Sensor Technology

Detctors technology is a technical science that describes the extraction of information by means of sensors and their conversion into electrical or optical output signals for efficient processing. Sensors include an encoder to convert the physical or chemical inputs and often also a signal preprocessor for the partially-standardized interface for subsequent device electronics, as well as a power supply.

Pyroelectric infrared sensors from InfraTec

Pyroelectric infrared sensors, the same as pyroelectric detectors, by InfraTec can detect and measure the intensity of electromagnetic radiation (UV, VIS, IR, THz). When radiation heats the pyroelectric crystal, a positive electrical charge is created. When radiation is no longer present, the crystal cools and a negative charge is generated.

Pyroelectric sensors are often used in gas analysis, for flame detection and in spectroscopy and pyrometry.

Pyroelectric detectors for gas sensor technology

For gas sensor technology, you can make use of the fact that molecular vibrations of many chemical compounds have fundamental waves in the infrared wavelength range and therefore absorb IR radiation. Each of these compounds has a characteristic absorption spectrum.

InfraTec gas analyzer

An NDIR (non-dispersive IR) gas analyzer consists of an electrically or mechanically modulated IR source, a gas cell and usually a pyroelectric detector. An end value is calculated from the signal voltage of the gas concentration. InfraTec offers a large number of standard IR narrow band filters (NBP), which are optimally tuned to the absorption properties of the gas to be measured. These filters are integrated into the cap of the pyroelectric detector and simplify the development of a complete gas sensor.

Pyroelectric detectors for flame sensor technology

Flame sensor technology with pyroelectric detectors / © Duncan Noakes,

In flame sensor technology, pyroelectric detectors detect radiation from burning gases, liquids or solids and can identify them by their characteristic IR spectrum. The typical spectral radiance of burning organic materials such as wood, natural gas, oil or plastics can be detected.

Two independent criteria of a flame are evaluated to exclude a false alarm caused by the sun or other bright light sources (such as arc welding):

  1. A typical flame (in contrast to solar radiation) is characterized by a flicker frequency of (1 ... 5) Hz.
  2. A hydrocarbon flame produces combustion gases of carbon CO and CO2. Their emission bands lie in the infrared spectral range from 4.0 to 4.8 micron wavelengths. In order to obtain a high signal, one uses wide IR band-pass filters as the detector window, which includes both the radiation emission of CO2 and CO.

Picture credits: © Duncan Noakes/