Abstract: A sensing system which comprises a material (30) formed of a matrix and a plurality of non-insulating particles (40) substantially equally spaced within the matrix such that the material has coherent electrical periodicity in at least one dimension; and a receiver (10), the receiver arranged to receive a source RF signal and a returned RF signal, the source RF signal being reflected by the non-insulating particles to produce the returned RF signal. A change in the position of one or more of the non-insulating particles causes the returned RF signal to change, such that a change in a property of the material can be determined from the returned RF signal.

Abstract: A sensing system which comprises a material (30) formed of a matrix and a plurality of non-insulating particles (40) substantially equally spaced within the matrix such that the material has coherent electrical periodicity in at least one dimension; and a receiver (10), the receiver arranged to receive a source RF signal and a returned RF signal, the source RF signal being reflected by the non-insulating particles to produce the returned RF signal. A change in the position of one or more of the non-insulating particles causes the returned RF signal to change, such that a change in a property of the material can be determined from the returned RF signal.

Abstract: Provided is a remote sensing apparatus comprising: (a) an electromagnetic field detector and (b) an acoustic resonator comprising an electromagnetic field generator and a sensing material in wireless communication with the generator; wherein the sensing material is in wireless communication with the detector, and an acoustic property of the sensing material is responsive to a change in state of an environment to which the sensing material is exposed, and wherein the sensing material is in the form of one or more particles and/or fragments.

Abstract: An acoustic monitor assembly for monitoring the particulate content of a liquid, comprising, a body having an electrically conductive portion, the body contacting a liquid whose content is to be monitored in use, a magnetic field generator for generating a magnetic field to which the electrically conductive portion of the body is exposed, the magnetic field generator being positioned such that magnetic particulates in the liquid are drawn on to said body, and a signal generator for inducing eddy currents which oscillate at an acoustic frequency in the electrically conductive portion of the body and in response to which the body is caused to vibrate, and a monitoring for observing the vibration condition of the body so as to provide an indication of the content of said particulates which are drawn onto the body in the liquid.