Thermometers: A Hot Take

With the end of summer, eyes across the country are turning to temperatures – for both the outdoors and ourselves. Rising temperatures (whether outside or in) can be a red flag for heat stroke, thermal damage to pets’ paws, fever, and more. To figure out if we’re nearing dangerous thresholds, we turn to a piece of technology centuries’ old that has, thankfully, had a few updates along the way.


Thermometers were first developed in the late 16th and early 17th centuries by inventors like Galeleo Galilei. Initially, thermometers were merely able to indicate a rise or fall in temperature based on the movement of liquids like alcohol or mercury inside of them as the liquids expanded and rose with increasing temperature or cooled and fell with a temperature decrease. Later inventors like Santorio, Fahrenheit, and Celsius developed ways to quantify and correlate movements in the liquid with precise degree scales correlated with freezing and boiling points of water.


“Today’s thermometers rely on more digital means to determine and convey temperature. The most common digital sensor used right now is a “thermistor,” which correlates changes in temperature with changes in the electrical resistance. Thermistors are present in oral and rectal thermometers.  


In contrast, thermometers placed in the ear use a device called a “thermopile” to detect and quantify the body’s infrared radiation from a distance. Infrared radiation increases with rising heat; devices called “thermocouples” on a silicon chip at the end of the thermopile pick up the IR and correlate it with the temperature that would lead to that much IR production.

Whether it’s being displayed on your family’s thermometer or your home’s thermostat, keep an eye on the temperatures around you, and take precautions to keep yourself and your temperature in a healthy range!

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By Dr. Miceala Shocklee

Created by Dynamic Graphic