Glenn Allan Millikan (May 23, 1906 – May 25, 1947) was an American

physiologist Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical a ...

, inventor and mountaineer. Millikan invented the first practical, portable

oximeter Pulse oximetry is a Invasiveness of surgical procedures, noninvasive method for monitoring a person's oxygen saturation (medicine), oxygen saturation. Oxygen saturation, Peripheral oxygen saturation (SpO2) readings are typically within 2% accurac ...

in 1940–1942.Severinghaus and Astrup, p. 276. The ''Millikan oximeter'' "is generally acknowledged as the beginning of

oximetry Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation. Peripheral oxygen saturation (SpO2) readings are typically within 2% accuracy (within 4% accuracy in 95% of cases) of the more accurate (and invasive) reading o ...

physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

and clinical medicine."Zijstra et al., p. 244. The word ''oximeter'' was introduced by Millikan.

Early life

Millikan, son of physicist

Robert Andrews Millikan Robert Andrews Millikan (March 22, 1868 – December 19, 1953) was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric e ...

, studied at the

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of higher le ...

and the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

. 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 Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compared to hemoglobin, myoglobi ...

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

reactions in Cambridge until 1937.Severinghaus and Astrup, p. 277. After the outbreak of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

Millikan was stranded in the United States. Unable to return to Cambridge, he accepted an unpaid laboratory appointment at the

University of Pennsylvania The University of Pennsylvania (also known as Penn or UPenn) is a private research university in Philadelphia. It is the fourth-oldest institution of higher education in the United States and is ranked among the highest-regarded universitie ...

and concentrated on

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

research. Later, he obtained teaching assignments at the University of Pennsylvania and at Harvard.

Career

In early 1940, Lord Adrian, Millikan's former advisor at Cambridge, asked Millikan to help the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) and ...

with the development of a reliable breathing apparatus. According to Adrian, pilots regularly lost consciousness during high-altitude

dogfight A dogfight, or dog fight, is an aerial battle between fighter aircraft conducted at close range. Dogfighting first occurred in Mexico in 1913, shortly after the invention of the airplane. Until at least 1992, it was a component in every majo ...

s, 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 (the ''Millikan oximeter'') in 1940 and presented it to the

American Physiological Society The American Physiological Society is a non-profit professional society for physiologists. It has nearly 10,000 members, most of whom hold doctoral degrees in medicine, physiology or other health professions. Its mission is to support research and ...

in 1941. The oximeter was integrated into the pilot's altitude mask and had to be clasped to the

earlobe The human earlobe (''lobulus auriculae''), the lower portion of the outer ear, is composed of tough areolar and adipose connective tissues, lacking the firmness and elasticity of the rest of the auricle (the external structure of the ear). In ...

. The oxygen supply system, developed by

Bendix Corporation Bendix Corporation is an American manufacturing and engineering company which, during various times in its existence, made automotive brake shoes and systems, vacuum tubes, aircraft brakes, aeronautical hydraulics and electric power systems, av ...

, relied on the oximeter as the primary sensor in its

feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled ...

loop. The earpiece of Millikan's oximeter (an open photocell-lamp assembly manufactured commercially by Coleman Electric) contained an

incandescent light bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxida ...

, a set of red and green filters, and a

selenium Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, ...

barrier level

photocell Photodetectors, also called photosensors, are sensors of light or other electromagnetic radiation. There is a wide variety of photodetectors which may be classified by mechanism of detection, such as photoelectric or photochemical effects, or by ...

.Zijstra, p. 245. According to Millikan's early statements, light absorbance of green light was independent of blood oxygen level, absorbance of red light depended on it.Severinghaus and Astrup, p. 278. However, in 1942 it was found that the flesh of human ear absorbs almost all green light. "Green light" sensed by Millikan's photocell was actually invisible

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

light emitted by the lamp and unaffected by green filter. Millikan's wartime work outlined three basic problems of oximetry: absence of suitable

theory A theory is a rational type of abstract thinking about a phenomenon, or the results of such thinking. The process of contemplative and rational thinking is often associated with such processes as observational study or research. Theories may be s ...

, inability to differentiate between blood and other tissues in the path of light, and inability to differentiate between arterial, venous and capillary blood, of which only arterial blood was relevant to oxygen measurement.Zijstra et al., p. 246. Millikan's own solutions to these challenges were poor. The third problem was solved by "fully flushing" the earlobe by heating it with the light bulb. The second one was not an issue in RAF breathing sets because they supplied pure oxygen. Calibration of the device for a patient breathing pure oxygen was quite straightforward. In 1946, Millikan became head of the Department of

Physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

Vanderbilt University Vanderbilt University (informally Vandy or VU) is a private research university in Nashville, Tennessee. Founded in 1873, it was named in honor of shipping and rail magnate Cornelius Vanderbilt, who provided the school its initial $1-million ...

School of Medicine A medical school is a tertiary educational institution, or part of such an institution, that teaches medicine, and awards a professional degree for physicians. Such medical degrees include the Bachelor of Medicine, Bachelor of Surgery (MBBS, MB ...

Death

In 1938, Millikan married Frances Clare Leigh-Mallory, daughter of

George Mallory George Herbert Leigh Mallory (18 June 1886 – 8 or 9 June 1924) was an English mountaineer who took part in the first three British expeditions to Mount Everest in the early 1920s. Born in Cheshire, Mallory became a student at Winchester ...

, the mountaineer who died while climbing

Mount Everest Mount Everest (; Tibetan: ''Chomolungma'' ; ) is Earth's highest mountain above sea level, located in the Mahalangur Himal sub-range of the Himalayas. The China–Nepal border runs across its summit point. Its elevation (snow heig ...

. In 1947 Millikan himself was killed by a falling rock while climbing "Buzzard's Roost" near

Fall Creek Falls State Park Fall Creek Falls State Resort Park is a state park in Van Buren and Bledsoe counties, in the U.S. state of Tennessee. The over park is centered on the upper Cane Creek Gorge, an area known for its unique geological formations and scenic waterf ...

, Tennessee. After his death his parents sponsored a series of ''Glenn Millikan lectures'' at Vanderbilt.

References

Sources

* Severinghaus, John W.; Astrup, Poul B. (1986).
History of blood gas analysis. VI. Oximetry
'. Journal of Clinical Monitoring and Computing. Volume 2, Number 4, pp. 270–288. . * Zijlstra, Willem G. et al. (2000).
Visible and near infrared absorption spectra of human and animal haemoglobin: determination and application
'. VSP. .

External links

* {{DEFAULTSORT:Millikan, Glenn Allan 1906 births 1947 deaths People from Chicago American physiologists Harvard University alumni Alumni of Trinity College, Cambridge Vanderbilt University faculty Mountaineering deaths Accidental deaths in Tennessee 20th-century American inventors