Sensing fiber member

A sensing fiber member, comprising:

• a first covered yarn;
• and
• a second covered yarn,
• wherein each of the first covered yarn and the second covered yarn includes:
• a core material,
• a first covering yarn, and
• a second covering yarn,
• wherein the core material is a linear electroconductive conductor,
• wherein the first covering yarn and the second covering yarn are each a low electrical conductivity yarn that includes multifilament yarns,
• wherein the low electrical conductivity yarn has an electric resistivity of 104 Ω·m to 5×109 Ω·m,
• wherein, in the first covered yarn and in the second covered yarn, the first covering yarn and the second covering yarn are wrapped around the core material and a wrapping direction of the first covering yarn and of the second covering yarn is the same,
• wherein the first covered yarn and the second covered yarn are plied to form a plied yarn in which the first covered yarn and the second covered yarn are mutually adjacent with the first covered yarn and the second covered yarn having crossing contact points,
• wherein, in the plied yarn, the first covered yarn and the second covered yarn are twisted in a twisting direction that is opposite from the wrapping direction of the first covering yarn and the second covering yarn,
• wherein each of the first covered yarn and the second covered yarn has a twist coefficient K, represented by the following formula:
• twist coefficient K=(SS+SC)1/2×R is 7000 to 30,000,
• where SS is a fineness (dtex) of the linear electroconductive conductor, SC is a total fineness (dtex) of the low electrical conductivity yarn, and R is a wrapping number of the low electrical conductivity yarn, whereby the wrapping number means a number of twists per meter, and
• wherein the sensing fiber member is configured to detect a change in electrical resistance between the linear electroconductive conductors of the first covered yarn and the second covered yarn.