1. Introduction

Otto Herbert Schmitt (April 6, 1913 – January 6, 1998) was an United States inventor, engineer, and biophysicist known for his scientific contributions to biophysics and for establishing the field of biomedical engineering. Schmitt also coined the term biomimetics and invented the Schmitt trigger, the cathode follower, the differential amplifier, and the chopper-stabilized amplifier.^[1]

He was awarded the John Price Wetherill Medal in 1972.

2. Childhood

Otto Herbert Schmitt was born on April 6, 1913 in St. Louis, Missouri, making him the third child of Otto Franz Johannes Schmitt and Clara Senninger Schmitt. At the time of Otto Jr.’s birth, Otto Sr. and Clara had an eleven-year-old daughter and a ten-year-old boy, Viola and Francis. The family lived in a large two story building that served as both a residence and as a business. Otto Sr. and Clara had formed Senninger & Schmitt Wallpaper & Painting Company with Clara’s father. After his death, they continued on with the business. Their business lives permeated their personal lives. In his memoirs, Otto’s older brother Francis recalls how, “Operating hours for the first-floor decorating business ran from 6:00 A.M. to 9:00 P.M.” [Schmitt] According to Harkness, “The Schmitt building…was full of energy and hard work during Otto’s youth.” [Harkness]

3. Education

Otto Schmitt began his educational journey in the fall of 1918 when he started kindergarten at Garfield Elementary School located only five blocks from his family’s house. Being quite a gifted child, he was able to complete elementary school a full semester ahead of schedule. This allowed him to begin attending Roosevelt High School in January 1927. It was during these high school years that Schmitt truly began to exhibit an extraordinary talent for invention, particularly with regards to novel circuitry. This was possible due to the position of his older brother Francis Otto Schmitt, who was a newly appointed assistant professor of zoology at the nearby Washington University. Recent construction at the university meant that Francis would have plenty of room for his laboratory work, but he was “almost completely without laboratory equipment.” In order to fill this void, Francis sought out the help of his younger brother Otto who was “nothing short of a prodigy with electrical instruments.” [Harkness] According to Francis, Otto was able to build “highly original and very effective instrumentation.” [Schmitt] This is a testament to amazing talent possessed by Otto Schmitt, even during his formative years.

Otto’s laboratory work caught the attention of several faculty members at Washington University. According to Francis, one such professor- the head of the physics department- was amazed by Otto’s abilities and “couldn’t understand why so brilliant a student [as Otto] should still be in high school.” [Harkness] This led to Otto’s early admission to the university. The university only required that he take a series of entrance exams prior to his enrollment. Otto had the support of “an illustrious assemblage of tutors from the faculty at Washington University”, most likely due to the laboratory demonstrations of his scholastic potential. Otto, of course, passed these entrance exams in marvelous fashion. So it came to pass that Otto began Washington University on September 18, 1930, short of earning his high school diploma.

While Otto previously had shown a tremendous amount of potential, his undergraduate work only served to reinforce the conclusion that he was destined to have a remarkable career. According to Harkness, Otto “…was positioned for multi-disciplinary study from his first day as a college student”, displaying a “clear affinity for physics, electronics, and mathematics.” [Harkness] He was also a research dynamo; in his time as an undergraduate, Otto was able to produce eight publications. The first publication, “A Vacuum Tube Method of Temperature Control,” was published in Science during his second semester of his freshman year and 24 days before his eighteenth birthday. Otto earned his B. A. degree in Zoology and Physics from Washington University in June 1934. Upon graduation from his undergraduate program, he smoothly transitioned into his graduate work at the same institution. Once again, his older brother had a pronounced influence on his research and education. Francis, a physiologist, was studying “the molecular organization of cells and tissues with particular reference to nerve fibers.” [Schmitt] Otto adopted this topic for his graduate research. He utilized his prowess for electrical engineering to attempt to create artificial constructs that were able to mimic the formation and propagation of impulses along nerve fibers. This unique pursuit inadvertently caused Otto to create novel forms of electrical circuitry that are still used today. Harkness uses the example of the differential amplifier, which is a basic component in instrumentation used to record and measure biological potentials. [Harkness] Otto earned his Ph.D. with majors in Physics and Zoology and with a minor in mathematics.

4. Career

During the final semester of his graduate degree, Otto applied for a National Research Council Fellowship. This fellowship was able to fund a year of postdoctoral study at University College in London. Otto began his postdoctoral work in September of his graduation year. In the time between graduation and his new research position, Otto was able to spend several weeks in Cape Cod working at the Woods Hole marine Biological Laboratory. According to Harkness, “the brothers were eager to go there together to use Otto’s new electrical apparatus on the unusually large nerve axons of squid, which were abundantly available at the seaside research center.” [Harkness] This would be the last time that the brothers were able to collaborate on a research project together.

After his time at Woods Hole, Otto and his wife Viola moved to London to continue his research with nerve impulses under Professor A.V. Hill – Nobel Prize winner and founder of biophysics. It was during this time that Schmitt published a report on a novel bit of circuitry that would win him a lasting degree of fame. Otto originally named it the “thermionic trigger.” As a testament to the profound impact that Otto and his device had on electronics, it is still widely referred to as the “Schmitt trigger.” Schmitt spent two years in his postdoctoral position, even though his fellowship funding on lasted for one year; Professor Hill, recognizing Otto’s talents, sought out additional sources of funding to keep Otto in London for as long as he could. Schmitt’s next opportunity would bring him back the U.S.

Once again, Otto’s older brother Francis would play a vital role in Otto’s career. While Otto was working at his fellowship in England, Francis tried to use his connections at Washington University to get his brother a faculty position. Unfortunately, it was to no avail; however, Francis was able to convince faculty members at the nearby University of Minnesota to consider Otto for their new biophysics program. Otto received an official invitation to the University of Minnesota in February 1939 with a dual appointment to the departments of Zoology and Physics. Otto and his wife narrowly missed the outbreak of World War II with their departure from England in August of the same year. Otto turned out to be less than satisfied with his new position, which was heavily focused on instruction rather than research. After revealing his dissatisfaction with his older brother, Francis would again play an important role in his younger brother’s advancement – this would be the final time that Francis would intervene for his younger brother. At the time, Francis was being offered a new position at MIT. As a stipulation, Francis wanted his brother Otto to be offered a tenure-track position as well. MIT obliged, and Otto was offered such a position. When word reached the University of Minnesota, they were quick to give Otto incentives to stay, including “…tenure as an associate professor (skipping the rank of assistant professor), a 28% pay raise, tripled research funding, and guaranteed support for two graduate students.” [Harkness] Otto decided to remain at the University of Minnesota.

5. Wartime Work

Otto only had a short while to enjoy his promotion. Shortly after making his decision to remain at the University of Minnesota, Schmitt received a letter notifying him of his appointment as an official investigator for the newly formed National Defense Research Committee (NDRC) – later renamed and refunded as the Office of Scientific Research and Development (OSRD). The NDRC was a federal organization whose purpose was to provide funding for top secret scientific research that had potential military applications. Schmitt had to place his biophysics research on the backburner in order to pursue such applications. His work initially let him stay in Minnesota while he investigated “solid state electronic controls and measurements via the Uranium Semiconductor Thermistor strategy.” [Harkness] In January 1942, Otto went on a leave of absence to join another research group in Rhode Island. Another professor from the University of Minnesota John Tate was appointed to be the head of the antisubmarine warfare research division for the OSRD. Since the U.S. officially became involved in World War II, the number of American ships that were falling victim to German U-boats skyrocketed. This resulted in a serious need for a way to locate submerged U-boats. Otto’s colleague was familiar with his talents, and recruited him for the project. This was certainly a smart move on his colleague’s behalf.

Otto had an immediate impact on the progress of the project. Harkness quoted John Tate as saying, ”Within one month, we were able to get into the air working MAD prototype detector systems…”[Harkness] The Magnetic Anomaly Detector or MAD System functioned by detecting small abnormalities in the earth’s magnetic field – such as those caused by large, steel submarines. [Patterson] The drastically reduced effectiveness of German U-boats during World War II can be largely attributed to “the effectiveness of MAD systems mounted in many American bombers.” This invention is particularly impressive due to the fact that Schmitt had “…previously shown no particular interest in terrestrial magnetism.” [Harkness] After developing the MAD system, Otto and some of his colleagues were relocated to Mineola, Long Island, where they formed the Airborne Instruments Laboratory (AIL). Otto was named the Supervising Engineering for the Special Devices Division of the AIL. In addition to refining the MAD system, Otto worked on quite the laundry list of projects. Harkness discusses Otto’s work during the war:

“A full accounting of Schmitt’s work during this period is difficult because of the veil of secrecy that shrouded his efforts, but a few examples serve to capture the broad scope of his engineering labors: he developed “degaussing” techniques to minimize the magnetic signature of a ship, which reduced detection by the enemy and diminished the threat of magnetically activated mines; he designed a realistic flight simulator that was eventually used to train hundreds of naval aviators; he devised radio antennas for high-speed aircraft that functioned without creating excessive aerodynamic drag; and he worked on techniques to jam enemy radio signals.” [Harkness]

Schmitt also developed a device that was capable of interpreting electronic data, and forming three-dimensional visual representations using cathode-ray oscilloscopes. All of this work was done while Schmitt worked with AIL. While much of his work resulted in patentable devices, Otto showed very little interest in patenting his work; he gave the patent rights of the devices he developed to the United States. This is a tribute to Otto’s commitment to scientific inquiry. Harkness quotes Schmitt, “I’ve never wanted to be a businessman. I didn’t want to make money; I always wanted to advance ideas.” [Harkness] Following the end of World War II, Schmitt remained with AIL until the end of 1946. Even though the war was over, cold war tensions still left a need for the development of military technology.

6. Postwar

Otto and his wife were finally able to return to the University of Minnesota in March 1947, and he would remain there for the remainder of his career, reaching the status of both full professor and professor emeritus. Schmitt’s return to academia reveals his deep devotion to research. Harkness tells that upon leaving AIL, Otto and his wife were earning $6,600 and $3,900 annually, respectively. Upon arriving back to Minnesota, Otto resumed his former salary of $4,300 and his wife worked as his unpaid research assistant. Otto commented on his reasons for returning:

“There is…on factor…which caused me to return here from an interesting and permanent engineering position at a sacrifice of some fifty percent in income. This is the persistent belief that fundamental biological phenomena can be understood in relatively simple physical and chemical terms once the painstaking effort has been made to study them adequately by quantitative biophysical methods.” [Harkness]

After the war, Otto continued his investigation into nerve impulse formation and propagation. He also looked for new applications for his war time inventions, particularly within the biomedical field. One such example is the applications of his three-dimensional oscilloscope display to electrocardiographs. Typical ECGs measured the electrical currents generated from heart contractions, and displayed them as a two-dimensional graph. Schmitt’s innovation allowed for the depiction of a three-dimensional representation of the electric potential of the heart. This depiction could even be manipulated in space to allow a more thorough analysis of the heart’s activity. Otto’s natural tendency for innovation would result in more than just new inventions; his efforts would directly result in the formation of biophysics and biomedical engineering as independent fields, rather than just the result of interdisciplinary study.

After Otto returned from his wartime work, he assembled a group of faculty members to serve as an informal biophysics faculty within the university’s graduate school. The point of doing so was to allow students to achieve a multidisciplinary degree in Biophysical study. This could be considered to be the beginning of Otto’s efforts of “fostering the creation of biomedical engineering.” [Geddes] Schmitt played a similar role on a much larger scale when he helped to found a large number of professional societies that related to this area of study, including the Biomedical Engineering Society, the Biophysical Society, the Association for the Advancement of Medical Instrumentation, the International Federation of Medical and Biological Engineering, and the International Union of Pure and Applied Biophysics. [Harkness] He is also responsible for naming one of the largest areas of study within biomedical engineering, biomimetics. According to Merriam-Webster, biomimetics is" the study of the formation, structure, or function of biologically produced substances and materials (as enzymes or silk) and biological mechanisms and processes (as protein synthesis or photosynthesis) especially for the purpose of synthesizing similar products by artificial mechanisms which mimic natural ones.” [“biomimetic”] The field of biomedical engineering still utilizes this approach for many engineering and research problems. Harkness postulates that perhaps his greatest contribution was “the concept of biomimetic approach to science and engineering – and idea rather than a gadget.” [Harkness] Otto’s efforts were without a doubt instrumental in the development of biomedical engineering as an independent discipline.