The researchers found that a temperature of 100.4(F (38(C) measured rectally could range anywhere from 98.6(F (37(C) to 102.6(F (39.2(C) when using an ear thermometer. Smyth says the results do not mean that infrared ear thermometers should be abandoned by pediatricians and parents, but rather that a single ear reading should not be used to determine the course of treatment.
Aug. 22, 2002 -- Those infrared ear thermometers that have become so popular with pediatricians and parents are fast and easy to use, but are they accurate? A review of the research suggests they may not be, and while temperature variations are slight, they could make a difference in how a child is treated.
True to its name, the $59.99 Kinsa Smart Ear Thermometer is just like a standard thermometer, only smarter. You can use it to quickly and accurately read in-ear temperature, which appears on the built-in display. Hook it up to your smartphone via Bluetooth, and it provides real-time medical guidance based on your temperature, age, and symptoms. Better yet, it shows nearby illnesses reported by other users, which helps you determine whether it's time to take some ibuprofen, or call the doctor.
Since compact and inexpensive methods of measuring and displaying temperature became available, electronic thermometers (often called , because they display numeric values) have been used. Many display readings to great (0.1 °C or 0.2 °F, sometimes half that), but this should not be taken as a guarantee of accuracy: specified accuracy must be checked in documentation and maintained by periodical recalibration. A typical inexpensive electronic ear thermometer for home use has a displayed resolution of 0.1 °C, but a stated accuracy within ±0.2 °C when new. The first electronic clinical thermometer, invented in 1954, used a flexible probe that contained a Carboloy thermistor.
Body temperature is routinely monitored in clinical settings with infrared ear thermometers which measure the infrared energy emitted from the patient's eardrum in a calibrated length of time. A short tube with a protective sleeve is inserted into the ear, and a shutter is opened to allow radiation from the tympanic membrane to fall on an infrared detector for a period which is typically from 0.1 to 0.3 seconds in the varieties surveyed. The device beeps when data collection is completed and a readout of temperature is produced on a liquid crystal display.
This kind of temperature from the eardrum has been found to be a clinically reliable indicator of body core temperature. The eardrum is located close to the hypothalmus, which is the body's temperature regulator. The membrane itself is thin and almost transparent in the visible, so you would presume that it reliably tracks the temperature inside the membrane so that the infrared energy it emits gives a good indication of the inside temperature.
The infrared energy falls on a thin pyroelectric crystal which develops a charge proportional to that collected energy. Discharging the crystal sends a current pulse through filters and conversion circuits which compare the signal to tabulated data on temperature and calculate a body temperature for the display.