WPI EVOM3 - Unit Area Resistance Calculation

42 World Precision Instruments
Fig. 54—Electrodes in solution
Unit Area Resistance
As the resistance is inversely proportional to the area of the tissue, instead of
reporting resistance, typically the product of the resistance and the area is calculated
and reported. The unit area resistance is independent of the area of the membrane
ed and ma e ed t mae data tained m inet  dieent ie
NOTE: Resistance readings for 24 mm or larger diameter inserts obtained by using
the EVOM3 with the STX electrodes should not be converted to unit area resistance.
The EndOhm is recommended for these larger inserts. The unit area resistance is
tained  mltiling the mete eading  the eetie ae aea  the filte
membrane. The dimension is Ω-cm
2
. The resistance is inversely proportional to the
surface area. Thus, the larger the membrane, the lower the resistance.
Reitane  a nit aea  Reitane (Ω)  etie emane ea (m
2
)
 ee manating eifiatin  the atila inet
nit ea   m
2
The unit area resistance is independent of the area of the membrane used and may
e ed t mae data tained m inet  dieent ie
Continuing with the previous example, in which the R
true tissue
  Ω, i an eetie
membrane diameter (d) was 6.5 mm, the unit area resistance would be:
Reitane  etie emane ea   Ω   
2
  Ω * 3.14* 3.25* 3.25 / 100
  Ω * 0.331 cm
2
  Ω-cm
2
.
2024 Ω is the resistance of a unit area of 1 cm
2
(TEER).