Teaching Materials - Introduction to BioMEMS - page 447

alkanesilanes, alkylsilanes: In organic chemistry, alkane (or, equivalently, the alkyl preix)
refers to a chemical compound that consists only of carbon and hydrogen linked
together exclusively by single bonds (i.e., the C and H are said to be “saturated”). A
silane is the -Si-R 3 terminal group (-SiCl 3 , for example). hus, alkanesilanes are mol-
ecules that are terminated in the -Si-R 3 group and that have a fully saturated hydrocar-
bon tail. Example: CH 3 -CH 2 -CH 2 -CH 2 -SiCl 3 , n -butyl-trichlorosilane. he “ n ” stands
for “normal,” the name of the coniguration when the functional group (in this case a
silane) hangs from the end of the chain.
alkanethiols, alkylthiols: As with alkanesilanes (see above), the “alkane” or “alkyl” portion of
the name means that the compound contains a chain which consists only of carbon
and hydrogen linked together exclusively by single bonds (i.e., the C and H are said
to be “saturated”). A thiol is the -SH terminal group or sulhydryl group. herefore,
alkanethiols are molecules that are terminated in the -SH group and that have a fully
saturated hydrocarbon tail. Example: CH 3 -CH 2 -CH 2 -SH, n -propanethiol.
aminosilane: In organic chemistry, any organosilane (such as an alkanesilane) that con-
tains or terminates in an amine group. Example: NH 2 -CH 2 -CH 2 -CH 2 -SiCl 3 ,
amino-propyl-trichlorosilane.
anisotropic etch: A chemical etch process that proceeds in a preferential direction. he etch
direction may be biased as a result of an applied voltage (e.g., during a reactive ion etch)
or as a result of a crystalline anisotropy of the substrate. he anisotropicity of an etch is
a quality that depends on the substrate as well as on the etchant; changing the etchant
may result in a diferent etch that proceeds isotropically.
anisotropic sieving: A strategy for separating DNA and proteins based on nanoluidic gaps
(which act as the “sieve”) and the simultaneous presence of low (which helps separate
the molecules) and electrical ields (which induce anisotropy, i.e., attract the molecules
preferentially in one direction).
Arabidopsis thaliana : A small lowering plant that is used as a model organism in plant biology
and genetics, well-suited for light and luorescence microscopy because the seedling
and the roots are translucent. Its genome was the irst plant genome to be sequenced.
Arabidopsis thaliana roots can grow inside PDMS microchannels.
axon guidance: Process that occurs during neural development by which neurons send out
axons to reach the correct target.
B
batch microfabrication: A process for microfabricating many units, devices or wafers in paral-
lel, which reduces the inal cost per device.
bead microarray: A microarray of beads, either self-assembled into microwells (e.g., for use as
a biomolecular binding assay) or tightly packed in a hexagonal array (e.g., for use as a
metal evaporation mask).
benzophenone: Photoinitiator that is widely used as the photoreactive functional group in
UV-photoreactive cross-linkers.
biodegradable polymers: Polymers that gradually break down into their monomer, nontoxic
components in the presence of water, usually by hydrolysis, such that (if implanted)
they can be excreted by natural processes ater breakdown.
BioMEMS: Abbreviation that stands for Biomedical MicroElectroMechanical Systems. By gen-
eralization, the term also includes micro-optical and microluidic devices for biomedi-
cal applications, even though they are neither electrical nor purely mechanical.
Boltzmann distribution: Probability measure for the distribution of the states of a system. he
Boltzmann distribution for the fractional number of particles N i / N occupying a set of
states i at energy E i is: