Patent Application
20250215639
The present invention generally relates to electronic textiles and systems and processes for their fabrication.
Electronic textiles (also called “e-textiles”) are a form of wearable technology that combines textiles with electrical capabilities, such as sensing elements with sensory capabilities that enable real-time and mobile monitoring of critical health signals. E-textiles are useful for various applications such as wearable healthcare devices, military equipment, and other wearable devices. A range of traditional techniques for overcoating conductive materials onto textiles, such as dip coating, electrochemical deposition, chemical vapor deposition (CVD), physical vapor deposition (PVD), and direct printing, have been developed to produce e-textiles. However, these techniques face challenges in creating intricate or personalized sensor designs for different fabric types due to the requirements of using heat, vacuum, precursors, plasma system, or vaporization process. Additive patterning techniques, such as screen printing, inkjet printing, and three-dimensional (3D) dispensing, have been used to create custom sensor designs on textiles by employing either a shadow mask or direct writing. However, these techniques may encounter challenges with clogging and high-throughput printing, particularly when covering large areas with active nanomaterials or molecules.
E-textiles can also include light-emitting textiles that make use of an electric-powered light-emitting component. The growth of the market for wearable displays has driven the development of electroluminescent threads as light-emitting components, but machine embroidery of electroluminescent threads has been challenging. Traditionally, light-emitting textiles have been created by directly gluing or depositing light-emitting diodes (LEDs) or electroluminescent thin films onto garments. However, these techniques can compromise the flexibility, wearability, and/or washability of the fabric and require difficult conditions to be successfully implemented. Although electroluminescent threads have facilitated the integration of light-emitting textiles on a larger scale, the arrangement of the electroluminescent threads is typically limited to straight lines or rectangular patterns due to the interweaving of conductive fibers. However, current electroluminescent threads are typically unable to meet the strict technical requirements for successful machine embroidery, such as having a high tensile strength of at least 6 N, a moderate elongation at breakpoint below 100%, and a smooth surface finish.
Conductive polymers, such as polypyrrole (PPy), are of particular interest for use in e-textiles because of their mechanical softness, high electrical conductivity, ease of synthesis, compatibility with human skin, and stability against corrosion and oxidation. However, achieving a uniform coating of conductive polymers onto different fabric types with high accuracy presents a challenge due to the nature of the wet polymerization process, which can lead to issues such as aggregation. For example, although reactive inkjet printing has been used for in-situ polymerization on substrates, it faces constraints in scalable patterning due to the lack of efficient and rapid chemical mixing mechanisms. A recent advancement to address this issue is the in-situ aerosol mixing using flow, which allows for compositional mixing of materials with high-throughput printing. However, this technique can also present manufacturing difficulties due to flow disruptions caused by the ongoing changes in viscosity during polymerization.
In view of the above, it would be desirable to have a system that facilitates high-throughput chemical mixing and high-speed spray printing capable of use in the creation of e-textiles. There would also be desirable to be able to incorporate light-emitting e-textiles into fashionable and/or customized designs on consumer fabric items with minimal impact on their desirable properties (e.g., softness, flexibility, durability, water resistance, breathability, etc.) to meet the specific needs of diverse applications.
The intent of this section of the specification is to briefly indicate the nature and substance of the invention, as opposed to an exhaustive statement of all subject matter and aspects of the invention. Therefore, while this section identifies subject matter recited in the claims, additional subject matter and aspects relating to the invention are set forth in other sections of the specification, particularly the detailed description, as well as any drawings.
The present invention provides, but is not limited to, processes of fabricating electronic textiles, processes of forming an electrically conductive polymer in-situ on substrates, dual regime spray systems, and electronic textiles formed thereby.
According to a nonlimiting aspect of the invention, a process of fabricating an electronic textile includes introducing atomized droplets of a monomer solution into a mixing chamber from a first port, introducing atomized droplets of a polymerization agent for polymerizing the monomer solution into the mixing chamber from a second port, and mixing the atomized droplets of the monomer solution and the polymerization agent in the mixing chamber to initiate a polymerization reaction. Before the polymerization reaction is completed in the mixing chamber, the droplets of the mixed monomer solution and polymerization agent are directed through a deposition nozzle and onto a fabric material where the polymerization reaction is completed to form an electrically conductive polymer on the fabric.
According to another nonlimiting aspect of the invention, a process of forming an electrically conductive polymer in-situ on a substrate includes introducing atomized droplets of a monomer solution into a mixing chamber from a first port, introducing atomized droplets of an oxidizing agent for polymerizing the monomer solution into the mixing chamber from a second port, mixing the atomized droplets of the monomer solution and the oxidizing agent in the mixing chamber to initiate a polymerization reaction, and before the polymerization reaction is completed in the mixing chamber, directing the droplets of the mixed monomer solution and oxidizing agent through a deposition nozzle and onto a substrate where the polymerization reaction is completed to form the electrically conductive polymer in-situ on the substrate.
According to yet another nonlimiting aspect of the invention, a dual regime spray system for forming an electrically conductive polymer in-situ on a substrate includes a mixing chamber with a first inlet port for receiving a flow of an atomized monomer solution and a second inlet port for receiving a flow of an atomized oxidizing agent, and a nozzle for spraying a mixture of the atomized monomer solution and the atomized oxidizing agent onto the substrate. The nozzle is configured to form a tortuous path from each of the first inlet port and the second inlet port to an inlet into the nozzle.
According to still another nonlimiting aspect of the invention, an electronic textile produced by any of the processes described above is provided. The electronic textile may form a wearable sensor and/or a wearable garment.
Technical effects of electronic textiles, elements, systems, and processes as described above preferably include the ability to fabricate custom, high-quality e-textiles with processes that are capable of large-scale production. The electronic textiles, elements, systems, and processes are preferably, though not necessarily, capable of overcoming challenges associated with incorporating e-textiles into medical and consumer fabric items, as a nonlimiting example, as embroiderable electroluminescent threads that meet the requirements of machine embroidery and are compatible with universal embroidery machines, allowing for the creation of customized light-emitting textiles with minimal impact on the fabric properties, facilitating large-scale applications in various fields.
Other aspects and advantages of this invention will be appreciated from the following detailed description in view of the drawings.
The intended purpose of the following detailed description of the invention and the phraseology and terminology employed therein is to describe what is shown in the drawings, which relate to one or more nonlimiting embodiments of the invention, and to describe certain but not all aspects of what is depicted in the drawings, including the embodiment(s) to which the drawings relate. The following detailed description also describes certain investigations relating to the embodiment(s) depicted in the drawings, and identifies certain but not all alternatives of the embodiment(s) depicted in the drawings. As nonlimiting examples, the invention encompasses additional or alternative embodiments in which one or more features or aspects shown and/or described as part of a particular embodiment could be eliminated, and also encompasses additional or alternative embodiments that combine two or more features or aspects shown and/or described as part of different embodiments. Therefore, the appended claims, and not the detailed description, are intended to particularly point out subject matter regarded to be aspects of the invention, including certain but not necessarily all of the aspects and alternatives described in the detailed description.
Although the invention will be described hereinafter in some examples in reference to the various types of textiles and garments shown in the drawings, it will be appreciated that the teachings of the invention are also more generally applicable to an even wider variety of types of applications, such as, but not limited to e-textiles to be worn by humans and/or other animals, different electrical circuits, different electronic couplings, and use with different electronic devices. In addition, unless otherwise indicated, the term e-textile is not limited to only traditional woven cloth textiles, but may include any type of flexible fabric material used for clothing, including by way of nonlimiting examples, woven fabrics of natural and/or synthetic materials, non-woven fabrics, such as blown fiber fabrics and felts, leather and other natural fabrics, and other non-woven fabrics such as flexible rubber films and polymer films.
As used herein the terms “a” and “an” to introduce a feature are used as open-ended, inclusive terms to refer to at least one, or one or more of the features, and are not limited to only one such feature unless otherwise expressly indicated. Similarly, use of the term “the” in reference to a feature previously introduced using the term “a” or “an” does not thereafter limit the feature to only a single instance of such feature unless otherwise expressly indicated
Electronic textiles (“e-textiles”) and electrical elements, including sensing elements and electroluminescent threads, that are capable of being realized therewith are disclosed, as well as processes and systems for incorporating electrical elements into e-textiles. In some embodiments, e-textiles and an additive patterning process that utilizes a dual-regime spray system (DRSS) to produce e-textiles that incorporate electrical elements made of electrically conductive polymers are provided. The e-textiles may have electrical components including, but not limited to, electrical sensing elements and electroluminescent threads. In some arrangements, processes of using the DRSS (also referred to as DRSS process or DRSS processes) can eliminate the need for masks and allows programmable inscription/printing of electrical elements onto medical and consumer fabrics. Unlike traditional spray techniques, the process enables in-situ, on-the-fly polymerization of electrically conductive polymers, enabling the production of intricate designs with sub-millimeter resolution across fabric areas spanning several meters. Moreover, the process may in some configurations mitigate nozzle clogging problems commonly encountered in such applications. The resulting e-textiles may preserve essential fabric characteristics, such as breathability, wearability, and washability, while delivering exceptional sensing performance.
In addition, various electrical elements and e-textiles fabricated with such elements using the DRSS are also disclosed. The e-textiles and electrical elements can be fabricated using universal embroidery machines and are compatible with various consumer fabrics. The threads may exhibit and maintain a light-emitting performance and withstand wear and tear. The electrical elements can be used to produce sensing elements and/or decorative designs having predetermined patterns, providing a toolkit for creating customized e-textiles that cater to diverse flexible and wearable medical and display needs. Nonlimiting example applications include sensing elements incorporated into wearable healthcare, military, and garments, illuminated messages or designs on consumer goods, and emergency alerts on helmet liners.
Turning now to the drawings,
In this example, the monomer solution 24 contains the monomer Py, and the polymerization agent 26 contains FeCl3 as an oxidizing polymerization agent; however other monomers and polymerization agents may be used. By way of some nonlimiting examples, respective monomers and oxidizer polymerization agents could be used suitable to form not only polypyrrole (PPy), but also conductive polymers such as polyaniline (PANI), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT), and/or polythiophene (PTh). Thus, the monomers and oxidizers may include pyrrole (Py) and iron (III) chloride (FeCl3) for PPy, aniline (C6H5NH2) and ammonium persulfate ((NH4)2S2O8) for PANI, 3,4-ethylenedioxythiophene (EDOT) and FeCl3 with polystyrene sulfonate (PSS) for PEDOT, and thiophene (C4H4S) and FeCl3 for PTh.
In operation, each of the monomer solution 24 and the polymerization agent 26 is introduced into the mixing chamber 22 along with a carrier gas, such as air, at a velocity and under a pressure sufficient to atomize both streams of the monomer solution 24 and the polymerization agent 26 into tiny droplets as they travel into and/or along the tortuous path through mixing chamber 22 to the inlet of the nozzle 32. The monomer solution 24 and the polymerization agent 26 may be delivered via hoses, pipes, or other suitable transport mechanisms from suitable sources, such as tanks or other containers. The monomer solution 24 and the polymerization agent 26 may be mixed with a carrier gas and then atomized by any suitable method and with any suitable atomizer, such as a venturi disposed in or upstream from each of the first and second inlet ports 28 and 30. Typically, the monomer solution 24 includes the selected monomer dissolved in a suitable solute sufficient to allow ready atomization and fluidic flow through the mixing chamber 22 and out the nozzle 32. Similarly, the polymerization agent 26 is provided in the form of an oxidizer solution of a suitable oxidizing agent and solute to promote atomization and fluidic flow. The monomer solution 24 and the polymerization agent 26 are introduced into the mixing chamber 22 at a first velocity using low-speed airflow, typically less than about 10 m/s. As the atomized monomer solution 24 and the polymerization agent 26 mix together within the mixing chamber 22, an oxidative polymerization reaction of the monomer of the monomer solution 24 begins to occur. When the flow enters the nozzle 32 from the mixing chamber 22, the velocity of the flow increases to a second, higher velocity and is ejected out the tip portion, which further accelerates the polymerization reaction. The velocity of the flow through the mixing chamber 22 into the nozzle 32 and eventually out the tip portion is preferably high enough that complete polymerization of the atomized monomer solution 24 and the polymerization agent 26 does not occur until after the mixture has exited the tip portion, and typically not until after the mixture has landed on the surface of the target fabric 36. In this way, the DRSS 20 prevents clogging of the nozzle 32, the mixing chamber 22, and the inlet ports 28 and 30 by preventing agglomeration of cured polymeric material inside the DRSS 20.
As shown in
Investigations, combining experimental, computational, and theoretical approaches, were conducted to examine the critical factors influencing the operation of the DRSS 20 and its role in e-textile fabrication. The DRSS 20 shown in
The kinetics of the spray polymerization can be readily controlled to tune the electrical conductivity of the conductive polymers formed by the DRSS 20. Proof-of-concept demonstrations included directly spraying conductive polymers into custom designs of stretchable strain gauges, with a gauge factor (GF) of over 85, onto various garments such as masks, gloves, and stockinettes. These e-textiles were capable of continuously and unobtrusively tracking a range of human body movements from subtle (e.g., breathing) to large (e.g., joint bending) movements, while minimally affecting the inherent fabric properties such as wearability, breathability, and washability.
For the investigations, two pneumatic glass atomizers (ArOmis Inc.) were used to prepare a solution of 2M Py (Sigma-Aldrich) in methanol and a solution of 500 mM FeCl3·6H2O (Sigma-Aldrich) in a 1:7 v/v mixture of water and methanol. Droplets of the atomized monomer and oxidant were fed into the mixing chamber 22 of the DRSS 20 using low-speed airflow (less than 10 m/s) where droplets of the atomized Py and FeCl3 contacted each other, and the polymerization process was initiated to form PPy nanoparticles. The polymerization process was further accelerated by the central airflow within a nozzle 32 of the mixing chamber 22 and finally completed as the PPy nanoparticles were sprayed onto surfaces of fabrics 36. The DRSS 20 integrated at least two different air flow modules: a low-speed air flow module that facilitated the atomization of the Py monomer and the FeCl3·6H2O oxidant entering the mixing chamber 22; and a high-speed air flow module that passes through the nozzle 32. Each atomization pressure was adjusted from 40 to 120 kPa. To mitigate the potential issue of the Py monomer reacting or changing its properties during atomization, each atomization pressure was adjusted and maintained above 40 kPa, which facilitated optimal aerosol mixing of the monomer and oxidant and efficient polymerization of the Py to PPy. The high-speed central air flow was maintained at a velocity of 100 m/s during spraying.
Oxygen plasma-treated stretchable cotton fabric 36 was placed at a distance of about 2 mm from the exit of the nozzle 32. The highest speed of linear travel of the nozzle 32 while spraying the PPy was about 50 cm/min. The DRSS 20 was mounted on the three-axis computer numerical control (CNC) gantry 42, which was controlled by conventional computer controls to cause the nozzle 32 to draw programmed patterns. Polymerization of Py to PPY was visually observed by the black color of the resulting PPy. Fabrics 36 with PPy deposited thereon were rinsed with water and dried at room temperature.
The DRSS 20 and process evaluated during the investigations were determined to offer several key advantages over existing spraying techniques. As illustrated by the patterns achieved in
In a further investigation, a nozzle 32 was prepared using resin and utilized for an extended period of time (greater than 90 minutes). The nozzle 32 turned slightly blackish after ninety minutes of usage, but no signs of clogging were observed. The nozzle 32 was able to provide uniform and uninterrupted coating of PPy over the entire surface of fabric yarns without agglomeration, in comparison to those using a conventional airbrush. Additional scanning electron microscope (SEM) images not only corroborated consistent results but also substantiated the absence of any corrosion or alterations in the morphology of the fabric surface. FT-IR analysis confirmed that the PPy synthesized through the DRSS 20 has similar qualities to that of PPy synthesized through conventional dip-coating methods. Furthermore, for in-situ spray polymerization, the DRSS process was determined to be versatile and adaptable for other conductive polymers. For instance, polyaniline (PANI), known for its high conductivity, environmental stability, and biocompatibility, was successfully polymerized and directly written onto cotton fabric using the DRSS process.
Implementing suitable spray conditions for operation of the DRSS process is advantageous for successful in-situ, on-the-fly polymerization of the PPy (or other electrically conductive polymer). Operational parameters that are believed to be particularly relevant to effective implementation of the DRSS 20 include the number of spray passes (NP), nozzle transverse velocity (VN), atomization pressure (PA), and carrier gas flow in the mixing chamber 22. Investigations of the atomization flow rates of Py and FeCl3 over a range of PA between 40 and 120 kPa showed that as the PA increased, the atomization flow rate also increased and reached its maximum value (approximately 16 μL s−1 for Py and 10 μL s−1 for FeCl3) at PA=120 kPa. This indicated that a higher amount of reactive chemical agents was carried into the mixing chamber 22 with the increased PA. A higher atomization flow rate observed in Py as compared to FeCl3 was believed to be attributable to the substantially lower viscosity of Py (6.22×10−4 Pa s) relative to FeCl3 (2.25×10−3 Pa s). The increased PA led to a greater quantity of atomized Py and FeCl3, as well as improved mixing inside the chamber. These factors led to accelerated polymerization and reduced resistance.
The impact of PA (60-120 kPa) and VN (10-50 cm/min) on the mass loading of PPy sprayed onto a cotton fabric was also observed during these investigations. The mass loading of PPy exhibited an increase with increasing PA, reaching a maximum value of approximately 87 mg cm−1 at PA=120 kPa and VN=10 cm min−1. At this point, the corresponding RPPy was measured as 1.6 kΩ at NP=10 passes. Conversely, when sprayed using a conventional airbrush, the resistance of PPy (RPPy) remained considerably higher even at NP=20 passes due to widespread dispersion and low mass load of PPy.
The effect of NP and VN on the RPPy over a range of NP=1-20 passes and VN=10-50 cm/min was also observed. The investigations showed that the RPPy tended to decrease as NP increased or VN decreased. The investigations also showed that the increased PA resulted in a decrease in RPPy. In addition, by adjusting the PA during the DRSS 20, the RPPy can be varied between 1.6-89.3 kΩ. To demonstrate this feature, four resistive heaters were sprayed onto a cotton fabric with the same width (6 mm) and serpentine shape but varying PA=90-120 kPa. This resulted in a range of RPPy from 0.8 to 3.3 kΩ, or a range of heat generation levels from 36 to 55° C. at an applied voltage of 30 V. The patterns also demonstrated consistent resistance (RPPy=5.05±0.17 kΩ) across several test specimens, highlighting minimal variations using the DRSS 20 and emphasizing the dependable polymerization and patterning capabilities of the DRSS 20 and process.
Computational fluid dynamics (CFD) modeling predicted that as the PA increases from 40 kPa to 120 kPa, the carrier gas flow inside the mixing chamber 22 becomes more uniform, resulting in improved mixing and polymerization of PPy. These CFD results were consistent with experimental data, indicating that the PPy was fully polymerized at PA=120 kPa, whereas incomplete polymerization was observed at PA=40 kPa. The PA for both Py and FeCl3 was balanced to prevent non-uniform carrier gas flow in the mixing chamber 22. The concentration ratio to Py and FeCl3 was maintained at 4:1 to provide the lowest RPPy (54.3±5.1 kΩ). Methanol (MeOH) was used as a mixing solvent for both Py and FeCl3, resulting in a nearly four-fold lower RPPy compared to those obtained when using water (H2O) and other polar solvents such as ethanol (EtOH). This is believed to be attributable to the unique interaction between Py and MeOH, including their high miscibility, lower boiling point of Py, faster evaporation rate, and polarity, as well as the ability of MeOH to reduce Coulomb interaction during polymerization. Taken all together, optimal conditions of this particular investigated DRSS process achieved highly uniform and conductive applied PPy patterns when the PA=120 kPa, NP=10 passes, and VN=10 cm/min., using a MeOH mixing solution with a Py:FeCl3 concentration ratio of 4:1. Of course, the optimal conditions may vary depending many other factors, such as the type of fabric used as a substrate, the type of monomer, the type of oxidizer, type of solute, environmental factors, and desired form of the final applied pattern 38.
In some embodiments, an overcoat of silicone sealer, such as Ecoflex™ 00-30 diluted in Silicone Thinner™, may be applied over the pattern 38 of the electrically conductive polymer. Preferably, the silicone sealer fully encapsulates the pattern 38. The silicone sealer can be applied by any suitable application method, such as with a brush, roller, or sprayer. The silicone sealer overcoat is preferably applied after the monomer applied to the fabric 36 has completely polymerized. The overcoating of silicone sealer can improve durability of the pattern 38 under repeated strain loading-unloading cycles and temperature change cycles, as well as over multiple washing cycles and environmental factors, such as sweating. The silicone sealer may also at least partially resist incursion of moisture and/or other surrounding environmental matter, such as sweat or laundry detergent, on the pattern 38.
In some embodiments, the pattern 38 can be configured to create a stretchable strain sensor on the fabric 36. For example, as illustrated by the strain gauge shown in
Continuous and unobtrusive monitoring of strains, ranging from minor (less than 5%) to substantial (10-40%), in various body motions is of particular interest not only for understanding the mechanics of human movements, joint responses, and fatigue, but also for aiding in the prevention and recovery of musculoskeletal injuries and disorders. The DRSS 20 and its associated process can be used to make a wide variety of sensors on a wide variety of wearable items made with the e-textiles. Some nonlimiting examples of such wearable sensors are shown in
The DRSS 20 and process provide a promising method of additive patterning that can be used to quickly transform traditional clothing into personalized e-textiles, while minimally affecting the intrinsic characteristics of the clothing. The programmable DRSS 20 can be used to perform in-situ, on-the-fly polymerization of conductive polymers, such as PPy, allowing direct spray writing of custom designs—from basic to complex patterns—for strain gauges, as well as many other types of electrical components. The DRSS 20 and process can achieve high resolution (e.g., down to at least 0.9 mm line width), high sensitivity (e.g., GF=85.15), high scalability (e.g., over a meter), and low electrical resistance (e.g., less than 1.6 kΩ). The DRSS 20 and process can also be used to form a seamless coating of electrically conductive polymers without nozzle blockage. The evenly distributed electrically conductive polymers across the yarns or other fibers of the fabrics allow the resulting e-textiles to maintain their mechanical flexibility, breathability, and wearability. When used on stretchable clothing, the e-textiles can provide a comfortable fit, enabling precise strain monitoring across a wide spectrum, from subtle to substantial body movements.
In addition to the various example configurations and use scenarios described herein, e-textiles manufactured using the DRSS 20 and processes disclosed herein hold immense potential in consumer markets such as interactive fashion, safety gear, and entertainment, offering opportunities for real-time environmental and biometric monitoring, dynamic user interaction, and immersive experiences. The DRSS 20 and processes offer new avenues for the creation of personalized e-textiles, bringing together custom functionality and stylish designs.
As previously noted above, though the foregoing detailed description describes certain aspects of one or more particular embodiments of the invention and investigations associated with the invention, alternatives could be adopted by one skilled in the art. For example, the e-textiles, threads and devices associated therewith could differ in appearance and construction from what is described herein and shown in the figures, functions of certain components could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, process parameters such as temperatures and durations could be modified, and appropriate materials could be substituted for those noted. As such, and again as was previously noted, it should be understood that the invention is not necessarily limited to any particular embodiment described herein or illustrated in the drawings.
This application claims the benefit of provisional U.S. Patent Application No. 63/616,277 filed Dec. 29, 2023, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63616277 | Dec 2023 | US |
