
54-1
54.1 Introduction
Chemical sensors can be loosely classied into those that use light to extract information about chemi-
cal
co
ncentration
(o
ptical
se
nsors)
an
d
th
ose
th
at
do no
t
(n
onoptical
se
nsors)
. Opt
ical
ch
emical
se
nsors
te
nd
to us
e
mu
ltiple
st
ages
of tr
ansduction
an
d
re
quire
la
rge
am
ounts
of sy
stem
an
d
sig
nal
pr
ocessing
ov
erhead
to co
nvert
ta
rget
an
alyte
in
formation
in
to
a us
eful
ou
tput
. e
se
se
nsors
o
en
be
come
co
m-
plex
sy
stems
or en
tire
pi
eces
of eq
uipment
in th
eir
n
al,
co
mmercialized
fo
rm
. Fo
r
th
is
re
ason,
opt
ical
ch
emical
se
nsors
ar
e
no
t
fr
equently
fo
und
in po
rtable,
ha
ndheld,
or e
ld-monitoring
un
its
. No
noptical
ch
emical
se ...