Estimation of thickness, complex bulk permittivity and surface conductivity using interdigital dielectrometry

Theoretical techniques for deducing continuum parameters from the gain-phase response of interdigital electrodes provide a basis for experiments that demonstrate the use of 50- mu m or 1-mm-wavelength interdigitated electrodes for the absolute measurement of: (1) the thickness and voltage of a layer formed by the sedimentation of 41- mu m particles in transformer oil; (2) the thickness and high-frequency bulk permittivity of plasma-deposited bromobenzene and vacuum-deposited parylene, the former in situ; (3) the complex permittivity of transformer oil without and with a parylene layer for passification against adsorption of water; (4) the dispersion of oil-impregnated paper having a finite thickness; and (5) the surface conductivity due to adsorption of water on a silicon dioxide substrate. The frequency range for (3)-(5) is 0.005 Hz to 10 kHz. Difficulties apparently due to charging effects on the integrated circuitry are discussed.<>