Development and Investigation of a Textile Heating Element Ensuring Thermal Physiological Comfort

The aim of this research was to develop a flexible heating element and investigate its heating capability in simulated wearing conditions. Polyester silver (Ag)-plated yarns incorporated in the reverse side of the knitted structure were used to provide electrical conductivity. A special knitted structure was selected to keep conductive yarn only in the reverse side of the material. All the heating element was made using only textile materials and yarns. A temperature sensor thermistor was used as an electronic element to follow the body temperature, and the remaining elements ensuring a correct electric circuit and heating were made of textile. Another type of heating element was produced using enamelled copper wire, which was inserted into the knitted fabric structure. Investigation of both types of heating elements was made by determining the dependences of the heating elements’ temperatures on the current and voltage applied. It was concluded that the heating element with silver plated yarns used gave out warmth more evenly over all the resistive area. The microcontroller, which has a heating dynamics data storage function, was programmed to control the operations of the two heating elements. A model of an intelligent apparel product with two heating elements ensuring a comfortable microclimate for the user was created. Field tests were performed for the model created by wearing the product and setting the temperatures of both heating elements, for which the continuous operating time was determined.