Humidity Adsorption Research Articles

An alternative approach for compliance testing of food and skin contact silicone elastomers by specific determination of volatile cyclic siloxane oligomers via GC-FID

To date, silicone elastomers intended for food and skin contact are considered compliant as long as their weight loss during a thermal treatment (200 °C, 4 h) is below 0.5 wt%. The common assumption is that this weight loss is caused almost entirely by potentially harmful volatile siloxane oligomers. The present study questions this assumption, first time balancing the initial content and the thermal removal of volatile siloxanes in 48 silicone materials. A GC-FID method for a specific determination of linear (L4 up to L24) and cyclic siloxane oligomers (D4 up to D25) was developed and validated against 1H NMR and thermal desorption GC-MS analysis. All samples contained significant amounts of cyclic siloxanes, while linear trimethylsiloxy terminated oligomers were not detected. Only a weak correlation between the weight loss after thermal treatment and the initial content of cyclic siloxanes was determined for most samples. However, rapid adsorption of humidity from ambient air and its incomplete removal during sample conditioning were determined as crucial aspects in conventional gravimetric compliance testing for silicone articles. Consequently, the specific determination of volatile cyclic siloxane profiles via GC-FID is suggested as the more reliable approach for a compliance decision.

Direct Writing of SiC-polymer nanocomposites for humidity sensing with enhanced performance

Humidity sensors are essential for monitoring humidity levels in various fields. This paper investigates the development and optimization of humidity sensitive SiC-Fe3O4 polymer nanocomposites with varying Fe3O4 concentrations fabricated using Direct Writing (DW) process. The inks were evaluated for flow behavior to ensure proper extrudability through the nozzle. The rheological behavior was then correlated with the printing parameters to optimize the printing accuracy of the nanocomposites. It was observed that all the inks exhibited shear-thinning behavior, enabling a smooth extrusion process. To ensure high-resolution features, a new image analysis method was introduced to quantify corner rounding in printed features, enabling the optimization of printing parameters. In terms of humidity sensing performance, all the inks displayed a change in electrical properties with humidity adsorption. The fabricated nanocomposites showed a decrease in electrical conductivity with increasing humidity, suggesting potential for humidity-sensing applications. Notably, the humidity sensitivity of the nanocomposites was highly dependent on the Fe3O4 concentration in the inks. These findings provide valuable insights into the DW of SiC-Fe3O4 polymer nanocomposites for humidity sensing applications.

Stability and performance of BTC-based MOFs for environmental applications

Two series of open metal site MOFs, HKUST-1 and MIL-100(Fe), have been successfully prepared using different methods of synthesis. Their features depend on the synthetic route as well as their role play in different environmental applications. The stability and performance of these BTC-based MOFs have been tested bearing in mind Congo Red (CR) removal, humidity adsorption and iodine capture and release. HKUST-1 and MIL-100(Fe) samples could offer a remarkable role in the adsorption of CR from aqueous solutions. However, the lability of HKUST-1 in water is revealed as a drawback for its reutilization in both static and agitation conditions. The former contrasts to the stability under ambient moisture. MIL-100(Fe) shows promising properties in both CR adsorption in aqueous solutions and humidity adsorption. Nonetheless, the performance largely depends on the synthesis conditions. Although CR removal is based on surface interaction, there is a relation between the adsorpted quantity and the specific surface area. The size and nature of iodine allows the diffusion in the pores of both HKUST-1 and MIL-100(Fe) MOFs. This way, the uptake of iodine is driving by the porosity and surface area of samples rather than their inherent nature. As a rule, the results of this work indicate that not only is it important the specific nature of the MOF chosen for a given application but also the way in which it has been synthesized and the conditions in which they are used. MIL-100(Fe)-R is revealed as the best suitable candidate to be used as a sorbent for CR in aqueous solutions, moisture and I2 gas.

Effect of hygro-mechanical treatment combined with saturated steam on bamboo cell wall: Structural, chemical, and hygroscopic properties

Bamboo has shown great potential in various fields such as construction, furniture, and decoration due to its fast growth rate, short degradation cycle, strong carbon sequestration ability, and excellent mechanical properties. The effects of hygro-mechanical treatment combined with saturated steam (SC treatment) on bamboo cell walls are less studied. This study explored the effects of SC treatment at different temperatures (140°C, 160°C, 180°C) on the cell wall structure, chemical composition, and hygroscopic properties of bamboo. The study utilized Fourier transform infrared spectroscopy (FTIR) and Confocal Raman microscopy (CRM) to analyze the chemical properties of bamboo, X-ray diffraction (XRD) to analyze the crystal structure, Small Angle X-ray Scattering (SAXS) to analyze the microstructure, Brunauer-Emmett-Teller (BET) to analyze porosity, and Dynamic Vapor Sorption (DVS) to assess humidity adsorption. The lignin and hemicellulose in the bamboo were degraded under saturated steam treatment, leading to reduced stability of the bamboo fiber structure. Compression under these conditions severely damages the orderly arrangement of the fiber structure, resulting in a decrease in the microfibril orientation. The reduction in orientation significantly affected the moisture transfer rate in bamboo and the micromechanical properties of the fiber cells. Simultaneously, the reduction of lignin and hemicellulose decreases the hygroscopic properties of bamboo. The results of this study indicate that SC treatment significantly improves the crystallinity and dimensional stability of bamboo while reducing its porosity, hygroscopicity, and micromechanical properties. Among the three experimental groups, the 160°C saturation steam-compression treatment was considered the best method for significantly improving bamboo performance while maintaining structural integrity.

Theoretical and experimental study of atmospheric water generation employing desiccant materials in a solar-powered single slope apparatus with internal reflectors

Theoretically and experimentally, this study examined how clean water may be generated from ambient air in Kirkuk City, Iraq. As desiccant materials, blue silica gel and a composite substance consisting of silica gel and calcium chloride were utilised, and a single-slope device consisting of two similar portions was used. The process entails humidity adsorption at nighttime and humidity desorption and vapour condensation during the daytime to generate water droplets. The regeneration process's theoretical outcomes were anticipated by employing the 4th-order Rung Kutta approach in MATLAB, and a price analysis was used to find out the price of producing freshwater. The findings demonstrated that the silica gel's theoretical cumulative productivity was significantly higher than its collected one. In contrast, the experimentally measured silica gel temperature was higher than the predicted one. Also, it was found that the adsorption rate, coefficient of mass transfer, as well as productivity of Silica gel, were higher than the composite material, and the yearly cost of generating water utilising silica gel and composite material was 2.54 $/L and 2.49 $/L, respectively. The accumulated water productivity using silica gel and composite material for the average results of November was 112 g/m2 and 73 g/m2, respectively. More significant water production levels may be attained if this procedure is applied in another area with high relative humidity, and the price of generating water will be significantly lower in this scenario.

Analysis of the integral zeolite molecular sieve process for helium CPS application

Zeolite Molecular Sieves (ZMSs) are commonly adopted in tritium handling facilities for impurity removal from gaseous streams, particularly for tritiated water trapping. Several activities have been conducted to characterize the adsorption and desorption behaviour of the sieving materials. Instead, less attention has been put on the analysis of the integral process comprising the adsorption of the tritiated humidity, the regeneration of the molecular sieve and the recovery of the desorbed water. Focusing on the application for the EU-DEMO helium Coolant Purification System (CPS), this work presents a process simulator relying on a MATLAB dynamic model of the ZMS bed and on a RELAP5/MOD3.3 model for the regeneration loop. The dynamic model can simulate both the adsorption and regeneration modes of the ZMS by providing the temperature and the adsorbate concentration profile along the column, while the thermal-hydraulic model is used to assess the conditions of the regeneration loop. By coupling the outcomes of the two models it is possible to establish the effective regeneration efficiency of the process and the amount of the tritiated water recovered. For the case of helium CPS, the analysis demonstrates the feasibility of the proposed operative scheme and the capabilities of the regeneration procedure to ensure a 74.4 % regeneration efficiency of the ZMS bed.

Transforming volcanic mud into mesoporous silica xerogel and its performance for efficient humidity adsorption

A high humidity level in the environment leads to the development of desiccants as hygroscopic material for adsorbing water vapor. Mesoporous silica xerogel, one of the solid adsorbents used for humidity adsorption, was synthesized from hazardous waste of volcanic mud via sol–gel methods by controlling the pH of the solution. The disordered amorphous silica was obtained, with the properties varied depending on the pH of the solution. Silica xerogel obtained at pH 8 exhibits the highest specific surface area of 576.527 m2g−1 and mesoporous surface area of 527.842 m2g−1. It also has the highest adsorption capacity of 18.90% gw/gads determined from the conventional method and 22.14% gw/gads from TG analysis. The performance for humidity adsorption exceeds the commercial silica with an efficiency of 0.9–7% gw/gads. This result indicates that the potential SiO2 extracted from volcanic mud can be commercialized as desiccants for humidity adsorption.

Development of Eggshell Waste Incorporated with a Porous Host as a Humidity Adsorption Material

Development of Eggshell Waste Incorporated with a Porous Host as a Humidity Adsorption Material

Effect of Process Variables and Zeolite Adsorbent in Coffee Bean Drying

Green coffee beans to be stored for transportation must meet storage quality standards, especially the maximum moisture content of 12.5%, so the drying process must be carried out to achieve quality standards, but still economical. The study aims to obtain optimum operating conditions on the drying of Arabica-type coffee beans using a fluidized bed dryer assisted by zeolite adsorbents in a separated fluidized bed prior to heating, as well as calculating the energy consumption of blowers and air heater. The operating conditions were varied, namely air flow rate of 1.79 – 2.29 m/s, air temperature of 45 o C, 50 o C, and 55 o C, zeolite adsorbent mass of 150 g, 175 g, and 200 g. The coffee beans quality tests carried out were the moisture, carbohydrates, protein content, and the visual appearance of the beans. The results show that the optimum drying process of coffee beans resulting a minimum protein and carbohydrate damage are the air velocity of 2.1 m/s, air temperature of 55°C, drying time of 240 minutes, and zeolite adsorbent mass of 150 grams, with energy consumption of 5.02 KWH (equivalent to 180 MJ/T). The addition of zeolite as much as 150 grams, 175 grams, and 200 grams as adsorbent was able to reduce the relative humidity (RH) of air by 16.65%, 18.60%, and 21.17% respectively. The drying rate of coffee beans is mainly influenced by air temperature (more predominantly) than the adsorption of air humidity by zeolite.

Initial Results of the Relative Humidity Observations by MEDA Instrument Onboard the Mars 2020 Perseverance Rover

AbstractThe Mars 2020 mission rover “Perseverance”, launched on 30 July 2020 by NASA, landed successfully 18 February 2021 at Jezero Crater, Mars (Lon. E 77.4509° Lat. N 18.4446°). The landing took place at Mars solar longitude Ls = 5.2°, close to start of the northern spring. Perseverance's payload includes the relative humidity sensor MEDA HS (Mars Environmental Dynamics Analyzer Humidity Sensor), which operations, performance, and the first observations from sol 80 to sol 410 (Ls 44°–210°) of Perseverance's operations we describe. The relative humidity measured by MEDA‐HS is reliable from late night hours to few tens of minutes after sunrise when the measured humidity is greater than 2% (referenced to sensor temperature). Data delivered to the Planetary Data System include relative humidity, sensor temperature, uncertainty of relative humidity, and volume mixing ratio (VMR). VMR is calculated using the MEDA‐PS pressure sensor values. According to observations, nighttime absolute humidity follows a seasonal curve in which release of water vapor from the northern cap with advancing northern spring and summer is visible. At ground level, frost conditions may have been reached a few times during this season (Ls 44°–210°). Volume mixing ratio values show a declining diurnal trend from the midnight toward the morning suggesting adsorption of humidity into the ground. Observations are compared with an adsorptive single‐column model, which complies with observations and confirms adsorption. The model allows estimating daytime VMR levels. Short‐term subhour timescales show large temporal fluctuations in humidity, which suggest vertical and spatial advection.

Utilization of clay based super-porous hydrogel composites in atmospheric water harvesting

Current research work reports the synthesis and performance evaluation of solid polymer desiccant materials based on the superporous hydrogel composites (SPHCs) comprising superporous hydrogel (SPHs) of sodium acrylate (SA) and acrylamide (AM) with different clays such as Laponite®, bentonite and palygorskite. Synthesized polymer desiccants were characterized using SEM, XRD, TGA and FTIR techniques. All the polymer desiccants followed type-III isotherm and the experimental data correlated well with Guggenheim, Anderson and Boer (GAB) model and suggested that these desiccants belong to macroporous adsorbents and adsorb water vapors largely via capillary condensation process. Parental SPH (i.e. P(SA-co-AM)-SPH) and different SPHCs i.e. SPHC-Laponite®, SPHC-bentonite and SPHC-palygorskite exhibited maximum adsorption capacities of 0.12, 0.17, 0.15 and 0.14 gw/gads, respectively at 50% relative humidity and 25 °C, however, at 90% relative humidity adsorption capacities increased upto 0.77, 1.05, 0.93 and 0.87 gw/gads, respectively, which suggested that the hydrophilicity of synthesized desiccants increased with increasing relative humidity. Exceptionally high adsorption capacities of these desiccants were because of the combined effects of highly porous structure of SPHs and hydrophilic nature of clays. Furthermore, experimental kinetics data correlated well with linear driving force model and suggested that the diffusion of water within polymer structure was via type-II diffusion mechanism. During multiple cycle adsorption, SPHCs exhibited much better re-use efficiency than SPHs which suggested that the incorporation of clays within the polymer matrix not only improved desiccant performance but also improved re-use efficiency of polymer desiccants.

Air Drying in an Industrial Compressor

In many industrial applications where compressed air is used it is necessary to increase the quality of the air by decreasing its humidity. This is done by either a condensation or adsorption dryer in the compressor circuit. In this article, the focus is on an industrial adsorption air dryer. The dryer is briefly described together with its function and a selected range of adsorbents suitable for air drying. The paper further deals with the development of a mathematical model of air humidity adsorption which is based on the Pseudo Gas-side Controlled (PGC) model. This paper contains a detailed description of the model and describes its implementation in MATLAB. Finally, the results of the simulations are discussed.

Evaluation of the Impact of Different Natural Zeolite Treatments on the Capacity of Eliminating/Reducing Odors and Toxic Compounds.

Unlike odorants that mask odors, natural zeolite acts as a molecular sieve that captures and eliminates odors. Different treatment methods can be applied to influence the properties of the natural zeolites. To enhance the odor adsorption capacities of the natural zeolite two types of treatment methods were applied: chemical (acid, basic) and thermal. The initial natural zeolites and the activated one were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM-EDX). Two experiments were performed to establish the odor adsorption capacity of the activated natural zeolites. The best zeolite for the adsorption of humidity, ammonia and hydrogen sulfide was the 1–3 mm zeolite activated through thermal treatment. For the adsorption of PAHs, the best zeolite was the one activated through basic treatment, with an adsorption capacity of 89.6 ng/g.

Study of Polyoxometalates Based Films Formation with High Gas Sensitivity

Introduction Inorganic oxide films activated with different additives are the unique sensitive layers for working at room temperature sensors. The sensor behavior of nanostructured activated silica films produced by sol-gel route was examined for environment control. Polyoxometalates (POMs) of Dawson type were used as additives in the silica matrix for gas sensitivity. POMs have good electronic conductivity and chemical stability. These compounds can act as reversible reagents in the reactions of ligand exchange and redox transformations, accompanied by changes in current carrier concentration or catalyze of such transformations that can be used in chemical sensors. Their redox properties can be varied within broad limits due to changing the heteropolyanion composition [1-4]. Porous silica is a unique matrix for chemical sensors, which has a lot of excellent physical and chemical properties [5]. Method The sensor’s interdigital structure was made by microelectronic planar technology as shown in figure 1. The active area of the sensor was 4 x 4 mm. The thickness of the electrodes was 0,2 mm. The width of finger pairs of electrodes and distance between them were 20 μm. The method of hydrolythic polycondensation from tetraethyl orthosilicate solutions was used for forming complex silica films in this work. Films were deposited by a centrifugation from solutions based on tetraethyl orthosilicate and polyoxometalate. POMs with various compositions have been incorporated into the initial solution. The developed technology of multistep temperature treatment up to 413 K allowed film properties stabilizing.The conditions of film formation varied during the tests: solution composition, temperature, and application modes. Morphology and infrared spectra of the layers were studied using Solver-P47 scanning probe microscope (NT-MDT, Russia) and spectrometer Bruker EQUINOX 55 (Germany). Standard gas mixtures (MGPZ, Russia) and Environics – 4000 gas-mixture generator (Environics, USA) were used to measure the properties of sensors. Electrical parameters of the sensors have been measured in real-time mode. Environment influence on sol preparation and films forming was investigated. Results and Conclusions Films had thickness of 200-300 nm and nanoscale pores. The metrological parameters of sensors depend mainly on different parameters: synthesis conditions and chemical content of sensitive film, temperature of the environment, annealing temperature, storage conditions and duration after heat treatment. Temperature treatment and decreasing of environment humidity lead to acceleration of hydrolythic polycondensation of solutions and stabilization of sensitive films at right conditions as demonstrated in figure 2. Introduction of heteropolyanion into film resulted in film’s mass stabilization. The temperature treatment don’t disturb POM molecule in the film. The polyoxometalates didn’t display their catalytic activity at weight content less than 10 % in the film. The increase in conductivity is observed due to an increase in the concentration of charge carriers on the surface of the film, donors of which are introduced into the film POM molecules. And gas sensitivity maximum decreases at weight content more than 50-60 % in matrix what is explained apparently by the formation of crystalline aggregates POM in the volume of the film. Besides the humidity adsorption on the film’s surface contribute to the sensor response. Adding of Mn3P2Mo18O62 into silica film resulted in high sensitivity to ethanolamine (up to 10 times) more than to ammonia as shown in figure 3. Obviously, this is explained by the reaction of ethanolamine complexation with Mn ions, among the possible valence states of which the strongest complex with ethanolamine molecules is formed by Mn3+. An equilibrium shift towards Mn3+ and a decrease in the redox potential of the Mn3+/Mn2+ pair leads to an intramolecular reduction reaction of the heteropolyanion. This interaction is quick (less than 30 s) and reversible at room temperature.

Cement-based composite with humidity adsorption and formaldehyde removal functions as an indoor wall material

Indoor air environment is of great significance for the comfort and health of residents while humidity adjustment and air purification are essential to provide favorable air environment. This paper aims to prepare multifunctional cement-based composite with both humidity adsorption and formaldehyde removal properties for indoor walls. Bamboo charcoal loading silver doped titanium dioxide (Ag/TiO2-BC) was synthesized and used in cement-based paste. Properties of the prepared paste including flowability, bonding strength, humidity adsorption and formaldehyde removal ratio, were investigated. Results show that Ag/TiO2-BC increases superplasticizer demand to keep the mini slump spread at a desirable level due to the higher specific surface area and porous structure of Ag/TiO2-BC. Besides, sample with higher content of Ag/TiO2-BC has lower bonding strength whereas the limit value of 0.5 MPa can be met if cement content is not lower than 30%. Humidity adsorption result indicates that Ag/TiO2-BC significantly improves the humidity content of mixture, which shows an approximately linear trend with Ag/TiO2-BC content. Cement paste with Ag/TiO2-BC has 226.5% higher humidity adsorption capacity compared to that with diatomite, which is the result of combined effects of specific surface area and effective pore volume. Formaldehyde removal result shows that formaldehyde removal ratio increases as Ag/TiO2-BC content rises and equilibrium removal ratio can be reached at 24 h. The removal of formaldehyde by cement with diatomite is due to the adsorption of diatomite while cement with Ag/TiO2-BC has both adsorption and photocatalytic decomposition effects. These findings demonstrate that cement-based composite with favorable humidity adsorption and formaldehyde removal performance as well as traditional properties can be prepared by incorporating Ag/TiO2-BC, showing a high potential to be used as wall materials to enhance indoor air environment.

Humidity adsorption characteristics of Moso bamboo charcoal oxidized at room temperature by HNO3

The bamboo charcoals (BC) in various range pyrolysis (400–900 °C) were modified by HNO3, and then the samples were tested for water vapor adsorption. The adsorption experiments were conducted follows to Japanese industrial standard JIS A 1470-1-2002. The physical and chemical properties of the samples were studied by scanning electron microscope, Brunauer–Emmett–Teller surface area analysis, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The humidity adsorption tests show that the modified BC samples with HNO3 at room temperature (about 22 °C) in pyrolysis temperature (400–500 °C) have a significant enhancement than the control one at lower relative humidity ( 60%). Whereas, at low relative humidity, surface functional groups on BC are a dominant factor compared to specific surface area on humidity adsorption.

Functionalization of renewable bamboo charcoal to improve indoor environment quality in a sustainable way

Abstract The increasing demand for health calls for a bacteria-free environment with proper humidity content. A composite with both bactericidal and humidity control properties is promising in an environmental and economic way for this purpose. In this paper, renewable bamboo charcoal (BC) was used to prepare this multifunctional material by loading silver doped titanium dioxide (Ag/TiO2) with a sol-gel method. The synthesized composite (Ag/TiO2-BC) was characterized by X-ray diffraction (XRD) and scanning electron microscope with energy disperse spectroscope (SEM-EDS) analyses. Antibacterial performance was evaluated by bactericidal rate on both Escherichia coli and Staphylococcus aureus strains. Photocatalytic activity was studied by methylene blue (MB) removal performance. Humidity adsorption and response speed were determined to evaluate the humidity control performance. Results show that Ag promote the transformation of rutile to anatase. SEM-EDS analysis proves the successful loading of Ag/TiO2 on BC surface. Both Ag doping on TiO2 and Ag/TiO2 loading on BC show significantly promoting effects on the bactericidal rate of Ag/TiO2-BC for both strains. MB removal results indicate that TiO2 loading on BC surface increases removal ratio while Ag doping on TiO2 shows further improvement. Humidity tests show that Ag, Ag/TiO2 and calcination temperature slightly decrease the humidity adsorption of Ag/TiO2-BC due to the decreased specific surface area and pore volume determined from nitrogen adsorption tests. However, all samples present prompt humidity adsorption and desorption responses. The overall results show that this biomass deprived composite could be used as a self-control material with bactericidal and humidity control functions.

Humidity sensor applications based on mesopores LaCoO3

Humidity sensor plays a pivotal role in determining the quality of products and the precision of instruments. In order to measure and control humidity, LaCoO3 mesopores sensor was prepared by a modified citrate technique. The sample was characterized by X-ray diffraction, Field emission scanning electron microscopy, High resolution transmission electron micrographs, Energy dispersive X-ray spectroscopy and Brunauer–Emmet–Teller. LaCoO3 exhibits rhombohedral distorted perovskite crystal structure with R3c space group. The humidity-sensing properties were investigated in a wide range of working humidity (11–97% RH) and frequency (100 Hz–100 kHz). The obtained results confirm that the optimum measuring frequency is 1 kHz. A great advantage of LaCoO3 is its porosity, which is essential for a humidity sensor. These pores serve as humidity adsorption sites. Another advantage is its high resistivity, which is reduced by approximately eight times its normal magnitude with increasing the surrounding humidity. The average crystallite size and surface area of the sample are 12.88 nm and 154.125 m2/g respectively. According to VSM results, the hysteresis loop of the sample indicates its paramagnetic nature. Furthermore, the ferroelectric hysteresis loop, that was observed at room temperature, implies the antiferroelectric nature of LaCoO3 nanoparticles. The obtained data confirms that the LaCoO3 sample is very sensitive to humidity and can be commercially used as a humidity sensing element.

Experimental and density functional theory study on humidity sensing properties of copper phthalocyanine (CuPc)

The quartz crystal microbalance (QCM) technique was applied to investigate humidity sensing properties of a copper phthalocyanine (CuPc) thin film prepared by drop cast method. The humidity adsorption and desorption kinetics of (CuPc) thin film was evaluated. The QCM and electrical measurements results showed that humidity sensing properties of CuPc is very sensitive to humidity changes and reversible adsorption/desorption performance which is an indicative of a good humidity sensor even at room temperature. Reproducible experimental results indicated that CuPc thin films have an abundant potential for humidity sensing applications at ambient temperature. According to the first-principle density functional theory calculations, the promising humidity sensing properties of CuPc can be attributed to the considerable charge transfer from the water molecule into Cu atom.

Development of TiO2 nanofibers based semiconducting humidity sensor: adsorption kinetics and DFT computations

The present study focuses on development of pure and Ru-doped TiO2 nanofibers as potential candidates for humidity sensing. Electrospun technique is used for fabrication of the nanofibers to evaluate their humidity sensing properties via QCM method. The obtained nanofibers are analyzed by X-ray diffraction and scanning electron microscopy techniques. The humidity adsorption kinetics and the mechanism of sensing humidity are explored, in details. The results of X-ray analyses reveal that TiO2 nanofibers with a mixture of anatase and rutile structures are successfully synthesized. Additionally, Ru reduces the crystalline size and intensity of the TiO2 peaks. The QCM results show that Ru-doping enriched the humidity sensing performance of TiO2 nanofibers. According to the DFT calculations, the introduction of Ru atoms into TiO2 leads to a sizable increase in the adsorption energy of the water molecule. It is also found that the Ru-doping makes an increase in the charge-transfer from the water molecule into the surface, which can result in an enhanced sensing response of TiO2 by decreasing the electrical resistance.