Sensor - Gas
Gas sensor is a device which can detect the presence of various toxic and combustible gases present in the environment.
Operating Principle
The interaction between the test gas and the sensing surface can be detected by the measurements of change in resistance, capacitance, work function, mass, optical characteristics etc. Below table is from Source1.
| Class of gas sensors | Operating principle |
|---|---|
| Electrochemical | Changes in current, voltage, capacitance/impedance: 1. Voltammetry (including amperometry) 2. Potentiometry 3. Chemically sensitized field-effect transistor 4. Potentiometry with solid electrolytes for gas sensing |
| Electrical | Metal oxide conductivity Organic conductivity Electrolytic conductivity Heterojunction conductivity (Schottky diode, FET, MOS) Work function Electric permittivity (capacitance) |
| Mass sensitive | Changes in the weight, amplitude, phase or frequency, size, shape, or position: 1. Quartz crystal microbalance 2. Surface acoustic wave propagation 3. Cantilever |
| Magnetic | Changes of paramagnetic gas properties |
| Optical devices | Changes in light intensity, color, or emission spectra: 1. Absorbance 2. Reflectance 3. Luminescence 4. Refractive index 5. Optothermal effect 6. Light scattering (Raman scattering, plasmon resonance) |
| Thermometric (calorimetric) | Heat effects of a specific chemical reaction. Changes in temperature, heat flow, heat content: 1. Thermoelectric 2. Pyroelectric 3. Catalytic bead (pellistors) 4. Thermal conductivity |
Table 1.The classification of gas sensors suggested in 1991 by Analytical Chemistry Division of IUPAC,
Field of Applicaitons
There are a numerous use of these gas sensors. Particularly, using these gas sensors human beings can be saved from potential dangers. Hence the gas sensors play important roles in various sectors, which include industry, medical, environmental applications, and domestic applications for monitoring toxic and flammable gases. Below table is from Source2.
| Field of application | Function | Examples of detected gases |
|---|---|---|
| Environment | Monitoring toxic gases present in the atmosphere, due to industrial emissions (weather stations, pollutionmonitoring) | CO, CH4, humidity, CO2, O3, VOCs, SOx |
| Safety at work | Control of indoor air quality; monitoring toxic gases in a working environment, for instance in a factory where dangerous chemicals are used | Toxic gases, combustible gases, O2 |
| Domestic safety/household application | Detection of poisonous gases or smoke in households, due to accidents such as fires and explosions; intelligent refrigerator or oven; fire alarm; natural gas heating; leak detection; air quality control; air purifiers; cooking control | CO, humidity, CO2, VOCs |
| Safety in car | Car ventilation control; gasoline vapor detection; alcohol breath tests | CO, LPG, VOCs, CH4 |
| Public security | Control of indoor air quality, detection of substances dangerous for the safety of the general public | Toxic gases, combustible gases, flammable gases, explosives, O2 |
| Medical/clinical | Diagnostics(breath analysis, disease detection); point-of-care patient monitoring; drug monitoring; artificial organs and prostheses; new drug discovery | O2, NH, NOx, CO2, H2S, H2, CL2, anesthesia gases |
| Agriculture | Plant/animal diagnostics; soil and water testing; meat/poultry inspect ion; waste/sewage monitoring | amines, humidity, CO |
| Food quality control | Detection of particular molecules, which are formed when food starts to rot and it is no longer good for consumption | humidity, CO2 |
| Utilities/automotive/power plants | Control of the concentration of the gases in the engine and gas boiler, to guarantee the highest possible efficiency of the combustion process. The same concept can also be applied to power plants, as the energy is generated by combustion | O2, CO, HCs, NOx, SOx, CO2, H2, HCs |
| Industry: Petrochemical Steel/Water treatment/Semiconductor | Process monitoring and control; quality control; workplace monitoring; waste stream monitoring; leakage alarm | HCs, conventional pollutants, O2, H2, O3, CO2, CL2, CH4,H2S |
| Defense/military | Detection of chemical, biological, and toxin warfare agents; treaty verification | Agents, explosives, propellants |
| Aerospace | Monitoring of oxygen and toxic and flammable gases in the environment atmosphere | H2, O2, CO3, humidity |
| Traffic/tunnels/car parks | City traffic control and management; air quality monitoring in tunnels or underground parking garages |
Table 2.Some examples of gas sensor applications
Seeed Gas Sensor
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| Name | Thumbnail | Target Gas | Class of gas sensors | Field of application | Sensor | Detecting Range | Accuracy | Operate voltage | Interface | Click to Buy |
|---|---|---|---|---|---|---|---|---|---|---|
| Grove - Multichannel Gas Sensor V2 |  | Besides Carbon monoxide (CO), Nitrogen dioxide (NO2), Ethyl alcohol(C2H5CH), Volatile Organic Compounds (VOC) and etc | Electrical | Environment | GM102B, GM302B, GM502B, GM702B | / | NA | 3.3V 5V | I2C | Order |
| Grove - Multichannel Gas Sensor V1 |  | Carbon monoxide,Nitrogen dioxide, Ethanol, Hydrogen, Ammonia, Methane, Propane, Iso-butane | Electrical | Environment | MiCS-6814 | CO: 1–1000ppm NO2: 0.05–10ppm H2: 10–500ppm C2H5OH: 1-1000ppm NH3: 1-500ppm CH4: >1000ppm C3H8: >1000ppm C4H10: >1000ppm | NA | 3.3V 5V | I2C | Order |
| Grove - Air Quality Sensor v1.3 |  | Alcohol, Smoke | Electrochemical | Environment | MP503 | 10-1000ppm(Alcohol) | NA | 3.3V 5V | Analog | Order |
| Grove - Alcohol Sensor |  | Alcohol | Electrochemical | Safety in car Public security | MQ303A | 20-1000ppm Alcohol | NA | 5V | Analog | Order |
| Grove - CO2 Sensor |  | CO2 | Electrochemical | Environment Agriculture | MH-Z16 | 0-5000ppm | ±(50ppm +5%) | 5V | UART | Order |
| Grove - CO2 & Temperature & Humidity Sensor (SCD30) |  | CO2 | Optical devices | Environment Agriculture | SCD30 | 0-40000ppm | ±(30 ppm + 3%) | 3.3V 5V | I2C | Order |
| Grove - VOC and eCO2 Gas Sensor (SGP30) |  | VOC,CO2 | Electrical | Environment Agriculture | SGP30 | VOC: 0 ppb to 60000ppb CO2: 400 ppm to 60000 ppm | VOC: (0-2008ppb/1ppb, 2008-11110ppb/6ppb, 11110-60000ppb/32ppb) CO2: (400-1479ppm/1ppm, 1479-5144ppm/3ppm, 5144-17597ppm/9ppm, 17597-60000ppm/31ppm) | 3.3V 5V | I2C | Order |
| Grove - Gas Sensor(MQ2) |  | LPG, i-butane, propane, methane, alcohol, Hydrogen, smoke | Electrochemical | Domestic safety/household application Safety at work | MQ2 | LPG and propane: 200ppm-5000ppm Butane: 300ppm-5000ppm Methane: 5000ppm-20000ppm H2: 300ppm-5000ppm Alcohol:100ppm-2000ppm | NA | 5V | Analog | Order |
| Grove - Gas Sensor(MQ3) |  | High sensitivity to alcohol and small sensitivity to Benzine | Electrochemical | Safety in car Public security | MQ3 | Alcohol: 0.05-10mg/L | NA | 5V | Analog | Order |
| Grove - Gas Sensor(MQ5) |  | High sensitivity to LPG, natural gas, town gas and Small sensitivity to alcohol, smoke | Electrochemical | Industry: Petrochemical Steel/Water treatment/Semiconductor Utilities/automotive/power plants | MQ5 | 200-10000ppm | NA | 5V | Analog | Order |
| Grove - Gas Sensor(MQ9) |  | High sensitivity to carbon monoxide and CH4，LPG | Electrochemical | Safety in car Industry: Petrochemical Steel/Water treatment/Semiconductor Utilities/automotive/power plants Domestic safety/household application | MQ9 | Carbon monoxide: 20-2000ppm CH4: 500-10000ppm LPG: 500-10000ppm | NA | 5V | Analog | Order |
| Grove - Gas Sensor(O2) |  | O2 | Electrochemical | Safety in car Industry: Petrochemical Steel/Water treatment/Semiconductor Utilities/automotive/power plants Domestic safety/household application | ME2-O2-Ф20 | 0～25%Vol | NA | 3.3V 5V | Analog | Order |
| Grove - HCHO Sensor |  | Toluene, methanal, benzene, alcohol, acetone | Electrochemical | Environment | WSP2110 | 1～50ppm | NA | 3.3V 5V | Analog | Order |
| Grove - Temperature, Humidity, Pressure and Gas Sensor (BME680) |  | IAQ | Electrical | Environment Domestic safety/household application | BME680 | 0-500 | NA | 3.3V 5V | I2C | Order |
|
Table 3.Seeed Gas Sensor Category
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