Abstract
A fabrication method for a stable entrapment of optically responsive dyes on a thread substrate is proposed to move towards a detection system that can be integrated into clothing. We use the dyes 5,10,15,20-Tetraphenyl-21H,23H-porphine manganese(III) chloride (MnTPP), methyl red (MR), and bromothymol blue (BTB), for a proof-of-concept. Our optical approach utilizes a smartphone to extract and track changes in the red (R), green (G) and blue (B) channel of the acquired images of the thread to detect the presence of an analyte. We demonstrate sensing of 50–1000 ppm of vapors of ammonia and hydrogen chloride, components commonly found in cleaning supplies, fertilizer, and the production of materials, as well as dissolved gas sensing of ammonia. The devices are shown to be stable over time and with agitation in a centrifuge. This is attributed to the unique dual step fabrication process that entraps the dye in a stable manner. The facile fabrication of colorimetric gas sensing washable threads is ideal for the next generation of smart textile and intelligent clothing.
Highlights
The detection of volatile gases in the environment is essential for applications in human health[1], monitoring food spoilage or allergens[2], and assessing public and workplace safety[3]
We demonstrated sensing of two common VOCs, ammonia and HCl gas using spectroscopy techniques for initial validation and later, comparing optical images of the thread devices
A simple dual step fabrication process with a dip and dry approach has been presented that allows for the entrapment of multiple dye types on thread substrates for use in wearable textiles applications
Summary
The detection of volatile gases in the environment is essential for applications in human health[1], monitoring food spoilage or allergens[2], and assessing public and workplace safety[3]. Popular techniques for gas sensing include electrochemical detection of oxidation of target analyte, optical detection of chemically responsive materials, and detection of light induced ionization of gases using photo-ionized detectors (PIDs)[4,5] These techniques have achieved high sensitivity and selectivity, though the vast range of applications (e.g. portable, wearable) prove a need for further operational advancements. Their group used arrays of chemically responsive dyes to sense and distinguish between volatile organic compounds, beer, and explosives, to name a few, for a wide field of applications[4,7,8,9,10] Their prior work focused on low-cost, but one time use optical gas sensors on paper[4,10]. This method showed stability in aqueous solutions, but was limited to anionic dyes to complex with the ionic liquid
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