Research Terms
Researchers at the University of Central Florida have developed a method for fabricating chalcogenide glass fiber preforms: one-step multi-material extrusion. Silica optical fibers are the industry standard for communication wavelengths due to their high optical quality and reliability, however, these fibers have a limited transmission window and cannot be used for mid-infrared (MIR) light applications. Fibers used in MIR applications can benefit from the optical functionality of chalcogenide (ChG) glasses, which are highly transparent in the infrared spectrum of interest and have attracted interest for MIR beam delivery, imaging fiber bundles, and nonlinear optics. However, the extremely brittle nature of ChG complicates handling and processing necessary to draw the material into fibers. Conventional attempts to use a polymer layer have been confined by the limited working temperature and an inability to co-draw the materials necessary for a robust ChG optical fiber.
Technical Details
The UCF invention consists of new ChG fiber with a polymer jacket harnesses the mechanical strength of the polymer without compromising the optical functionality of ChG. The optical properties of the fiber are determined by the ChG, while the mechanical properties are determined by the polymer. By separating the functionalities this way, each can be optimized independently. The new fiber is extruded under pressure, allowing the use of lower temparatures and higher viscosities compared to fiber drawing, thereby reducing glass crystallization. The polymer protects the fragile ChG from contacting the die during extrusion or subsequently with the ambient environment and allows for convenient handling and reduced aging of the fiber but does not participate in the optical functionality of the fiber, determined by the ChG alone.
Researchers at the University of Central Florida have developed technologies that manufacturers and designers can use to produce ChroMorphous® fabric for clothing and textiles. The e-textile innovation enables a user to change colors and patterns on demand. For example, a person wearing a shirt and slacks made with ChroMorphous® can use her smartphone to change the colors and patterns without switching to another outfit. The same applies to a purse or backpack to match the outfit. Unlike existing color-changing technologies, the UCF inventions do not depend on a wearer’s body heat, a room’s ambient temperature, or sunlight to work. ChroMorphous® is like traditional fabric—cut it, sew it, wash and iron it. Various applications include fashion and accessories, upholstery, medical, defense, and artistic uses.
The UCF inventions comprise dynamically-controllable color-changing fibers, fabrics, products, and manufacturing methods. In one example application, a color-changing monofilament has an electrically conductive core or multi-core and a coating around and along the core. The coating includes a layer of polymeric material with a color-changing pigment, for example, a thermochromic pigment. The monofilament can be a filament, a strand, or a fiber twisted or braided into a multifilament (such as yarn or thread). In turn, the multifilament can be stitched, sewn, or embroidered onto an existing fabric or product. It can also be woven to form a new fabric or product. The coating can include one or more layers, each with different color-changing portions or segments and thermochromic pigment.
A control system (the controller) operates the color-changing product. The controller can include a control device with a processing circuit such as an application-specific integrated circuit (ASIC) and a power supply, such as a lithium battery. During operation, an electrical current (provided by a power source such as a battery, a solar panel, a photovoltaic fiber) passes through the core. The resistance of the core to the electrical current causes the temperature of the core to elevate and thereby activate the thermochromic pigment of the coating to transition from one color to another color (for example, from a darker color to a lighter color or from one opaque color to a different opaque color). In some embodiments, the color-changing fiber transitions in tens or hundreds of milliseconds (depending on the amount of power applied). The color-changing fiber may operate at low voltages (for example, 12 volts or less).
An example manufacturing method includes loading a polymeric material and a thermochromic pigment material (both raw materials) into a fiber fabrication machine that comprises an extruder and a spinneret. During production, the extruder provides a molten mixture of the polymeric material and the thermochromic pigment material to the spinneret. In turn, the spinneret coats an electrically conductive core with the molten mixture to produce the color-changing fiber.
The research team is looking for partners to develop the technology further for commercialization.
Prototype available.
