Microfluidics for Biologists Fundamentals and Applications

bonded silicon-glass platform with electrodes, micro-channels and chambers built
on it is used for identification purpose (Fig.2.33).
DEP forces are used to divert cells using one set of interdigitated electrodes in
big chamber while the diverted cells are collected in smaller chamber with second
set of interdigitated electrodes to trap and concentrate the cells. In the trapped cells,
under DEP force, PCR mix is injected for PCR amplification with SYBR green
detection for identification of Listeria monocytogenes V7 cells. Using DEP forces,
higher sensitivity was achieved from 10^6 to 10^4 cfu/mL cells. Very specific
identification technique for identifying as low as 60 cells in 600 nL volume. Further
optimization of fabrication process for PCR micro-chip through system identifica-
tion technique is performed [ 100 ]. Design and optimal placement of a thin film
resistance based temperature detector (RTD) in the PCR microchip is studied and
the most optimal design is suggested. RTD integration is done to eliminate the need

t=0.45mm

t=10mm

t=0.15-0.35μm

Φ=3.0mm

Φ=1.5mm

t=0.9mm

1 2 3 4 5 6 7

Fig. 2.30 Schematic of the
silicon PDMS cassette.
(1) Glass housed
thermocouple, (2) epoxied
inlet/outlet ports,
(3) polydimethyl siloxane
channels, (4) inlet/outlet
reservoirs, (5) SOG layer,
(6) thermally oxidized
silicon wafer, (7) heaters
(Reproduced from
Bhattacharya et al. [ 97 ] with
permission from the
Institute of Electrical and
Electronics Engineers)

Fluidic

Ports

Ab-based

conjugation

On-chip

Dielectro-

phoresis

Temp.

Mediated

Lysing

Real-Time

PCR

Amplification

Selective

Capture

Conc.

Sorting

Cell

Lysing

Optical

Detection

DNA

Heat

Heat

CCD

e

Fig. 2.31Schematic of detection microorganisms (Reproduced from Nayak et al. [ 98 ] with
permission from the Nature Publishing Group)

70 G. Bhatt et al.

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