Impedance -based single cell analysis systems are commonly known as Coulter counters . They represent a well-established method for counting and sizing virtually any kind of cells and particles. The label-free technology has recently been enhanced by a " lab-on-a-chip " based approach and by applying high frequency alternating current (AC) in the radio frequency range (from 100 kHz to 30 MHz) instead of a static direct current (DC) or low frequency AC field.  This patented technology allows a highly accurate cell analysis and provides additional information like membrane capacitance and viability . The relatively small size and robustness allow battery powered on-site use in the field.