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Electromagnetic, differential pressure, positional displacement, thermal mass, etc. Level Sensors – Differential pressure, ultrasonic radio frequency, radar, thermal displacement, etc. Proximity and displacement – LIVED, photoelectric, capacitive, magnetic, ultrasonic. Obsessions – Resonant mirror, electrochemical, surface Plasmas resonance, Light addressable potent;metric. Image ; Charge coupled devices, COSMOS Gas and chemical – Semiconductor, Infrared, Conductance, Electrochemical. Acceleration – Gyroscopes, Accelerometers. Others – Moisture, humidity sensor, Speed sensor, mass, Tilt sensor, force, viscosity.
Principles of some of the common sensor: Thermocouple – They are made of two wires (each of different homogeneous alloy or metal) which form a measuring junction by Joining at one end. This measuring junction is open to the elements being measured. The other end of the wire is terminated to a measuring device where a reference junction is formed. The current flows through the circuit since the temperature of the two Junctions are different. IR Sensor -This device emits and/or detects infrared radiation to sense a particular phase in the environment.
Generally, thermal radiation is emitted by all the objects in the infrared spectrum. The infrared concreteness this type of radiation which is not visible to human eye. Touch Sensor- A touch sensor acts as a variable resistor as per the location where it is touched. The figure is as shown below. The partially conductive material opposes the flow of current. The main principle of the linear position sensor is that the current flow Is more opposed when the length of this material that must be traveled by the current Is more. As a result, the resistance of the material Is varied by
Proximity Sensor -A proximity sensor detects the presence of objects that are nearly placed without any point of contact. Since there is no contact between the sensors and sensed object and lack of mechanical parts, these sensors have long functional life and high reliability. Different definitions are approved to distinguish sensors and transducers. Sensors can be defined as an element that senses in one form of energy to produce a variant in same or another form of energy. Transducer converts the measured into the desired output using the transduction principle.