## 1 Introduction
For example, metal-oxide-based humidity sensors have been shown to degrade significantly in high-temperature and high-humidity environments [14]. Polymer-based humidity sensors exhibit reduced durability in high-humidity environments [15]. Therefore, research on reliable detection materials is necessary to address these issues. Two-dimensional (2D) materials, such as molybdenum disulfide (MoS2), with a high surface-to-volume ratio, large specific areas, and numerous active sites, such as graphene and transition metal dichalcogenides (TMD), have demonstrated considerable potential as sensing materials [13; 16; 17; 18]. In general, 2D TMDs belong to a family of layered semiconducting structures with the chemical formula of MX2, where M represents a transition metal atom such as Mo or W, and X is a chalcogen atom such as Se or S. The layered nature of these materials results in strong anisotropy in their physical and chemical properties, such as their electrical, mechanical, and thermal properties. The most extensively studied 2D-TMD is MoS2, which has three crystalline structures: 1T (tetragonal), 2H (hexagonal), and 3R (rhombohedral) [19]. The lattice parameters of 1T MoS2 are 5.6 A and 5.99 A, those of 2H MoS2 are 3.15 A and 12.36 A, and those of 3R MoS2 are 3.17 A and 18.38 A [20]. Furthermore, the electronic properties of MoS2 vary with the phase; it behaves as a metal in the 1T phase and as a semiconductor in the 2H and 3R phases [19; 20]. Among the mono- to few-layer structures, 2H-MoS2 is the most thermodynamically stable and commonly found phase. In its monolayer form, MoS2 has an octahedral or a trigonal prismatic coordination phase [21]. However, the progress made in humidity-sensing technology based on pure MoS2 is not substantial. These sensors have exhibited low reactivity at low humidity levels and even longer recovery times of over 30 s, showing even lower recovery rates than the existing capacitive humidity sensors. Further studies are required to identify and address the causes of these issues [22; 23]. [PERSON] reported that the crystal phase of MoS2, having S vacancies, reduced the bandgap of MoS2, indicating an increased conductivity and decrease in the hydrogen adsorption free energy, implying a significant improvement of hydrogen evolution reaction activity [24]. [PERSON] reported that there is a significant change in the density of states near the Fermi level as well as greater charge transfer between the gas and the MoS\({}_{2}\) when the gas is adsorbed onto 1T\({}^{\prime}\) MoS\({}_{2}\) and WS\({}_{2}\) compared to 2H MoS\({}_{2}\) and WS\({}_{2}\). Thus, phase selection is important for improving the gas-sensing performance of monolayer MoS\({}_{2}\) and WS\({}_{2}\)[25]. However, the crystalline nature of MoS\({}_{2}\) in response to respiration has not been studied. In this study, we attempted to determine the origin of the slow recovery rates of MoS\({}_{2}\)-based respiration sensors. We compared two respiration sensors fabricated using MoS\({}_{2}\) synthesized using the chemical vapor deposition (CVD) and hydrothermal methods. We confirmed that the crystallinity of MoS\({}_{2}\) thin films varies greatly depending on the synthesis method. It was confirmed that the change in the crystal structure greatly affects the adsorption and desorption of water vapor. In this research, we confirmed that the problem with MoS\({}_{2}\) humidity sensors and respiration sensors, which made it difficult to secure a fast response speed, was caused by the crystal structure.