Microfluidic Tools for DNA Analysis - DNA Nanotechnology: From Structure to Function - page 114

Fig. 7.2 Flow-through PCR on a 3D qiandu ( right triangular prism )-shaped polydimethylsiloxane
( PDMS ) microdevice employing a single heater. ( a ) Fabrication protocol ( 1 - 8 ) of the device;
( b ) infrared image of the temperature gradient generated on the slanted plane; ( c ) schematic
comparison for the temperature profile between thermocycler ( straight line ) and the qiandu-shaped
PDMS microdevice ( dotted line ) (Reproduced from Ref. [ 11 ] with permission of The Royal
Society of Chemistry)

vapor [ 14 ] and can be easily integrated with microfluidic devices, which allows them
to get rid of external power source and fully stand alone.
Relying on the development of thermal control mentioned above, various DNA
analyses based on amplifications can be realized on a chip.

7.2.1.2 Liquid-Phase Amplification

Normal PCR is all carried out in the liquid phase. A straightforward way to reach
a high-throughput PCR is shrinking the volume of individual reactions which
are performed in a miniaturized device consisting of a large number of small
compartments (e.g., micro-wells). The prevention of cross-contamination among
different compartments is critical for the reliability of the system. Different strate-
gies have enabled the fabrication of the device, based on a smart combination of
microfabrication techniques and surface chemistry. Huang and coworkers fabricated
micro-wells on a glass slide by standard wet etching and transferred perfluorosilane
molecules on the planar surface out of the wells by PDMS stamping, rendering
a hydrophilic surface inside the well and a hydrophobic surface outside the well
[ 15 ]. They showed the applicability of PCR reactions with hundreds of nanoliters.
Fang and coworkers presented a chip with micro-wells fabricated from a silicon
wafer deposited with a hydrophilic SiO 2 layer outside the well and coated with