You might not know Georgios Papanikolaou’s name, but you certainly know his most famous creation. The scientist is being celebrated in Monday’s Google Doodle for what would have been his 136th birthday, along with his invention of the Pap smear.

Papanikolaou was a cytopathologist who worked alongside his wife to come up with the test that enabled the early discovery of cervical cancer and other diseases. Today, it’s one of the most common cancer tests, with doctors ordering the simple, low cost test 28.5 million times in 2015. (Other tests are now being offered that replace the Pap smear.)

The son of a doctor, Papanikolaou initially considered another field, but by the age of 15, he was starting medical school. Six years later, he graduated with top honors. He immigrated to the U.S. in 1913, initially working as a carpet salesman and playing violins in restaurants until Cornell recruited him to join their staff.

He was nominated for the Nobel prize twice and has been featured on a U.S. postage stamp as well as the Greek 10,000 drachma note.

To conduct a study for his research, he not only convinced his wife (and lab technician) Mary to be a test subject, but also a group of close friends, taking vaginal smears and studying them under a microscope for malignant cells. In conducting that research, he found that one of his wife’s friends had cervical cancer. (It’s unclear if that detection came in time to cure the disease.)

Papanikolaou initially introduced the test in 1928, but the medical community was skeptical of its accuracy initially. Undeterred, he continued research and in 1941 published a paper backing up the test that led to greater acceptance.

Known for putting in grueling hours, Papanikolaou died in 1962 of a sudden heart attack at the age of 78. Mary continued his work until her own death in 1982.