Impedance measurement of bipolar stimulation electrodes immersed in medium

We measured the impedance of bipolar stimulation electrode immersed in two media of interest for electrostimulation: extracellular fluid (ECF), and cerebrospinal fluid (CSF). Using a convenient method, the impedance magnitude and phase were measured within a frequency range from 10 Hz to 20 kHz. The impedance magnitudes were in 1 kΩ range, having capacitive character, a strong frequency dependence, and observable dependence on temperature and medium layer thickness.