A
major category of high performance materials
is that of synthetic polymers, commonly known
as plastics. A new invention of the 20th century,
they are now found everywhere in a wide variety
of forms.
One application
of high performance plastics is the artificial
lung.The main
component of the artificial lung is a microporous
membrane that allows the diffusion of oxygen
into the blood, while carbon dioxide diffuses
out of the blood into the gas stream and is
thereby removed.
Adolf
Eugen Fick(German, 1829-1901)
introduced Fick’s Laws of Diffusion
in 1855, which govern the diffusion of
a gas across a fluid membrane. In 1887
he constructed and fitted what was to
be considered the first successful model
of a contact lens.
The
mechanics of this process are defined by Fick’s
Laws of Diffusion:
Fick’s
First Law of Diffusion:
Steady-state diffusion
Fick’s Second Law
of Diffusion:
Non-steady state diffusion
where J
is the diffusion flux, D
is the diffusion coefficient
or diffusivity, is
the concentration, and x
is the position.
is
the concentration, and 