
7-6 Sensors and Sensor Technology
TABLE 7.1 continued Overview of Various Needle-Type Environmental Microsensors
Measurement Type
Analytical Methods/
Mechanisms Slope
a
, Response Time Conc. Range, (LOD
b
)
Key Materials/Compound/
Procedures References
NH
2
Cl Solid • Amperometry
• Reaction between
PtOH and NH
2
Cl
18 pA/(mg Cl
2
/L), <5 s 0–10 mg Cl
2
/L (0.3 mg Cl
2
/L) • Pt wire
• Polarization
• Controlled condition where
predominant chlorine species
are NH
2
Cl (i.e., Cl
2
:N = 4:1,
pH8.0)
[18]
Redox
p
otential Solid •
Po
tentiometry
•
Ner
nstian
e
lectrode
res
ponse
1
mV/mV
,
<1 min — • Pt w
ire
•
Et
ching
in 2 M K
CN
s
olution
•
Wi
thin
10 mV o
f
t
he
n
ominal
re
dox
p
otentials
(A ...