DISTINGUISHING BETWEEN ACTIVATED AND NONACTIVATED EOSINOPHILS BY AC-IMPEDANCE MEASUREMENTS

A cellular electrical impedance device which can detect the activated state of eosinophils has been developed and tested. This impedance dev ice consists of a small gold electrode (50 mu m x 50 mu m) and a large gold electrode (1.5 cm x 0.5 cm) on a glass substrate, and it was fab ricated by standard photolithographic techniques. Eosinophils, which b elong to the granulocytic class of white blood cells, exhibit differen t physical properties when they change from the nonactivated state to the activated state. Hypothetically, these changes should correspond t o a change in the measured electrical impedance. In this paper, data f rom the measured electrical impedance of eosinophils is presented. The measurements show that the average impedance of the activated eosinop hils is 26% lower than the average impedance of the nonactivated eosin ophils. Statistical analysis of the measured data shows that there is a significant difference between the measured impedances of activated and nonactivated eosinophils.