Ear thermometer which measure the infrared energy emitted from the patient’s eardrum in a calibrated length of time.
The ear thermometer turns out that the eardrum is an extremely accurate point to measure body temperature from because it is recessed inside the head (just like your tongue). The problem with the eardrum is that it is so fragile. You don’t want to be touching the eardrum with a thermometer.
This makes the detection of the eardrum’s temperature a remote sensing problem. Granted, it is not very remote — just a centimeter or so. But it’s remote nonetheless! It turns out that the remote sensing of an object’s temperature can be done using its infrared radiation. This technique is a very good way to detect the temperature of a person’s eardrum.
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.
The ear canal of babies and small children is smaller than the probe of the thermometer so it can not reach the sensitive parts of the ear. Pull the ear as explained in the instruction manual and gently insert the probe into the ear.
Moreover Infrared ear thermometers measure the heat generated by the eardrum and surrounding tissue. They give an accurate temperature on an easy-to-read digital display in just a few seconds.