From 1958 to 1961, he was the chairman of the Bio-Astronautics Council, which studied how to support human life in space.

He is best known for development of the Schmitt thermionic trigger in 1938, which allows a constant electronic signal to be changed to an on/off state. It is in use today in millions of electronic applications, including computers. He developed electronic circuitry now common in everything from industrial controls to amplifiers and audio-video systems. Many of his inventions are fundamental components in any electronics shop – emitter followers (amplifiers of weak currents); differential amplifiers, devices that measure the difference between two signals and amplify the difference; and many others. One of his developments, called the Schmitt trigger, is fundamental to all computers. It is used to convert analog signals into digital signals when data are entered into a computer, and is frequently used with keyboards or communications lines that send data to the computer for processing. The Schmitt trigger can be found in the input mechanism of virtually every computer in use today.

He earned his bachelor’s degree doctoral degrees in 1937 in zoology, physics and mathematics. For his doctoral dissertation, he described a "thermionic trigger," which later became known as the "Schmitt trigger." This small circuit allowed a constant electronic signal to be changed to an on/off state. It was a direct result of his study of nerve propagation in squid nerves. It is the perfect example of inventing an artificial method to imitate a natural process for the benefit of humanity. Dr. Schmitt chose not to enforce the patent on this invention, choosing throughout his life to focus on ideas and methods, rather than the business side of life.

Schmitt’s real genius, said good friend Bill DeLaittre, came from his expansive way of viewing the world. He learned a lot from watching frogs. "By watching frogs, he designed electrical circuits that make most of our modern-day electronics possible," said DeLaittre. "How does a frog know it’s going to land on a particular lily pad? Schmitt deduced that the frog keeps observing its position and sending feedback to its muscles until it has the perfect trajectory. He used this information to develop electronic feedback circuits that are self-adjusting." "He didn’t take the frog apart to find this out," DeLaittre said. "He thought from the outside in instead of inside out." Schmitt was a man of inordinate curiosity. He coined the phrase "mental jogging" to describe his philosophy of giving the brain regular workouts with a varied regimen of exercise.

In 1937, he married Viola Elise Muench, his wife and secretary for 57 years. Shortly after becoming an associate professor at the University of Minnesota, he and his wife worked as scientists on important, top-secret projects during World War II. In addition to other projects, she worked on the Manhattan Project, the code name for the atomic bomb effort. He did secret research during World War II and invented a magnetic anomaly detector that detected changes in magnetic fields to pinpoint the presence of enemy submarines. He also found a way to distract German radar operators by transmitting jokes slightly off channel. "When the operators listened to the jokes, they couldn’t keep track of their radar signals. It fooled some of them for months."

Schmitt’s work as a bioengineer is resulting in developments to improve the accuracy of electrocardiographic tests and other medical diagnostic tools. If his work pans out, a person might someday be able to have a machine in the home to do a wide variety of diagnostic tests for a fraction of what it costs in a hospital or doctor’s office.

He authored over 270 publications on such topics as nerve impulses, tri-dimensional oscilloscopic displays, bioastronautics, and stereo-vectorelectrocardiography, and was published in many medical and scientific journals. One of the many words Schmitt invented is "biomimetics," which first appeared in Webster's Dictionary in 1974, with the following definition: "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." He had used the term at least as early as 1969, when it appeared in the title of a paper he presented at the Third International Biophysics Congress in Boston.