Colorimetric Dye-Loaded Nanofiber Yarn: Eye-Readable and Weavable Gas Sensing Platform

Abstract

The colorimetric gas sensor offers an opportunity for the simple and rapid detection of toxic gaseous substances based on visually discernible changes in the color of the sensing material. In particular, the accurate detection of trace amounts of certain biomarkers in a patient's breath provides substantial clues regarding specific diseases, for example, hydrogen sulfide (H 2 S) for halitosis and ammonia (NH 3 ) for kidney disorder. However, conventional colorimetric sensors often lack the sensitivity, selectivity, detection limit, and mass-productivity, impeding their commercialization. Herein, we report an inexpensive route for the meter-scale synthesis of a colorimetric sensor based on a composite nanofiber yarn that is chemically functionalized with an ionic liquid as an effective H 2 S adsorbent and lead acetate as a colorimetric dye. As an eyereadable and weavable sensing platform, the single-strand yarn exhibits enhanced sensitivity supported by its high surface area and well-developed porosity to detect the breath biomarker (1 ppm of H 2 S). Alternatively, the yarn loaded with lead iodide dyes could reversibly detect NH 3 gas molecules in the ppm-level, demonstrating the facile extensibility. Finally, we demonstrated that the freestanding yarns could be sewn into patterned textiles for the fabrication of a wearable toxic gas alarm system with a visual output.

Smart Materials Enabled with Artificial Intelligence for Healthcare Wearables

“…Section 2.1.2) have been used in many wearable devices. [133][134][135][136][137][138] Color changes can be detected by the Figure 6. Electrochemical sensors for wearable applications.…”

Thread-based wearable devices

“…63 In another colorimetric gas sensor, electrospun nanofiber yarn was loaded with lead acetate and lead iodide for sensing breath biomarker hydrogen sulfide and hazardous ammonia gas (Figure 7b). 64 Note that ammonia is also a breath biomarker associated with kidney malfunction. 65 Colorimetric dyes were incorporated into yarns by adding them in the electrospinning solutions.…”

Liquid Metal-Based Epidermal Flexible Sensor for Wireless Breath Monitoring and Diagnosis Enabled by Highly Sensitive SnS 2 Nanosheets

“…A different study developed a pressure sensor consisting of composite films based on polyaniline hollow nanospheres integrated into face masks where they could be used for respiration monitoring [10]. Nanogenerators, such as pyroelectric nanogenerators (PyNGs), alveolus-inspired membrane sensors (AIMSs), or nanofiber-based triboelectric sensors (SNTSs), have been developed to serve as self-powered breath analyzers [11][12][13][14][15]. While these sensors typically focus on monitoring the frequency and amplitude of respiration, they cannot simultaneously analyze the exhaled air for biomarkers.…”

“…The detection of gas biomarkers depends on specific techniques or instrumentation such as electrochemistry, surfaceenhanced Raman scattering (SERS), chemiluminescence, colorimetric sensor, and infrared sensor [16][17][18][19]. For example, Il-Doo Kim group fabricated colorimetric dye-loaded nanofiber yarn which is sensitive to ppm-level H 2 S and NH 3 biomarkers [15]. Zhou et al utilized a mid-infrared hollow waveguide gas sensor to realize real-time measuring of CO 2 isotopes [20].…”