Miniaturized Detection Systems - Waterborne Pathogens: Detection Methods and Applications - page 331

unit also features hydrodynamic cavitation to disaggregate clumps. The inclu-
sion of this unit also makes the system relatively large (182 × 139 × 76 cm)
and heavy (around 200 kg), making it difficult for portable field test usage.
After concentration and filtration, analytes of interest in the sample are subse-
quently separated using IMS, lysed and parasite RNA is amplified by NASBA.
The detection happens when the hybridization of target RNA amplicons on
specific biomolecular probes generates a current via a guanine oxidation pro-
cess. The reported LOD of this device after concentration, filtration and detec-
tion on the biosensor chip was 10 oocysts per 10 L. Additionally the total load
quantification and viability testing of up to 25 species can be performed on
a single chip with a total processing time under 3 h from sampling to results.
10.3. SUMMARY
For a very interesting discussion on the future potential of micro-
fluidics we recommend a 2010 review by Rios et al. 105 This chapter has
presented some basics behind microfluidics and reviewed the applications
for waterborne pathogens. Detection to the single-cell level has been dem-
onstrated, though the range of pathogens studied needs to be expanded.
For all the detection methods discussed previously in this topic there are
microfluidic systems for performing these tests. Of optical, electrical and
biosensor systems, optical detection seems to have received the most atten-
tion from the lab-on-a-chip community.
The advantages of performing fluorescent detection on-chip are: the
reduced sample volume resulting in a lower background noise signal and there-
fore improved sensitivity and signal to noise ratio; the small sample volume
and control of flow enhancing binding kinetics and increasing sensitivity; and
the reduced consumption of reagents. 89 However, there are challenges, espe-
cially with the relatively short shelf life of reagents for portable, field devices,
and particularly in the production of low-cost, sensitive, and portable optics.
There has been some progress toward this latter goal with the development of
on-chip microscopes and photodiode detectors. Despite this, label-free tech-
nologies seem more promising for ease of integration with microfluidics. 89
Molecular methods, discussed further below, exploit many of the
advantages of lab-on-a-chip miniaturization and are likely to be one of
the main future directions for microfluidic waterborne pathogen detection.
The different detection methods, described in Chapters 5-7 for whole-cell
microorganisms can mostly also be applied to molecular detection and so
there are many options to perform the on-chip detection.