EVOM
INTRODUCTION
EVOM
was the first instrument designed to perform routine TEER (Trans Epithelial
Electrical Resistance) in tissue culture research. The confluence of the cellular monolayer
is determined by a sharp increase in TEER detected using the unique electronic circuit of
the
EVOM
and
STX2
electrode (included with the instrument). The
EVOM
qualitatively
measures cell monolayer health and quantitatively measures cell confluence. When
combined with WPI’s
EndOhm
chamber, the
EVOM
can also be used to perform trans
endothelial
electrical resistance measurement.
The battery-powered
EVOM
produces an AC current that avoids electrode metal deposits
and adverse effects on tissues, which can otherwise be caused by a DC current. In
addition, resistance readings are unaffected by membrane capacitance and membrane
voltage.
A modified
version of the EVOM
, the
EVOMX
, has been adapted for multi-well
testing by replacing the momentary R (resistance) measurement pushbutton with a
toggle switch, allowing constant monitoring of resistance. The
EVOMX
also has a BNC
connector for data output to a chart recorder.
WORLD PRECISION INSTRUMENTS 1
NOTE:
If the
EVOM
system is to be used
for resistance measurement only
, sections
in this manual pertaining to use of the electrode for voltage measurement can be
disregarded. For resistance measurement, the electrode does not need to be equilibrated
or preconditioned before use.