Abstract: A method and structure for designing near-field probes with high sensitivity used in detecting a wide variety of materials and objects such as biological anomalies in tissues, cracks on metallic surfaces, location of buried objects, or composition of material such as permittivity and permeability . . . etc., is disclosed. The present invention includes using single or multiple metamaterial unit cells or metamaterial particles as near-field sensors. Metamaterial unit cells are defined as the building blocks used for fabricating metamaterials that provide electrical or magnetic properties not found in naturally occurring media. Metamaterial unit cells or particles include split-ring resonators, complementary split-ring resonators, or a variety of other electrically-small resonators made of conducting wires or conducting flat surfaces. Metamaterial unit cells are excited by appropriate excitations such as small loops, microstriplines, etc.