These dyed threads when woven into clothing can detect various gases, which is indicated by change in color.
The threads that can detect gases were developed by engineers from Tufts University. According to the researchers, the threads can be read visually or by using a smartphone camera to get more precise view to detect changes in color due to analytes as low as 50 parts per million. As these smart threads can be woven into clothes, it could provide a reusable, washable, and affordable safety asset in medical, workplace, military, and rescue environments. The fabrication method and its ability to extend to a wide range of dyes and detection of complex gas mixtures are discussed in this study.
A manganese-based dye, MnTPP, methyl red, and bromothymol blue was used in the study to prove the concept. MnTPP and bromothymol blue detects ammonia and methyl red is capable of detecting hydrogen chloride gases. The dye is added to the thread through a three-step process. It is first dipped in the dye. Then, it is treated with acetic acid to make the surface coarser and swells the fiber. This will in turn allow more binding interactions between the dye and thread. In the last step, the thread is treated with polydimethylsiloxane (PDMS), which creates a flexible, physical seal around the thread and dye. Moreover, PDMS is gas permeable, which allows the analytes to reach the optical dyes.
The change in color by the tested dyes was dependent and proportional to the concentration of the gas as measured using spectroscopic methods. Moreover, these threads worked under water, thereby detecting the existence of dissolved ammonia. The dye does not get diluted with repeated washing or use underwater. Therefore, the threads can be relied upon for consistent quantifiable detection many times over.
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