Abstract:

In order to develop an optical macro-bending sensing fabric to detect respiration and heartbeat of human body, a way knitted sensing fabric was designed by using a combined structure in which locknit stitches were knitted with cotton yarns and abopted as a ground structure, and optical fiber with a radius of 1 000 μm was used as the inlay yarn. The relationship between the bending curvature radius of the optical fiber and the loss of its optical signal outprt was investigated by experimental method. 10 mm and 2 cycles were determined as the initial curvature radius of the initial curvature radius of the optical fiber and optical fiber and the number of sensing unit, respectively. Then, the properties of two guide bar warp knitted structures were compared and analyzed, and the modified Sharkskin structure was chosen as the ground structure of sensing fabrics. Based on  them, lapping diagram adn stitch density were designed, and the sensing fabrics were produced on a hand driven warp-knitting machine. Finally, these fabrics were tested, and the results show that the optical signal changes can effectively reflect the change of the fabric shape by means of voltage changes in the stretching peocess.

Key words: macro-bending sensor, optical fiber, warp knitting, weft insertion, sensing fabric