Takuo Aoyagi, Inventor of Pulse Oximetry, Dies at 84

By Phil Isaacson | Executive Chairman and Chief Technology Officer May 13, 2020

Dr. Takuo Aoyagi, an engineer from Japan, who developed the technology for the modern pulse oximeter in the early 1970s.

I wish to acknowledge the great contribution Dr. Takuo Aoyagi made to pulse oximetry.

He invented the principle of pulse oximetry in the early 1970s and received his doctorate in 1993. Among other great honors, Dr. Aoyagi received the IEEE Medal for Innovations in Healthcare Technology in 2015 for the invention of the pulse oximeter. He continued working at Nihon Kohden until his passing.

His death, in a hospital, was announced by his employer, Nihon Kohden.

Dr. Aoyagi has been engaged in research and development of pulse oximeters for about half a century, from the time he joined Nihon Kohden in 1971 to the present.

In 1974, he invented the principle of pulse oximetry. He continued to make improvements to pulse oximetry throughout his lifetime. In his early work, he used dye dilution to measure cardiac output. The pulsatile signals were an interference, but Dr. Aoyagi realized that this interfering pulsatile signal could be used to accurately measure arterial oxygen saturation. All of today’s pulse oximeters use technology based on Dr. Aoyagi’s original principles of pulse oximetry.

I had the pleasure of first meeting him at an early international pulse oximetry conference.

His obituaries are in the The New York Times, The Washington Post, and The Wall Street Journal.