Micro-electric impedance spectra of isolated cells recorded in micro-channels

Electric impedance (EI) spectra (1kHz-20Mhz) of isolated polymorphonuclear leukocytes and red blood cells were recorded by positioning individual cells between pairs of metal electrodes in slender rectangular channels (∼40 10^-12 m² cross-sectional area). The present study was designed to demonstrate that cell type, viability and dielectric properties can be discerned on the basis of raw micro-EI spectral data. Each micro-EI MEMS device was tested to quantify the frequency-dependent impedance of the electrode-electrolyte interface at the experimental current density. Sensitivity of the technique to changes in sample properties was tested by filling the recording zone with a variety of materials and cells with known dielectric properties. Small changes in cell media ionic concentration and cellular dielectric properties were quantifiable by analysis of EI data. Results further show that micro-EI signatures of the device when loaded with red blood cells (RBCs) vs. polymorphonuclear leukocytes (PMNs), or vital vs. non-vital PMNs were significantly different thus allowing cell identification on the basis of spectral signatures.