Development of hysteresis-free and linear knitted strain sensors for smart textile applications

Abstract

Smart textiles have been attracting considerable interest in imparting a wide range of functions to traditional clothing ranging from sensing, actuation, data processing, and energy storage. In the case of textile-based strain sensors, most of the studies proved that they can work in principle, however, producing strain sensors with desirable properties such as stable sensitivity, small hysteresis, large enough working range, and good repeatability still remains a challenge necessitating the developments of novel technologies for soft sensors. This paper conducts a systematic approach to investigate the electromechanical properties of the knitted strain sensors to find out the optimum process parameters. We found a repeatable and robust method to produce knitted strain sensors with low hysteresis at a working range of at least 40%.

RobotSweater: Scalable, Generalizable, and Customizable Machine-Knitted Tactile Skins for Robots

“…Conductive-Stripe Layers. We choose the 1x1 rib structure for high extension potential, good elastic recovery, and minimal strain-induced hysteresis [32]. The insulating stripes separate neighboring conductive stripes.…”

“…Conductive stripes are co-knitted with nylon stretch yarn (Maxi Lock Stretch Textured Nylon) and Baekert BK 9036129, a Bekinox-polyester blend in 50/2Nm with a specified resistance of 20 Ω/cm. The high-elasticity nylon stretch yarn decreases hysteresis [32]. The conductive yarn is plated outside of the nylon yarn (top left in Fig.…”

Assessing the Role of Yarn Placement in Plated Knit Strain Sensors: A Detailed Study of Their Electromechanical Properties and Applicability in Bending Cycle Monitoring

“…Many studies have used plating techniques in knitting to create strain sensors. This approach, which is marked by its design flexibility [ 17 , 18 , 19 ] and robust processing capabilities [ 20 ], significantly enhances the sensors’ sensitivity, longevity, and resistance to washing [ 21 , 22 ]. A crucial consideration with these sensors is the interaction between the two types of yarns, which is largely influenced by the chosen placement of the conductive yarn within the knitting structure [ 20 ].…”

“…This approach, which is marked by its design flexibility [ 17 , 18 , 19 ] and robust processing capabilities [ 20 ], significantly enhances the sensors’ sensitivity, longevity, and resistance to washing [ 21 , 22 ]. A crucial consideration with these sensors is the interaction between the two types of yarns, which is largely influenced by the chosen placement of the conductive yarn within the knitting structure [ 20 ]. Specifically, the conductive yarn can be integrated into either the knit or purl stitches on the fabrics of the plated structures.…”

Classifying Gait Alterations Using an Instrumented Smart Sock and Deep Learning

“…T HE ability for wearable textile devices to be worn comfortably, in close proximity to the human body makes them potent candidates for continuous monitoring of physiological parameters [1]- [4]. For this reason, numerous wearable electronic textile (E-textile) sensors have been generated and used to monitor various parameters including temperature [5], sweat production [6], heart rate [7], and strain [8]- [10]. The capacity of this type of data collection to facilitate the diagnosis and monitoring of different medical conditions provides opportunities to improve patient care and rehabilitation outcomes [11]- [15].…”