the invention relates to a capacitive sensor system for measuring environmental parameters by activating a capacitive array and causing fringe electric fields to intersect the surrounding environment . an oscillator is coupled to the capacitive array and the frequency of oscillation depends upon the capacitance of the array , which represents an environmental parameter . the sensor is suitable for measuring resistivity and dielectric constant parameters in geophysical , environmental , hydro - geological and related applications . the conductors of the capacitive array can be arranged around a perimeter for use , for example , in a borehole or the conductors can be arranged in the same plane for use , for example , beneath a raft in shallow water . in the situation where the boreholes are fluid - filled , there are economic and technical advantages in using the metal plugs , as the capacitive array in galvanic contact with the fluid .