What the EVOM3 System does:

The EVOM system measures a membrane so the researcher can determine if the cells are fully “confluent” in a nondestructive way. This is similar to passing a liquid through a full rack of billiard balls versus one that has a few balls missing. The complete rack will pass less water (electricity) through it than a rack with a few holes in it. The EVOM measures electrical resistance and when an cell line growing on an insert completely covers the bottom filter in the insert, the resistance peaks or plateaus. By measuring the resistance of the growing membrane on a periodic basis the researcher can determine when that confluence occurs an then move on to deeper experimental research. In the past this test was done with dyes like lucifer yellow, but that dye was not biocompatible with some cell lines. Further use of this electrical measurement system over time eventually lead to a standardization of cell line resistance measurement to ohms per 1 square centimeter and each cell line can now be represented to a TEER (Trans Epithelial Electrical Resistance) measurement).

Deeper research that the EVOM3 can be used for is permeability. A permeability study is where a drug is introduced to the membrane and noting if the resistance lowers allowing for drug transport and other studies.