Ultrasound

The invention: 

A medically safe alternative to X-ray examination,
ultrasound uses sound waves to detect fetal problems in pregnant
women.

The people behind the invention:

Ian T. Donald (1910-1987), a British obstetrician

Paul Langévin (1872-1946), a French physicist

Marie Curie (1867-1946) and Pierre Curie (1859-1906), the French husband-and-wife team that researched and developed the field of radioactivity

Alice Stewart, a British researcher

Ultramicroscope

The invention: 

A microscope characterized by high-intensity illumination
for the study of exceptionally small objects, such as colloidal
substances.


The people behind the invention:

Richard Zsigmondy (1865-1929), an Austrian-born German
organic chemist who won the 1925 Nobel Prize in Chemistry
H. F. W. Siedentopf (1872-1940), a German physicist-optician
Max von Smouluchowski (1879-1961), a German organic
chemist.

Ultracentrifuge

The invention: 

Asuper-high-velocity centrifuge designed to separate
colloidal or submicroscopic substances, the ultracentrifuge
was used to measure the molecular weight of proteins and
proved that proteins are large molecules.

Typhus vaccine

The invention: 

The first effective vaccine against the virulent typhus
disease.

The person behind the invention:

Hans Zinsser (1878-1940), an American bacteriologist and
immunologist