Development of a Oxygen Sensor for Marine ... - DTU Nanotech

Chapter 3
Theory of the Clark Sensor
The Clark sensor was named after its creator Leland C. Clark[21], who in
the late fifties and mid sixties studied the electrochemistry of oxygen gas
reduction at platinum (Pt) metal electrodes. Clark began pioneering the
use of what would later be an oxygen- (and therefore chemical-) sensor. In
fact, Pt electrodes used to detect oxygen electrochemically are often referred
to generically as ’Clark electrodes’. While the sensor he originally came up
with was intended for the measurement of glucose concentration in blood,
the sensor itself was the start of biosensor history, and the Clark sensor is
still around today with many different shapes and several applications far
from the original design.
Liquid measured
on (Blood, water,
etc.)
Membrane
Ag Wire
Pt
KCl Solution (electrolyte)
Figure 3.1: Sketch of a basic 2 electrode Clark Oxygen Sensor, with a Ag
reference electrode (the anode) and a Pt working electrode (the
cathode).
The electrodes as seen in figure 3.1 have a thin organic membrane covering
a layer of electrolyte and two metallic electrodes. Oxygen diffuses through
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