What is the principle behind impedance-based cell counting?

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Multiple Choice

What is the principle behind impedance-based cell counting?

Impedance-based counting uses the Coulter principle: a constant current flows through a tiny aperture filled with conductive solution. When a cell passes through that aperture, it briefly increases the electrical resistance (impedance) because the cell is less conductive than the surrounding saline. This tiny impedance pulse is detected, counted, and its height is roughly proportional to the cell’s size. By counting the pulses per unit time, you get the cell concentration, and by analyzing pulse height, you get an estimate of cell size distribution. The sample must be in a conductive, isotonic medium, and readings can be affected by bubbles or cell clumps. This approach relies on electrical properties, unlike optical methods (which use light scattering or fluorescence) or magnetic methods.

Impedance-based counting uses the Coulter principle: a constant current flows through a tiny aperture filled with conductive solution. When a cell passes through that aperture, it briefly increases the electrical resistance (impedance) because the cell is less conductive than the surrounding saline. This tiny impedance pulse is detected, counted, and its height is roughly proportional to the cell’s size. By counting the pulses per unit time, you get the cell concentration, and by analyzing pulse height, you get an estimate of cell size distribution. The sample must be in a conductive, isotonic medium, and readings can be affected by bubbles or cell clumps. This approach relies on electrical properties, unlike optical methods (which use light scattering or fluorescence) or magnetic methods.

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