Impact of Manufacturing Variability and Washing on Embroidery Textile Sensors

Abstract

In this work, an embroidered textile moisture sensor is presented. The sensor is based on a capacitive interdigitated structure embroidered on a cotton substrate with an embroidery conductor yarn composed of 99% pure silver plated nylon yarn 140/17 dtex. In order to evaluate the sensor sensitivity, the impedance of the sensor has been measured by means of a impedance meter (LCR) from 20 Hz to 20 kHz in a climatic chamber with a sweep of the relative humidity from 25% to 65% at 20 °C. The experimental results show a clear and controllable dependence of the sensor impedance with the relative humidity. Moreover, the reproducibility of the sensor performance subject to the manufacturing process variability and washing process is also evaluated. The results show that the manufacturing variability introduces a moisture measurement error up to 4%. The washing process impact on the sensor behavior after applying the first washing cycle implies a sensitivity reduction higher than 14%. Despite these effects, the textile sensor keeps its functionality and can be reused in standard conditions. Therefore, these properties point out the usefulness of the proposed sensor to develop wearable applications within the health and fitness scope including when the user needs to have a life cycle longer than one-time use.

A wearable system to detect urine leakage based on a textile sensor

“…The urine leakage sensor is embroidered with a commercial Shieldex 117/17 dtex 2-ply conductive yarn with a polyester/cotton support yarn. Shieldex yarn is made by filaments of polyamide coated by pure silver, which provides a good conductivity and fastness to washing [11]. The sensor has been embroidered on a commercial cotton underwear due to both, its hydrophilic behaviour and the comfort that cotton provides to the user.…”

Washability of e-textiles: current testing practices and the need for standardization

“…The average number of cycles run in this cluster is 19, but there is a large variation in the number of conducted test cycles (see Table 2): Martinez-Estrada et al wash their test samples only twice, while Liang et al test for three cycles. 26,29 In contrast, five sources have conducted 50 wash cycles, four of which stem from the University of Lille. 12,30,38,40 Gerhold does not run a predetermined number of cycles, but instead stops testing at the first occurrence of detached components, after 16 cycles.…”

Fabrics and Garments as Sensors: A Research Update

“…Factors that interfere with sensor functionality, such as manufacturing variability, have been explored. Shieldtex ® 117/17 dtex 2-ply embroidered on cotton fabric (0.43 mm) with a satin fill stitch pattern (Singer Futura XL-550 embroidery machine) was reported with an error of up to 6% in impedance measured from 25%RH to 65%RH over 10 specimens [55]. If the textile sensors are designed for use in critical applications such as health care and safety, scrutiny of the variability in sensor performance is essential.…”