Knitted Strain Sensors: Impact of Design Parameters on Sensing Properties

Abstract

This paper presents a study of the sensing properties exhibited by textile-based knitted strain sensors. Knitted sensors were manufactured using flat-bed knitting technology, and electro-mechanical tests were subsequently performed on the specimens using a tensile testing machine to apply strain whilst the sensor was incorporated into a Wheatstone bridge arrangement to allow electrical monitoring. The sensing fabrics were manufactured from silver-plated nylon and elastomeric yarns. The component yarns offered similar diameters, bending characteristics and surface friction, but their production parameters differed in respect of the required yarn input tension, the number of conductive courses in the sensing structure and the elastomeric yarn extension characteristics. Experimental results showed that these manufacturing controls significantly affected the sensing properties of the knitted structures such that the gauge factor values, the working range and the linearity of the sensors varied according to the knitted structure. These results confirm that production parameters play a fundamental role in determining the physical behavior and the sensing properties of knitted sensors. It is thus possible to manipulate the sensing properties of knitted sensors and the sensor response may be engineered by varying the production parameters applied to specific designs.

Physiological parameters monitoring of fire-fighters by means of a wearable wireless sensor system

“…On the other hand, our intention is to replace all cables, even the transmission lines carrying the RF signal, with conductive yarn routes on the firefighter suit [8][9][10][11]. Moreover, we intend to replace ECG sensors with textile electrodes, either based on conductive yarns or screen-printed [12,13], while respiration rate, temperature and skin moisture (perspiration) could be monitored using appropriately designed variations of conductive yarn based knitted sensors [14][15][16][17]. Finally, even the antenna could be partially or fully textile [18,19].…”

Study of the Contact Resistance of Interlaced Stainless Steel Yarns Embedded in Hybrid Woven Fabrics

“…Related research [7][8][9][10] studied the contacts between electro-conductive yarns embedded in knitted fabrics. Unlike in woven hybrid fabrics, in knitted fabrics, contacts appear between two consecutive conductive loops and not only at the intersection of weft and warp yarns.…”

“…Atalay et al [7] concluded that it is possible to manipulate the sensing properties of knitted sensors and the sensor response may be engineered by varying the production parameters applied to specific designs [8]. Zhang et al [9] created knitted strain sensors by using stainless steel and carbon yarns and identified that the contacting electrical resistance between overlapped fibers is the primary factor in the sensing mechanism.…”

Design and Fabrication of a Capacitance Based Wearable Pressure Sensor Using E-textiles

“…This significantly broadens the potential for 'smart' product applications across industries associated to sports performance, ergonomics, rehabilitation, etc. where design customisation to individual user requirements of performance and quantitative evaluation is currently highly desirable [8][9][10][11][12][13][14].…”