Devices and methods of the invention can be used in many industries, including, but not limited to, utilities, agriculture, food, textile, pharmaceutical, photovoltaic and semiconductor, medical devices, chemical and petro-chemical, material science, and defense, where monitoring and/or analysis of various properties of materials are desired. Sensors and methods of using same are provided for measuring at least one impedance of an object under test (or a tested object) at a predetermined frequency and/or a predetermined frequency range, particularly where resonance conditions are provided for such measurement.