Thermometer, ear: A thermometer that registers body temperature via the ear canal.
The ear thermometer was invented in 1964 by Dr. Theodor H. Benzinger. Dr. Benzinger worked from 1947 to 1970 at the Naval Medical Research Institute in Bethesda, Maryland where he studied temperature regulation and helped create the field of biothermodynamics. He created the ear thermometer while looking for a way to take a person's temperature and get a reading as close as possible to the temperature center of the brain temperature, the hypothalamus. Because the hypothalamus and the eardrum share blood vessels, Benzinger decided to use the ear canal to take a reading. (Until that time, attaching electrodes to the hypothalamus was the only way to get a brain temperature reading.) Prior to Benzinger's invention of the ear thermometer, temperature readings were typically obtained by placing a thermometer in the mouth, rectum or under the arm. The ear temperature most closely correlates with the brain temperature and is therefore, if properly taken, the best body temperature reading. Theodor Hannes Benzinger was born in Stuttgart, Germany, in 1905 and died in Bethesda in 1999 at the age of 94. He was also the inventor of a device to measure calorie loss and made many other important contributions to medicine and science including the Planck-Benzinger modification of the second law of thermodynamics.