and sealing technologies. High conversion rate microcup PMEPDs with a threshold voltage in the range of 5V to 50V having a sharp electro-optical conversion ("γ") have been demonstrated in conventional products and technologies. Due to the lack of inherent threshold characteristics to suppress or eliminate unwanted crosstalk or cross-offset between adjacent pixels during matrix driving, PMEPDs using traditional column and row electrode patterns typically pose significant technical challenges.

[0056] Several attempts have been made to solve the threshold problem. For example, additional conductive layers or grid electrodes have been employed to suppress unwanted particle movement in non-addressed pixels. Such PMEPDs have been developed, but due to the required multi-layer electrode structure (which is costly in itself), high manufacturing costs are generally required. Alternatively, magnetic particles and magnetic electrodes have been proposed to provide the required threshold, again at the expense of manufacturing cost. Electrophoretic fluids with inherent threshold characteristics have been reported, but there are trade-offs in, for example, response time, operating voltage, brightness, image uniformity, and display lifetime.

[0057] As Figure 1C shown, the walls or partitions of the microcups 114C provide mechanical support throughout the EPD and can provide advantageous physical-mechanical properties, including scratch resistance, impact resistance, and bend resistance. They are also capable of achieving color separation by effectively isolating the fluids with different properties (such as color and / or switching rate) in each individual cup. Through continuous filling and sealing techniques, the EPD can be manufactured at relatively low cost in a high-speed roll-to-roll process.

[0058] Limitations in conventional technologies

[0059] Although they are generally produced and operated at a relatively low cost due to their relative simplicity compared to other types of modern flat panel display devices, compared to other display technologies such as liquid crystal displays (LCDs), electronic paper technology can provide a very low refresh rate (which is undesirable). This shortcoming prevents producers from implementing complex modern interactive applications (using, for example, fast-moving menus, mouse pointers, or scrolling), such as those commonly found on standard mobile devices such as smart phones. An example of this limitation during use is that documents on a conventional EPD device may not scale smoothly without:

[0060] (1) extreme blurring during conversion; or,

[0061] (2) very slow scaling (both are highly undesirable).

[0062] Another limitation is that after refreshing a partial screen, a shadow of the image may be visible, leaving an unwanted residue that visually interferes with subsequent images displayed on the screen. Such a shadow is a serious nuisance and is known in the industry as a "ghost image", and the effect is called "ghosting". This effect is reminiscent of screen aging, but unlike screen aging, it can be resolved after the screen is refreshed several times.

[0063] A novel EPD device including a 3D hierarchical open porous structure acting as a stationary phase through which particles can migrate.

[0064] To address the limitations encountered in conventional EPD device technologies,Figure 1D A cross-sectional schematic view of an EPD device 100D is shown, which includes a carbon-based three-dimensional (3D) structure 130D and includes essentially "layered" tuning openings or passages, such as organized by opening or passage width. Thus, the structure 130D is generally open and porous. In Figure 1D the configuration shown, the EPD device 100D includes a plurality of layers 145D deposited on a substrate 110D by any one or more known methods and using commercially available tools.

[0065] As Figure 1D shown, the EPD device 100D includes a first electrode layer 120D disposed on the substrate 110D, a structure 130D disposed on the first electrode layer 120D, a plurality of charged electrophoretic ink capsules 140D dispersed within and around a porous arrangement 148D formed in the structure 130D, and a second electrode layer 150D disposed thereon. The structure 130D can be sealed with an isolation seal layer 139D and laminated to the second electrode 150D using an optically transparent (clear) adhesive material 149D. The plurality of charged electrophoretic ink capsules 140D electrophoretically migrate (which refers to the movement of dispersed particles relative to a fluid under the influence of a spatially uniform electric field) through the structure 130D towards the layer 150D (essentially as previously described for the conventional EPD device in Figures 1A to 1C where the charged electrophoretic ink capsules 140D (which can be white and negatively charged) will be attracted to the positively charged first electrode 102B) to form a high-resolution image (such as a pattern, graphic, text) viewed from the layer 150D, as shown by the icon of the eye 105D, and essentially replicates the appearance of traditional ink on paper.

[0066] Generally speaking, the structure 130D forms a fixed solid phase between the first electrode layer 120D and the second electrode layer 150D respectively, and may include a porous carbon material interconnected with each other. Electrophoretic ink particles (having a contrasting color with the fixed carbon solid phase) including titanium dioxide (which may be interchangeably referred to as "titanium oxide", "titanium IV oxide" herein, and refers to the naturally occurring titanium oxide with the chemical formula TiO2) migrate to any one or more of the first electrode layer 120D and the second electrode layer 150D respectively according to the application of voltage. In operation, negatively charged movable titanium dioxide particles can be attracted to the positively charged first electrode layer 120D to display white, or be repelled away from the negatively charged first electrode layer 120D to cause the display of black (or darker than white). Any one or more movable titanium dioxides can be guided or dragged in and out (non-reactively) through the structure 130D (also referred to as the fixed solid phase). This method can be easily distinguished from conventional techniques, which rely on electrophoretic ink dispersed in a dielectric solvent, and the dielectric solvent is trapped or at least substantially restricted in microcups or microcapsules, where the movement is respectively limited by the organization and placement of any microcup or microcapsule.

[0067] Fabrication of Carbon-Based 3D Hierarchical Open Porous Structures

[0068] Conventional EPD devices can be fabricated by a roll-to-roll form of flexible manufacturing method, and may include charged titanium dioxide and / or ink particles dispersed in a dielectric solvent within microcups, and the charged particles migrate through the dielectric solvent to form and display an image. The EPD device may include hydrocarbon oil positioned between adjacent electrode layers, and the charged particles migrate through the oil to form an image. The EPD device may also include a carbon structure prepared by annealing or sintering techniques as previously discussed, both of which are conventional and well-known techniques, and cannot provide the fidelity required to achieve Figure 1D the structure 130D shown and discussed.

[0069] Different from the (or other) conventional techniques discussed, the structure 130D can nucleate and grow in an atmospheric pressure plasma-based vapor stream of a reagent gaseous substance including methane (CH4) to self-form initial carbon-containing and / or carbon-based particles (without the need for additional dedicated seed particles). The initial particles can expand by forming a plurality of orthogonally interconnected aggregates 132D, each aggregate 132D having a diameter of at least 400 nm, such as 400 nm to 20 μm, or an average diameter such as 1 μm to 20 μm, and each aggregate contains a plurality of graphene nanosheets.

[0070] The initial particles then expand by:

[0071] ·Synthesis “in flight,” which describes the systematic coalescence of additional carbon-based materials derived from carbon-containing gases entering mid-air within a microwave plasma reaction chamber (referring to nucleation and / or growth from initial carbon-based homogeneous nucleation independent of seed particles); and / or,

[0072] ·Direct deposition or growth (alternatively referred to as “self-nucleation”) onto a support or sacrificial substrate such as a current collector within a thermal reactor; and / or

[0073] ·Exposure to one or more post-treatment operations to achieve specific desired properties.

[0074] Coalescence refers to the process in which two phase domains of the same composition come together and form a larger phase domain. Or, if separate chunks of two or more miscible substances (carbon derivatives formed from flowing methane gas) make the slightest contact, the process by which they seemingly “pull” each other together.

[0075] Accordingly, Structure 130D forms a display architecture in which carbon-based materials uniquely self-nucleate to separately synthesize or otherwise produce a tunable porous (non-conductive) network positioned between a first electrode layer 120D and a second electrode layer 150D, and the tunable porous (non-conductive) network can direct the migration movement of particles therein and thus generate and reproduce clear high-quality images that could not be achieved by conventional means.

[0076] Returning to the synthesis process for forming Structure 130, as introduced above, a vapor stream of a carbon-containing composition such as methane (CH4) can flow into one of two general reactor types:

[0077] ·A thermal reactor; or,

[0078] ·A microwave-based (and / or “microwave”) reactor. A suitable type of microwave reactor is described by Stowell et al., “Microwave Chemical Processing Reactor,” U.S. Patent 9,767,992 (September 19, 2017), which is incorporated herein by reference in its entirety.

[0079] As used herein, the term “in flight” refers to a novel chemical synthesis method based on contacting particulate materials derived from incoming carbon-containing gaseous substances (such as those containing methane (CH4)) to “crack” such gaseous substances. As commonly understood and as mentioned herein, “cracking” refers to the technical process of methane pyrolysis to produce elemental carbon (such as high-quality carbon black) and hydrogen, without the potential pollution problem of carbon monoxide and with substantially no carbon dioxide emissions. A representative endothermic hydrocarbon cracking reaction that can occur within a microwave reactor as described above is shown by the following formula (1):

[0080] CH4+74.85kJ / mol→C+2H2(1)

[0081] The carbon derived from the above "cracking" process can fuse (self - bond) together while being dispersed in the gas phase, called "in - flight", to form carbon - based particles, structures, (substantially) 2D graphene sheets, and aggregates 132D derived therefrom. Aggregates 132D (collectively defining structure 130D) can each individually include multi - layer graphene nanosheets fused together (or composed thereof), with each layer of graphene nanosheets fused at an angle orthogonal to the adjacent graphene nanosheets, to serve as a kind of inherent, self - supporting scaffold, which can also be structurally supplemented by conventional chemical (wet) binders or other joining materials, thus allowing the favorable structural features of structure 130D to be maintained even in the case of bending or other movement of the second electrode layer 120D and / or the substrate 110D.

[0082] The conductivity of the deposited carbon and / or carbon - based materials used to form structure 130D can be tuned (or eliminated) by adding metal additives to the carbon phase during the first part of the deposition stage or by changing the ratio of the various carbon particles derived from the cracked hydrocarbon gas under discussion. As part of the energy deposition process, other parameters and / or additives can be adjusted such that the energy level of the deposited carbon and / or carbon - based particles will: (1) bond together; or, (2) not bond together. Also, by nucleating and / or growing structure 130D "in - flight" or directly in an atmospheric - plasma - based vapor stream on a support or sacrificial substrate, many operations and components present in the EPD device and the EPD device manufacturing process can be reduced or completely eliminated. Moreover, customization and tunability can be achieved or added to the carbon and / or carbon - based materials under discussion.

[0083] The pore size of the carbon - based 3D hierarchical open - porous structure

[0084] As described above, carbon structure 130D can be synthesized in - flight to have a 3D hierarchical structure, which includes a combination of short - range, local nanostructuring and long - range approximately fractal - like structuring, which in this context refers to the formation of successive layers, including 90 - degree rotations of each successive layer relative to the layer below it, etc., thus allowing the formation of vertical (or substantially vertical) layers and / or intermediate ("inter") layers. This orientation is referred to herein as "orthogonal layering" or "orthogonal interconnection" to form structure 130D in which a porous arrangement 148D is formed. To achieve the desired EPD performance quality, the porous arrangement 148D can be tuned to include:

[0085] · Inter-particle pores 151D, which are void spaces, cavities or openings within and around the aggregates 132D, the aggregates extending between mesopore and macropore sizes (defined by the International Union of Pure and Applied Chemistry IUPAC as having pore diameters extending from 2 nm and greater than 50 nm respectively) and sized 200 nm to 2 μm, 400 nm to 5 μm, or up to 10 μm, which refers to the average distance between parts of the self-assembled aggregates 132D forming the structure 130D; and

[0086] · Intra-particle porosity 155D, which is defined as between materials within each aggregate 132D, such as between graphene layers, and may have an average pore diameter of 200 nm to 2 μm.

[0087] The structure 130D may include aggregates 132D interconnected by a polymer, such as a cross-linked polymer.

[0088] The substrate 110D can be a flexible material, such as a polymer film or a paper-based material, and is relatively low-cost and disposable, being particularly suitable for single-use applications. Exemplary materials suitable for forming the substrate 110D include any one or more of cardboard, paper, polymer-coated paper and polymer films, as well as cardstock, labels and boxes. Due to the dormant, non-power-consuming nature of the EPD 100D when not activated, an alternative configuration of the EPD 100 can achieve an extended usage period.

[0089] Functions of an electrophoretic display (EPD) device

[0090] Any one or more of the first electrode layer 120D and the second electrode layer 150D can be combined for use as an electrical conductor that contacts a non-metallic portion of a circuit (such as a semiconductor, electrolyte, vacuum, or air) and generates an electric field for various components (such as pixels) of the EPD device 100D. The first electrode layer 120D and the second electrode layer 150D can be made of the same, similar, or different materials from each other. In some implementations, the first electrode layer 120D and the second electrode layer 150D can each include a plurality of individual electrodes that are positioned substantially adjacent to each other, where any one or more of the individual electrodes are printed with a conductive ink. The potential-forming material used to fabricate the electrode layers 120D and 150D can include indium tin oxide (ITO). The second electrode layer 150D is at least substantially transparent to allow viewing of an image formed by the migration of the plurality of charged electrophoretic ink capsules 140D guided by the structure 130D. The second electrode layer 150D can be an ITO-coated film, such as polyethylene terephthalate (PET), while the first electrode layer 120D can be made of a carbon-containing material, such as graphene or a metal-functionalized carbon allotrope (including graphene). The carbon particles prevalent in the first electrode layer 120D can be interconnected by a binder such as a polymer, which includes cellulose, cellulose acetate butyrate, styrene butadiene, polyurethane, polyether-polyurethane, or a crosslinkable resin.

[0091] The structure 130D can be initially synthesized without the need for nucleation (alternatively referred to as "seed" particles), but can then be exposed to one or more post-processing operations to achieve high-sensitivity tuning of any one or more of the porous pathways of the porous arrangement 148D (in terms of width, length, or any other dimension), while remaining completely non-conductive overall. Carbon and carbon-based materials can be post-processed (as further described at least in Figure 4B to prepare the porous arrangement 148D such that electrophoretic particles can move into and out of the structure 130 through the porous arrangement 148D unobstructed. The unique morphology of the carbon used to produce the structure 130 guides the migrating particles without generating, promoting, or in any way conducting electricity and / or current. In essence, the structure 130 is completely non-conductive because one or more processes used to form crosslinked carbon (as detailed in Figure 4B of the structure 130) produce non-conductive materials.

[0092] Accordingly, the pores 151D between the carbon particles 132D enable the plurality of charged electrophoretic ink capsules 140D to electrophoretically migrate (which refers to the movement of dispersed particles relative to a fluid under the influence of a spatially uniform electric field) through the structure 130D either individually or at least predominantly separately in response to the activation and / or deactivation of any one or more of the first electrode layer 120D and the second electrode layer 150D, without experiencing undesirable electrical interference from the structure 130D itself. For example, the charged ink capsules among the plurality of charged (usually white or light-colored) electrophoretic ink capsules 140D can electrophoretically migrate by being guided by the structure 130D to the second electrode layer 150D to form a detailed visible image at a resolution level that is not achievable using conventional techniques lacking the unique particle-guiding ability of the structure 130. In some configurations, most or all of the plurality of charged electrophoretic ink capsules 140D can be light-colored to contrast with the dark color of the structure 130D.

[0093] Most or all of the plurality of charged electrophoretic ink capsules 140D can be titanium dioxide (titanium oxide) or other white colloidal particles of approximately 100 nm dispersed in a low dielectric solvent such as any one or more of isoparaffins such as Isopar-L and Isopar-G, xylene, 1,2-dichlorobenzene, tetralin, diethylbenzene, toluene, decane, dodecane, hexadecane, cyclohexane, 2-phenylhexane, 1-phenylheptane, 1-phenyldecane, tetrachloroethylene. The plurality of charged electrophoretic ink capsules 140D can be configured to include a charge control agent (CCA) such as aerosol dioctyl sulfosuccinate (AOT), poly(isobutylene succinimide) (PIBS), or sorbitan oleate to have a defined polarity such that they move in response to a voltage difference applied to any one or more of the first electrode layer 120D and the second electrode layer 150D, respectively.

[0094] To better maintain a defined overall structural shape or pattern during the bending of the substrate 110D, the structure 130D can include aggregates 132D interconnected to each other by a binder such as a polymer including cellulose, cellulose acetate butyrate, styrene butadiene, polyurethane, polyether-polyurethane, or a crosslinkable resin that forms polymerizable covalent bonds such as acrylate, epoxy resin, vinyl resin. The binder connects the aggregates 132D together but does not consume or otherwise fill the pores 151D and / or other voids, spaces, or gaps encountered between the aggregates 132D interconnected to form the structure 130D.

[0095] In some implementations, the aggregate 132D may include constituent forming elements, including carbon allotropes such as graphene, carbon nano-onions (CNO), carbon nanotubes (CNT), or any combination thereof, such that in some implementations, the structure 130D may include graphene defining a weight and / or volume percentage, including greater than 50%, greater than 80%, or greater than 90%. Due to the conductive nature of the structure 130D, the thickness 131D of the structure 130D can be made thinner than conventional EPD materials, which enables electrode connection therein.

[0096] Fabricating the structure 130D as a thin layer can result in a situation where less energy is required to move multiple charged electrophoretic ink capsules 140D, thus making the EPD device 100D more favorable for being powered only by energy harvesting methods, such as an energy harvesting antenna 190D, or other methods disclosed in U.S. Patent Serial No. 16 / 282,895, titled "Antenna with Frequency-Selective Elements", filed on February 22, 2019 by Stowell et al., the entire content of which is incorporated herein by reference. For example, the thickness 131D of the structure 130D can be configured to be about 10 μm to about 40 μm, or about 10 μm to about 100 μm. The conductivity of the structure 130D can be greater than 20,000 S / m, or greater than 5,000 S / m, or greater than 500 S / m, or greater than 50 S / m. In terms of resistance, the sheet resistance of the structure 130D can be less than 1 Ohm / sq., or less than 10 Ohm / sq., or less than 100 Ohm / sq., or less than 1,000 Ohm / sq.

[0097] Figure 1E An exemplary EPD device 100E that may include the EPD device 100D having the structure 130D is shown, both Figure 1D shown and discussed therein. The exemplary EPD device 100E can generate high-resolution text 102E and images that can be viewed from a wide angle, thus enhancing the desirability of the EPD device 100E.

[0098] Figure 2 An enlarged view of the structure 130D of the EPD display 100D according to some implementations is shown (shown in Figure 1D therein). As previously shown in Figure 1D therein, the porous arrangement 148D can be tuned to include:

[0099] · Inter-particle pores 151D, which are void spaces, cavities, or openings inside and around the aggregate 132D, the size of which is set to 200 nm to 2 μm, 400 nm to 5 μm, or up to 10 μm, referring to the average distance between parts of the self-assembled aggregate 132D forming the structure 130D; and

[0100] · The intra-particle porosity 155D, which is defined as the space between materials within each aggregate 132D, such as between graphene layers, and may have an average pore size of 200 nm to 2 μm.

[0101] The size of the aggregate 132D itself can be set to have an average diameter of at least about 400 nm, such as about 400 nm to about 20 μm, or such as about 1 μm to about 20 μm, and are cross-linked together (orthogonally) by a polymer. Figure 2 The detailed schematic 135 shown presents an enlarged schematic of an exemplary aggregate 132D comprising organized graphene nanosheets fused together orthogonally, where each nanosheet may include several layers of graphene (FLG) 136 and single-layer graphene 137. Figure 2 The representative inter-particle porosity 138a shown is between FLG 136 (similarly, in some implementations, FLG 136 can be aggregate 132B), while the intra-particle porosity 138b is within any one or more FLG 136, such as between individual graphene layers of graphene, and is sized to be about 200 nm to about 2 μm.

[0102] Figure 3A and Figure 3B are scanning electron microscope (SEM) micrographs of carbon network 300 and carbon network 301 (any one or more of which represent Figure 1D the structure 130D shown), where carbon networks 300 and 301 are composed only of carbon-based materials (such as aggregates 132D grown "in-flight" in an atmospheric vapor stream of a carbon-containing gaseous substance such as methane, as previously discussed with respect to Figure 1D ) without applying or using a resin to connect the aggregates 132D. Figure 3A Shows carbon network 300, which includes various larger inter-particle pores 304 of different sizes (sized 200 nm to 2 μm, 400 nm to 5 μm, or up to 10 μm) and smaller intra-particle pores 308 (average pore size of 200 nm to 2 μm), which are shown by the highly textured 3D structure of the carbon network 300 shown. Figure 3A The highly textured 3D structure of the carbon network 300 shown. Figure 3B is Figure 3AA higher magnification micrograph of the carbon network 300 shown, showing the porosity of the carbon network 301. The carbon networks 300 and 301 show exemplary carbon-based porous structures that do not use a resin material to bond the carbon materials together. Under certain use or bending conditions, the carbon networks 300 and 301 may break and decompose, and thus cannot provide guidance for migrating electrophoretic ink particles to form a high-resolution image, thereby limiting their ability to be applied to an electrophoretic display (such as the EPD device 100 shown in FIG. 1). To address these potential performance issues, a resin (which refers to a solid or highly viscous substance of plant or synthetic origin that can generally be converted into a polymer) can be systematically incorporated into any one or more of the carbon networks 300 and 301 for the purpose of strengthening and maintaining the structure, so that they can be used in an EPD device without encountering breakage or other performance problems.

[0103] Figure 4A and Figure 4B show a flowchart with the attached illustrative schematics 400a and 400b, both of which relate to the manufacture of carbon-based scaffolds or structures, such as the structure 130D shown in 1D and the carbon networks 300 and 301 shown in Figure 3A and Figure 3B respectively, any one or more of which are suitable for incorporation into an electrophoretic display, such as Figure 1D the EPD device 100D shown. Figure 4B The schematic 400b shown represents Figure 4A a continuation of the schematic 400a shown. In Figure 4A operation 410, carbon particles such as Figure 1D the aggregates 132D shown can be grown "in-flight" in a substantially atmospheric vapor stream as previously described and / or using a microwave plasma reactor and / or the methods described in U.S. Patent 9,812,295 entitled "Microwave Chemical Processing" or U.S. Patent 9,767,992 entitled "Microwave Chemical Processing Reactor", the entire texts of which are incorporated herein by reference for all purposes. The carbon particles (such as the aggregates 132D) can be composed of a number of smaller carbon-based constituent elements (such as orthogonally fused FLG and / or SLG), as Figure 2As shown. Such aggregates can be further deconstructed or broken down into their constituent nanoparticles in operation 420 to functionalize these nanoparticles with nucleophilic functional groups in operation 430 to facilitate bonding of crosslinkable monomers to the exposed carbon. The breaking and / or functionalization can be carried out in the reactor in which the aggregates are formed, such as immediately during or after their functionalization. Alternatively, or in addition to the in-situ (within the same reactor) treatment as described, after the growth of the aggregates 132D, the breaking and / or functionalization can be carried out in a post-treatment operation outside the reactor. The nucleophilic moieties added during functionalization can facilitate coupling with the electrophilic moieties of the crosslinkable monomers. The nucleophilic moieties can include, for example, hydroxides and / or amines, where in the Figure 4A example, the exposed carbon can be oxidized to form hydroxylated carbon.

[0104] Go to Figure 4B As shown in the schematic 400b, the nucleophilic moieties of the functionalized carbon in operation 430 can be converted into crosslinkable carbon in operation 440 by, for example, functionalizing one or more exposed surfaces of the structure 130D shown in Figure 1D and adding monomers to the exposed and / or reactive surfaces of the carbon nanoparticles. Examples of monomers include moieties of oligomers, such as polyurethanes, polyethers, or polyesters linked with acrylates or epoxides. Organic coupling agents such as toluene diisocyanate (TDI) or methylene diphenyl diisocyanate (MDI) can also be added in operation 440 to further link the bond between the carbon nucleophile and the crosslinkable monomer. Operation 440 can also include combining the carbon nanoparticles with a solvent and a polymer initiator, where the polymer initiator will later be used to facilitate crosslinking of the carbon. The polymer initiator can include ultraviolet (UV) or photoinitiators, such as α-hydroxy ketones and monoacyl phosphines. Specific examples include Irgacure 184, Irgacure 819, Irgacure 1300, Darocur 1173, and Darocur TPO. Thermal initiators such as benzoyl peroxide, 2,2'-azobisisobutyronitrile (AIBN), tert-butyl peroxide, 1,1'-azobis(cyclohexanecarbonitrile), cyclohexanone peroxide, tert-butyl peracetate, and 4,4-azobis(4-cyanopentanoic acid) can also be (or alternatively) used. Solvents include, for example, isopropyl alcohol, ethanol, 2-methoxyethanol, propylene glycol monomethyl ether acetate, methyl ethyl ketone, cyclohexanone, N-methyl-2-pyrrolidone, N,N-dimethylformamide, xylene, toluene, dichloromethane, and / or various mixtures and combinations thereof.

[0105] The material generated by operation 440 can be used to form an ultraviolet (UV) and / or thermally curable carbon paste by adding a solvent and a radical initiator. Operation 440 can include washing to remove excess monomer that has not successfully attached to the exposed surfaces of the carbon particles, such that the resulting carbon will have a small amount of functional groups available for cross-linking on the surfaces of the carbon particles. In operation 450, the carbon paste is cast as a paste layer 452 and dried onto a substrate 454 (such as any one or more of polyethylene naphthalate, polyethylene terephthalate, polyimide, polycarbonate, and polymethyl methacrylate films) that provides support for the paste layer 452. The solvent in the paste layer 452 can be at least partially removed after casting onto the substrate 454. In operation 460, a pixel pattern for an electrophoretic display is formed by debossing (which refers to the embossing technique that means the process of forming raised or sunken relief images and designs in paper and other materials) in the surface of the paste layer, such as by forming a plurality of recesses 463 in the surface of the paste layer 452. After the pattern is formed, the cross-linkable carbon in layer 452 is polymerized into a structure 462 (similar to Figure 1D the structure 130D shown). For example, a metal halide type lamp (such as UVA light of 320 nm - 390 nm, 100 mW / cm 2 ) can be used to cure the surface of the carbon paste layer in a 5-minute UV exposure. The resulting layer can be further cross-linked by heating the film at 90 °C for 10 minutes. Other free radical polymerization methods known to those of ordinary skill in the art can also be or alternatively used to cross-link the carbon. The structure 462 formed on the substrate 454 can be incorporated into an EPD such as the EPD device 100D of FIG. D1.

[0106] Carbon-containing electrophoretic ink capsules (configured to migrate through the carbon structure)

[0107] Figure 5 and Figure 6 illustrate implementations of an exemplary EPD using carbon-containing electrophoretic ink (interchangeably referred to as electronic ink) (any one or more of which can be equivalent to or similar to Figure 1D the EPD100D shown). Conventional electrophoretic ink can include negatively charged white particles and positively charged black particles and is suspended in a transparent fluid. The white and black particles (which refer to charged electrophoretic ink microspheres or capsules) can be organized into thin films to be incorporated into various end-use applications such as EPDs, thereby enabling new applications in telephones, watches, magazines, wearables, and e-readers, etc., to form detailed human-readable images, where the black electrophoretic ink capsules can include carbon black (which refers to the material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, or ethylene cracking tar).

[0108] The uniformity of pigment particle size and ζ potential is desirable in EPD device applications because differences in charged particles can lead to corresponding (and undesirable) differences in migration rates when exposed to the applied electric field, resulting in undesirable variations and a lack of predictability in the resulting image quality. For example, smaller-sized particles tend to migrate at a faster rate than larger particles. The electrophoretic ink disclosed by the present invention includes any one or more highly structured carbons, such as graphene, carbon nano-onions (CNO), carbon nanotubes (CNT), or any combination or derived resulting structures, in order to achieve higher particle uniformity than conventional inks and a high phase purity of the highly structured carbon, rather than carbon black alone. For example, the provided carbon-based electrophoretic ink may have a highly structured carbon content greater than 90% or greater than 95% or greater than 99%. The carbon ink of the present invention can be manufactured by simultaneously functionalizing and fragmenting carbon particles, resulting in a more uniform distribution of particle sizes and a higher dispersion of carbon particles in the ink. For example, the carbon ink can be monodisperse, having a polydispersity index (PDI) less than 0.1, or having a narrow particle size distribution of <0.2.

[0109] Figure 5 The EPD device 500 is similar to the EPD device 100D shown in FIG. 1, where the substrate 510 corresponds to the same features as described for the substrate 110D, and so on. Different from the EPD device 100D, the device 500 utilizes a carbon-based ink 540 dispersed within the structure 530, and also includes a contrast layer 560 positioned between the structure 530 and the second electrode layer 550. Since the presence of carbon will cause the color of the carbon ink 540 to darken, the contrast layer 560 can be used to provide a contrasting color such that when the ink 540 is close to the bottom surface of the layer 560, the user can see the pattern formed by the carbon ink 540. For example, the contrast layer 560 can be white, including aluminum oxide, antimony trioxide, barium sulfate, silicon dioxide, titanium dioxide, zinc sulfide, or other white particles, contrasting with the black color of the carbon ink 540.

[0110] Figure 6 Another EPD display device 600 is shown, which can be used with any one or more of the carbon-containing inks disclosed by the present invention. Figure 6 The EPD device 600 can be substantially similar to Figure 1DThe EPD device 100D shown, where the substrate 610 corresponds to the same features as described for the substrate 110D, and so on. Different from other EPD implementations, the EPD device 600 may include a structure 630 having a contrasting color (such as white) with the carbon ink 640, rather than having a structure and ink of the same color as in other exemplary EPD implementations. The structure 630 may be made of a polymer composite material, the polymer composite material including light-colored (such as white) aggregates 632, such as aluminum oxide, antimony trioxide, barium sulfate, silicon dioxide, titanium dioxide, zinc sulfide, or other white aggregates. The aggregates 632 in the structure 630 may be surface-functionalized to achieve cross-linking, such as using acrylate functional groups, epoxy groups, or organically modified silica ("ORMOSIL"). The structure 630 may be reflective such that the carbon ink is not visible when the ink is dispersed away from the viewing surface of the device 600.

[0111] Figure 7A A flowchart 700 for preparing carbon ink for an EPD device and the accompanying illustrative schematic diagrams are shown. In Figure 7A operation 710, carbon particles (similar to or equivalent to Figure 1D the aggregates 132D shown) are prepared using a microwave plasma reactor and / or the method described in any one or more of the aforementioned U.S. Patent No. 9,812,295 and U.S. Patent No. 9,767,992. In operation 720, the carbon particles may be combined with reactive monomers (such as styrene, 4-vinyl-benzyl chloride, and vinyl-benzyl trimethyl ammonium chloride), where in operation 730, ultrasonic energy is applied to the mixture to simultaneously break and functionalize the particles. The carbon particles are broken into nanoparticles, each nanoparticle having an average size, for example, less than 200 nm. The ultrasonic treatment in operation 730 also generates free radicals such that the sub-particles are functionalized with the reactive monomers. The monomers polymerize on the surface of the carbon particles to form a linear polymer used as a dispersant. Operation 730 may also include adding a radical initiator, such as AIBN or other thermal initiators. In operation 730, the resulting particles may be dispersed in a low-dielectric solvent having a charge control agent (CCA) such as AOT, PIBS, or SPAN to make a carbon-containing electrophoretic ink. In operation 730, ultrasonic energy may be used to perform both breaking and functionalization together to form particles that are relatively uniform in size and highly dispersed in the electrophoretic ink. Alternatively, the carbon nanomaterials may be oxidized, which may be coupled with fatty acids (such as oleic acid, isopalmitic acid, and isostearic acid) or amines (such as octadecylamine, hexadecylamine, and oleylamine) to make functionalized carbon that can be dispersed in a low-dielectric solvent. Then CCA is added to increase the ζ potential of the carbon particles. The resulting electrophoretic ink may have a high ζ potential value of at least 30 mV magnitude, such as from about -30 mV to about -60 mV (negative value for carbon ink).

[0112] Figure 7BFIG. is a schematic illustration of another method 740 for preparing carbon ink for electrophoretic visual displays according to some implementations. Different from Figure 7A as shown and discussed, carbon particles can be prepared in operation 750 in a manner similar to operation 710 and reacted with octadecylamine in operation 760 to make functionalized carbon in operation 770. Also, in some configurations of the examples and / or implementations disclosed herein, black or dark carbon-based electrophoretic ink can be used to migrate within a white (or light-colored) stationary carbon-based porous matrix or structure. Such functionalized carbon can then be mixed with a charge control agent in operation 780 (such as described in Example 1).

[0113] EPD Device Configuration

[0114] Figures 8 to 11 shows an exemplary configuration of any one or more of the EPD devices disclosed herein that use a carbon structure (such as Figure 1D the structure 130D shown) and / or carbon ink. In these figures, only the electrode layer and the matrix layer are shown for clarity. Also, the figures are schematic and not drawn to scale; for example, the dimensions of the recesses and layers can be proportioned differently than shown.

[0115] Figure 8 shows a portion of an EPD 800 that includes a first electrode layer 820 (“bottom electrode”), a structure 830 located on the first electrode layer 820 (which can be carbon-based or carbon-containing, similar to Figure 1D the structure 130D shown) and a second electrode layer 850 (“top transparent electrode”) located on the structure 830. The structure 830 is non-conductive, porous, and made of carbon particles 831. To illustrate the movement of the ink, the ink 840 is shown as a droplet, but it should be understood that the ink 840 includes white submicron particles injected into the structure 830 that move between the pores of the structure 830 as described above. The ink 840 is an electrophoretic white ink and is positively charged in this implementation.

[0116] The first electrode layer 820 and the second electrode layer 850 are shown to have pixels 832a, 832b, and 832c, where in operation, each pixel of the first electrode layer 820 has an opposite charge to the corresponding pair of pixels in the second electrode layer 850. Since the ink 840 is positively charged, the ink 840 is attracted to the negatively charged pixel 832b of the second electrode layer 850, making pixel 832b appear white in the EPD800. Conversely, the positively charged pixels 832a and 832c of the second electrode layer 850 appear black because there is no ink 840 at the second electrode layer 850. The pixels 832a, 832b, 832c of the display can have rectangular, circular, hexagonal, or other shapes in the plane of the electrode layer 850, where the pixels form a pattern such as an orthogonal or diagonal array.

[0117] Figure 9 is a cross-sectional view of EPD900, showing an implementation using a non-conductive, non-porous carbon-based structure 930 instead of Figure 8 structure 830. EPD900 also uses a colored ink 940 instead of the white ink 840. Figure 9 includes a first electrode layer 920 ("bottom electrode"), a non-porous carbon-based structure 930 located on the first electrode layer 920, a porous TiO2 layer 960 located on the non-porous carbon-based structure 930, and a second electrode layer 950 ("top transparent electrode") located on layer 960. The non-porous carbon-based structure 930 is patterned with a recessed area 935 formed in the non-porous carbon-based structure 930 through which the ink 940 can travel. The ink 940 is made of negatively charged electrophoretic carbon. The ink 940 can be black or other colors, such as by adding colored pigments instead of carbon. The pixel pairs 932a, 932b, and 932c in the first electrode layer 920 and the second electrode layer 950 are similar to the pixels described above for Figure 8 described.

[0118] In Figure 9 pixel 932b is shown to be white with no carbon particles (black ink 940) in layer 960, and pixels 932a and 932c are shown to be the color of the ink 940 (ink 940 in the porous TiO2 layer 960). The pixels 932a, 932b, 932c together form an image on the EPD900. Figure 9 shows one implementation of driving the ink, where when a voltage is applied between the first electrode in the first electrode layer 920 and the second electrode in the second electrode layer 950 (e.g., the electrodes in each pixel 932a, b, c), the ink 940 moves vertically between the electrode layers 920 and 950. The electrodes can be individually addressed by an addressable array in the first electrode layer 920 and the second electrode layer 950, as understood by those of ordinary skill in the art. InFigure 9 In an example, the first electrode in pixel 932a of the first electrode layer 920 has a negative charge, and the second electrode in pixel 932a of the second electrode 950 has a positive charge. Since the ink 940 is negatively charged, the ink 940 will move through the recess 935, towards the second electrode layer 950 and stay within the porous layer 960, thus becoming visible in the image generated by the EPD 900. When an opposite voltage is applied, as shown by the negative charge on pixel 932b of the second electrode layer 950 and the positive charge on pixel 932b of the first electrode layer 920, the ink 940 will move towards the electrode layer 920, and pixel 932b will appear blank.

[0119] Figure 10 and Figure 11 Illustrates implementations of EPDs 1000 and 1100, which are similar to the EPD 900, but have openings (e.g., recesses) with a triangular cross-section. The EPD 1000 includes a first electrode layer 1020, a non-porous carbon-based structure 1030 located on the first electrode layer 1020, a porous TiO2 layer 1060 located on the non-porous carbon-based structure 1030, and a second electrode layer 1050 located on the porous TiO2 layer 1060. The non-porous carbon-based structure 1030 is non-conductive and non-porous. The recess 1035 in the non-porous carbon-based structure 1030 has a triangular vertex that points away from the image viewing surface (e.g., away from the second electrode layer 1050). The ink 1040 includes negatively charged electrophoretic carbon. Figure 10 Illustrates a configuration in which, due to the voltage applied to the pixels in the first electrode layer 1020 and the second electrode layer 1050, the ink 1040 vertically shuttles in and out of the recess 1035, as described above.

[0120] Figure 11 Illustrates a configuration in which the non-porous structure 1130 is a non-porous layer with patterned triangular recesses 1135 similar to Figure 10 However, the non-porous carbon-based structure 1130 is conductive, rather than non-conductive like the non-porous carbon-based structure 1030. Figure 11 The bottom electrode 1120, the top electrode 1150, and the porous TiO2 layer 1160 of Figure 10The corresponding layer in. The insulating seal layer 1170 between the porous TiO2 layer 1160 and the top electrode 1150 is used to electrically insulate the non-porous structure 1130 from the top electrode 1150. Examples of seal compositions for the seal layer 1170 include thermoplastic precursor dispersions that are immiscible with the electrophoretic ink and have a lower specific density than the ink. After the stationary phase is filled with a mixture of the seal precursor and the electrophoretic ink, the precursor phase separates and forms a thin layer on top of the fluid. This layer can then be polymerized by heat or radiation to hermetically seal the stationary phase. Since the non-porous structure 1130 is conductive, the ink 1140 moves towards the entire surface (e.g., the side walls) of the triangular recess 1135, rather than only towards the downward vertex as Figure 10 shown. Compared with the EPD1000, this implementation can provide a faster response time when forming an image of the EPD1100 because the distance traveled by the ink 1140 is smaller.

[0121] Figure 12 and Figure 13 show images of exemplary electrophoretic display units 1200 and 1300 according to some implementations, respectively. When a voltage difference of about ±1V is applied to any one or more of the display units 1200 or 1300, a contrast image (relative to no electric field) is observed. Similarly, Figure 14 shows an image of an exemplary electrophoretic display unit 1400 indicating a stylized mark, which can be reconfigured according to voltage application and is suitable for e-readers, supermarket displays, etc.

[0122] Figure 15A shows a cross-sectional view of an exemplary EPD1500A (which can be substantially equivalent in structure and function to Figure 1D the EPD130D shown and / or any one or more of the EPD devices disclosed in the present invention). The EPD1500A can include one or more layers, including a protective layer 1502A, a transparent conductive layer 1504A, a porous reflective layer 1506A, a porous carbon matrix with an integrated microporous layer 1508A, a seal layer 1510A, and a flexible layer 1512A (similar to a substrate on which any one or more other layers can be formed or deposited). The protective layer 1502A can be substantially transparent, providing a transparency greater than 90% in the visible range, and can also be tuned or configured according to the needs of a specific end-use scenario (such as supermarket or grocery store applications compared to e-reader applications, etc.). The protective layer 1502A can be deposited on top of the transparent conductive layer 1504A, which can have a resistivity of about R S <100Ω / sq → R SA resistance value of <30 Ω / sq (or within its approximate range). The transparent conductive layer 1504A can be deposited on the porous reflective layer 1506A, which is optional in some configurations and can be achieved based on the color of the carbon-based ink. The porous reflective layer 1506A can be deposited on a porous carbon matrix having an integrated microporous layer 1508A, and the porous carbon matrix can be substantially equivalent in form and function to Figure 1D the structure 130D shown, including pores with a size of about 20 μm, or other sizes according to, for example, the size of the carbon-containing electrophoretic ink particles or capsules used, etc. The porous carbon matrix having the integrated microporous layer 1508A can be deposited on the sealing layer 1510A, and the sealing layer can be configured to include a carbon-doped polymer or otherwise be adjacent to or held together with a carbon-doped polymer. The sealing layer 1510A can be deposited on the flexible layer 1512A, and the flexible layer can substantially simulate the function of any one or more of the substrates disclosed in the present invention to complete the multi-layer exemplary EPD 1500A.

[0123] Figure 15B A list of features 1500B associated with a multi-layer electrophoretic display according to some implementations is shown. The top electrode ( Figure 15A not shown in ) used with the exemplary EPD 1500A can include or be formed of a conductive but silver (Ag)-free optically transparent conductor. The porous carbon matrix having the integrated microcell layer 1508A can include patterned microcups, microcapsules, or recessed areas configured to enhance the migration of the electrophoretic ink therein, thereby achieving optimal image formation quality at a reduced power consumption level. The first electrode layer and the second electrode layer ( Figure 15A not shown in ) can be prepared to be solvent-resistant. All transparent components of the exemplary EPD 1500A can contain carbon, such as including any one or more highly structured carbons associated with the implementations disclosed in the present invention.

[0124] Figure 16A An exemplary implementation of a multi-layer electrophoretic display 1600 disposed on a container 1610 is shown. The multi-layer electrophoretic display 1600 can be the same as or different from the previously described EPD device 600. In this example, the EPD device 600 is disposed near other components that interact to form a sensor system having a visual readout 1601. In some cases, and as shown, the container (e.g., shipping carton, envelope, etc.) has a surface on which one or more sensors and visual readout devices can be printed. In some cases, the one or more sensors and the one or more visual readout devices are interconnected to form an analyte sensor system, and the analyte sensor system can be printed (e.g., 3D printing, inkjet printing, lithographic printing, etc.) onto one or more labels, and the labels are in turn fixed to the container.

[0125] Figure 16A A exploded view showing a sample configuration of a set of components that interact to form an analyte sensor system for detecting a fluid (e.g., gas or liquid) analyte and for displaying (e.g., visual readout 1601) an indication of the presence and / or concentration of the analyte. The multi-layer electrophoretic display can be composed of any number and / or juxtaposed pixels. The analyte sensor of the analyte sensor system can be electrochemical, high-frequency, resonant, chemiluminescent, or any combination thereof. In some cases, the first analyte sensor and the second analyte sensor are printed on the same substrate (e.g., a label or a container surface). Each analyte sensor can include a first electrode, a second electrode, and an electrolyte, and some components include particulate carbon and a redox mediator. An analyte sensor array can be used to increase functionality, such as the ability to detect multiple gases and / or subtract background moisture levels and / or increase the sensitivity to any particular analyte. As shown, the EPD device 600 is coupled to the analyte sensor 1660 via a power and signal interconnect 1650.

[0126] Multiple analyte sensors disposed on a container can be synergistically utilized to detect a combination of chemical substances, which in turn results in the characterization of the entire compound. The presence of multiple analyte sensors can be used to rule out false positives. Such a multi-analyte sensor system can include a first sensor configured to detect a first target chemical and a second sensor configured to detect a second target chemical different from the first target chemical. If and when the first sensor positively detects the first target chemical and the second sensor positively detects the second target chemical, an indicator such as the shown EPD device 600 presents a visual indication. For example, if and when the first sensor positively detects the first target chemical, a first concentric ring (e.g., as a visual readout 1601) can be displayed, and if and when the second sensor positively detects the second target chemical, a second concentric ring can be displayed.

[0127] In addition, other components can be integrated with the analyte sensor system to increase the additional functionality of the analyte sensor system. For example, an energy harvesting antenna 1670 can provide the electrical power required for the sensor and / or the display. Further details regarding the general methods of preparing and using an energy harvesting antenna are described in U.S. Application Serial No. 16 / 282,895, entitled "Antenna with Frequency-Selective Elements", filed on February 22, 2019, which is hereby incorporated by reference in its entirety.

[0128] As another example for providing the required electrical power for a sensor and / or a display, an energy storage device (not shown) may be provided near the sensor and / or near the display. Further details regarding general methods of preparing and using energy storage devices are described in U.S. Application Serial No. 16 / 740,381, filed on January 10, 2020, and titled "MULTI-PART NONTOXIC PRINTED BATTERIES", which is hereby incorporated by reference in its entirety.

[0129] Strictly as a non-limiting variant of the electroactive tag on which a display system is printed, the electroactive tag may include an EPD device configured to display telemetry data, Q-codes or barcodes, and / or icons. Exemplary variants include telemetry data with updatable information, and / or an image having any variant using digital data and / or alpha or alphanumeric text formats (e.g., metering images, Q-code images, QR-code images, or barcode images, etc.). In some implementations, color changes or image changes are displayed in sequence. In such implementations, changes in the display such as changes in one or more colors of the displayed symbol or image, or front-to-back changes in chronological order can be used to indicate any current condition such as the condition of the surrounding environment, or a change in the display indicating the presence of an analyte, or the condition of the container contents, etc.

[0130] The above-described device may also optionally include low-power communication components such as may be configured to communicate with other electronic devices. In some non-limiting examples, a cardboard shipping container is equipped with a first electrochemical sensor similar to the analyte sensor 1660 and a second electrochemical sensor that is a variant of the analyte sensor 1660. The energy harvesting and / or energy storage device drives the sensor and the display device.

[0131] The beneficial properties of particulate carbon in combination with the foregoing sensor design enable very low-power devices, such as devices that operate at currents of 0.1 microamps to 5 microamps and voltages of around 1 volt. This example illustrates that an analyte sensor utilizing the particulate carbon described herein can be prepared using low-cost, low-power driver / detection electronics that can be integrated onto the surface of even very small packages. Additionally, this example shows that such low-cost printed displays can also be integrated with other system components such as analyte sensors, energy harvesters, batteries, and communication chips.

[0132] In some cases, such as Figure 16BAs shown, two different sets of components can be printed on two different substrates, and then, in use, the two different substrates can be combined into a single detection and display system. In the and other detection and display systems, the characteristics of the first set of components 1661 can be different from the characteristics of the second set of components 1662. Thus, the first set of components 1661 can be disposed on the first substrate 1641, and the second set of components 1662 can be disposed on the second substrate 1642. Electrical connectivity (e.g., for power supply and / or for electrical signal conduction) can be provided by mating conductive terminals. In Figure 16B an example, the mating positive terminals (e.g., the first positive terminal 1651, the second positive terminal 1652) and the mating negative terminals (e.g., the first negative terminal 1653, the second negative terminal 1654) provide power. In other implementations, additional paired terminals can be configured to provide signal conduction between members of the first set of components 1661 and members of the second set of components 1662. Additionally, in cases where the characteristics of the first set of components 1661 are different from the characteristics of the second set of components 1662, the printing techniques may be different for forming the first set of components 1661 on the first substrate 1641 and the second set of components 1662 on the second substrate 1642.

[0133] Any of the above printing techniques can be used to construct the various devices of the first set of components or the second set of components 1662. In some cases, the composition and / or characteristics of any one or more layers of the components can indicate the use of high-energy lithography. More specifically, in cases where a slurry (e.g., to form an electrolyte) is required, and / or when the 3D structure is deeper in the depth dimension than can be formed using the aforementioned 3D printing techniques, and / or when a binder is required to provide mechanical integrity to a portion of the device, and / or when a higher throughput than can be provided by additive 3D printing techniques is required, then the use of subtractive high-energy photolithography can be indicated. In some cases, the first printing technique is used to print the first set of components of the first substrate, while the second printing technique is used to print the second set of components of the second substrate.

[0134] Strictly as an example and referring again to the second set of components 1662 disposed on the second substrate 1642, the second set of components can be formed by lithography using light having a wavelength in the ultraviolet range. More specifically, various techniques for performing vacuum ultraviolet (VUV) lithography can be applied.

[0135] In some cases, the pressures involved when performing VUV lithography can be pressures other than vacuum or near vacuum. In fact, some printing / deposition techniques have pressures much higher than atmospheric pressure. Furthermore, to support the wide range of pressures used when performing VUV lithography, the irradiation wavelength is selected to be in a region of low air absorption so that a vacuum environment is not required to perform high energy lithography. This flexibility regarding the wavelengths and pressures in use leads to higher printing throughput when performing VUV lithography.

[0136] The selection of the wavelength of light (in the range of about 120 nm to about 172 nm, which corresponds to photon energies of about 7 eV to about 10.1960 eV) results in achieving the desired feature size. In the context of the present disclosure, small feature sizes (e.g., 1 micron, 0.5 micron, 0.25 micron, and smaller) can result in smaller and smaller display pixels, which in turn result in displays with higher and higher resolutions.

[0137] Example

[0138] Example 1, electrophoretic ink 1.

[0139] Graphene is prepared using any one or more of the aforementioned techniques and / or the methods reported in U.S. Pat. No. 9,812,295 entitled “Microwave Chemical Processing” or U.S. Pat. No. 9,767,992 entitled “Microwave Chemical Processing Reactor”. 10 g of graphene is added to 250 mL of 96% sulfuric acid cooled in an ice bath, and the resulting mixture is stirred for at least 90 minutes. 50 g of KMnO4 is slowly added to the reaction mixture to prevent any heating. After stirring for 30 minutes, the reaction mixture is heated to 35°C and stirred for another 2 hours. 450 mL of H2O and 50 mL of H2O2 are initially added, followed by an additional 700 mL of H2O. The reaction mixture is filtered and washed with 5% HCl and a large amount of H2O until the eluent pH reaches 7 to obtain graphene oxide.

[0140] 300 mg of graphene oxide was dispersed and sonicated in 30 mL of H2O for 2 h using a probe sonicator (Sonics VCX750) set at 30% amplitude. The sonication yielded submicron particles with an average particle size of 149 nm, which were measured using dynamic light scattering. Next, 500 mg of a solution of octadecylamine (ODA) in 50 mL of ethanol was added and the mixture was refluxed overnight. The resulting ODA-functionalized graphene particles were washed with 50 mL of H2O and then with 3 x 50 mL of ethanol. To prepare the electrophoretic ink, 150 mg of ODA-functionalized graphene was mixed with 150 mg of Span 80 in 3.75 g of 1,2,3,4-tetrahydronaphthalene (tetralin). The mixture was sonicated in a bath for 1 h and then filtered through a 0.7-um glass fiber filter to obtain the electrophoretic graphene ink.

[0141] Example 2, electrophoretic ink 2.

[0142] Example 1 was repeated using carbon nano-onions (CNO) instead of graphene to prepare a CNO-based ink.

[0143] Example 3, electrophoretic ink 3.

[0144] 900 mg of graphene was dispersed in 90 mL of CH2Cl2 and irradiated with a sonication probe at 20 kHz and 0 °C. After 2 h of sonication, the average particle size was 191 nm, which was measured using dynamic light scattering. A solution of 9.0 g of tetrabutylammonium bromide in 15 mL of H2O, a solution of 1.2 g of KMnO4 in 15 mL of H2O, and 40 mL of acetic acid were added to the fragmented carbon dispersion and the mixture was stirred overnight. The resulting graphene hydroxide was washed with aqueous ethanol (50 wt%, 100 mL) at least 5 times to remove impurities. 5 g of oleic acid was added to a solution of 500 mg of graphene hydroxide in 100 mL of hexane and the mixture was stirred at 60 °C for 20 h. The oleic acid-functionalized carbon was obtained by centrifugation and washed with 30 mL of hexane at least three times. To prepare the electrophoretic ink, 100 mg of oleic acid-functionalized graphene was mixed with 100 mg of Span 85 in 2.5 g of dodecane. The mixture was sonicated in a bath for 1 h and then filtered through a 0.7-μm glass fiber filter to obtain the electrophoretic ink.

[0145] Example 4, electrophoretic ink 4.

[0146] 2 g of graphene, 100 mg of benzoyl peroxide, 350 g of styrene, and 700 mL of toluene were added to a round-bottom flask. The reaction mixture was degassed by bubbling argon for 1 hour and then irradiated with high-intensity ultrasound at 20 kHz for 2 hours at 0 °C. The mixture was filtered through a Teflon filter (0.22 um) and washed with toluene at least three times. The polystyrene-functionalized graphene (100 mg) was dried and redispersed in xylene (2.5 g) with 100 mg of Span 85 using an ultrasonic bath to prepare the electrophoretic ink.

[0147] Example 5, crosslinkable carbon material.

[0148] 10 g of graphene hydroxide prepared in Example 3 was dispersed in 1 L of DMF using an ultrasonic generator. After degassing the dispersion solution with nitrogen, 0.5 mL of dibutyltin dilaurate was added, and 300 g of tolylene diisocyanate pre-dissolved in 200 mL of DMF was added dropwise at 70 °C. After stirring for 4 hours, the reaction mixture was cooled to 50 °C, then 300 g of 2-hydroxyethyl acrylate was added dropwise, and the mixture was stirred for another 12 hours. Finally, acrylate-functionalized graphene was obtained by vacuum filtration and washing with dichloromethane. To prepare the crosslinkable carbon formulation, 10 g of acrylate-functionalized graphene was dispersed in a 1:1 mixture of 10 mL of ethanol and xylene together with 500 mg of Darocur 1173 and 500 mg of benzoyl peroxide. The resulting formulation was mixed using a mechanical stirrer.

[0149] Example 6, electrophoretic display unit 1.

[0150] Using a doctor blade with a 50-μm gap, the ITO-coated PET was coated with the crosslinkable carbon formulation prepared as described in Example 5. After removing the solvent, the resulting film was cured with UVA light at 100 mW / cm2 for 5 minutes, followed by heat treatment at 90 °C for 10 minutes. A separate ITO-coated glass was coated with a titanium dioxide / polyacrylate composite. Electrophoretic ink 1 was added between the ITO glasses, and then sealed using an epoxy sealant. Applying ±1 V to the display unit showed a contrast image as Figure 12 shown.

[0151] Example 7, electrophoretic display unit 2.

[0152] Using Figure 13 the electrophoretic ink 2 shown in Example 6 was repeated.

[0153] Example 8, electrophoretic display unit 3.

[0154] Using Figure 14 the electrophoretic ink 2 shown in Example 6 was repeated to form a text image.

[0155] Implementations of the invention disclosed herein have been referenced. Each example has been provided by way of explaining the technology of the invention, rather than as a limitation of the technology. In fact, although this specification has been described in detail with reference to specific implementations of the invention, it should be understood that those skilled in the art can readily conceive of alternatives, variations, and equivalents of these implementations after understanding the foregoing. For example, features shown or described as part of one implementation can be used with another implementation to yield yet another implementation. Accordingly, the subject matter is intended to cover all such modifications and variations that fall within the scope of the appended claims and their equivalents. Those of ordinary skill in the art can make these and other modifications and variations to the invention without departing from the scope of the invention more specifically set forth in the appended claims. In addition, those of ordinary skill in the art will understand that the foregoing description is only by way of example and is not intended to limit the invention.

Claims

1. An electrophoretic display system, the electrophoretic display system comprising: A first electrode disposed on a substrate; A second electrode disposed on the substrate; And A 3D carbon-based structure disposed between the first electrode and the second electrode, the 3D carbon-based structure configured to direct the migration of charged electrophoretic ink particles dispersed throughout the 3D carbon-based structure, the charged electrophoretic ink particles responsive to a voltage applied to the first electrode, the 3D carbon-based structure comprising: A plurality of 3D aggregates defined by the morphology of graphene nanosheets orthogonally fused together and crosslinked by a polymer; And A plurality of channels dispersed throughout the 3D carbon-based structure defined by the morphology, each of the plurality of channels comprising at least one of an inter-particle pathway or an intra-particle pathway.

2. The electrophoretic display system according to claim 1, wherein the size of the intra-particle pathway is smaller than the size of the inter-particle pathway.

3. The electrophoretic display system according to claim 1, the electrophoretic display system further comprising a plurality of recesses formed in any one or more of the plurality of 3D aggregates or the plurality of channels.

4. The electrophoretic display system according to claim 1, wherein the plurality of inter-particle pathways have an average radial size of no greater than 10 µm.

5. The electrophoretic display system according to claim 1, wherein the intra-particle pathway has an average radial size greater than 200 nm.

6. The electrophoretic display system according to claim 1, wherein each 3D aggregate further comprises any one or more of graphene, carbon nano-onions, carbon nanosheets, or carbon nanotubes.

7. The electrophoretic display system according to claim 1, wherein the plurality of 3D aggregates are crosslinked to each other.

8. The electrophoretic display system according to claim 1, wherein the polymer comprises any one or more of cellulose, cellulose acetate butyrate, styrene butadiene, polyurethane, polyether-polyurethane, acrylate, epoxy resin, or vinyl resin.

9. A method of fabricating an electrophoretic display structure, the method comprising: Causing a 3D open porous structure defined by a plurality of 3D carbon-based aggregates from a carbon-containing vapor stream to self-nucleate; Functionalizing one or more exposed surface functionalities of the 3D open porous structure with a nucleophilic moiety; And Crosslinking the plurality of 3D carbon-based aggregates in the 3D open porous structure by defining porosity in the 3D open porous structure.

10. The method according to claim 9, wherein the self-nucleation of the 3D open porous structure further comprises defining a porosity with an average pore size greater than 200 nm.

11. The method according to claim 9, wherein the self-nucleation of the 3D open porous structure further comprises forming a plurality of pathways in the 3D open porous structure defined by the plurality of 3D carbon-based aggregates.

12. The method according to claim 11, wherein the plurality of pathways are configured to direct a plurality of charged mobile titanium dioxide particles towards a charged electrode disposed on the electrophoretic display structure.

13. The method according to claim 12, wherein the plurality of charged movable titanium dioxide particles are configured to be non-reactively dragged into or out of the 3D open porous structure.

14. A display device, the display device comprising: a pair of electrodes disposed on a substrate; and a 3D carbon-based structure disposed between the pair of electrodes and configured to direct the migration of a plurality of charged electrophoretic ink particles dispersed throughout the 3D carbon-based structure based on the application of a voltage difference across the pair of electrodes, the 3D carbon-based structure comprising: a plurality of 3D aggregates defined by the morphology of graphene nanosheets orthogonally fused together and cross-linked by a polymer; and a plurality of channels dispersed throughout the 3D carbon-based structure defined by the morphology, each of the plurality of channels including at least one of an inter-particle pathway or an intra-particle pathway.

15. The display device according to claim 14, wherein the size of the intra-particle pathway is smaller than the size of the inter-particle pathway.

16. The display device according to claim 14, wherein the 3D carbon-based structure does not rely on any one or more of microcups or microcapsules.

17. The display device according to claim 14, wherein the plurality of charged electrophoretic ink particles further comprises a plurality of negatively charged movable titanium dioxide particles.

18. The display device according to claim 17, wherein the negatively charged movable titanium dioxide particles are configured to display a substantially white color.

19. The display device according to claim 17, wherein the 3D carbon-based structure is configured to be in a non-conductive state.

20. The display device according to claim 19, wherein the plurality of negatively charged movable titanium dioxide particles are configured to be non-reactively guided through the 3D carbon-based structure when the 3D carbon-based structure is in the non-conductive state.

21. The display device according to claim 14, the display device further comprising an antenna configured to supply power to the display device.

22. The display device according to claim 14, the display device further comprising a contrast layer disposed between the 3D carbon-based structure and the pair of electrodes.

23. The display device according to claim 22, wherein the contrast layer is a first color and the plurality of charged electrophoretic ink particles is a second color different from the first color.

24. The display device according to claim 14, wherein the 3D carbon-based structure is defined by a polydispersity index of less than 0.5.

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