
8-1
8.1 Introduction
Detection of very small amount of chemical and biological agents had been an active area of research for
many years. From carbon monoxide detection for environmental applications to biological and biomed-
ical
mo
nitoring,
mi
ssile
fu
el
le
akage
de
tection
an
d
se
curity
ap
plications
re
quire
hi
gh-sensitivity
se
nsors
th
at
ca
n
me
asure
lo
w
pa
rts
pe
r
bi
llion
(p
pb)
or pa
rt
pe
r
mi
llion
(p
pm)
of ch
emical
or bi
ological
ag
ents
.
Re
cent
de
velopment
of mi
croelectronic
te
chnology
ha
s
pr
ovided
a go
od
op
portunity
fo
r
fa
brication
of
se
nsor
an
d
th
e
in
terface
ci
rcuit
on a sin
gle
ch
ip
. Si
ngle-chip
fa
brication
of th
e
se
nsor
an
d
th
e
in
terface
ci
rcu ...