Patent ID: 8803536

Claim:
A detector comprising a sensor and a control circuit in which: said sensor is responsive to interactions of varying intensities, and comprises a first layer, a second layer and a third layer, wherein said first layer includes a first set of electrically conducting elements which are mutually connected and a second set of electrically conducting elements which are mutually connected, said third layer comprises an electrically conducting plane, and said second layer extends between said first layer and said third layer and the electrical conductivity of said second layer varies in accordance with variations in the intensity of said interactions; and said control circuit is configured to: in a first mode of operation, apply voltage between said first layer and said third layer to generate a first current through said second layer, and thereby obtain a measurement of a first electrical characteristic which depends upon electrical resistance of said second layer; and in a second mode of operation, apply voltage between said first set of electrically conducting elements and said second set of electrically conducting elements to generate a second current through said second layer, and thereby obtain a measurement of a second electrical characteristic which depends upon electrical resistance of said second layer; wherein: when operated in said first mode, said sensor is sensitive to an initial first range of intensities of interactions; and when operated in said second mode, said sensor is less sensitive over said first initial range of intensities but provides a varying output over a second range of intensities that is substantially greater than said first range of intensities.