Glenn Allan Millikan

Who is Glenn Allan Millikan?

Glenn Allan Millikan, American physiologist, invented the first practical, portable pulse oximeter in 1940–1942. The Millikan oximeter "is generally acknowledged as the beginning of oximetry in physiology and clinical medicine." The word oximeter was introduced by Millikan.

Millikan, son of physicist Robert Andrews Millikan, studied at the Harvard University and the University of Cambridge. During his doctorate studies in Cambridge he built a dual-wavelength colorimeter for blood oxygen level measurements. The Fellowship of Trinity College awarded Millikan a four-year scholarship for this work. The award allowed Millikan to continue research of myoglobin-oxygen reactions in Cambridge until 1937. After the outbreak of World War II Millikan was stranded in the United States. Unable to return to Cambridge, he accepted an unpaid laboratory appointment at the University of Pennsylvania and concentrated on bioluminescence research. Later, he obtained teaching assignments at the University of Pennsylvania and at Harvard.

In the spring of 1940 Lord Adrian, Millikan's former advisor at Cambridge, asked Millikan to help the Royal Air Force with the development of a reliable breathing apparatus. According to Adrian, pilots regularly lost consciousness during high-altitude dogfights, and needed "an oxygen delivery system with a demand valve responsive to altitude and activity". Millikan built the device for monitoring the state of pilot's organism in flight in 1940 and presented it to the American Physiological Society in 1941. The oximeter was integrated into the pilot's altitude mask and had to be clasped to the earlobe. The oxygen supply system, developed by Bendix Corporation, relied on the oximeter as the primary sensor in its feedback loop.