scientists from the university of massachusetts (umass) amherst have developed a new technique for creating electrically-heated textiles using vapor deposition to nano-coat fabrics into sewable, weavable, material, according to a report from the university.
the umass researchers created heated gloves. (university of massachusetts)
researchers demonstrated the effectiveness of this new technique by creating gloves that stayed warm for up to eight hours. the glove was made of three layers coated by a conducting polymer known as pedot, poly(3,4-ethylenedioxytiophene), and powered by a button battery that weighed only 1.8 grams.
gloves were chosen as the demonstration piece of clothing because it emphasized the flexibility of the material. the battery runs on nano-amps of current, which is not enough to pass current in the skin and it also was able to be dunked in water without creating a shock. the multi-layer design means that the electrically conductive cloth will not come into contact with the skin.
“until recently, textile scientists have not used vapor deposition because of technical difficulties and high cost of scaling up from the laboratory,” the article explained. “but recently, manufacturers are finding that the technology can be scaled up while remaining cost-effective, the researchers say.”
the researchers have also worked with thick cotton yarn that is commonly used in sweaters and have shown that they can create soft fabrics that are heated but not enough to make someone sweat. also, the scientists showed that the fabrics could withstand hours of use, going through the laundry, rips, repairs, and overnight charging.
“they arranged for biocompatibility testing at an independent lab where mouse connective tissue cells were exposed to pedot-coated samples and responses compared to positive and negative controls,” the article added. “they report that their pedot-coated materials are safe for contact with human skin without causing adverse reactions to the chemicals used.”
“in a test of the fabric’s ability to resist cracking,” it continued, “creasing or other changes when heated, they generated a temperature of 28 degrees c (82.4 f) with connection to a 4.5-v battery and 45°c (113°f) connected to a 6-v battery for an hour, and found ‘no dramatic morphology changes,’ indicating that the pedot-coated cotton textile was rugged and stable enough to maintain its performance when used as a heating element.”
the research was recently published in applied materials and interfaces. the abstract stated:
“we describe a process to transform commercial textiles and threads into electric heaters that can be cut/sewn or woven to fashion lightweight fabric heaters for local climate control and personal thermal management.
“off-the-shelf fabrics are coated with a 1.5 μm thick film of a conducting polymer, poly(3,4-ethylenedioxythiophene), using an improved reactive vapor deposition method. changes in the hand feel, weight, and breathability of the textiles after the coating process are imperceptible.
“the resulting fabric electrodes possess competitively low sheet resistances—44 ω/? measured for coated bast fiber textiles and 61 ω/? measured for coated cotton textiles—and act as low-power-consuming joule heating elements. the electrothermal response of the textile electrodes remain unaffected after cutting and sewing due to the robustness of the conductive coating.
“coated, conductive cotton yarns can also be plain-woven into a monolithic fabric heater. a demonstrative circuit design for a soft, lightweight, and breathable thermal glove is provided.”