Ear thermometer: A device designed to measure body temperature through the ear canal. This innovative tool was developed in 1964 by Dr. Theodor H. Benzinger. Between 1947 and 1970, Dr. Benzinger was associated with the Naval Medical Research Institute in Bethesda, Maryland, where he focused on the study of temperature regulation and contributed to the establishment of biothermodynamics. He invented the ear thermometer while seeking a method to measure a person's temperature as accurately as possible in relation to the brain's temperature center. Due to the shared blood vessels between the hypothalamus and the ear canal, Benzinger opted to use the ear canal for temperature readings. Before this invention, brain temperature could only be measured using electrodes attached to the hypothalamus. Traditional methods involved using a thermometer orally, rectally, or under the arm. However, the ear temperature offers the closest approximation to brain temperature, making it the most accurate body temperature reading when taken correctly. Born in Stuttgart, Germany, in 1905, Theodor Hannes Benzinger passed away in Bethesda in 1999 at 94. He also invented a device for measuring heat loss and made significant contributions to medicine and science, including the Planck-Benzinger modification of the second law of thermodynamics.