Abstract: Packaged materials are tested in a capacitive sensor which has plates whose spacing can be accurately adjusted, and whose plates are segmented so that selected segments can be employed. An a.c. voltage is applied across the capacitive plates at accurately known amplitude, phase, and frequency for a number of frequencies. A ratio bridge is tied to each number of frequencies. A ratio bridge is tied to each of the segments and provides outputs that reflect the a.c. voltage and current, both capacitive and ohmic. A zero-crossing detection method or time domain method can be employed to provide precise amplitude and phase, or a quadrature or phase-sensitive detection method can provide amplitude and phase, or a quadrature or phase-sensitive detection method can provide amplitude and phase of the a.c. current through each segment.