posted on 2023-11-03, 17:03authored byMengqi Jiang, Hongci Hu, Chun Jin, Ru Lv, Jiawei Guo, Shouxiang Jiang, Ziqian Bai
The advancement of smart textiles has resulted in significant
development
in wearable textile sensors and offers novel interfaces to sense physical
movements in daily life. Knitting, as a traditional textile fabrication
method, is being used in promising ways to realize fully seamless
fabrication and unobtrusive sensing in wearable textile applications.
However, current flat-knitted sensors can sense strain only in the
horizontal plane. This research presents a novel fully machine-knitted
spacer piezoresistive sensor structure with a three-directional sensing
ability that can detect both the pressure in the vertical direction
and the strain in the warp/weft direction. Besides, it can sense the
pressure under 1 kPa, which is critical in comfortable on-body interaction,
one-piece integration, and wearable applications. Three sizes spacer-knitted
sensors are evaluated in terms of their mechanical performance, stability
cycles, and reaction to external factors such as sweat, laundering,
etc. Then, the effect of material choice on sensor performance is
evaluated and the rationale behind the use of different materials
is summarized. Specifically, this research presents a detailed evaluation
of the applications with both a single sensor and multiple sensor
arrays for fine and gross motion sensing in several scenarios. The
testing results demonstrate a fully machine-knitted piezoresistive
sensor that can detect multidirectional motions (vertical, warp, and
weft directions). In addition, this knitted sensor is scalable and
can be facilely and seamlessly integrated into any garment piece.
This universal knitted sensor structure could be made with a wide
variety of materials for high sensitivity for multidirectional strain/pressure
sensing, making it a high-compatibility sensor structure for wearable
applications.