- Electronic thermometers work in a different way than the traditional mercury and glass thermometers. Electronic thermometers have the same probe (the contact point for taking temperature) as traditional thermometers, but it is not used to expand mercury.
- Instead, electronic thermometers use a thermoresistor to measure resistance as the temperature changes. Once the probe is placed into a person's mouth, it heats up to the same temperature of the mouth. The thermoresistor inside the thermometer then expands, increasing its resistance. Then a microcontroller (a small computer processor used to process one specific task) measures the resistance and converts it into a temperature.
- Once the microcontroller has processed the correct temperature, it creates a reading. But for the user to be able to gain any useful information from the electronic thermometer, it must send the information to an LCD screen. The microcontroller will apply a charge to the appropriate liquid crystal molecules in the screen, which causes them to untwist. When they untwist, light can no longer pass through them, and as a result, they appear darker than the surrounding area around them. The result of all the appropriate liquid-crystal molecules being charged is an accurate temperature reading in a numeric form.
