Resistive Sensors Research Articles

Vacuum Filtration-Coated Silver Electrodes Coupled with Stacked Conductive Multi-Walled Carbon Nanotubes/Mulberry Paper Sensing Layers for a Highly Sensitive and Wide-Range Flexible Pressure Sensor

Flexible pressure sensors based on paper have attracted considerable attention owing to their good performance, low cost, and environmental friendliness. However, effectively expanding the detection range of paper-based sensors with high sensitivities is still a challenge. Herein, we present a paper-based resistive pressure sensor with a sandwich structure consisting of two electrodes and three sensing layers. The silver nanowires were dispersed deposited on a filter paper substrate using the vacuum filtration coating method to prepare the electrode. And the sensing layer was fabricated by coating carbon nanotubes onto a mulberry paper substrate. Waterborne polyurethane was introduced in the process of preparing the sensing layers to enhance the strength of the interface between the carbon nanotubes and the mulberry paper substrate. Therefore, the designed sensor exhibits a good sensing performance by virtue of the rational structure design and proper material selection. Specifically, the rough surfaces of the sensing layers, porous conductive network of silver nanowires on the electrodes, and the multilayer stacked structure of the sensor collaboratively increase the change in the surface contact area under a pressure load, which improves the sensitivity and extends the sensing range simultaneously. Consequently, the designed sensor exhibits a high sensitivity (up to 6.26 kPa−1), wide measurement range (1000 kPa), low detection limit (~1 Pa), and excellent stability (1000 cycles). All these advantages guarantee that the sensor has potential for applications in smart wearable devices and the Internet of Things.

Directional Characteristic Enhancement of an Omnidirectional Detection Sensor Enabled by Strain Partitioning Effects in a Periodic Composite Hole Substrate.

An omnidirectional stretchable strain sensor with high resolution is a critical component for motion detection and human-machine interaction. It is the current dominant solution to integrate several consistent units into the omnidirectional sensor based on a certain geometric structure. However, the excessive similarity in orientation characteristics among sensing units restricts orientation recognition due to their closely matched strain sensitivity. In this study, based on strain partition modulation (SPM), a sensitivity anisotropic amplification strategy is proposed for resistive strain sensors. The stress distribution of a sensitive conductive network is modulated by structural parameters of the customized periodic hole array introduced underneath the elastomer substrate. Meanwhile, the strain isolation structures are designed on both sides of the sensing unit for stress interference immune. The optimized sensors exhibit excellent sensitivity (19 for 0-80%; 109 for 80%-140%; 368 for 140%-200%), with nearly a 7-fold improvement in the 140%-200% interval compared to bare elastomer sensors. More importantly, a sensing array composed of multiple units with different hole configurations can highlight orientation characteristics with amplitude difference between channels reaching up to 29 times. For the 48-class strain-orientation decoupling task, the recognition rate of the sensitivity-differentiated layout sensor with the lightweight deep learning network is as high as 96.01%, superior to that of 85.7% for the sensitivity-consistent layout. Furthermore, the application of the sensor to the fitness field demonstrates an accurate recognition of the wrist flexion direction (98.4%) and spinal bending angle (83.4%). Looking forward, this methodology provides unique prospects for broader applications such as tactile sensors, soft robotics, and health monitoring technologies.

Advancements in Flexible and Stretchable Electronics for Resistive Hydrogen Sensing: A Comprehensive Review.

Flexible and stretchable electronics have emerged as a groundbreaking technology with wide-ranging applications, including wearable devices, medical implants, and environmental monitoring systems. Among their numerous applications, hydrogen sensing represents a critical area of research, particularly due to hydrogen's role as a clean energy carrier and its explosive nature at high concentrations. This review paper provides a comprehensive overview of the recent advancements in flexible and stretchable electronics tailored for resistive hydrogen sensing applications. It begins by introducing the fundamental principles underlying the operation of flexible and stretchable resistive sensors, highlighting the innovative materials and fabrication techniques that enable their exceptional mechanical resilience and adaptability. Following this, the paper delves into the specific strategies employed in the integration of these resistive sensors into hydrogen detection systems, discussing the merits and limitations of various sensor designs, from nanoscale transducers to fully integrated wearable devices. Special attention is paid to the sensitivity, selectivity, and operational stability of these resistive sensors, as well as their performance under real-world conditions. Furthermore, the review explores the challenges and opportunities in this rapidly evolving field, including the scalability of manufacturing processes, the integration of resistive sensor networks, and the development of standards for safety and performance. Finally, the review concludes with a forward-looking perspective on the potential impacts of flexible and stretchable resistive electronics in hydrogen energy systems and safety applications, underscoring the need for interdisciplinary collaboration to realize the full potential of this innovative technology.

The Development of a Flexible Humidity Sensor Using MWCNT/PVA Thin Films.

The exponential demand for real-time monitoring applications has altered the course of sensor development, from sensor electronics miniaturization, e.g., resorting to printing techniques, to low-cost, flexible and functional wearable materials. Humidity sensing has been used in the prevention and diagnosis of medical conditions, as well as in the assessment of physical comfort. This paper presents a resistive flexible humidity sensor composed of silver interdigitated electrodes (IDTs) screen printed onto polyimide film and an active layer of multiwall carbon nanotubes (MWCNT) dispersed in a water-soluble polymer, polyvinyl alcohol (PVA). Different MWCNT/PVA sensor sizes and MWCNT percentages are tested to study their effect on the initial electrical resistance (Ri) values and sensor response at different humidity percentages. The results show that the Ri values decrease with the increase in % MWCNT. The sensor size did not influence the sensor response, while the % MWCNT affected the sensor behavior upon relative humidity (RH) increments. The 1% MWCNT/PVA sensor showed the best response, reaching a relative electrical resistance, ΔR/R0, of 509% at 99% RH. Comparable with other reported sensors, the produced MWCNT/PVA flexible sensor is simpler, greener and shows a good sensitivity to humidity, being easily incorporated in wearable monitoring applications, from sports to medical fields.

Multifunctional tri-electrode sensors for the measurement of displacement, force, and infrared irradiation

Abstract Here we described the effect of displacement, force and infrared irradiation on the resistance and impedance of tri-electrode multifunctional sensors. These sensors are based on the gel type composite of carbon nanotubes (CNT), nickel phthalocyanine (NiPc) and edible oil. The channel of this tri-electrodes (field effect transistors) structure is made of CNT-NiPc-oil gel composite using rubbing-in technology. The tri-electrode sensors’ response depends upon the direction of force/displacement and shows an anisotropy. Application of force or displacement from the top causes to decrease resistance and the impedance and vice versa in case of applying force or displacement from the side. The displacement and force sensitivities were up to -273.3 Ω/µm and -46.5 Ω/gf from the top and 480.0 Ω/µm and 3.1 x 102 Ω/gf from the side, respectively, for the sensing ranges 0-150 µm and 0-215 gf. Under the effect of the infrared irradiation from any direction the impedance and the resistance of the sensor reduces. On changing infrared irradiation intensity from 0 to 2500 W/m2 the sensitivities from top and side of the sensor were -37.4 Ωm2/W and -16.5 Ωm2/W, respectively. The investigated sensors may potentially be used as prototypes to develop gel-electronic-based shockproof sensors. The technological achievement in fabricating these devices is the consumption of environmentally friendly materials, particularly edible oil (organic). The edible oil allows to formulate uniform composite gel-films, that may not be comprehended only by ingredients mixing. The fabricated sensors are highly attractive for commercialization.

Breadth-first search algorithm on the finite element simulation of the electrical resistivity of the carbon black elastomeric pressurized sensor

Resistivity and piezoresistive sensitivity of Carbon Black (CB) elastomeric nanocomposites are studied using a finite element method with a conductive network model. CB spheres are placed into Representative Volume Elements (RVEs) in random positions to perform simulations and obtain the strained state and new position of particles. Numerical results are implemented into a breadth-first search algorithm tailored to find percolation pathways from one end of the RVE to another based on the shortest distance between CBs in the strained regime. Percolation pathways are used by the conductive network model to determine the critical distance for resistivity. Resistivity diminishes as the critical distance increases attributed to a greater number of electrons penetrating the barriers. Critical distance at which tunneling can occur expands with an increase in barrier potential. Smaller CBs that can more efficiently occupy the gaps lead to a reduction in the critical distance range necessary for percolation to happen.

Investigation and Demonstration for immunoassay technology based on impedance Amplifies of magnetic and dielectric microbeads

BackgroundBead-based immunoassays typically require researchers to perform the analysis in a laboratory setting, involving complex processing procedures, most of the time, constant potential or current instruments are used to measure the bio-impedance change. However, almost all biological materials are decorated on the electrode surface to obtain the maximum sensitivity, resulting in difficulty to clean, separate, and other applications of fixed bead-based immunoassay. ResultWe present an innovative unfixed bead-based immunoassay technology that utilizes electrical impedance characteristics, offering the advantages of being rapid, portable, miniaturized, and cost-effective. This technique which is known as Impedance-enhanced electrochemical immunoassay (IE-ECIA) employs antibody-coated Magnetic beads (MBs) and Dielectric beads (DBs) linked to antigens for quantitative with miniaturization electronic devices, which has been successfully applied in an immune impedance sensor for detecting the Dengue virus (DENV), which is an affordable test with a low-cost microfluidic impedance biosensor combined with immune magnetic and dielectric micro/nanobeads for antigen detection. HighlightThe proposed immunoassay technology introduces a novel microfluidic platform incorporating magnetic and dielectric beads alongside with an electrochemical impedance biosensor, therefore facilitating continuous-fluid quantitative analysis. This innovative and unconventional approach leverages free-motion multiplex beads housing magnetic and dielectric bead-bound antigens within a simple linear microchannel of microfluidic chip architecture, making the high-through measurements more efficient, enhanced Electrochemical immunoassay (ECIA) signals of Bio-on-magnetic-beads (BOMB). This advancement holds significant potential for enhancing diagnostic capabilities for emerging infectious diseases within clinical environments, thereby bolstering rapid detection capabilities and aiding in the advancement of novel pharmaceuticals, benefiting all the stakeholders.

Integrated Precision High-Frequency Signal Conditioner for Variable Impedance Sensors

Integrated Precision High-Frequency Signal Conditioner for Variable Impedance Sensors

Dual-Hydrogen Bond Donor-Functionalized Carbon Nanotube Fibers: Enhancing Anion-Sensing Performance Through Functionalization Approaches.

In this study, chemiresistive anion sensors are developed using carbon nanotube fibers (CNTFs) functionalized with squaramide-based dual-hydrogen bond donors (SQ1 and SQ2) and systematically compared the sensing properties attained by two different functionalization methods. Model structures of the selectors are synthesized based on a squaramide motif incorporating an electron-withdrawing group. Anion-binding studies of SQ1 and SQ2 are conducted using UV-vis titrations to elucidate the anion-binding properties of the selectors. These studies revealed that the chemical interaction with acetate (AcO-) induced the deprotonation of both SQ1 and SQ2. Selectors are functionalized onto the CNTFs using either covalent or non-covalent functionalization. For covalent functionalization, SQ1 is chemically formed on the surface of the CNTFs, whereas SQ2 is non-covalently functionalized to the surface of the CNTFs assisted by poly(4-vinylpyridine). The results showed that non-covalently functionalized CNTFs exhibited a 3.6-fold higher sensor response toward 33.33mm AcO- than covalently functionalized CNTFs. The selector library is expanded using diverse selectors, such as TU- and CA-based selectors, which are non-covalently functionalized on CNTFs and presented selective AcO--sensing properties. To demonstrate on-site and real-time anion detection, anion sensors are integrated into a sensor module that transferred the sensor resistance to a smartphone via wireless communication.

Double-Chamber Underwater Thruster Diaphragm with Flexible Displacement Detection Function.

The purpose of this paper is to develop a self-detecting diaphragm integrated with a flexible sensor, which is utilized in an underwater thruster. Resistive strain sensors are easy to manufacture and integrate due to their advantages in reliable stretchability and ductility. Inspired by the structure of neurons, we fabricated resistive flexible sensors using silica gel as the matrix with carbon black and carbon nanotubes as additives. All fabricated sensors demonstrated positive resistance characteristics under 60% strain conditions, with the sensor containing a mass ratio of 9 wt % carbon black and carbon nanotubes exhibiting the best resistance-strain linearity. To verify the anti-interference capability of sensors with silica gel substrates of varying hardness values under changing environmental pressure, we tested the pressure sensitivity of the sensors by altering the hardness of the silica gel. The results indicate that silica gel with the highest hardness value provides the best resistance to environmental pressure interference. To detect the motion and deformation of the internal functional components of the thruster, we combined strain detection with the movement operation function of a silica gel diaphragm, resulting in a new integrated diaphragm with sensor detection capabilities. The integrated diaphragm was evaluated by using a tensile testing machine and an LCR tester. The results demonstrate that the mechanical properties of the diaphragm are stable, exhibiting reliable resistance characteristics and a sensitive response during underwater operation. This research can also be applied to the detection of motion amplitudes of other types of soft robots.

A new method for the characterization of perforated facings using a wide frequency range Impedance Sensor

Perforated facings (like fabrics, micro-perforated screens, ...) are widely employed in noise reduction solutions. Following previous works, it has been shown that they can be described as a porous media with identical cylindrical perforations. Then, a classical five parameters JCA model can be employed to predict the acoustical behaviour of perforated facings and, due to their small thicknesses, these five parameters can be obtained from only two independent quantities: the perforation average radius and the perforation rate. The CTTM and LAUM have recently developed a new approach for the measurement of JCA porous model parameters. This approach relies on the properties of two innovative apparatuses: an Impedance Sensor which allows for accurate impedance measurements over a wide frequency range combined with a patented compact anechoic termination. These devices are used to propose an improvement of an existing method for perforated facings characterisation. By using a non-resonant acoustic load and the Impedance Sensor, an accurate estimation of facing bulk magnitude can be done over a wide frequency range. Then the possible impact of the facing vibrational mode and of the acoustic load resonances is reduced, allowing for a more accurate estimation of facing parameter. Results are presented and discussed for different samples.

PEDOT:PSS-Based Wearable Flexible Temperature Sensor and Integrated Sensing Matrix for Human Body Monitoring.

Flexible temperature sensors have been widely used in electronic skins and health monitoring. Body temperature as one of the key physiological signals is crucial for detecting human body's abnormalities, which necessitates high sensitivity, quick responsiveness, and stable monitoring. In this paper, we reported a resistive temperature sensor designed as an ultrathin laminated structure with a serpentine pattern and a bioinspired adhesive layer, which was fabricated with a composite of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/single-wall carbon nanotubes/reduced graphene oxide (PEDOT:PSS/SWCNTs/rGO) and polydimethylsiloxane (PDMS). The temperature sensor exhibited a high temperature sensitivity of 0.63% °C-1, coupled with outstanding linearity of 0.98 within 25-45 °C. Furthermore, it showed fast response and recovery speeds of 4.8 and 5.8 s, respectively, between 25 and 36 °C. It also demonstrated exceptional stability when subjected to stress and bending disturbances with the maximum bending interference deviation of 0.03%. Additionally, it displayed good cyclic stability over a broad temperature range from 25 to 85 °C, and the standard deviation at 25 °C is 0.14%. A series of experiments including blowing detection, respiratory monitoring with or without a mask, and during rest or sleep were conducted to show the potential of the flexible temperature sensors in human body monitoring. Furthermore, a 4 × 4 flexible temperature sensor matrix was integrated to detect and map objects such as wrenches and blood vessels through human hand skin. The results were consistent with those of infrared measurements. The flexible temperature sensor is capable of real-time temperature monitoring and has the potential in tracking human respiration, assessing sleep quality, and mapping the temperature of various objects.

Humidity-independent NO2 gas sensors based on ZnO-NiOFx nanocomposites and the synergistic humidity-immune effect of fluorine doped NiO

Clean, alternative energy sources, especially fuel cells, are gradually attracting global attentions while the produced toxic nitrogen dioxide (NO2) is a greatly hazardous chemical impacting their energy efficiencies. Metal oxide semiconductors (MOS) hold significant promise as NO2 sensors. However, intensive humidity interaction intensifies signal drifts and reliable response inhibitions under variable humidity conditions. In this study, we present a novel approach to address this issue by engineering in-situ F-doped NiO nanocomposites (NiOFx) decorated on ZnO snowflakes achieved through decomposition modulation of ZnOHF precursors. The optimized NO2 sensor demonstrates unparalleled humidity-independence across a wide operating temperature range with prime sensitivity, low detection limit and rapid response/recovery. Matrix algorithm is also implemented in highly precise NO2 identification under complicated atmospheric and humid conditions. Mechanism studies based on temperature programmed desorption (TPD), quasi in-situ X-ray photoelectron spectroscopy (Quasi in-situ XPS) reveal that F− dopants facilitate interfacial electron transferring and inhibit oxygen activity. In-situ diffuse reflectance infrared Fourier transform spectroscopy (In-situ DRIFTS) demonstrates that hygroscopic NiO and electronegative F− synergistically obstruct hydroxyl adsorptions on sensing materials. The innovative approach offers a promising solution for enhancing moisture resistance of MOS sensors for real-time NO2 concentration monitoring in fuel cells and provides valuable insights into anti-humidity mechanisms.

Synthesis-in-place of V2O5 nanobelts for wide range humidity detection

Resistive type humidity sensors offer advantages in simplicity, low cost, compact size, and remote operation. Due to the benefits, they have great potential for use in a variety of environments and future applications, including the Internet of Everything (IoE). However, resistive humidity sensors have limitations in detecting extreme humidity levels below 10 % or above 90 % relative humidity (RH) and are also vulnerable to high temperatures, which hinders their use in harsh environments applications. For broader applications, humidity sensors with reliable performance across the full range of humidity levels and high stability at elevated temperatures need to be developed. Here, we report high performance resistive humidity sensors based on V2O5 nanobelts operating at high temperatures. The V2O5 nanobelts are directly deposited between Pt electrodes by O2-assisted physical vapor transport (PVT) method. The V2O5 nanobelt humidity sensor exhibits reliable humidity sensing properties over a wide range from 1 % to 100 % RH. Furthermore, long-term stability and reproducibility of V2O5 nanobelts are demonstrated through 25 consecutive humid air pulses and measurements obtained after 4 months of storage. The high performance of the V2O5 nanobelt humidity sensor is advantageous for practical use in applications ranging from IoE environments to harsh industrial conditions.

Single feature to achieve gas recognition: humidity interference suppression strategy based on temperature modulation and principal component linear discriminant analysis

Metal oxide semiconductor (MOS) sensors have been broadly employed for gas detection. However, the distinctive chemical detection principle of MOS sensors renders them susceptible to interference by humidity. This paper proposes a novel method for suppressing humidity interference. This method possesses advantages, including rapid recognition, low power consumption, and the capability to achieve recognition using a single feature. Temperature modulation technology was used to record the sensor's resistance variation, and the response features of the obtained dynamic response signal are affected by both humidity and the measured gas. The suppression of humidity interference is achieved through the investigation of the response features of humidity and the measured gas. The response features of humidity and gas are amplified by column normalization. Principal Component Linear Discriminant Analysis (PC-LDA) is utilized to acquire humidity and gas information within data. Using ethanol as the primary experimental subject, suppression of humidity interference is achieved through a single feature (PC-LD2). Quantitative recognition of relative humidity (RH) can be achieved using PC-LD1. Multiple types of waveform and sensor were used to demonstrate the generalization of this method.

Damage monitoring on inter-lamination of GFRP via the resistance change of the MWCNT@GF sensor

The paper aimed to investigate the performance of multi-walled carbon nanotube-coated GF (MWCNT@GF) sensors on interlayer shear damage monitoring and sensing capability of glass fiber-reinforced polymers (GFRPs) based on the resistance change under short beam shear (SBS) load. The MWCNT@GF sensor, manufactured by physical vapor deposition (PVD), was embedded into the neutral layer of laminates to form an in-situ sensing network in different directions and positions. “The MWCNT@GF sensor, manufactured by physical vapor deposition (PVD), was embedded into the neutral layer of laminates to form an in-situ sensing network.” “With the help of Keithley 2700 programmable electrometer and the 3D-digital image correlation(3D-DIC), monotonic and cyclic tests were carried out.” The monotonic test found that the off-axis sensor is more sensitive to shear failure than the on-axis sensor because of its lower shear strength. In addition, the qualitative relationship between shear damage and relative resistance was established by selecting crucial moments. In the cyclical test, the relative resistance of off-axis sensors presented a cyclic mode under cyclic load. Furthermore, the relative resistance under the first 20 cyclic loads was similar to that under monotonic loads. “Furthermore, the relative resistance under the first 20 cyclic loads was similar to that under monotonic loads, which shows that the sensor has superior sensing ability. Finally, the quantitative relation between shear damage and relative resistance was established.” “That means MWCNT@GF sensors can be used to reasonably evaluate the damage state and further evaluate the service performance, reliability and remaining life of the structure.”

Intelligent System Design for Oyster Mushroom Cultivation Using Mamdani Fuzzy Inference with Internet of Things (IoT)

Oyster mushroom (Pleurotus ostreatus) has great potential in agricultural development with increasing global market demand. This research develops an intelligent cultivation system based on Mamdani fuzzy and IoT to control air temperature, air humidity, and soil moisture automatically and in real-time, using DHT22 sensor, resistive soil moisture sensor, and ESP32 as microcontroller. The test results show a high level of accuracy, with an average sensor error of 1% for air temperature, 3.8% for air humidity, and 9.3% for soil moisture. The validation of watering, humidification, and fan prediction times compared to MATLAB calculations is excellent, with MAPE values of 1.52%, 1.43%, and 1.43%, respectively. This system offers a more accurate and responsive automated solution compared to conventional cultivation management. Further testing on actual oyster mushroom farms is required to determine whether the system can adapt to varying environmental conditions. The system relies heavily on a stable internet connection to optimally perform the real-time Mamdani fuzzy calculation function.

Synthesis of copper-containing metal–polymer nanocomposites and their use as a humidity sensor

Recently, the synthesis of new gas-sensitive materials for use in resistive humidity sensors has attracted considerable interest. In the study, copper-containing metal–polymer nanocomposites were obtained by thermolysis of copper fumarate (I) and its complexes with 2,2′-dipyridyl (II) and 1,10-phenanthroline (III). The nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, elemental analysis, energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The most common particle sizes of the thermolysis products of compounds I, II, and III were 18.7, 8.3, and 20.7 nm, respectively. The manufactured sensor samples exhibited good sensitivity to the relative humidity (RH) of air: 2.48%/%RH, 3.77%/%RH, and 3.11%/%RH for the thermolysis products of compounds I, II, and III, respectively. Because of the high porosity and moisture absorption of the film, the maximum sensitivity was approximately 0.005 MΩ/%RH, which indicates fairly effective behavior of the film with respect to humidity. The response and recovery times were 23.7, and 37.3 s; 24.7, and 35.8 s; 32.4, and 58.4 s, respectively. The experiment had 88%–97% reproducibility. The fabricated sensors have great potential as humidity-sensing elements for humidity monitoring.

A new organic–inorganic chloride (H3N–(CH2)6–NH3)[SnCl6]: Crystal structure, thermal analysis, vibrational study, and electrical properties

In this work, a new Organic-Inorganic chloride (H3N–(CH2)6-NH3)[SnCl6] (1) has been synthesized and characterized by single crystal X-ray diffraction (XRD), IR, Raman and impedance spectroscopies. The crystallographic study displays that the title compound crystallizes in the triclinic system with the P−1 space group. The vibrational study (IR, Raman) at room temperature confirmed the existence of the organic and inorganic functional groups. Differential scanning calorimetry (DSC) analysis reveals the existence of three reversible phase transitions at T1 = 345/325 K, T2 = 483/443 K, and T3 = 496/465 K (Heating/Cooling). Furthermore, the conductivity analysis and the dielectric properties confirm the presence of these phase transitions. AC-conductivity measurement of (1) has been investigated using complex impedance spectroscopy in frequency and temperature range 10 Hz–5 MHz and 313–523 K, respectively. The study of Nyquist plots showed the contribution of grains and grain boundaries in the electrical study, confirming the existence of a non-Debye type relaxation. The AC conductivity shows that the material has the potential of impedance sensors.

Observation on Switching Properties of WO3-Based H2 Sensor Regulated by Temperature and Gas Concentration.

Transition metal oxide semiconductors have great potential for use in H2 sensors, but in recent years, the strange phenomena about gas-sensitive performance associated with their special properties have been more widely discussed in research. In some cases, the resistance of transition metal oxide gas sensors will emerge with some changes contrary to their intrinsic semiconductor characteristics, especially in gas sensor research of WO3. Based on the hydrothermal synthesis of WO3, our work focuses on the abnormal change of tungsten oxide resistance to different gases at low temperature (80-200 °C) and high temperature (above 200 °C). Through in situ FT-IR and in situ XPS, combined with density functional theory calculations, a new reasonable explanation of WO3 is proposed for the abnormal resistance change caused by temperature and the strange response due to gas concentration. The occurrence of these findings can be attributed to the synergistic effect resulting from the presence of two contributing factors. One of them is attributed to the alteration in the surface valence state of WO3 induced by gas, resulting in the reduction of W6+. The other one is due to the reaction between gas and adsorbed oxygen on the surface of WO3. This work presents a novel and rational concept for addressing the reaction mechanism between gas and transition metal oxide semiconductors, thereby paving the way for the development of highly efficient gas sensors based on transition metal oxide semiconductors.