gas-sensors.ppt

Sensor

1. Gas sensors
Introduction:
Sensor:
Asensorisatechnologicaldevicethat
detects/sensesasignal,physicalcondition
andchemicalcompounds.
Itisalsodefinedasanydevicethatconverts
asignalfromoneformtoanother.
Sensorsaremostlyelectricalorelectronic.

2. Gas sensors
Introduction:
Sensor:
Applications
Automobiles
Machines
Robotics
Industry
Medicine
Aerospaceetc.

3. Gas sensors
Introduction:
Sensor:
Examplesofsensors
Thermometer
Thermocouple
Phototransistor
Photoresistor
Microphone
Seismometer
Hydrophoneetc.

4. Gas sensors
Introduction:
Gas Sensor:
Gassensorisasubclassofchemical
sensors.
Gassensormeasurestheconcentrationof
gasinitsvicinity.Gassensorinteractswitha
gastomeasureitsconcentration.Eachgas
hasauniquebreakdownvoltagei.e.the
electricfieldatwhichitisionized.Sensor
identifiesgasesbymeasuringthesevoltages.
Theconcentrationofthegascanbe
determinedbymeasuringthecurrent
dischargeinthedevice.

5. Gas sensors
Applications of Gas Sensor:
Process control industries
Environmental monitoring
Boiler control
Fire detection
Alcohol breath tests
Detection of harmful gases in mines
Home safety
Grading of agro-products like coffee and
spices

6. Gas sensors
Operating parameters:
Operating temperature
Operating humidity
Disadvantages:
Bulky
Consume lots of power
Require “risky” high voltage to operate.

7. Gas sensors
Gas sensing technologies:
Metal Oxide Based Gas Sensors
Capacitance Based Gas Sensors
Acoustic Wave Based Gas Sensors
Calorimetric Gas Sensors
Optical gas sensors
Electrochemical gas sensors

8. Gas sensors
1. Carbon monoxide gas sensor
Carbon monoxide sensor can be of
different types such as:
Semiconductorsensor
Electrochemicalsensor
Digitalsensor
Biometricsensor(chem-opticalorgelcell
sensor)

9. Gas sensors
2. Carbon dioxide (CO
2) gas sensor
CO
2absorbsinfraredlightthereforeCO
2
sensorconsistsofatubecontainingan
infraredsourceatoneendandaninfrared
detectorattheotherend.
Theinfrareddetectordetectstheinfrared
lightwhichisnotabsorbedbyCO
2
betweensourceanddetector.

10. Gas sensors
2. Carbon dioxide (CO
2) gas sensor (Contd.)
Infraredradiationwhichisnotbeing
absorbedbyCO
2producesheatsothe
temperaturewillincrease.
Theinfrareddetectormeasuresthe
temperature.
Avoltageisproducedduetothe
temperatureincreaseintheinfrared
sensor.
Wecanreadamplifiedvoltageintothe
datalogger.

11. Gas sensors
3. Hydrogen gas sensor
Mostlypalladiumisusedtodetecthydrogen
becausepalladiumselectivelyabsorbs
hydrogengasandformsthechemical
palladiumhydride.
Types of hydrogen gas sensor:
Opticalfiberhydrogensensors
Nanoparticle-basedhydrogenmicrosensors
Diodebasedsensor