A sensor system accurately measures, with a high level of sensitivity, one or more vector components of a small electric field, through the use of multiple, relatively fixed sensors, at least one of which constitutes a weakly coupled capacitive sensor. The sensor system enables the electric field to be determined in a direction normal to a surface or along multiple orthogonal axes. Measurement of the electric field vector can provide improved resolution and characterization of electrical signals produced, for example, by organs within the human body.