Microfluidic Tools for DNA Analysis - DNA Nanotechnology: From Structure to Function - page 141

Fig. 7.26 Timeline of the evolution of microfluidic technology (From Ref. [ 111 ], reproduced with
permission, copyright 2010, IBM Corporation)
has aroused extensive concerns in industrial community in the past few decades
[ 107 ]. The most critical success criterion for a real product is the stability, or
reproducibility of the assay. Various components must be integrated into one device
due to successive steps required for DNA analysis such as sample pretreatment,
target and/or signal amplification, and final readout, while at least fluidic control
and temperature control (for hybridization or thermal reactions) should also be
considered simultaneously, which can make DNA analysis more challenging than
that for proteins. Together with the lack of standardization [ 108 , 109 ], there is a
long way to go from the laboratory benches to the commercial shelves [ 110 ].
On the way, researchers are reconsidering/ reselecting suitable materials that
can be fabricated or treated in bulk. The fabrication cost is also a key factor
that should be taken into account (Fig. 7.27 )[ 112 ]. PDMS is predominantly
used for microfluidic devices in the academic arena and also being successively
industrialized by a few companies [ 113 ]. But some basic research showed the
potential risk using replica-molded PDMS chip due to its intrinsic properties
(such as unwanted absorption or evaporation) [ 114 ] and some microfabrication
limitations (such as unwanted bubble formation) [ 115 ]. Many academic works
were done by using PDMS, but few were commercialized. The final goal of
the development of biomedical microfluidic devices by engineers is the public
acceptance from biologists or physicians in biological laboratories or hospitals.
Unfortunately, PDMS has not been widely accepted by them, and they prefer
to use polystyrene or polypropylene. It posed the challenges in microfabrication
for engineers [ 116 ]. The best choice of material for real products is still under
discussion [ 117 ].
So far, the most successful commercial product in the arena of point-of-care
testing is the lateral flow test (LFT) strip [ 118 ]. It was originally developed for
immunoassays such as HIV antibody detection. The important features of LFT
are simple/rapid operation and naked-eye readout. It holds huge market and thus