A detector comprising control circuitry and a sensor, responsive to interactions of varying intensities, comprising three layers. The first layer includes a first set of mutually connected electrically conducting elements and a second set of mutually connected electrically conducting elements. The third layer comprises an electrically conducting plane, and the second layer extends between the first and third layers. The electrical conductivity of the second layer varies in accordance with variations in the intensity of the interactions. In a first mode, the control circuit applies voltage between the first and third layers to generate a first current through the second layer, and provides a measurement of the first current. In a second mode, the control circuit applies voltage between the first and second sets of electrically conducting elements to generate a second current through the second layer, and provides a measurement of the second current.