Metal Oxide Semiconductor Gas Sensors Research Articles

The stability of SnO2 and In2O3 gas sensors to water under temperature modulation mode

Temperature modulation technology has been extensively used in metal oxide semiconductor (MOS) gas sensors, especially based on micro-hotplate sensor structure. The technique not only enhances the selectivity but also increases the sensor’s sensitivity by allowing it to exhibit a highly active surface due to the effect of oxygen accumulation. However, when the MOS sensor is in a state of high surface activity, the corresponding hydroxide formation may occur when exposed to water, negatively affecting the gas sensing performance and stability of the sensor. This study focuses on the stability of SnO2 and In2O3 gas sensors during storage process after temperature modulation test. The results indicate that SnO2 exhibits good stability, while In2O3 stability is poor. The mechanism responsible for deactivation was discussed with infrared spectroscopy results. The formation of In(OH)3 was confirmed by high resolution transmission electron microscope, which further confirmed the above conclusion. These findings suggest that after temperature modulation, the gas sensitive materials stored in an atmospheric environment (20 ℃, 40%−60%RH) would generate hydroxides. When temperature modulation was repeated at (100–400 ℃), Sn(OH)4 decompose into SnO2, thus maintaining stability. In contrast, the decomposition temperature of In(OH)3 is higher. At 400 ℃, it will not decompose into In2O3 in a short time, which would lead to poor stability.

An IoT-Enabled E-Nose for Remote Detection and Monitoring of Airborne Pollution Hazards Using LoRa Network Protocol.

Detection and monitoring of airborne hazards using e-noses has been lifesaving and prevented accidents in real-world scenarios. E-noses generate unique signature patterns for various volatile organic compounds (VOCs) and, by leveraging artificial intelligence, detect the presence of various VOCs, gases, and smokes onsite. Widespread monitoring of airborne hazards across many remote locations is possible by creating a network of gas sensors using Internet connectivity, which consumes significant power. Long-range (LoRa)-based wireless networks do not require Internet connectivity while operating independently. Therefore, we propose a networked intelligent gas sensor system (N-IGSS) which uses a LoRa low-power wide-area networking protocol for real-time airborne pollution hazard detection and monitoring. We developed a gas sensor node by using an array of seven cross-selective tin-oxide-based metal-oxide semiconductor (MOX) gas sensor elements interfaced with a low-power microcontroller and a LoRa module. Experimentally, we exposed the sensor node to six classes i.e., five VOCs plus ambient air and as released by burning samples of tobacco, paints, carpets, alcohol, and incense sticks. Using the proposed two-stage analysis space transformation approach, the captured dataset was first preprocessed using the standardized linear discriminant analysis (SLDA) method. Four different classifiers, namely AdaBoost, XGBoost, Random Forest (RF), and Multi-Layer Perceptron (MLP), were then trained and tested in the SLDA transformation space. The proposed N-IGSS achieved "all correct" identification of 30 unknown test samples with a low mean squared error (MSE) of 1.42 × 10-4 over a distance of 590 m.

Au Nanocage/In2O3 Nanoparticle-Based Hybrid Structures for Formaldehyde Sensors

Detecting the trace ppb level of formaldehyde (HCHO) in indoor ambient and human exhaled breath using a metal oxide semiconductor gas sensor has attracted increasing attention. A hybrid nanostructure consisting of In2O3 nanoparticles grown on a Au nanocage (NC) surface was synthesized using a one-step solvothermal method, which was then used to be fabricated as HCHO sensors. The 0.5 wt % Au NC/In2O3 sensor featured an ultrahigh response of 8.8 for 1 ppm of HCHO at a low operating temperature (145 °C), which was nearly 2.5 times higher than that of the pure In2O3 sensor. Furthermore, it possessed outstanding selectivity and a low detection limit (25 ppb) toward HCHO. This excellent sensing property was possibly due to the increase in chemisorbed oxygens on its surface due to the Au NC spillover mechanism, an enhanced adsorption capability for HCHO because of the phase transition from cubic to rhombohedral In2O3, good gas diffusion, and a large surface area with a Au NC/In2O3 3D hierarchical structure, as well as the widened electron depletion layer derived from the Schottky barriers and homojunctions between the components of Au NC/In2O3.

Dual sensitization of three-dimensional ordered macroporous Co3O4 thin films with Pt/Rh for enhanced NO2 detection

Metal oxide semiconductor (MOS) gas sensors currently still suffer from a challenge to achieve high response in humid environment. In this work, a gas sensor based on porous Co3O4 thin films decorated by dual Pt/Rh catalysts is demonstrated for efficient NO2 detection with high humidity-resistivity. The porous Co3O4 thin films with three-dimensional ordered microstructure are synthesized by sacrificial template method. The loading of Pt/Rh catalysts by atom layer deposition (ALD) not only improve the detection sensitivity but also improve the moisture resistance of the sensor. ALD of Pt is proved to have a crucial effect on the sensor response. The Co3O4/Pt sensor with optimized Pt loading exhibits a response of 9.74–10 ppm NO2 at 145 °C, which is nearly 5 times higher than that (2.04) of pristine Co3O4 sensor. Further ALD of Rh on Co3O4/Pt enables the sensor to have a stable response even under 90% relative humidity. With optimized ALD Pt (15 cycles) and Rh (10 cycles), the sensor can well detect 0.5–10 ppm NO2 with fast response/recovery speed, as well as a low detection limit of 49 ppb. The strategy reported herein will pave the way to the development of new sensing materials and devices.

Apparatus development for detecting the freshness of chicken meat using TCS 3200, PH-98108, and MOS gas sensors

Meat can be determined as a muscle that has entered a rigour mortis state. Due to its high nutritional content, the quality of chicken meat quickly decreased. The changes in meat colour, pH, and metabolite gas production, especially ammonia and hydrogen sulfide, are the typical indicators for meat degradation. This research aimed to design and build an apparatus to evaluate the freshness of the chicken meat displayed for sale or storage. In the following study, four different sensors, including TCS 3200 colour sensor, Metal Oxide Semiconductor (MOS) gas sensors (MQ 136, MQ 137), and PH-98108 sensors, were assembled with the aid of a microcontroller and personal computer to become a meat freshness detection apparatus. After being calibrated, the apparatus was then used to evaluate the freshness of the chicken meat sample. The results indicated that the apparatus showed satisfactory performance in detecting the freshness of the chicken meat sample. This apparatus was movable, simple, cheap, easy to operate, and suitable to be used by meat sellers or related institutions. The sensors used were capable of detecting the changes in colour, pH, NH3 gas, and H2S of the sample. The parameters of L*, b*, pH, H2S, and NH3 gas effectively detected the freshness of chicken meat. After 12 hrs of storage, the values of L*, b*, pH, H2S, and NH3 gas of the sample were 50.34, 17.26, 6.59, 134.08 ppm, and 42.34 ppm, respectively.

A Method of Ultra-Low Power Consumption Implementation for MEMS Gas Sensors

In recent years, there has been a growing need for the development of low-power gas sensors. This paper proposes pulse heating and a corresponding measurement strategy using a Pulse Width Modulation (PWM) signal to realize the ultra-low power consumption for metal oxide semiconductor (MOS) gas sensors. A Micro-Hot-Plate (MHP) substrate was chosen to investigate the temperature and power characteristics of the MHP under different applied heating methods. The temperature of this given substrate could respond to the applied voltage within 0.1 s, proving the prac ticability of a pulse heating strategy. In addition, Pd-doped SnO2 was synthesized as the sensing material in the implementation of an ultra-low power gas sensor. The sensing performance and power consumption under different conditions were compared in the detection of reducing gases such as ethanol (C2H5OH) and formaldehyde (HCHO). Additionally, the results revealed that the sensor could work under PWM excitation while reducing the operating power to less than 1mW. The features shown in the measurements provide the feasibility for MOS gas sensors’ application in wearable and portable devices.

GAS SENSORS BASED ON METAL OXIDE NANOPARTICLES AND THEIR APPLICATION FOR ENVIRONMENTALLY HAZARDOUS GASES DETECTION A MINI-REVIEW

Hazardous gases have adverse effects on living organisms and the environment. They can beclassified into two categories, i.e. toxic gases (e.g. H2S, SO2, CO, NO2, NO and NH3) and greenhousegases (e.g. N2O, CH4 and CO2). Moreover, their presence in confined areas may lead to fireaccidents, cause serious health problems or even death. Therefore, monitoring of these substanceswith gas sensors allows assessing the quality of the atmosphere, helps avoiding accidents and saveslives. Metal oxide semiconductor gas sensors (MOS) are one of the most popular choices for theseapplications owing to their numerous advantages, i.e. high sensitivity, long lifetime and shortresponse time. However, these devices have their limitations as well. They exhibit baseline drift,sensor poisoning and poor selectivity. Although much has been done in order to deal with thoseproblems, the improvement of MOS sensors continues to attract researchers attention.The strict control of gas sensing materials preparation is one of the approaches that helps to improveMOS sensors performance. Nanomaterials have been found to be more suitable candidates for gasdetection than materials designed at microscale. Moreover, it was found that the regular and orderedmorphology of metal oxide nanostructures, their loading with noble metals, or the formation ofheterojunctionscan exert additional influence on the properties of these nanostructures andimprove their gas sensing performance, which will be described in the following sections of thispaper. Following a discussion of the operation principle of MOS sensors, a comprehensive review ofthe synthesis and application of metal oxide nanoparticles in the construction of the MOS sensorsdedicated for environmentally hazardous gases is presented. The paper discusses also present issuesand future research directions concerning application of nanotechnology for gas sensing.

Macroporous Perovskite-Structured LaFeO3 Microspheres and Their Highly Sensitive and Selective Sensing Properties to Alcohols Gas

Alcohols detection is essential for the health of chemical and food production personnel. Metal oxide semiconductor (MOS) gas sensors are widely used, however, sensitive and selectivity of traditional MOS gas sensor is still a bottleneck issue. Recently, ABO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> perovskite-type MOS has attracted much attention due to its abundant and controllable physicochemical properties. In this article, macroporous perovskite-type LaFeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LFO) microspheres were prepared by simple one step hydrothermal process. The gas sensing test results show that the LFO gas sensor is highly sensitive and selective to alcohols, especially methanol. For 100 ppm methanol, the response value can reach 120 at 215 °C. The excellent gas sensing properties are attributed to the macroporous characteristics (>100 nm), which facilitates the diffusion of methanol molecules inside the nanospheres, enhancing the contact between the gas molecules and the material and improving the gas sensing performance. In addition, the adsorption characteristics and electron exchange processes of eight gases on the material surface were investigated based on first principles analysis. The results show that the hydroxyl group is the main contributor to the stable adsorption of alcohols gas on the material surface. The perovskite-type LFO is a very promising sensitive material for alcohols detection.

Personal VOCs Exposure with a Sensor Network Based on Low-Cost Gas Sensor, and Machine Learning Enabled Indoor Localization

Indoor locations with limited air exchange can easily be contaminated by harmful volatile compounds. Thus, is of great interest to monitor the distribution of chemicals indoors to reduce associated risks. To this end, we introduce a monitoring system based on a Machine Learning approach that processes the information delivered by a low-cost wearable VOC sensor incorporated in a Wireless Sensor Network (WSN). The WSN includes fixed anchor nodes necessary for the localization of mobile devices. The localization of mobile sensor units is the main challenge for indoor applications. Yes. The localization of mobile devices was performed by analyzing the RSSIs with machine learning algorithms aimed at localizing the emitting source in a predefined map. Tests performed on a 120 m2 meandered indoor location showed a localization accuracy greater than 99%. The WSN, equipped with a commercial metal oxide semiconductor gas sensor, was used to map the distribution of ethanol from a point-like source. The sensor signal correlated with the actual ethanol concentration as measured by a PhotoIonization Detector (PID), demonstrating the simultaneous detection and localization of the VOC source.

Continuous monitoring of volatile organic compounds through sensorization. Automatic sampling during pollution/odour/nuisance episodic events

Volatile organic compounds (VOCs) are a highly diverse class of chemical contaminants and between 50 and 300 of them may be found in ambient air. In urbanized areas, VOCs are emitted from industrial activities, as well as from vehicle-related and combustion sources. VOCs outdoors can be detected in a broad range of concentrations, usually varying seasonally. The presence of VOCs at relatively high concentrations has been related to poor air quality, discomfort and odorous nuisances. Additionally, they can have negative health effects to the human organism. Hence, in locations where recurrent sporadic situations of high VOCs levels take place, episodic samples' evaluation is necessary instead of 24 h or longer sampling period's evaluations. The use of commercially available metal oxide semiconductor gas sensors for a continuous monitoring of VOCs concentrations in outdoor air is an interesting and innovative technology. Additionally, the use of these sensors for the activation of a VOCs sampler when episodic events of nuisance/odorous annoyance occur was successfully evaluated. The sensor activation is induced by higher VOCs concentrations from a wide number of VOC chemical families. Two sensor stations, developed at our laboratory and provided with sampling pumps, were located in the municipality of Santa Margarida i els Monjos (Catalunya, Spain) in January 2021. The stations started recording data continuously from two different types of VOCs sensors, temperature, relative humidity and pressure in 1.5-min periods. Automatic VOCs sampling was conducted, using multi-sorbent bed tubes, during the months of June–July when the sensors electronic values exceeded a set point value. Samples were analysed through TD-GC/MS. TVOC concentrations in episode samples ranged between 78-669 and 12–159 μg m−3 in Site 1 and Site 2, respectively. Although TVOC concentrations were not high in all cases, relevant concentrations of chloroform were observed, especially in Site 1, with concentrations ranging from 19 to 159 μg m−3.

Co/Au bimetal synergistically modified SnO2-In2O3 nanocomposite for efficient CO sensing

For improving the sensitivity and selectivity of metal oxide semiconductor (MOS) materials to CO, Co/Au bimetal modified SnO2-In2O3 nanocomposite was prepared to fabricate MOS gas sensors and tested the gas-sensing performance. The results showed that 1 mol%Au decorated 3 mol%Co-doped SnO2-In2O3 nanocomposite (1Au-40ISC0.03O, the mole ratio of Sn0.97Co0.03O2 to In2O3 is 3:1) exhibited the response of 14.01 towards 1000ppm CO at 400 °C, which was about 7.5 and 2.3 times higher than that of pristine SnO2 and 40ISO (the mole ratio of SnO2 to In2O3 is 3:1), respectively. Besides, it showed a rapid response time of 4s and good selectivity towards CO against H2, which was about 12 times higher than that of SnO2. Furthermore, the gas sensing enhancement mechanism was revealed based on the results of XPS, UPS and UV–Vis DRS tests. It was found that the oxygen vacancy content was increased by Co doping modification, bringing about the higher baseline resistance and adsorbed oxygen content. Simultaneously, the Fermi level position of Sn0.97Co0.03O2 (SC0.03O) shifted towards the valence band by 1.08eV, resulting in the increase of potential barrier at the interface between SC0.03O and In2O3. After Au decorating, the Schottky barrier also increased due to the different work function values among Au, SC0.03O and In2O3, which were 4.8, 4.68 and 4.17eV, respectively. It facilitated the oxygen adsorption on SC0.03O and Au, improving the material sensitization. Additionally, electron exchange was greatly improved via the spill-over catalytic effect of Au, accelerating the reaction between oxygen ions and CO, and shortening the response time.

Room‐Temperature NH3 Sensor Based on SnO2 Quantum Dots Functionalized SnS2 Nanosheets

AbstractTraditional metal oxide semiconductor gas sensors are facing significant challenges for portable devices and integration due to large power consumption caused by high working temperature. 2D nanomaterials with large specific surface areas, rich active sites, and tunable electrical properties are proved to be promising candidates for room‐temperature gas sensors. However, several disadvantages including weak response, sluggish response/recovery kinetics, and poor selectivity still need to be overcome for high‐performance gas sensors. Herein, SnO2 quantum dots (QDs) with a diameter of ≈3 nm functionalized SnS2 nanosheets with a thickness of ≈17 nm are synthesized via a two‐step solvothermal method, which exhibits a high response of 11.1 to 100 ppm NH3 at room temperature of 25 °C with fast response speed and good repeatability, high selectivity, and long‐term stability. The sensing mechanism is mainly ascribed to 0D/2D heterostructure, synergistic effect, and n‐n heterojunction constructed across the interfaces between SnO2 QDs and SnS2 nanosheets. The as‐prepared nanomaterials may contribute to the reasonable design of heterostructure between 0D QDs and 2D nanomaterials, and offer a promising candidate for room‐temperature NH3 detection.

Synthesizing Metal Oxide Semiconductors on Doped Si/SiO2 Flexible Fiber Substrates for Wearable Gas Sensing.

Traditional metal oxide semiconductor (MOS) gas sensors have limited applications in wearable devices owing to their inflexibility and high-power consumption by substantial heat loss. To overcome these limitations, we prepared doped Si/SiO2 flexible fibers by a thermal drawing method as substrates to fabricate MOS gas sensors. A methane (CH4) gas sensor was demonstrated by subsequently in situ synthesizing Co-doped ZnO nanorods on the fiber surface. The doped Si core acted as the heating source through Joule heating, which conducted heat to the sensing material with reduced heat loss; the SiO2 cladding was an insulating substrate. The gas sensor was integrated into a miner cloth as a wearable device, and the concentration change of CH4 was monitored in real time through different colored light-emitting diodes. Our study demonstrated the feasibility of using doped Si/SiO2 fibers as the substrates to fabricate wearable MOS gas sensors, where the sensors have substantial advantages over tradition sensors in flexibility, heat utilization, etc.

Metal oxide semiconductor gas sensors in clinical diagnosis and environmental monitoring

Environmental pollution is the main issue in most countries due to industrialization and fossil fuel burning. Pollution affects the quality of air and the fertility of the soil, which causes infections in the respiratory system and affects our immune system through food. Wherefore the environment has to be monitored to regulate its quality as these hazardous gases affect human health and marine life. Another vital requirement in today’s medical science is the diagnosis of disease at the earliest through a noninvasive process. These tasks are accomplished by gas sensors that detect noxious gases in the surroundings and are also used in the medical field to diagnose diseases by breathing analysis. Metal oxide semiconductors are extensively used in gas sensors due to their high sensitivity and compatibility but selectivity and high operating temperature are their main drawbacks. This review overviews the major metal oxide semiconductors, the sensing mechanism of chemiresistive metal oxide semiconductor-based gas sensors, and various approaches that have been carried out to overcome their limitations. In this paper, we have reviewed the detection of acetone and ammonia which act as a biomarker for some diseases, and the detection of harmful gases such as alcohol and carbon monoxide using gas sensors developed on metal oxide semiconducting materials for a safe living environment.

The enhanced sensing properties of MOS-based resistive gas sensors by Au functionalization: a review.

Gas sensors are essential for detecting toxic gases that can harm social life or industrial production. Traditional metal oxide semiconductor (MOS)-based sensors suffer from shortcomings such as high operating temperature and slow response time, which limits their detection capabilities. Thus, there is a need to improve their performance. One useful technique is noble metal functionalization, which can effectively enhance the response/recovery time, sensitivity and selectivity, sensing response, and optimum operating temperature of MOS gas sensors. Among the noble metals, Au NPs are considered a promising material for forming composite sensing materials to achieve better sensing performance. This paper aims to review and discuss the recent research on Au-decorated MOS-based sensors, including Au/n-type MOS-based sensors, Au/p-type MOS-based sensors, Au/MOS/carbon composite materials, and Au/MOS/perovskite composite materials. The sensing mechanism of Au-functionalized MOS-based materials will also be examined.

Detection of n-Propanol Down to the Sub-ppm Level Using p-Type Delafossite AgCrO2 Nanoparticles.

As an important biomarker of lung cancer, n-propanol at the sub-ppm level is still challenging to be detected for a simple and immediate early diagnosis. In this work, a new n-propanol gas sensor with an ultralow detection limit down to 100 ppb is presented using AgCrO2 nanoparticles synthesized by a simple hydrothermal method. Compared with the congeneric CuCrO2 and commercial SnO2, AgCrO2 exhibits prevailing performances, including a higher selectivity, dynamic response, and logarithmical linearity but lower working temperature. The first-principles calculation and the energy band theoretical analysis are combined to elucidate the sensing mechanism, in which the chemical adsorption of gaseous molecules to silver followed by the dehydrogenation on chromium on the surface of AgCrO2 is responsible for the outstanding susceptibility toward n-propanol. The proposed metal oxide semiconductor gas sensor capable of sub-ppm n-propanol detection provides a route to design and optimize the sensitive material system for the advanced trace detection of the volatile organic compounds.

Metal Oxide Heterostructures for Improving Gas Sensing Properties: A Review.

Metal oxide semiconductor gas sensors are widely used to detect toxic and inflammable gases in industrial production and daily life. The main research hotspot in this field is the synthesis of gas sensing materials. Previous studies have shown that incorporating two or more metal oxides to form a heterojunction interface can exhibit superior gas sensing performance in response and selectivity compared with single phase. This review focuses on mainly the synthesis methods and gas sensing mechanisms of metal oxide heterostructures. A significant number of heterostructures with different morphologies and shapes have been fabricated, which exhibit specific sensing performance toward a specific target gas. Among these synthesis methods, the hydrothermal method is noteworthy due to the fabrication of diverse structures, such as nanorod-like, nanoflower-like, and hollow sphere structures with enhanced sensing properties. In addition, it should be noted that the combination of different synthesis methods is also an efficient way to obtain metal oxide heterostructures with novel morphologies. Despite advanced methods in the metal oxide semiconductors and nanotechnology field, there are still some new issues which deserve further investigation, such as long-term chemical stability of sensing materials, reproducibility of the fabrication process, and selectivity toward homogeneous gases. Moreover, the gas sensing mechanism of metal oxide heterostructures is controversial. It should be clarified so as to further integrate laboratory theory research with practical exploitation.

Gas-sensing performance of Au loading Sn0.97Cu0.03O2 and its use on quantifying CO and H2 concentration by BP-temperature modulation method

Based on the temperature modulation, the quantification of CO and H2 is carried out to solve the problem of poor selectivity for metal oxide semiconductor gas sensors. In this work, the effect of the synergistic modification as Cu2+ doping and Au loading of SnO2 gas-sensing material on sensitivity and selectivity of CO and H2 was investigated. The stable resistance value as the static characteristics and the following-up time as the dynamic characteristics were used by an algorithm of BP neural network to establish a model for quantifying CO and H2 concentrations. The result shows that the operating temperature were reduced to 250 °C from 350 °C by Au loading of 3.0 mol%Cu2+ doping SnO2 gas-sensing material, the response value was increased to 58.3 from 9.3 at 1000 ppm of CO, and the selectivity (RCO/RH2) was increased to 1.55 from 0.33 due to the grain size decrease of SnO2 gas-sensing material and the catalytic effect of Au. And these data including the resistance value and the following-up time were used to obtain WijT, Vjq, ΘjT and ΓqT matrices including the weight values wij, vjq and threshold values θj, γq for the model by training through the algorithm of BP neural network the weight values and threshold values matrices, where the relative error of the quantitative results of CO and H2 concentrations was less than 2.0%, which provides a new way for the quantification of mixed gas.

Synthesis of Mesoporous Ag2O/SnO2 Nanospheres for Selective Sensing of Formaldehyde at a Low Working Temperature.

Formaldehyde (HCHO) is a prevalent indoor gas pollutant that has been seriously endangering human health. Developing semiconductor metal oxide (SMO) gas sensors for selective measurement of formaldehyde at low working temperatures remains a great challenge. In this work, silver/tin-polyphenol hybrid spheres are applied as a sacrificial template for the fabrication of spherical mesoporous Ag2O/SnO2 sensing materials. The obtained mesoporous Ag2O/SnO2 spheres have a uniform particle size (∼80 nm), large pore size (5.8 nm), and high specific surface area (71.3 m2 g-1). The response is 140 toward formaldehyde (10 ppm) at a low working temperature (75 °C). The detection limit reaches a low level of 23.6 ppb. Most importantly, it has excellent selectivity toward interfering gases. When the concentration of the interfering gas (e.g., ethanol) is 5 times as high as that of formaldehyde, the response is little affected. Theoretical calculations suggest that the addition of Ag2O can significantly enhance the adsorption energy toward formaldehyde, thus improving formaldehyde sensing performance. This work demonstrates an efficient self-template synthesis strategy for noble metal catalyst-decorated mesoporous metal oxide spheres, which could boost gas sensing performance at a lower working temperature.

Discriminating gas molecules at room temperature by UV light modulation (ULM) of nonselective metal oxide sensors

Though temperature modulation has demonstrated its capability in addressing selectivity issue of metal oxide semiconductor (MOS) gas sensors, integration of (micro)heater not only drastically adds power consumption and device manufacture complexity, but also hinders the use of flexible polymer substrate/platform. Exploring an approach enabling outstanding selectivity at room temperature (RT) is highly required, but it remains a big challenge. Herein, UV light modulation (ULM) with a rectangular UV wave has been proposed to regulate the transient response signals of sensor arrays, composed of ZnO/(Sr0.6Bi0.305)2Bi2O7 (ZnO/SBO), ZnO and In2O3. Upon pulsed UV excitation, chemisorption (or redox reaction) of injected target vapors (on MOS surface) could be activated at RT. Arising from the specific gas/MOS binding configurations for different gases and MOSs, quite different recovery kinetics under UV illumination (associated with deactivation of chemisorbed target molecules) were found, which endow nonselective MOS sensors with superior selectivity. Multilayer perceptron (MLP) indicates a 99% recognition accuracy ratio of eleven kinds of tested gases, including four kinds of benzene molecules. Our work demonstrates that transient response signals during ULM contain rich features of adsorbed gas molecules, which offers an opportunity for the facile design of advanced smart gas molecule recognition chips on both rigid and flexible platforms.