Otto Herbert Arnold Schmitt ( English Otto Herbert Arnold Schmitt , April 6, 1913 - January 6, 1998) - American biophysicist , inventor, engineer, administrator of science, who made a significant contribution to the development of methods and technical means of biomedical research. In the 1930s, Schmitt invented a nonlinear threshold element — a Schmitt trigger — and improved the basic electronic cascades — the differential cascade , the cathode follower, and the DC modulator-demodulator type amplifier ; In the 1940s, Schmitt invented a three-dimensional display of electrocardiographic signals and a non-contact radio frequency converter of stimulating pulses for electrophysiological instruments.
Otto Herbert Arnold Schmitt | |
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Otto Herbert Arnold Schmitt | |
Date of Birth | |
Place of Birth | St louis |
Date of death | |
Place of death | Minneapolis |
A country | USA |
Scientific field | Biophysics |
Place of work | University of Washington at St. Louis |
Alma mater | University of Washington at St. Louis |
Academic title | Professor |
supervisor | [2] |
Schmitt's name is the award of the established in 2014 .
Content
Biography
Otto Schmitt was born to a prosperous Lutheran family from St. Louis [5] . Otto's older parents co-operated the family business; Older brother Francis, who was destined to become a mentor and patron of Otto, was ten years older than him [6] . In 1927, when Otto moved from elementary school to secondary school, Francis received a doctoral degree in physiology from St. Louis University in Washington [6] , and went to postdoctoral studies at Berkeley University , and then went to Europe [6] . In the fall of 1929, Francis returned to the University of Washington as a lecturer in the Department of Zoology , who had recently moved to a new building and practically did not have laboratory equipment [6] . Sixteen-year-old Schmitt became the first assistant of the elder brother in the arrangement of the laboratory, thereby gaining experience in practical instrumentation and scientific research [6] . On the recommendation of professors who noticed a capable student, Schmitt Jr. passed the exams ahead of time for the last year of the school curriculum, and in September 1930 he entered the undergraduate program at the University of Washington [2] . Having no solid plans for the future, Otto focused simultaneously on two disciplines: zoology and physics [2] .
In March 1931, when seventeen-year-old Otto was still in his first year, the journal Science published his first scientific article (“A method of temperature stabilization using vacuum tubes ”); In total, in the years 1931-1934, Otto became the author of eight articles in refereed journals (three individually and five in collaboration with his brother) [2] [7] . In March 1933, he filed a patent application, and a year later he received a US patent on the principle of using current sources on pentodes as the active load of amplifier stages , which allowed them to multiply their gain [8] . Soon, RCA began using the Schmitt idea and flatly refused to pay royalties to the inventor without a court decision [8] . The costs of litigation were prohibitively high for Schmitt, he refused to continue the dispute, and in subsequent years often did not even try to patent their own ideas and inventions [8] .
At the end of the university course, in the summer of 1934, Otto moved to doctoral studies - also at the junction of zoology and physics - and under the leadership of Francis began to develop biophysical methods for studying the nervous system [2] . For three incomplete years, he built an experimental test bench - an analog computer that imitated the generation and passage of electrical signals in the nerves; as part of this project, he invented his most important circuit solutions, first described in his doctoral dissertation of the year [2] . Her defense took place in May 1937 and was rewarded with an annual stipend from the ; in August, Schmitt married his fellow student and assistant, teacher of mathematics, Viola Münsch, and in September the newlyweds went to University College London , to the laboratory of the Nobel laureate Archibald Hill [3] . In England, Schmitt prepared for publication articles describing his development of 1934–1937, including an article on the “thermal trigger” ( Schmitt trigger ) published in January 1938, and engaged in experimental biophysical studies of the squid's nervous system (thanks to the giant size of the axons, squid served as a convenient model by the body ) [3] .
Returning to the University of Washington a few days before the start of World War II , Schmitt was content with a modest position as a junior lecturer, who did not leave time for scientific research and did not promise career growth [9] . The situation changed only in the spring of 1941, when Francis, who headed the Department of Biology at the Massachusetts Institute of Technology , tried to lure Otto to him [9] . Schmitt, who did not want to remain in the shadow of his elder brother, managed to obtain favorable conditions from the leadership of the University of Washington and switched to a full-fledged educational and scientific work, with his own budget for research and scientific guidance for graduate students [9] . However, soon, at the insistence of Vanivar Bush, Schmitt was mobilized for military applied research - first at the University, and from January 1942 - at the State Laboratory of Aviation Instruments (AIR) on Long Island [4] . During the war, Schmitt designed and tested anti-submarine magnetometers , aircraft simulators , devices for demagnetization of ships [4] . Among Schmitt's inventions of this period is the declassified stereoscopic display for radar stations after the war, which allowed the operator to view the target from an arbitrary angle [4] . This and his other inventions were patented at the insistence of the AIL leadership; Schmitt himself was still not interested in patenting and transferred all rights to his work to the federal government [4] .
In September 1946, the Schmitt couple returned to St. Louis: despite a more than two-fold drop in income, they preferred to work in the AIL privatized by that time for purely scientific work [10] . Schmitt returned to the studies of the nervous system of squid and in 1948 published a description of his next major invention, the non-contact radio-frequency converter of stimulating pulses [10] . Having occupied the post of full professor in 1949, Schmitt focused on the adaptation of military-applied developments in practical medicine [10] . The first result of this work was the “stereo vector-electrocardiograph” (SVEC), a three-dimensional ECG display based on his wartime inventions [10] .
Schmitt until the end of his life worked at the junction of medicine and electronics; in the late 1960s, it was he who introduced the concept of biomimetics , in Russian bionics [10] . Over the years, he became more and more immersed in the organizational, social side of scientific activity; not being sophisticated in university policy, at the national level, he proved to be an extremely active and effective coordinator and promoter of science [11] . Schmitt was at the forefront of many scientific and professional associations and was constantly on the move, traveling within the country and beyond its borders (only in 1960, he flew more than 80,000 miles on business trips) [11] . In 1958–1961, he headed the United States Air Force Scientific Council on Space Medicine , and in the 1970s, the Council on Medical Safety of Long-Wave Communication [11] . At the university, Schmitt refused to establish a special department of biophysics, but at the national level achieved recognition by the National Institutes of Health , which allocated budget funding for science and biophysics as a separate discipline [11] . Schmitt still did not trust the legal, patent side of scientific activity, and urged fellow scientists not to hinder the “theft of ideas” by those who are able to put them into practice: “About once a month I can allow entrepreneurs or politicians to steal my idea ... that's all just one of the ways to spread a new one. This is a “marketing ploy” that allows me to introduce a useful idea into society without contacting either financiers or officials ” [12] . In spreading knowledge, Schmitt relied primarily on personal communication and oral speech; he wrote little and published little [10] . The only book “written” by him alone (“Electronic and Computer Research on Biomedical Problems”) is the verbatim transcript of a three-day seminar held in September 1961 [10] .
In 1979, Schmitt was elected a full member of the National Academy of Engineering ; among the professional awards and prizes he received are the Morlock Prize (Morlock Prize, 1963), the Century Medal (Centennial Medal, 1987) and the Lifetime Achievement Award (1987) of the Institute of Electrical and Electronics Engineers [13] . In 1983, according to the university statute, the seventy-year-old Schmitt moved to the emeritus position [10] . Disappointed by the fact that many colleagues perceived him not as an encyclopedic scientist, but as a technician and instrument maker, Schmitt focused on social activities [13] . He condemned the unhealthy, from his point of view, state of the national health policy, and insisted on its reform from firm scientific positions [13] . Schmitt's rational, scientific approach to administering medicine got along with an irrational belief in the relationship between body and consciousness, which over the years led him to recognize the possibility of paranormal phenomena [13] (according to Schmitt, he believed in the supernatural at the age of seven, having experienced the vision of a deceased grandmother [6] ).
Schmitt continued to be active until his wife’s death in 1994; left alone, he began to fade away quickly [13] . Three years later, Schmitt, who suffered from Alzheimer's disease , died in a nursing home in Minneapolis [13] .
Scientific Heritage
The largest, by the number of publications, Schmitt's areas of interest were practical electrocardiography (93 works) and interdisciplinary subjects of biomedical or clinical instrument making [14] . Several papers from the 1960s focus on chronobiology issues; in 1970, Schmitt co-authored the American space chronobiological research program (partially implemented) [14] . 21 Schmitt's work is devoted to the topics of experimental electrophysiology : the current-voltage characteristics of cell membranes, changes in the resistance and capacity of membranes when excited by an external stimulus, and the propagation of electrical stimuli [15] . The works of this circle, judging by the importance of topics, the level of journals and the level of co-authors (including the Nobel laureates Archibald Hill and Bernard Katz ) - Schmitt's highest achievement [15] . However, he was destined to enter the textbooks not as biophysics, but as the developer of the Schmitt trigger [16] .
Electronic Contribution
Of the approximately three hundred published articles and sixty Schmitt patents, less than 3% are directly devoted to electronics, more precisely, to electronics of biomedical devices [17] . But it was precisely these works that had the greatest practical significance, and brought Schmitt recognition [17] .
Schmitt trigger - a nonlinear scheme with two switching thresholds - was developed by Schmitt alone in the years 1934-1937, as part of an experimental test bench that simulated the passage of electrical signals in nerve cells [17] . Schmitt knew that when the cell membrane is excited by an electric signal, its active and capacitive resistances change abruptly, and that the thresholds for the transition from the “low” state to the “high” state differ [17] . To simulate the electrical properties of the membrane, he applied a circuit on three triodes (an input amplifier and a differential pair — the Schmitt trigger itself), through a relay that physically connected a capacitor to the signal path [17] . Schmitt presented a detailed but not clear description of the work of the scheme in the doctoral dissertation of 1937, an abbreviated description in a journal article of 1938 [17] . How the Schmitt scheme spread beyond the limits of biomedical instrumentation is not known reliably [15] , but it (or rather, its principle embodied in other circuit solutions) became the basic element of analog and digital systems engineering, and the name of Schmitt entered the textbooks along with the names of Kirchhoff and [18] .
Another Schmitt publication in 1937 described a differential cascade to amplify weak biological signals [15] . This topic, in contrast to the Schmitt trigger, attracted many researchers working in parallel [19] [15] . In 1936–1937, Alan Blumlein and Franklin Offner proposed their versions of the differential cascade — however, their schemes were designed to amplify high-frequency signals and could not serve as DC amplifiers [19] . The Schmitt scheme of 1937, in turn, did not satisfactorily suppress common mode interference, but it could amplify the direct current and was built not on triodes, but on pentodes [19] . In 1938, Schmitt published a new design of the differential cascade, optimized for operation in an asymmetric inverting mode and capable of amplifying direct current [20] [21] . Finally, in 1941, Schmitt published a detailed analysis of the operation of the differential cascade, including the use of local feedback through cathodic resistance, and an alternative configuration with two current sources and one feedback resistance [22] .
Schmitt's third major invention, the non-contact radio frequency converter of stimulating pulses for electrophysiological studies, as well as the Schmitt trigger, goes back to his experiments of the 1930s [15] . Experimental biophysicists are faced with the problem of galvanic and capacitive coupling between the source of exciting pulses and the receiver (sensor) of the body's response; the disturbance that came through these connections to the input of a highly sensitive amplifier generated a long-term overload [23] . Schmitt proposed to break the connection in the exciting path, separating the source of the pulse from the exciting electrode by an air layer. The output pulse of the source arrived at a simple single-tube high-frequency generator, and the generated signal was demodulated by a passive detector on a germanium diode [24] . In contrast to isolation transformers, the Schmitt contactless transducer distorted slightly the pulse shape, and therefore became an indispensable part of electrophysiological instruments [15] .
Sources
- ↑ 1 2 SNAC - 2010.
- ↑ 1 2 3 4 5 6 Harkness, 2002 , Washington University.
- ↑ 1 2 3 Harkness, 2002 , Postdoctoral years.
- ↑ 1 2 3 4 5 Harkness, 2002 , War Work.
- ↑ Harkness, 2002 , Family.
- ↑ 1 2 3 4 5 6 Harkness, 2002 , Early Years.
- ↑ Harkness, 2002 , Note 21 (full list).
- ↑ 1 2 3 Schwan and Geselowitz 2002 , p. 203.
- ↑ 1 2 3 Harkness, 2002 , To Minnesota.
- ↑ 1 2 3 4 5 6 7 8 Harkness, 2002 , Back to Minnesota.
- ↑ 1 2 3 4 Harkness, 2002 , Beyond Campus Borders.
- ↑ Harkness, 2002 , Sidebar 4: Idea Stealing Program.
- ↑ 1 2 3 4 5 6 Harkness, 2002 , Senior Statesman of Science and Engineering.
- ↑ 1 2 Valentinuzzi, 2004 , p. 44.
- ↑ 1 2 3 4 5 6 7 Valentinuzzi, 2004 , p. 43.
- ↑ Abramashvili N.I., Ermolov P.P. We say Schmitt - we mean a trigger (on the 100th anniversary of the birth of Otto Herbert Schmitt) // The 9th International Youth Scientific and Technical Conference "Modern problems of radio engineering and telecommunications RT-2013 , April 22—26, 2013, Sevastopol. - 2013.
- ↑ 1 2 3 4 5 6 Valentinuzzi, 2004 , p. 42
- ↑ Valentinuzzi, 2004 , p. 45.
- ↑ 1 2 3 Jung, 2005 , p. 773
- ↑ Jung, 2005 , p. 774.
- ↑ Jung, 2005 , p. 785
- ↑ Jung, 2005 , pp. 774-775.
- ↑ Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle: Principles and Practice. - Oxford University Press. - P. 94. - ISBN 9780198029717 .
- ↑ Schmitt O. A Radio Frequency Coupled Tissue Stimulator // Science. - 1948. - № April 23. - P. 432. - DOI : 10.1126 / science.107.2782.432 .
Literature
- Harkness J. A Lifetime of Connections. Otto Herbert Schmitt, 1913–1998 // Physics in Perspective. - 2002. - № 4. - p. 456-490.
- . Op Amp Applications Handbook . - Analog Devices / Elsevier , 2005. - ISBN 0916550265 . - ISBN 0750678445 .
- Schwan H., Geselowitz D. Otto H. Schmidt // Memorial Tributes. - 2002. - Vol. ten.
- Valentinuzzi M. Otto Herbert Arnold Schmitt (1913–1998), a Pioneer // IEEE Engineering in Medicine and Biology Magazine. - 2004. - № December. - P. 42—46. - DOI : 10.1109 / MEMB.2004.1378632 .