With aging population and prevalence of chronic diseases, daily healthcare system became an important interest for many people. There has been much research to combine medical knowledge and engineering technology for easy access of self-health management, and wearable respiratory monitoring system which is the result of sensing and wearable technological integration is considered as a cornerstone in daily healthcare system. Since early detection essentially equals to more chances of treatment that ultimately result in improvement of patient outcomes, the device for continuous respiratory monitoring could be life-saving system. Wearable gas sensor is anticipated as a promising daily healthcare device to play an important role of physiological monitoring by checking human’s breath. For wearable gas sensors, sensor should be weaved into clothing or accessories in which functional materials that distinguish amounts of gases also should be coated.

Many recent studies have discussed to improve the gas response of resistive metal oxide gas sensor (MOGS). However, selectivity is one important parameter for the implementation of MOGS. Little efforts to investigate selective gas sensing were made in graphene based sensor. In MOGS, incorporating two materials such as zinc oxide and tin dioxide is known as a heterostructure. As two Fermi levels equilibrate to the same energy, charge carrier was transferred from one another, resulting in increasing sensor performance. As a similar approach, graphene oxide nanocomposite would enhance selectivity.

In this study, graphene oxide (GO) was constructed into the fabrics by simple solution method after sputtering interdigitated electrode, and ammonia gas sensing was conducted at room temperature. After that, we newly explored to use heterostructure of GO and TiO₂ composite in order to improve selectivity which is the ability to discriminates the response of target gas from other interferents. The use of photon source enabled ethanol and methanol gas sensing at room temperature as the electrons stored in TiO₂ reduced GO, which the color of solution was clearly changed. The morphologies of GO+TiO₂ nanocomposite film on fabrics were analyzed with SEM and XRD, and comprehensive mechanism on GO’s ammonia, ethanol and methanol gas sensing will be drowned in detail.

This research was partially supported by the KIET Evaluation and Planning (20158520000210) grant funded by the Korea Government Ministry of Trade, Industry and Energy, and Agency for Defense Development (ADD) as global cooperative research for high performance and light weight bio-urine based fuel cell (UD160050BD).