This time I am giving below the details of a scientist who may not be welknown but started to study engineering, but got degree in Physics and later switched to biology and invented a lot!
Leo Szilard (February 11, 1898 – May 30, 1964) was a Hungarian-German-American physicist and inventor. He conceived the nuclear chain reaction in 1933, patented the idea of a nuclear reactor with Enrico Fermi in 1934, and in late 1939 wrote the letter for Albert Einstein's signature that resulted in the Manhattan Project that built the atomic bomb.
Szilard initially attended Palatine Joseph Technical University in Budapest, but his engineering studies were interrupted by service in the Austro-Hungarian Army during World War I. He left Hungary for Germany in 1919, enrolling at Technische Hochschule (Institute of Technology) in Berlin-Charlottenburg, but became bored with engineering and transferred to Friedrich Wilhelm University, where he studied physics. He wrote his doctoral thesis on Maxwell's demon, a long-standing puzzle in the philosophy of thermal and statistical physics. Szilard was the first to recognize the connection between thermodynamics and information theory.
In addition to the nuclear reactor, Szilard submitted patent applications for a linear accelerator in 1928, and a cyclotron in 1929. He also conceived the idea of an electron microscope. Between 1926 and 1930, he worked with Einstein on the development of the Einstein refrigerator. After Adolf Hitler became chancellor of Germany in 1933, Szilard urged his family and friends to flee Europe while they still could. He moved to England, where he helped found the Academic Assistance Council, an organization dedicated to helping refugee scholars find new jobs. While in England he discovered a means of isotope separation known as the Szilard–Chalmers effect.
Foreseeing another war in Europe, Szilard moved to the United States in 1938, where he worked with Enrico Fermi and Walter Zinn on means of creating a nuclear chain reaction. He was present when this was achieved on December 2, 1942. He worked for the Manhattan Project's Metallurgical Laboratory on aspects of nuclear reactor design. He drafted the Szilard petition advocating a demonstration of the atomic bomb, but the Interim Committee chose to use them against cities without warning.
After the war, Szilard switched to biology. He invented the chemostat, discovered feedback inhibition, and was involved in the first cloning of a human cell. He publicly sounded the alarm against the possible development of salted thermonuclear bombs, a new kind of nuclear weapon that might annihilate mankind. Diagnosed with bladder cancer in 1960, he underwent a cobalt-60 treatment that he had designed. He helped found the Salk Institute for Biological Studies, where he became a resident fellow. Szilard founded Council for a Livable World in 1962 to deliver "the sweet voice of reason" about nuclear weapons to Congress, the White House, and the American public. He died in his sleep of a heart attack in 1964. According to György Marx he was one of The Martians.
For more details see his Wikipedia page.