7
NOTE: Wrong polarization may destroy the sensor
For most sensors, the polarization will never need to be modified. The N
2
O sensor requires that the
polarization is adjusted manually as this requires a period of pre-polarization at a more negative
polarization before it is set to the measuring polarization (see the Nitrous Oxide Sensor Manual. To
be downloaded at:
https://www.unisense.com/manuals/
).
7.4
Adjusting the offset
The Offset may be set manually. It may be used to displace the signal in a positive or negative
direction (Figure 3).
7.5
Setting STOX sensor parameters
The STOX sensor is a double O
2
sensor, one sensor acts as the measuring sensor and the other acts
as the front guard. The front guard will, when it is polarized, prevent O
2
from reaching the measuring
O
2
sensor. The measuring signal, with the front guard on, is thus the signal for zero oxygen. The
measuring signal, with the front guard off, is thus the signal for O
2
. This difference in signal with
front guard on and off is proportional to the O
2
concentration. Please see the STOX Sensor Manual
for details (
https://www.unisense.com/manuals/
The cyclic polarization of the front guard must be set individually for each sensor depending on the
sensor characteristics. See the STOX sensor manual for details.
When a STOX sensor is connected to a pA channel, the
Enable STOX-mode
checkbox will be available
(Figure 4). Check this box to display the
STOX zero on-time (s)
and
STOX zero off-time (s)
fields.
Setting the cyclic front guard polarization timing (seconds):
•
The front guard on period is specified in the
STOX zero on-time (s)
field
•
The front guard off period is specified in the
STOX zero off-time (s)
field
