73

The History of Bioelectromagnetism

respiration, and the attachment of an earpiece, without the need for ischemic manipulation or calibra­

tion. Terefore, it can be easily operated by doctors and nurses. Te Misumai National Sanatorium was

reorganized into Hokkaido Medical Center of National Hospital Organization. Nakajima is now the

director of Moriyama Memorial Center, Asahikawa.

Professor John Wendell Severinghaus (1922–2021), an anesthesiologist at the University of California,

was searching for the origin of pulse-oximeter and reached to two Japanese (Severinghaus, 1987;

Severinghaus and Honda, 1987).

Te Aoyagi’s type pulse-oximeter has been improved by many people at many stages, and at year 2021,

the size of the pulse-oximeter is small enough can be held on one hand. It is not necessary to add that

the pulse-oximeter is widely used in anesthesiology, ambulance, respiratory section, and many other

sections in the hospital. It can be said that the fnger-tip pulse-oximeter is one of the most signifcant

advance of red and infrared wave length radiation in medicine and biology in the twentieth century.

2.5.4 New Instrumental Era

At the beginning of the twentieth century, the electronic inventions opened the new era in bioelectro­

magnetism. Te year 1905 was the birth of the age of electronic, afer Lee de Forest invented a three-

electrode valve (vacuum tube) and the original was known as Audion valve. His invention was not

only a detector of signals but also an amplifer (Rowbottom and Sussind, 1984). Historically, before de

Forest’s invention, Tomas Alva Edison (1847–1931), an American inventor, observed in 1883 the elec­

tron current fow in a vacuum, now called the Edison efect. Sir John Ambrose Fleming (1849–1945), a

British engineer and physicist, professor at University of College London, utilized the Edison efect and

invented the diode for rectifying high-frequency oscillation in 1904. Until the invention of the transis­

tor, three-electrode valves were excellent devices for amplifcation. At the same time, Karl Ferdinand

Braun invented the Braun tube. He won, with Guglielmo Marconi (1874–1937), an Italian inventor, the

Nobel Prize in Physics in 1909 for their contributions to the development of wireless technology.

From the point of view of medical applications, the twentieth century began with the discovery of

X-rays by Wilhelm Conrad Röntgen (1845–1923), professor of Physics at the University of Würzburg and

its use in diagnosis. Röntgen won the frst Nobel Prize in Physics 1901, for in recognition of the extraor­

dinary services he has rendered by the discovery of the remarkable rays subsequently named afer him.

Te clinical ECG recorder was commercially available in the 1920s, diathermy in the 1930s, discovery of

EEG in the 1930s, and inventions of the pacemakers and defbrillators appeared in the 1950s and 1960s,

respectively.

During the 1920s and 1930s, the use of electronic amplifers and oscillators had increasingly gained

popularity in electrophysiological research felds. In 1920, Alexander Forbes (1882–1965), professor of

Physiology at Harvard Medical School, made the pioneering study of the nervous system. He invented

with Catherine Tacher, the vacuum-tube amplifer and recorded nerve impulse from a single nerve

fber of frogs with it (Forbes and Tacher, 1920a, b). Joseph Erlanger and Herbert Spencer Gasser (1888–

1963), an American physiologist, invented in 1921 the cathode-ray oscilloscope with a vacuum tube

amplifcation device. Using this oscilloscope, they investigated the time course, transmission velocity of

the nerve impulse from nerve fber and action potential. Erlanger and Gasser received the Nobel Prize

in Physiology or Medicine in 1944 for their discoveries relating to the highly diferentiated functions of

single nerve fbers. However, these instrumental achievements had their weaknesses such as being hard

to handle, low Signal-to-Noise Ratio and drifing with time. To overcome these weaknesses, we had to

wait until the introduction of solid-state electronic with transistors in the 1950s.

In 1947, John Bardeen (1908–1991), Walter Houser Brattain (1902–1987), and William Bradford

Shockley (1910–1989) made an outstanding invention, the junction transistor (transfer+resistor). Tey

worked together at the Bell Telephone Laboratory. Te frst n-p-n junction transistor appeared in

1950. Tis invention led to the outstanding development of electronic technology. Tis development

in electronic technology allowed the miniaturization for the instruments of detection, recording, and