Fig. 1
From: Low-power transcutaneous current stimulator for wearable applications
Effective network impedance of two electrodes connected to a human appendage driven by a current source. r is typically in the order of 2 k\(\Omega \), and can be thought to roughly represent the resistance of the limb itself. R and C are usually in the order of 20–60 k\(\Omega \) and 30–600 nF and represent the resistance and capacitance of the electrode connection to the skin