Impedance plethysmography in human limbs. Part 1. On electrodes and electrode geometry.

Electrode design and electrode positioning are important factors in blood flow measurements using impedance plethysmography. Optimal electrode type and accurate positioning will decrease measurement errors and improve the signal-to-noise-ratio. Disk electrodes were found to be superior to tape electrodes because of their better skin-electrode stability and because they prevent limb compression. The distance between current electrodes and potential electrodes should be greater than 2.3 R (disk electrodes) and 1.5 R (tape electrodes) to avoid the influence of the so-called diffusion resistance (R is the radius of the limb at the electrode site).