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The History of Bioelectromagnetism

Herman Paul Schwan (1915–2005), born in Aachen, Germany, later German-born-US biophysicist,

professor at the University of Pennsylvania. Schwan studied mathematics and physics at Göttingen and

Frankfurt. Before World War II, in 1937, Schwan started his carrier at the time when the electrical

properties of tissues and cells had attracted the scientifc attention at the Kaiser Wilhelm Institute for

Biophysics (Max Planck Institute of Biophysics afer 1948) where his main research areas were the bio­

logical efects of electromagnetic radiation (both non-ionizing and ionizing) including hazards and

safety standards for microwaves, blood and blood serum conductivity in low-frequency, heating and

body tissue properties in ultra-high-frequency, tissue relaxation, and electrode polarization (Grimmes

and Martinsen, 2000). He was employed as Boris Rajewsky’s technician. Boris Rajiewsky (1893–1974)

was a Russian biophysicist at the University of Frankfurt am Main. In early 1946, Schwan was awarded

his Dr. Habilitation by his work entitled “Te determination of the dielectric properties of semicon­

ductors, especially biological substances in the decimeter wave range.” In 1947, he came to the United

States, and joined the University of Pennsylvania in Philadelphia in 1952. Schwan is the founder of bio­

physical studies related to the dielectrical properties of cells and tissues which gave the understanding

of the efects of the electromagnetic felds on biological systems and the health efects of non-ionizing

electromagnetic felds. In 1985, he was recognized as the frst recipient of the d’Arsonval Medal of the

Bioelectromagnetics Society for his lifelong contributions to the understanding of microwave radiation.

One of Schwan’s earlier theories predicted that electromagnetic radiation of 0.9 GHz or below would be

better for therapeutic diathermy than 2.45 GHz. Te understanding of the interactions between elec­

tromagnetic felds and biological systems must be based on the knowledge of electric properties of the

tissues. Tis understanding has led to many applications in biomedical engineering, agriculture, etc.

2.5.1.3 Electric Field-Force Effect

Te electric feld is very important for biological studies. Several electric feld-force efects can be induced

in cells. Tese efects are illustrated in Figure 2.12 (Schwan, 1988). Te term “force efect” of an electric

feld means how the cells and bioparticles respond to the applied electric felds. Electric-force efects are

the basis of bioelectric phenomena such as electroporation, electrofusion, electrorotation, pearl chain

formation, and traveling wave dielectrophoresis.

FIGURE 2.12 Electric feld-force efects can be induced in cells and biologically simulating particles by time-

varying electric felds (From Schwan, 1988.)