Application of strain-sensitive graphite layers on fabric

Abstract

The possibility of manufacturing wearable electronics elements, for example, strain gauges or antennas of RFID tags, by applying or locally applying a layer of electrically conductive graphite polymer compositions to the surface of a fabric (knitwear) using printing technologies has been studied. The pliable tape-shaped prints can be used as strain gauges to be placed on human clothing or robot arms. The tensile limits of sensors made on fibrous substrates of various structures using graphite dispersions in the form of powders and aerosols have been established. The strain sensitivity coefficients of the sensors are determined. The advantage of glueless spraying of a liquid composition of graphite in the form of an aerosol onto fibrous materials is shown.

Production and properties of electrically conductive polymer composites reinforced with cotton threads

“…21 With elastic contraction of knitwear during unloading after stretching, contact between graphite particles is restored and electrical conductivity increases. The strain sensitivity of a fibrous composite GF varies up to 130 for laboratory samples obtained under the patent, 23 and is not inferior to the published values for the composites with various electrically conductive fillers in Table 1. [25][26][27][28][29][30][31][32][33][34] Table 1 lists the maximum GF values from the literature and obtained in this paper, which are higher.…”

“…The segments of the tape of equal length were placed mirror-like and the segments were stacked in pairs on top of each other, that is, they duplicated the conductive layer inside the knitwear. 23 A flat electrode made of copper foil with wires was placed between the ends of the segments. The sample was placed in a universal tensile testing machine to obtain real-time loaddisplacement curves along with electrical measurements using a multimeter and a computer in Figure 3.…”

“…The choice of fibers interlacing in the knitted base of strain gages and the tape cutting orientation relative to the direction of the fibers of the knitted base have been previously justified. 23 After treatment under different conditions, composites were tested by cyclic loading at a constant strain rate up to 50% strain. The electrical resistance of a 10 mm wide knitwear ribbon with a graphite layer increases by orders of magnitude when stretched to 60% in Figure 4.…”

“…The possibility of measuring electrical resistance of composites made from various fibrous materials with a coating containing three different commercially available carbon dispersions used for stencil printing of radio frequency identification (RFID) tag antennas has been demonstrated. 9 The role of fibrous material structure in increasing the electrical conductivity of the composite has been established, although there were no significant differences between the electrical conductivity of fibrous materials with a layer of carbon dispersions of various allotropic forms. Fibrous composites based on knitwear have a looser structure and higher electrical resistance than composites based on twill weave fabrics.…”