Biomedical Engineering Reference
In-Depth Information
quorum sensing:
A system of communication signals with which certain species such as bac-
teria and some social insects are able to adapt to their environment based on their
population density by controlling gene expression, where to nest, etc.
R
Re:
See
Reynolds number.
reactive ion etch:
A chemical etch that is conducted in the presence of a highly ionized plasma
of a chemically reactive gas (as opposed to, for example, a plasma of a noble gas such as
argon, which can also etch a surface through the momentum with which accelerated
argon ions impinge on the surface but attack all surface species nonselectively); for
example, in MEMS processing, SF
6
is commonly used to produce a plasma of F
-
ions,
which etches Si but does not attack photoresist.
resonance frequency:
Frequency at which a mechanical or electrical system that is being driven
to oscillation reaches its maximum oscillation amplitude.
rete ridges:
hickenings in the human epidermis that extend downward between dermal papil-
lae, the interdigitations of the dermis into the epidermis.
Reynolds number:
Dimensionless number that gives a measure of the relative importance of
inertial versus viscous forces in luid lows.
RGD:
Sequence of three amino acids (R, arginine; G, glycine; D, aspartic acid) that is present
in many extracellular matrix proteins; when integrin receptors on the membranes of
adherent cells recognize the RGD sequence, the cells attach and spread on the sur-
face that is covered with RGD. his fundamental mechanism was discovered by Erkki
Ruoslahti and Michael D. Pierschbacher in 1986. Other similar sequences responsible
for cell attachment and survival have been discovered since then.
RIE:
See
reactive ion etch.
S
S. cerevisiae
:
See Saccharomyces cerevisiae
.
Saccharomyces cerevisiae
:
A species of yeast, one of the most widely studied eukaryotic model
organisms in molecular and cell biology.
SAEC:
Abbreviation that stands for Small Airway Epithelial Cell, a human cell type.
SAM:
See
Self-Assembled Monolayer.
SAW:
See
Surface Acoustic Wave.
scanning probe lithography:
In nanotechnology, the use of scanning probe microscopes for
fabricating nanostructures and microstructures on a surface.
Scanning probe microscope:
A class of non-light-based microscope that uses a sharp tip in
proximity with a surface of interest to obtain a topographic image of the surface.
Schwann cells:
Main glial cells of the peripheral nervous system; they are involved in nerve
impulse conduction along axons, nerve development and regeneration, and ECM
secretion, among other key processes.
self-assembled monolayer:
Organized layer or ilm of single-molecule thickness in which one
end of the molecule has a strong ainity for the substrate; the “tails” of the molecules,
usually alkyl chains, attract each other via van der Waals interactions to form a tightly
packed monolayer so that, ater completion of the monolayer, the substrate is no longer
accessible—the substrate has been efectively “replaced” by the functional group of the
self-assembled monolayer.
self-assembly:
Spontaneous creation of an ordered multi-component structure from a set of
smaller (nanoscale, microscale, or mesoscale) components that does not require the
