Development of a yarn capable of measuring localised temperature

Lugoda, P., 2018. Development of a yarn capable of measuring localised temperature. PhD, Nottingham Trent University.

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Abstract

In this research an electronic temperature sensor (ETS) yarn has been developed by embedding a commercially available thermistor chip into the fibres of a yarn. A polymer resin is used to encapsulate the thermistor creating a micro-pod which protects the thermistor from mechanical and chemical stresses during use, and also allows the ETS yarn to be washed. The thermistor micropod and interconnects were then encased within a warp knitted braid to from the ETS yarn.

Temperature is the most widely measured physiological bio-marker in medicine. Temperature changes can indicate underlying pathologies such as wound infections or the formation of ulcers in diabetic patients. A temperature sensor capable of providing remote, continuous and localised (temperature at a given point) temperature measurements could provide clinicians with a powerful tool when handling such complications. Even though there are many flexible temperature sensors they lack true textile characteristics making them unsuitable in many situations. The existing textile-based temperature sensors are incapable of providing localised measurements and can suffer from hysteresis.

At the start of the project a geometrical model of the ETS yarn was developed in-order to understand its design parameters. Then the crafting of the ETS yarn was achieved in three key stages. Hardware and software necessary to obtain temperature from the ETS yarn have been developed. Thereafter work has been conducted to characterise the behaviour of the thermistor and understand the design rules for the micro-pod. Theoretical models were created in COMSOL in-order to study the heat flow through the micro-pod and warp knitted braid, and the effect they have on the response and recovery times of the thermistor. The model has been validated using experiments. Results have shown that encapsulating the thermistor in a micro-pod and making it into a yarn has a minimal effect on the thermal time constant and that the resin of the micro-pod and fibres of the warp knitted braid have no significant impact on the accuracy of the temperature readings. The research into calibrating the ETS yarn has shown that the resistance-temperature conversion equation provided by the thermistor manufacturer provided the most accurate temperature measurement with 63 % of the readings being within ± 0.5 °C accuracy. Cyclic tests have been carried out on the ETS yarn to ensure that its performance is not effected by mechanical strain. Thereafter an evaluation of the response of the ETS yarn to operational conditions (ambient temperature, moisture content, wind speed) was studied.

Finally, prototype temperature sensing garments have been produced using a network of ETS yarns. The necessary hardware and software to capture the temperature data from these prototypes has been developed. Finally, two prototypes have been created, a temperature sensing sock with five ETS yarn for detecting non-freezing cold injuries and a dressing with 16 ETS yarns to provide a temperature map of a wound. The temperature sensing sock was tested on volunteers. Both the wound dressing and the sock can provide remote, continuous and localised temperature measurements without compromising the textile characteristics of the fabric.

Item Type: Thesis
Creators: Lugoda, P.
Date: February 2018
Rights: This work is the intellectual property of the author (Note: if there are other owners of the IP, they must also be named here). You may copy up to 5% of this work for private study, or personal, noncommercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed in the owner(s) of the Intellectual Property Rights.
Divisions: Schools > School of Art and Design
Record created by: Linda Sullivan
Date Added: 17 Aug 2020 14:47
Last Modified: 17 Aug 2020 14:47
URI: http://irep.ntu.ac.uk/id/eprint/40463

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