Biomedical Engineering Reference
In-Depth Information
(iv) Application of surface layers creating hydrophobic or hydrophilic surface patterns to
direct fluids (
Zhao et al., 2002
)
Mautner emphasizes that the application of readily available pumps can help the unsteady
wall jets obtain the required time dependent wall jet conditions which would mix both
existing and merging flow stream conditions.
Mautner (2004)
has proposed the application of macroscale jets to be applied to the low
Reynolds (
Re
10) two-dimensional channel flows that may be found in biosensor
microfluiidc systems. The method includes a hybrid approach of the Lattice Boltzmann (LB)
method for flow field computations and a finite difference, convection-diffusion equation for
passive scalar transport. This author emphasizes that the forced jet imparts momentum to the
channel flow, thereby enhancing fluid mixing.
¼
2.2.7 Kinetics of Analyte Capture on Nanoscale Sensors (
Solomon and Paul, 2006
)
Solomon and Paul (2006)
point out that nanoscale electromechanical systems have been used
to detect biomolecular targets with increasing sensitivity (
Roukes et al., 2000; Paul and
Cross, 2004; Ekinci and Roukes, 2005
).
Solomon and Paul (2006)
call these devices
BioNems devices. These BioNems devices may be used to detect proteins, enzymes, viruses,
and bacteria. They point out that the sensitivity of these devices is directly related to the
binding kinetics of the analytes to the receptors immobilized on these BioNems devices.
The BioNem device that these authors have developed and analyzed are different from the
conventional devices that measure, for example, the binding rate coefficients, in that they
identify the presence or absence of biological macromolecules such as large proteins,
enzymes, viruses, and enzymes.
The
Solomon and Paul (2006)
system uses a single (or multiple) cantilever(s). The multiple
cantilever configuration improves detection probabilities. The cantilever is located in a small
channel (or “via”). Fluid containing the target analyte flows through these channels at some
fixed velocity. The detection of the analyte by the cantilever is based on either (a) the mass-
loading effects or (b) by a change in the effective damping constant of the cantilever that
alters the mean-square displacement of the cantilever tip.
Solomon and Paul (2006)
point
out that a small region of the cantilever tip is functionalized with immobilized receptors spe-
cific to the target analyte. SAM (self-assembling monolayers) constructed with alkanethiols
permits the functionalization by a linkage to analyte specific receptors. These emphasize
that their device is able to detect specific biomolecules down to concentration levels of
1 nM or less.
Solomon and Paul (2006)
also attempted to analyze the influence of surface-diffusion
enhancement on the analyte capturer. Their quantitative results indicate that under certain
