In impedance-based cell counting, what is measured?

In impedance-based cell counting, the method relies on measuring changes in electrical impedance as cells pass through an electric field, which is indicated by a difference in voltage before and after the cells traverse the detection area. When cells are present in the measurement region, they disrupt the flow of electric current, causing a measurable change in impedance. This change is directly related to the number of cells and their characteristics, allowing for quantification.

This approach contrasts with other methods that do not involve electrical measurement, such as those focusing on weight or coloring of the cells. The weight of cells would not provide the necessary data about cellular characteristics and counts, while color intensity is more relevant in optical methods like flow cytometry, which utilizes staining rather than electrical properties. The size of the electrode is also not a relevant measurement in this context since it pertains more to the design of the counting apparatus rather than the actual counting mechanism. Thus, measuring the difference in voltage before and after cells attach is the fundamental principle behind impedance-based cell counting.