How Does A Digital Thermometer Work?
by David Naghi on Dec 24, 2021
Whether you think your child has a fever or you’re wondering if your baby’s food is at the right temperature, a digital thermometer is the right device for the answers you need. But how does a digital thermometer work?
It may be simpler than you think.
While every company has its proprietary secrets, most digital thermometers work on the same principles – and all use similar technology. The difference is in the way the devices are designed and constructed and the quality of the components used.
How Digital Thermometers Work
Digital thermometers contain a small computing mechanism and a resistor. A change in temperature causes the sensor to notice a change in resistance. The computer converts the difference in resistance into a difference in temperature and offers a digital readout in degrees. The thermoreceptor sensor is called a thermistor.
High-quality digital thermometers like the MOBI DualScan Prime Thermometer are available for a relatively low cost because good thermistors are available at a low cost. When a quality sensor is combined with other quality parts and a well-designed housing, the result is a useful and accurate instrument that can serve the whole family for years.
Thermistors are used in a variety of electronic devices where changes in temperature must be taken into account. They can take the place of circuit breakers or fuses to shut down temperature-sensitive electronics to prevent overheating damage. They can also be used in heating and air conditioning thermostats. In that case, they replace bimetallic strips or mercury sensors, which are more likely to fail.
Other Kinds Of Thermometers
Digital thermometers and the thermistors on which they’re based are safer, faster and easier to read than old-fashioned mercury thermometers. Mercury inside a glass tube is perhaps the simplest kind of thermometer. As the mercury gets hotter, it expands by an amount that relates directly to the temperature increase.
While not often used in medical thermometers, there are also dial thermometers that work by showing how much a metal coil expands with heat. The higher the temperature, the more the internal bimetallic strips expand and the higher the hands on the dial read.
Electronic thermometers and the thermistors inside them have an important advantage over mercury and mechanical thermometers. Thermistors react to temperature changes almost immediately. Mercury and metallic strips take some time to react, meaning that getting an accurate reading takes from a minute to several minutes.
Plus, the computer inside an electronic thermometer can display results in Fahrenheit, Celsius or any other units for which it’s programmed. The only downside is that the results can vary from moment to moment while mechanical and mercury thermometers are slow to move and therefore don’t have time to respond to minor fluctuations.
Quicker Results Mean Quicker Response
Today’s digital thermometers are the result of years of evolution in measuring temperatures. It’s now possible to quickly and accurately assess whether your child – or yourself – has a fever and needs medical attention. And you can check bathwater or a baby’s bottle for the correct temperature in just a second or two.
When you understand how digital thermometers work, you can understand just how useful having an accurate, well-made one in your home is. When you need answers about fever and whether it’s getting better or getting worse, there’s no time to waste.