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Printed humidity sensor for packaging / ABIRAM MODEM

Swansea University Author: ABIRAM MODEM

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    Copyright: The author, Abiram R. Modem, 2022. This thesis is released under the terms of a Creative Commons Attribution-Non Commercial No–Derivatives (CC-BY-NC-ND) license. Third party content is excluded for use under the license terms.

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Abstract

Printed electronics is the process of developing electrical devices on different substrates by printing inks by various methods. Flexograhpic printing a Humidity sensor was investigated. Flexographic printing can be cost effective for volume production on label presses. In this research, conductive...

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Published: Swansea 2022
Institution: Swansea University
Degree level: Master of Research
Degree name: MSc by Research
Supervisor: Claypole, Timothy ; Lau, John
URI: https://cronfa.swan.ac.uk/Record/cronfa60286
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Abstract: Printed electronics is the process of developing electrical devices on different substrates by printing inks by various methods. Flexograhpic printing a Humidity sensor was investigated. Flexographic printing can be cost effective for volume production on label presses. In this research, conductive silver nano-particle ink with a Silver content of 50 (+/-2) Wt.% was used to develop an Interdigitated Electrode (IDE). The printed base Silver interdigitated electrodes had an average resistance of 11.96Ω with a standard deviation of 1.21 indicating that the Silver printed sensors were consistent in the print quality.Nafion (a sulfonated tetrafluoroethylene-based copolymer) resin solution with a 20 wt.% in lower aliphatic alcohols and water, was printed on top of the silver Interdigitated electrode as the active layer for the detection of the change in humidity. Substrate used for the experiment was white Polyethylene terephthalate (PET White) of 0.175mm thickness. The sensors were tested in a Humidity chamber over a range of 40-80% relative humidity at of 25◦C to ascertain the effective working of the design by measuring their resistivity and repeatability. When the resistance of the sensors was checked with Direct Current (DC), there was a change in the resistance. The formation of dendrites due to electro-chemical reactivity on the surface of the sensor was observed, which caused the sensors to short circuit and fail. When the sensors were tested with Alternating Current (AC), it limited the growth of dendrites and the sensors were self-consistent with a repeatability of resistance pattern, but there was variation in the range of resistance between the sensors, where few showed sensing activity that started at around 500 KΩ and others around 2000 KΩ at 40%RH (Relative Humidity). This proved that the materials used worked and showed potential in developing a humidity sensor via Flexographic printing, further worked is required to eliminate the Dendrites formation and to stabilize the range of resistance.
Keywords: Printing Technology, Printed Electronics, Sensors, Flexography
College: College of Engineering