Papers Published

1. Plonsey, Robert and Collin, Robert, ELECTRODE GUARDING IN ELECTRICAL IMPEDANCE MEASUREMENTS OF PHYSIOLOGICAL SYSTEMS EM DASH A CRITIQUE., Medical & Biological Engineering & Computing, vol. 15 no. 5 (1977), pp. 519 - 527 .
   (last updated on 2007/04/16)

   Abstract:
   The application of the guard ring has been advanced as a method for focusing the applied current in performing electrical-impedance measurements of volume conductors. The objective is to obtain impedance and/or its variation at localized regions of heterogeneous tissue. The paper discusses the capabilities and limitations of both guarded and unguarded measurements and shows that the application of guarding does not, normally, fulfil the capabilities being ascribed to it. A comparison is made of the guarded system under constant-current and constant-voltage constraints with an unguarded electrode system, and it is shown that the guarded system does not have any significant advantages.

   Keywords:
   ELECTRIC MEASUREMENTS - Impedance;BIOLOGICAL MATERIALS - Tissue;BIOMEDICAL EQUIPMENT - Electrodes;