A sensor is a device that responds to an input quantity by generating a functionally related output usually in the form of an electrical or optical sight. There are many different types of sensors: position sensors, load sensors, tilt sensors, and vibration sensors to name a few, and they are present in multiple fields that warrant the technology.

In the past twenty years there has been tremendous growth in the number of products and services that utilize information acquired by monitoring and quantifying different types of sensors. Sensors have been produced to match the need of these afore mentioned services, and is referred to as sensor technology. Sensor technology encompasses a broad range of services including those applicable in the environment, medicine, commerce, and industry.

Organizations of the relevant areas are realizing the implications of encouraging the growth of sensor technology. Most sensors are electrical or electronic, though other types exist. Sensors are used in everyday life with applications in areas such as automobiles, machines, medicine, and robotics.

Sensor Networks
Sensors usually work in a network, called sensor networks. A sensor network is a group of specialized transducers with a communications infrastructure intended to monitor and record conditions at varying locations. Areas commonly monitored include temperature, humidity, pressure, wind direction and speed, illumination intensity, vibration intensity, sound intensity, power-line voltage, chemical concentrations, pollutant levels, and vital body functions. This intelligent is achieved by using solely or a combination of the tilt, load, vibration, and position sensors mentioned in the introduction.

A sensor network can be broken down further into multiple detection stations called ‘sensor nodes.’ Each sensor node is minute, lightweight, and portable. Each node is equipped with a transducer, microcomputer, transceiver, and power source. The transducer generates electrical signals based on sensed physical effects. The microcomputer both processes and stores the sensor output. The transceiver (being hard-wired or wireless) receives commands from a centralized computer and transmits data back to the computer. The power for each sensor node is derived from the electric utility or from a battery.

Applications

Sensors and Sensor Networks can be applied to:

- Industrial automation
- Automated and Smart homes
- Video surveillance
- Traffic monitoring
- Medical device monitoring
- Monitoring of weather events
- Air traffic control
- Robot control

Types

Sensors are classified according to the type of energy transfer they detect:

- Thermal
- Electromagnetic
- Mechanical
- Chemical
- Optical and radiation
- Acoustic
- Motion
- Orientation
- Distance