WPI EVOM Manual - Page 10

6 World Precision Instruments
Zeroing the blank handling value
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Blank Handling button.
4. Set the reading to zero.
5. Return to the Setup page and open the electrodes to remove the short.
Zeroing the probe null oset
1. Select Setup .
2. Then, press Short Electrodes .
3. Press the Probe Null button.
4. Set the reading to zero.
5. Return to the Setup page and open the electrodes to remove the short.
Resistance levels that are unexpectedly lower or higher can be attributed to a number
of things besides an incompletely grown membrane. Any of these items can change
the resistance reading:
• Electrode resistance (Keep the electrodes clean.)
• Fluid levels (Try to maintain the same volume for every insert. A variation of 50µL
can have a large eect in a small insert.)
• Changing CO
2
levels and temperature drift can account for large changes in the
resistance reading. The use of a warming plate can reduce this eect.
• We recommend that both uid levels are at the same height so that you do not
have any pressure dierentials and the apical well is lled rst so that you do not
dislodge the membrane from the lter by hydrostatic pressures. If the membrane
detaches itself, then it was not adhering to the inserts lter. A small gap from
dislodged tissue at the edge of the membrane can open a clear path for the
EVOM™ Manual to read a lower resistance. Instead of the current going through
the membrane, the electricity is going around the membrane. Electricity will take
the path of least resistance and the EVOM™ Manual will measure that as a lower
resistance.
NOTE: Cleaning the electrode often corrects most of these issues. Refer to the
Maintenance section of the electrode manual for cleaning protocols.
Charging the EVOM™ Manual
The EVOM™ Manual battery may also be charged with a Mini-B USB cable P/N
803026 (not supplied).