Micro Sensor Operating at Room Temperature

2004 ◽  
Vol 828 ◽  
Author(s):  
Song-Kap Duk ◽  
Duk-Dong Lee
Keyword(s):  
Work Function ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Gate Voltage ◽  
Room Temperature ◽  
Film Surface ◽  
High Sensitivity ◽  
Gas Detection ◽  
Pani Film ◽  
Response Characteristics

ABSTRACTIn the study, low power micro gas sensors operated at room temperature for the detection of NH3 and NOx gases are proposed. As candidate material of gas sensor for NH3 gas detection at room temperature, polyaniline(PANi) synthesized by chemical polymerization was selected. And Te(Tellurium) thin film was used for NOx gas detection at room temperature. By using these sensing materials, micro gas sensors for room temperature operation were prepared and measured the response characteristics for NH3 and NOx.In case of PANi sensor, the structure was inverted staggered FET type having advantage of useful one for Lab-On-a-Chip. The operating principle of the sensor is based on the change in work function of PANi film caused by adsorption of gas molecules in air on the film surface. The change in work function was measured indirectly from that in gate voltage of the FET device. The responses to various gases (NH3, CH4, Methanol and CH3CN) were obtained in gate voltage step mode in R.H. 30%. And in case of Te sensor, the sensing material was thermally evaporated on glass substrate. The thickness and annealing temperature were 500 Å −2000 Å and 100 °C −300 °C, respectively. The Te-based micro gas sensor exhibited high sensitivity to NOx and good selectivity against CO and hydro-carbon gases. And by adding Ti to Te film, the sensor has a good selectivity to CO gas.

scholarly journals Ammonia Gas Detection by Tannic Acid Functionalized and Reduced Graphene Oxide at Room Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sweejiang Yoo ◽  
Xin Li ◽  
Yuan Wu ◽  
Weihua Liu ◽  
Xiaoli Wang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Gas Sensor ◽  
Tannic Acid ◽  
Room Temperature ◽  
Gas Sensing ◽  
High Sensitivity ◽  
Gas Detection ◽  
Ammonia Gas ◽  
Reduced Graphene

Reduced graphene oxide (rGO) based chemiresistor gas sensor has received much attention in gas sensing for high sensitivity, room temperature operation, and reversible. Here, for the first time, we present a promising chemiresistor for ammonia gas detection based on tannic acid (TA) functionalized and reduced graphene oxide (rGOTA functionalized). Green reductant of TA plays a major role in both reducing process and enhancing the gas sensing properties ofrGOTA functionalized. Our results showrGOTA functionalizedonly selective to ammonia with excellent respond, recovery, respond time, and recovery times.rGOTA functionalizedelectrical resistance decreases upon exposure to NH3where we postulated that it is due to n-doping by TA and charge transfer betweenrGOTA functionalizedand NH3through hydrogen bonding. Furthermore,rGOTA functionalizedhinders the needs for stimulus for both recovery and respond. The combination of greener sensing material and simplicity in overall sensor design provides a new sight for green reductant approach of rGO based chemiresistor gas sensor.

2D/2D/2D Ti3C2Tx@TiO2@MoS2 Heterostructure as Ultrafast and High-sensitivity NO2 Gas Sensor at Room-temperature

2022 ◽  
Author(s):  
Zhuo Liu ◽  
He Lv ◽  
Ying Xie ◽  
Jue Wang ◽  
Jiahui Fan ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
2D Materials ◽  
High Sensitivity ◽  
Two Dimensional ◽  
No2 Gas Sensor ◽  
2D Structure ◽  
Sensing Application

The very diverse two-dimensional (2D) materials have bloomed in NO2 gas sensing application that provide new opportunities and challenges in function oriented gas sensors. In this work, a 2D/2D/2D structure...

scholarly journals Ultraviolet Photoactivated Room Temperature NO2 Gas Sensor of ZnO Hemitubes and Nanotubes Covered with TiO2 Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 462 ◽  
Author(s):  
Hee-Jung Choi ◽  
Soon-Hwan Kwon ◽  
Won-Seok Lee ◽  
Kwang-Gyun Im ◽  
Tae-Hyun Kim ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Tio2 Nanoparticles ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
Prolonged Exposure ◽  
Volume Ratio ◽  
High Sensitivity ◽  
Detection Property ◽  
No2 Gas Sensors

Prolonged exposure to NO2 can cause lung tissue inflammation, bronchiolitis fibrosa obliterans, and silo filler’s disease. In recent years, nanostructured semiconducting metal oxides have been widely used to fabricate gas sensors because of their unique structure and surface-to-volume ratio compared to layered materials. In particular, the different morphologies of ZnO-based nanostructures significantly affect the detection property of NO2 gas sensors. However, because of the large interaction energy of chemisorption (1–10 eV), metal oxide-based gas sensors are typically operated above 100 °C, overcoming the energy limits to attain high sensitivity and fast reaction. High operating temperature negatively affects the reliability and durability of semiconductor-based sensors; at high temperature, the diffusion and sintering effects at the metal oxide grain boundaries are major factors causing undesirable long-term drift problems and preventing stability improvements. Therefore, we demonstrate NO2 gas sensors consisting of ZnO hemitubes (HTs) and nanotubes (NTs) covered with TiO2 nanoparticles (NPs). To operate the gas sensor at room temperature (RT), we measured the gas-sensing properties with ultraviolet illumination onto the active region of the gas sensor for photoactivation instead of conventional thermal activation by heating. The performance of these gas sensors was enhanced by the change of barrier potential at the ZnO/TiO2 interfaces, and their depletion layer was expanded by the NPs formation. The gas sensor based on ZnO HTs showed 1.2 times higher detection property than those consisting of ZnO NTs at the 25 ppm NO2 gas.

Properties of gas sensor using CNTs thin film prepared by PLD/CVD method

2005 ◽  
Vol 900 ◽  
Author(s):  
Tsuyoshi Ueda ◽  
Hideyuki Norimatsu ◽  
M.M.H. Bhuiyan ◽  
Tomoaki Ikegami ◽  
Kenji Ebihara
Keyword(s):  
Thin Film ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
Catalyst Particle ◽  
High Sensitivity ◽  
Laser Pulses ◽  
Nano Particles ◽  
Film Sensor ◽  
Cvd Method

ABSTRACTCarbon nanotube (CNT) is a promising material which has potential for applications to various nanotechnology devices owing to its unique features like high electrical conductivity, mechanical strength and large specific surface area. Recently, gas sensors using CNTs or carbon nano-fiber, which have extremely high sensitivity at a room temperature with fast response, have been reported. Being exposed to oxidizing gas like NO, NO2 or O3, the conductance of the single-walled carbon nanotubes (SWNTs) changes due to charge transfer between the SWNT surface and gas molecules adsorbed. Therefore CNTs will be applicable to O2 and O3 gas sensors in various fields.CNTs thin film sensor was prepared and its performance was investigated. CNTs thin film was prepared on a SiN substrate using PLD/CVD method. To prepare a sensor device an Al2O3 substrate with Pt interdigital electrodes (sensor substrate) was used. In this method, Fe catalytic thin film was deposited by pulsed laser deposition (PLD) method using KrF excimer laser of wavelength 248 nm, repetition rate 10 Hz, energy fluence 3 J/cm2. During PLD process the substrate temperature and the ambient gas pressure were kept at room temperature of 25 °C and 3.5×10−5 Torr, respectively. The thickness and roughness of the films were modified by changing a number of ablation laser pulses from 300 to 3,000. A small number of laser pulses deposited Fe nano-particles of less than 10 nm in diameter on the substrate. We used 1000 pulses for a catalytic Fe film preparation as small-sized catalyst is necessary to grow SWNTs. CNTs were grown from Fe thin film on Si or sensor substrates by thermal CVD method. Ethylene gas was used as carbon source. The substrate was set in the quartz reaction tube heated to 1000 °C in an electric furnace. CNTs were grown for 20 ∼ 40 minutes. In our previous studies, it was found that SWNTs can grow under this process. The prepared CNTs were characterized using SEM, TEM and Raman spectroscopy. From SEM observation, randomly oriented CNTs were found on both the Si substrate and the sensor substrate. A diameter of CNTs was found 20 ∼ 50 nm which tended to be proportional to the size of catalyst particle.The Sensitivity of CNT gas sensor was evaluated by measuring the electrical characteristic of the sensor. The sensor was exposed to NO gas of different concentration in a chamber. Resistance of the sensor was measured by two-terminal method, while the sensor was heated from room temperature to a high temperature on a block heater. The Sensitivity of CNT gas sensors, response time and reproducibility was measured. Initial resistance of the film was about 450 and it decreases with temperature increase. This shows that a prepared CNTs sensor film has semiconductor characteristics. Measured maximum sensitivity of CNTs gas sensor was 6.9 % at sensor temperature 290 deg. Detail studies and the latest data will be presented at the symposium.

Fabricating ZnO Nanorods Sensor for Chemical Gas Detection at Room Temperature

2007 ◽  
Vol 7 (12) ◽  
pp. 4439-4442 ◽  
Author(s):  
Chuanwei Cheng ◽  
Guoyue Xu ◽  
Haiqian Zhang ◽  
Yan Luo
Keyword(s):  
Gas Sensors ◽  
Potential Application ◽  
Room Temperature ◽  
Gas Sensing ◽  
Zno Nanorods ◽  
High Sensitivity ◽  
Gas Detection ◽  
Highly Sensitive ◽  
Sensing Characteristics

We present a sensor fabricated by simply casting ZnO nanorods on a microelectrodes array for chemical gas detection at room temperature. The ammonia and ethanol gas sensing characteristics were carefully investigated. The sensor exhibited high sensitivity for both ammonia and ethanol gases. The response and recover time are less than 20 seconds, respectively. Present results demonstrate the potential application of ZnO nanorods for fabricating highly sensitive gas sensors.

Porous ZnO/rGO Nanosheet‐Based NO 2 Gas Sensor with High Sensitivity and ppb‐Level Detection Limit at Room Temperature

2021 ◽  
pp. 2101511
Author(s):  
Ziwei Chen ◽  
Haojie Guo ◽  
Fusheng Zhang ◽  
Xiaowen Li ◽  
Jiabing Yu ◽  
...  
Keyword(s):  
Detection Limit ◽  
Gas Sensor ◽  
Room Temperature ◽  
High Sensitivity

Exploiting Free-Standing p-CuO/n-TiO2 Nanochannels as a Flexible Gas Sensor with High Sensitivity for H2S at Room Temperature

ACS Sensors ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 3387-3397
Author(s):  
Haoxuan He ◽  
Chenxi Zhao ◽  
Jing Xu ◽  
Kuanzhi Qu ◽  
Zhen Jiang ◽  
...  
Keyword(s):  
Gas Sensor ◽  
Room Temperature ◽  
High Sensitivity ◽  
Free Standing

scholarly journals A Novel Type Room Temperature Surface Photovoltage Gas Sensor Device 

2018 ◽  
Author(s):  
Monika Kwoka ◽  
Michal A. Borysiewicz ◽  
Pawel Tomkiewicz ◽  
Anna Piotrowska ◽  
Jacek Szuber
Keyword(s):  
Gas Sensor ◽  
Room Temperature ◽  
Gas Sensing ◽  
Signal To Noise Ratio ◽  
High Sensitivity ◽  
Fast Response ◽  
Surface Photovoltage ◽  
Kelvin Probe ◽  
Sensor Device ◽  
Developed Surface

In this paper a novel type of a highly sensitive gas sensor device based on the surface photovoltage effect is described. The developed surface photovoltage gas sensor is based on a reverse Kelvin probe approach. As the active gas sensing electrode the porous ZnO nanostructured thin films are used deposited by the direct current (DC) reactive magnetron sputtering method exhibiting the nanocoral surface morphology combined with an evident surface nonstoichiometry related to the unintentional surface carbon and water vapor contaminations. Among others, the demonstrated SPV gas sensor device exhibits a high sensitivity of 1 ppm to NO2 with a signal to noise ratio of about 50 and a fast response time of several seconds under the room temperature conditions.

Bifunctional gas sensor based on Bi2S3/SnS2 heterostructures with improved selectivity through visible light modulation

2022 ◽  
Author(s):  
Tingting Wang ◽  
Juanyuan Hao ◽  
Jiaying Liu ◽  
Yanling Zhang ◽  
Qihua Liang ◽  
...  
Keyword(s):  
Internet Of Things ◽  
Visible Light ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Room Temperature ◽  
The Internet ◽  
Light Modulation ◽  
Sensing Platform ◽  
Hazardous Gases ◽  
The Internet Of Things

Effective monitoring of hazardous gases at room-temperature is extremely indispensable in the “Internet of things” application; however, developing bifunctional gas sensors for the advanced sensing platform still remains a challenge....

scholarly journals Cellulose Nanopaper Cross-Linked Amino Graphene/Polyaniline Sensors to Detect CO2 Gas at Room Temperature

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5215 ◽  
Author(s):  
Hanan Abdali ◽  
Bentolhoda Heli ◽  
Abdellah Ajji
Keyword(s):  
Bacterial Cellulose ◽  
Room Temperature ◽  
Morphological Structure ◽  
High Sensitivity ◽  
Fast Response ◽  
Aniline Monomer ◽  
Resistance Response ◽  
Covalent Interaction ◽  
Response Characteristics ◽  
Carbon Dioxide Co2

A nanocomposite of cross-linked bacterial cellulose–amino graphene/polyaniline (CLBC-AmG/PANI) was synthesized by covalent interaction of amino-functionalized graphene (AmG) AmG and bacterial cellulose (BC) via one step esterification, and then the aniline monomer was grown on the surface of CLBC-AmG through in situ chemical polymerization. The morphological structure and properties of the samples were characterized by using scanning electron microscopy (SEM), and thermal gravimetric analyzer (TGA). The CLBC-AmG/PANI showed good electrical-resistance response toward carbon dioxide (CO2) at room temperature, compared to the BC/PANI nanopaper composites. The CLBC-AmG/PANI sensor possesses high sensitivity and fast response characteristics over CO2 concentrations ranging from 50 to 2000 ppm. This process presents an extremely suitable candidate for developing novel nanomaterials sensors owing to easy fabrication and efficient sensing performance.

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