How Does a Digital Ear Thermometer Work?
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Why Ear Thermometers Exist
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Traditional glass thermometers seemed to be working just fine before the digital ear thermometer was introduced to the market, so why do we need it in the first place? The short and simple answer is that digital ear thermometers provide faster and more accurate readings than almost all other designs. The reason why they produce faster readings is because of the sophisticated infrared sensors that these styles of thermometers rely on to collect their data. Perhaps more importantly, they also produce more accurate results because the eardrum is a more stable and accurate indicator of body temperature than the underside of the tongue or the rectum--the other two most common sites for measuring body temperature. The eardrum is such a great source for this data because it is situated deeper inside the head and is more closely surrounded by protective tissue.
What Ear Thermometers Measure
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Specifically, digital ear thermometers measure the infrared radiation coming from an eardrum. Ordinary glass bulb thermometers don't measure temperature as much as they react to it. Heat is transferred from the mouth to a metal conductor, which focuses the heat into a sensitive liquid that rises or falls as the temperature changes. Infrared radiation, in layman's terms, is heat, something we can all feel and maybe even approximate through our sense of touch. But the only way to really measure it accurately is to use advanced technological tools like those inside your digital ear thermometer.
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How Ear Thermometers Measure and Display Temperature
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The real powerhouse inside an infrared radiation thermometer is an electronic node called a thermopile. When thermopiles are exposed to changes in temperature, their expelled voltage increases or decreases proportionally to that temperature change. This correlation is accurate to within 1/10 of 1 degree F.
There is a thermopile nested just inside the tip of a digital ear thermometer's sensor. The thermopile is connected to a small, simple computer which translates the voltage output of the thermopile into a temperature in degrees Fahrenheit or Celsius, depending on the measurement standards in the market where the thermometer is sold. The computer then displays this temperature on a small digital LCD screen on the outside of the thermometer.
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- Photo Credit Photo by Sanja Gjenero
