UVMED devices have multiple Passive IR or Microwave sensors mounted on the devise at appropriate locations to cover 360 degrees surroundings. A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. The term passive refers to the fact that PIR devices do not radiate energy for detection purposes. They work entirely by detecting infrared radiation (radiant heat) emitted by or reflected from objects. All objects with a temperature above absolute zero emit heat energy in the form of radiation. Usually this radiation isn't visible to the human eye because it radiates at infrared wavelengths, but it can be detected by electronic devices designed for such a purpose, like our PIR sensors. The PIR sensor consists of a pyroelectric sensor and a Fresnel lens. This curved lens concentrates infrared radiation toward a detector’s sensor. A PIR sensor can detect changes in the amount of infrared radiation impinging upon it, which varies depending on the temperature and surface characteristics of the objects in front of the sensor. ("How Infrared motion detector components work". Non commercial research page. Glolab Corporation.).

When an object such as a person, passes in front of a background such as a wall, the temperature at that point in the sensor's field of view will rise from room temperature to body temperature, and then back again. The sensor converts the resulting changes in the incoming infrared radiation into a change in the output voltage, and this triggers the detection. Objects of similar temperature but different surface characteristics may also have a different infrared emission pattern, and thus moving them with respect to the background may trigger the detector as well ("PIR sensor technology". ecosirius.com. Retrieved 1 February 2014.)