Textile-based strain sensors

Textile-based strain sensors have been demonstrated using stretch fabrics modified with inherently conductive polymers (Rovira et al., 2011) or carbon-loaded mbbers (Tognetti et al., 2005). Knitting with conductive yams is another approach to creating... 

Another way to obtain a flexible textile compatible strain sensor is based on conductive polymer composites (Cochrane et al., 2007). Carbon black nanoparticles are captured in a thermoplastic elastomer matrix that can be printed onto a textile substrate (Fig. 2.4). Upon strain deformation, the distance between the particles will change and an electrical current will pass less easily through the composite, resulting in a resistance change. 

Hantzsche E, Matthes A, Nocke A, Cherif CH. Characteristics of carbon fiber based strain sensors for sfiucmral-health monitoring of textile-reinforced thermoplastic composites depending on the textile technological integration process. Sens Actuators A Phys 1 December 2013 A203 189-203. 

Cochrane, C., Koncar, V., Lewandowski, M., Dufour, C., 2007. Design and development of a flexible strain sensor for textile structures based on a conductive polymer composite. Sensors 7, 473 92. 

Atalay, O., Kermon, W.R., Husain, M.D., 2013. Textile-based weft knitted strain sensors effect of fabric parameters on sensor properties. Sensors 13 (8), 11114-11127. 

Respiratory rate is measured by techniques based on either measuring thoracic expansion or based on measuring changes in skin impedance. For the former technique, most systems use strain gauges made from piezoresistive material combined with textile structures. Hertleer et al. reported a fabric sensor made of SS yam knitted in spandex belt [18]. For the latter technique, noninvasive skin electrodes are placed on the thorax, and the variation of the electrical impedance can be detected during respiration cycles. 

Most textile sensors are based on the use of conductive materials. Indeed, the electrical resistance is dependent on other factors (Castano and Flatau, 2014) such as mechanical strain, temperature or humidity. When a mechanical strain is applied on conductive elements, the resulting change in electrical resistance is called piezoresistivity (Carmona et al., 1987) and can be estimated by deriving Ohm s law ... 

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