Biomedical Engineering Reference
In-Depth Information
of the particle and that of the surrounding medium, the particle shape and size, and the
frequency and magnitude of the applied electric ield. Dielectrophoresis was discovered
by Herbert Pohl in 1951.
dielectrophoretic traps:
Devices that allow for conining cells or particles using the principle
of dielectrophoresis.
difusion coeicient:
he proportionality constant between the molar lux (due to molecular
difusion) and the concentration gradient (that causes the lux).
difusion immunoassay:
Immunoassay performed in solution, relying entirely on observing the
difusion of the antibodies as they bind to the analytes (as opposed to surface-bound or
heterogeneous-phase immunoassays such as ELISA); the difusion immunoassay was
invented by Paul Yager's laboratory at the University of Washington (Seattle) in 2001.
See
heterogeneous-phase immunoassay, homogeneous-phase immunoassay, ELISA.
difusion length:
In considering Fick's second law of difusion in one dimension (
x
), its solu-
tion is the complementary error function
C
(
x
,
t
) that has a term 2
Dt
, called difusion
length, which provides a measure of how far the initial concentration has difused in
the
x
direction in the amount of time
t.
difusivity:
See
difusion coeicient
digital microluidics:
Manipulation of droplets by electrowetting using electronic automated
platforms.
digital micromirror device:
Projection device invented by Texas Instruments in 1987 that con-
sists of an array of hundreds of thousands of aluminum-coated silicon micromirrors
(each 16 μm in size) that can be individually delected at megahertz rates.
digital PCR:
Strategy for performing PCR based on subdividing the sample into a large number
of small, nanoliter-scale (or smaller) volumes; by virtue of its size, in each small volume
there are only one or a few DNA molecules at most, so ampliication always leads to a
luorescent signal that is quantized—hence the name “digital.”
dilution generator:
A microluidic device that creates a number of dilutions (titrations) from a
given input solution and a diluent (usually water).
direct laser writing:
Microfabrication technique that is based on multiphoton polymerization
of an adequate photoresist by means of a laser, allowing for the fabrication of arbitrary
3-D structures with submicron resolution.
dissociated culture:
Culture of dissociated cells, that is, of tissue that has been enzymatically or
mechanically separated into single cells.
DMD:
See
digital micromirror device.
DNA chip:
See
oligonucleotide chip.
DNA microarray:
A square matrix of ~100-μm-diameter dried spots of cDNA, usually depos-
ited on glass by means of metal pins; the microarray can detect the presence of com-
plementary DNA strands (luorescently labeled) from a sample. he technology was
invented in 1995 by Patrick Brown at Stanford University.
DNA prism:
A microluidic device containing a hexagonal post lattice that acts as an asym-
metrical sieve for DNA difusion (i.e., DNA molecules of diferent length difuse at
diferent speed in diferent directions) when electrical ields of diferent magnitude are
applied along the axes of symmetry of the lattice. he DNA prism was invented in 2002
by a team led by Edward Cox, Robert Austin, and James Sturm at Princeton University.
droplet microluidics:
A set of microluidic techniques that allow for creating, manipulating,
and analyzing miniature droplets.
Drosophila
:
Genus of small lies commonly referred to as “fruit lies” or “vinegar lies” that
contains more than 1500 species. One
Drosophila
species,
Drosophila
melanogaster
, has
been widely used in genetics and developmental biology research.
dry etch:
In microfabrication processing, an etch that uses gaseous chemistry (as opposed to an
etch that uses liquid chemistry;
see
wet etch).
