Motion detectors are gadgets or devices which signal the alarm whenever it “sees” or detects any movement within the area it is covering. These devices have been widely used with the purpose of security and also in different systems which need automatic functions like the automatic doors.
The Motion detectors work according to the kind of the sensor which has been installed in them. The active sensors have introduced either sound, microwave, or light energy to an environment because it has the capacity of detecting even the tiny change in an environment. Passive sensors can detect the motion by using infrared energy.
The pyroelectric sensors are the common motion detector systems used today. They are based on the detection of a ‘change in the heat of an environment.’ For them to detect people, the pyroelectric sensor is made sensitive to a person’s temperature. The skin of a person has the temperature of around 93 degrees Fahrenheit where this radiates the infrared energy having the wavelength of between 9 and 10 micrometers.