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Hydrogen sulfide(H2S) is a highly toxic, corrosive, flammable gas. It is produced from the microbial breakdown of organic matter in the absence of oxygen. H2S also occurs naturally in volcanic gases, hot springs, and industrially in waste water treatment, gas drilling, tanneries, etc. H2S is colorless, and it reacts with metal ions to form metal sulfides, which are insoluble. For example, lead(II) acetate, soluble white crystalline, is converted lead(II) sulfide(PbS) which is black colored insoluble solid when it exposed to H2S. Recently, there has been development in field of semiconducting metal-oxide sensors [1], optical sensors [2], electrochemical sensors [3] to real time, portable detection of H2S. This study aims to use of a cost-effective, easy to fabricate chemical textile sensor for the detection of H2S. Lead(II) acetate was chosen because of its white color crystalline and solubility. It is easy to recognize changes in color after exposure to harmful gas, H2S. Lead(II) acetate printed textile gas sensor demonstrated dark brown color upon exposure to the H2S under 1 ppm whereas no response was observed to other gas and ambient conditions. And the textile gas sensor was placed between a LED and photodiode to readout the electrical signal. Resistance of photodiode was increased with color change (H2S exposure). It can be noted that extremely small concentrations of H2S even under 1 ppm can be recognized and measured by naked eye and photodiode. This textile-based sensor is disposable, cost effective, easy to fabricate, and simple approach to detect H2S. [1] G. F. Fine et al., “Metal Oxide Semi-Conductor Gas Sensors in Environmental Monitoring,” Sensors, vol. 10, no. 6, pp. 5469–5502, Jun. 2010. [2] K. Hayashi, “Optical Chemical Sensor,” IEEJ Trans. Sensors Micromachines, vol. 135, no. 8, pp. 299–304, 2015. [3] K. E. Kramer, S. L. Rose-Pehrsson, M. H. Hammond, D. Tillett, and H. H. Streckert, “Detection and classification of gaseous sulfur compounds by solid electrolyte cyclic voltammetry of cermet sensor array,” Anal. Chim. Acta, vol. 584, no. 1, pp. 78–88, 2007. Figure 1

Accuracy and precise measurement of gas values is crucial for recognizing many critical biological and physical signs, as gas values present significant signals for monitoring chemistry, biology, environments and medical industries. Many sensing materials such as metal compounds, composite, nanowires, and polymers, for detecting gas have been investigated, and the merits and demerits of each have been reported [1,2]. Recently, carbon-based nanomaterials, including zero-dimensional fullerenes, one-dimensional carbon nanotubes (CNT), and two-dimensional graphene, have shown probable in gas sensor applications. Many prior works have reported their superior properties, including higher electrical conductivity, mechanical durability and chemical stability, and a larger surface area.In particularly, CNTs are well known material for sensor applications due to their stable graphite configuration, structural endurance under chemical/physical treatment processes, and mechanical characteristics. Moreover, lots of efforts to realize CNTs as chemical sensor material were performed by many groups previously [3]. They reported that the concentrations of electrons and holes in CNTs play important role in sensitivity of the CNT-based gas sensor. However, although many techniques were introduced to fabricate the CNT-based gas sensors, such device manufacturing processes were intricate and have limited repeatability and reliability, which makes hard them to be commercialized.The CNT yarn was introduced, reported and characterized previously by group using simple dry spinning method [4]. The CNT yarn has good electrical property with a high conductivity, and flexible structural property, and chemical stability. In this work, we develop the ability of CNT yarn for detecting hydrogen and carbon monoxide concentrations. Furthermore, we demonstrate that metal nanoparticles on the surface of CNT yarn highly affect the sensitivity of the CNT yarn-based gas sensor. Therefore, this study focused on the analysis and characteristics of the gas sensor using binary composite as gas sensor. References [1] Liu et al., Sensors 12, 9635 (2012). [2] Varghese et al., Sens. Actuators. B 218, 160 (2015). [3] Llobet et al., Sens. Actuators. B 179, 32 (2013). [4] Hwang et al., Puller. Nanotub. Car. N. 24, 305 (2016).

Strain sensor has been used in variety of industrial applications for structural healthy monitoring and biological signal analysis. The fabrication of a highly sensitive strain sensors are underwent many complex and delicate processes, as many fabrication parameters and conditions must be keep equilibrium to achieve good sensor performance, such as high linearity and sensitivity, stable responsivity, fast response time, mechanical durability, and signal processing steps [1]. Carbon based-nano materials such as fullerene, carbon nanotube (CNTs), and graphene have been considered as sensing materials for optical sensor, chemical sensor, physical sensor and environmental sensor, which possess their own strengths and weakness. Especially, CNTs have been widely employed as sensing species for strain/pressure, gas, temperature, and humidity sensor in recent years. CNT-based sensors were generally fabricated by transferring the individual or bundles of CNTs to the substrates using spin-coating, spraying, dip coating, and inkjet printing methods [1-2]. On the other hand, spin-capable CNTs were reported previously, which simply make transparent conductive CNT webs, ribbon or yarns. The spin-capable CNT forest can give an easy and effective way to fabricate highly-aligned CNT yarn with high flexibility and a electrical conductivity for sensor applications [1-3]. In this paper, we present performance of the CNT yarn based strain sensor. Especially, CNT yarn was associated with stretchable polymers to apply tensile and compressive force. The experimental results reveal that CNT yarn with elastic rubber can be stretch up to 300 %. References Jung et al, J. Vac. Sci. Technol. 32 (2014), 04E107. Han et al. Microelectron. Eng., 168 (2017), 50-54. Jung et al., J. Sensors. Sci. & Tech,. 22 (2013), 315-320

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