Temperature Sensors - Group B

Temperature sensors are used in many modern day electronics to monitor heat levels to avoid overheating.  Since some processes only work within a narrow range of temperatures, accurate measurements are needed so that preventative measures can be enacted, or the system can shut down to avoid any damages.  Also, as Tyler Woyshner described in his blog post, temperature sensors are utilized in many buildings to control the comfort levels of the occupants.  He goes on to mention how measurements can be used to adjust the temperature settings of the building itself.  A variety of sensors exist including thermocouples, thermistors, sensor integrated circuits, and resistance temperature detectors (RFDs).  These are all considered contact sensors which have to touch an object to obtain a measurement.

Audrey Ryan gives a more descriptive account in her blog post about how different types of temperature sensors perform measurements, but to give a brief explanation of how these types of sensors operate, thermocouples work by having “two dissimilar metals joined together at one end, to produce a small unique voltage at a given temperature.” (Hareendran)  These types of sensors can measure a range of up to 1700 degrees but tend to not be very sensitive.  Thermistors measure a change of electrical resistance that corresponds to different temperature changes but have a smaller range of measurements and can be cheaper.  RFDs are sensors “that contain a resistor that changes resistance value as its temperature changes” (Omega) and tend to have better accuracy and stability than thermocouples. 

Temperature sensors monitor “the atomic activity and movement of an object. When temperature sensor devices read an object with zero atomic activity, the temperature point is considered absolute zero.” (DeVale)  The more atomic activity leads to higher temperatures which cause more electronic activity or resistance in the sensor taking the measurements.  Based on the strength of the temperature, the sensor can produce an analog or digital output which can be sent to databases that store measurements, or devices that display the measured temperature.

One form of non-contact temperature sensors are infrared sensors.  These “convert thermal energy sent from an object in a wavelength range of 0.7 to 20 um into an electrical signal that converts the signal for display in units of temperature after compensating for any ambient temperature. “ (Mathas)  Because these temperature measurements can be made from a distance, they are often used in hazardous environments. 

References:

Hareendran, T. K. "Working With Temperature Sensors: A Guide." Electronics Zone, 2012. Web. 18 Feb. 2014. <http://electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=1476&title%20=%20Working+With+Temperature+Sensors%3A+A+Guide&id=12364&article_type=8&b_type=new>.

Mathas, Carolyn. "Temperature Sensors; the Basics." Digi-Key Corporation, 27 Oct. 2011. Web. 18 Feb. 2014. <http://www.digikey.com/en-US/articles/techzone/2011/oct/temperature-sensors-the-basics>.

"Temperature Sensor: Understanding How They Work." DeVale Industries Inc, 2013. Web. 18 Feb. 2014. <http://www.devale.com/temperature-sensor/temperature-sensing.html>.

"What Are RTD Sensors? Why Use Them? How Do They Work?" Omega Engineering Inc, n.d. Web. 18 Feb. 2014. <http://www.omega.com/Temperature/pdf/RTD_Gen_Specs_Ref.pdf>.