Atmospheric Pressure Sensors
Atmospheric pressure sensors are also called barometric pressure sensors, because barometers are instruments that measure atmospheric pressure, which is the force per unit area exerted against a surface by the weight of air. A column of air measured from sea level to the top of the atmosphere weighs approximately 14.7 pounds per square inch (PSI). There is less pressure at high elevations because there is not as much air or atmosphere above: the higher above sea level, the lower the pressure. Because atmospheric pressure varies, these sensors are useful and very important. The size and shape of these sensors varies depending on the intended application. For example, scientists hiking up a volcano will use a battery powered sensor with a thick plastic case to protect it from the rough conditions whereas research conducted in a lab requires only a small electronic model. Atmospheric pressure sensors provide mountaineers with information about their elevation, helping keep them safe.
Atmospheric pressure sensors are designed using a silicon diaphragm that bends or resonates with increased and decreased intensities, depending on the pressure. For example, on top of a mountain the diaphragm would not have as much pressure from the atmosphere above and would therefore not bend as much as it would at sea level, where the air column exerting force is taller and weighs more. A charge running through the sensor detects and transmits the frequency information to the display, usually producing a reading that compares the atmospheric pressure to
absolute pressure, or the pressure of a perfect vacuum, which is 0 PSI. This provides a common starting place for readings and helps standardize results that are important to the scientific community. Atmospheric pressure sensors need to be calibrated at times to ensure that the readings are accurate.
Calibrators are instruments that make sure that everything is functioning correctly and accurately; it is a safety hazard if air pressure is unregulated or misread. Air is less dense at lower pressures and is therefore much cooler than at normal elevation; many atmospheric pressure sensors have a temperature compensation feature to take this into account.
