Biomedical Engineering Reference
In-Depth Information
solid phase) and predicts the contact angle if the three surface tensions are known.
Young is also known for the wave theory of light (including Young's double-slit experi-
ment that demonstrates wave interference), Young's modulus of elasticity, the Young-
Laplace equation that describes the capillary pressure diference across the interface
between two static luids, and other contributions to various other ields, including
medicine, Egyptology, and music.
Young's modulus:
Measure of the stifness of an elastic material that is calculated by dividing
the tensile stress (
F
/
A
0
) by the tensile strain (Δ
L
/
L
0
) in the elastic portion of the stress-
strain curve (i.e., when the curve is still linear, for small strain)
≡
/
F A
L L
E
o
o
∆
/
where
F
is the force applied to the object,
A
0
is the original cross-sectional area through
which
F
is applied, Δ
L
is the amount by which the length of the object changes, and
L
0
is the original length of the object.
Z
zeta potential:
In colloidal science (which deals with suspensions of particles in luids), it is the
potential diference between the dispersion medium and the stationary layer of luid
attached to the dispersed particle. It is related to the quantiication of Debye length in
the electrical double layer (e.g., on microchannel walls in capillary electrophoresis on
a chip) because the zeta potential coincides with the electric potential in the electrical
double layer at the location of the “slipping plane” (a conventionally introduced plane
that separates mobile luid from luid that remains attached to the surface). Hence, we
can use as a deinition of zeta potential the potential at the slipping plane.
Zigmond chamber:
Passive device used for traditional chemotaxis assays, which consists of
two chambers or reservoirs etched in glass and separated by a shallow ridge or weir.
he chambers are irst covered with a glass coverslip before loading any solutions. One
of the chambers is loaded (usually by capillarity illing) with the cells and the other
chamber is loaded with the chemoattractant of interest. he chemoattractant reaches
the cells by difusion across the weir.