A Wearable Textile Thermograph

Abstract

In medicine, temperature changes can indicate important underlying pathologies such as wound infection. While thermographs for the detection of wound infection exist, a textile substrate offers a preferable solution to the designs that exist in the literature, as a textile is very comfortable to wear. This work presents a fully textile, wearable, thermograph created using temperature-sensing yarns. As described in earlier work, temperature-sensing yarns are constructed by encapsulating an off-the-shelf thermistor into a polymer resin micro-pod and then embedding this within the fibres of a yarn. This process creates a temperature-sensing yarn that is conformal, drapeable, mechanically resilient, and washable. This work first explored a refined yarn design and characterised its accuracy to take absolute temperature measurements. The influence of contact errors with the refined yarns was explored seeing a 0.24 ± 0.03 measurement error when the yarn was held just 0.5 mm away from the surface being measured. Subsequently, yarns were used to create a thermograph. This work characterises the operation of the thermograph under a variety of simulated conditions to better understand the functionality of this type of textile temperature sensor. Ambient temperature, insulating material, humidity, moisture, bending, compression and stretch were all explored. This work is an expansion of an article published in The 4th International Conference on Sensor and Applications.

Wash Testing of Electronic Yarn

“…The general construction of temperature sensing E-yarns is well reported in the literature [19,23]. For this work temperature sensing E-yarns were fabricated using a semi-automated pilot production system (previously detailed elsewhere [11]).…”

Flexible Temperature Sensor Integration into E-Textiles Using Different Industrial Yarn Fabrication Processes

“…The RTDs, when embedded within a textile yarn, are not in direct contact with the surface being measured. Literature has shown alterations in the effective sensitivity of rigid thermistors incorporated within textile yarns [29]. In these experiments, we investigate the impacts of the textile filaments and the yarn fabrication techniques on the effective sensitivity of textile-embedded flexible RTD.…”

“…In addition, these sensors were affected by hysteresis and were unable to provide localised temperature measurements due to their large topology. Rigid surface mount temperature sensors were previously embedded within textile yarns [28][29][30]. The thickness of these yarns has been in the range of 2 mm, which significantly adds to the thickness of the resulting textile knitted or woven using these yarns [28].…”

Flexible Sensors—From Materials to Applications

“…Electrical contact sensors change their electrical properties with respect to temperature. Most of the flexible temperature sensors fall into the electrical contact sensors category and they are either resistive [103,337,339,341,342,344,345,349,[437][438][439][440][441][442][443][444][445][446][447][448][449][450][451], pyroelectric [296,375,[452][453][454][455][456][457], capacitive [145,[458][459][460], thermoelectric [145,458,459], transistors [11,460], or diodes [441]. The performance of a temperature sensor is generally assessed by investigating its temperature sensitivity, temperature range, hysteresis and response time.…”

“…A flexible temperature sensing network was created by incorporating rigid surface mount NTC thermistors (dimensions of 0.5 mm × 0.5 mm × 1 mm) within textile substrates [443][444][445][446]463]. The thermistors were embedded within the fibres of textile yarns to create a flexible temperature sensing yarn.…”