1. Sensors and its types By: Nutronics India

2. What are sensors? • A sensor is a device that detects and responds to some type of input from the physical environment. • The specific input could be light, heat, motion, moisture, pressure, or any one of a great number of other environmental phenomena. • The output is generally a signal that is converted to human-readable display at the sensor location or transmitted electronically over a network for reading or further processing. 

3. Criteria to choose a Sensor • There are certain features which have to be considered when we choose a sensor. They are as given below: • Accuracy • Environmental condition – usually has limits for temperature/ humidity • Range – Measurement limit of sensor • Calibration – Essential for most of the measuring devices as the readings changes with time • Resolution – Smallest increment detected by the sensor • Cost • Repeatability – The reading that varies is repeatedly measured under the same environment

4. Types of Sensors • Temperature – Thermistors, thermocouples, RTD’s, IC and many more. • Pressure – Fibre optic, vacuum, elastic liquid based manometers, LVDT, electronic. • Flow – Electromagnetic, differential pressure, positional displacement, thermal mass, etc. • Level Sensors – Differential pressure, ultrasonic radio frequency, radar, thermal displacement, etc. • Proximity and displacement – LVDT, photoelectric, capacitive, magnetic, ultrasonic. • Biosensors – Resonant mirror, electrochemical, surface Plasmon resonance, Light addressable potentio-metric. • Image – Charge coupled devices, CMOS • Gas and chemical – Semiconductor, Infrared, Conductance, Electrochemical. • Acceleration – Gyroscopes, Accelerometers. • Others – Moisture, humidity sensor, Speed sensor, mass, Tilt sensor, force, viscosity.

5. Sensors sold by Nutronics India • Temperature Sensors • This device collects information about temperature from a source and converts into a form that is understandable by other device or person. • The best illustration of a temperature sensor is mercury in glass thermometer. The mercury in the glass expands and contracts depending on the alterations in temperature. • The outside temperature is the source element for the temperature measurement. The position of the mercury is observed by the viewer to measure the temperature.

7. Humidity Sensor • A humidity sensor (or hygrometer) senses, measures and reports both moisture and air temperature. • The ratio of moisture in the air to the highest amount of moisture at a particular air temperature is called relative humidity. • Relative humidity becomes an important factor, when looking for comfort.

8. pH Sensors • pH sensor basically works on the fact that interface of two liquids produces a electric potential which can be measured. • In other words when a liquid inside an enclosure made of glass is placed inside a solution other than that liquid, there exists an electrochemical potential between the two liquids.