1. Sensors are mostly electrical or electronic.
Gas sensors
Introduction:
Sensor:
A sensor is a technological device that detects / senses a signal, physical condition and chemical compounds.
It is also defined as any device that converts a signal from one form to another.
Sensors are mostly electrical or electronic.

2. Introduction: Sensor: Applications Automobiles Machines Robotics
Gas sensors
Introduction:
Sensor:
Applications
Automobiles
Machines
Robotics
Industry
Medicine
Aerospace etc.

3. Introduction: Sensor: Examples of sensors Thermometer Thermocouple
Gas sensors
Introduction:
Sensor:
Examples of sensors
Thermometer
Thermocouple
Phototransistor
Photo resistor
Microphone
Seismometer
Hydrophone etc.

4. Gas sensor is a subclass of chemical sensors.
Gas sensors
Introduction:
Gas Sensor:
Gas sensor is a subclass of chemical sensors.
Gas sensor measures the concentration of gas in its vicinity. Gas sensor interacts with a gas to measure its concentration. Each gas has a unique breakdown voltage i.e. the electric field at which it is ionized. Sensor identifies gases by measuring these voltages. The concentration of the gas can be determined by measuring the current discharge in the device.

5. Applications of Gas Sensor: Process control industries
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. Operating parameters: Operating temperature Operating humidity
Gas sensors
Operating parameters:
Operating temperature
Operating humidity
Disadvantages:
Bulky
Consume lots of power
Require “risky” high voltage to operate.

7. 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. 1. Carbon monoxide gas sensor
Gas sensors
1. Carbon monoxide gas sensor
Carbon monoxide sensor can be of different types such as:
Semiconductor sensor
Electrochemical sensor
Digital sensor
Biometric sensor (chem-optical or gel cell sensor)

9. 2. Carbon dioxide (CO2) gas sensor
Gas sensors
2. Carbon dioxide (CO2) gas sensor
CO2 absorbs infrared light therefore CO2 sensor consists of a tube containing an infrared source at one end and an infrared detector at the other end.
The infrared detector detects the infrared light which is not absorbed by CO2 between source and detector.

10. 2. Carbon dioxide (CO2) gas sensor (Contd.)
Gas sensors
2. Carbon dioxide (CO2) gas sensor (Contd.)
Infrared radiation which is not being absorbed by CO2 produces heat so the temperature will increase.
The infrared detector measures the temperature.
A voltage is produced due to the temperature increase in the infrared sensor.
We can read amplified voltage into the data logger.

11. Types of hydrogen gas sensor: Optical fiber hydrogen sensors
Gas sensors
3. Hydrogen gas sensor
Mostly palladium is used to detect hydrogen because palladium selectively absorbs hydrogen gas and forms the chemical palladium hydride.
Types of hydrogen gas sensor:
Optical fiber hydrogen sensors
Nanoparticle-based hydrogen microsensors
Diode based sensor