Abstract: A pressure monitoring device includes a rigid base (2) which has secured thereto a lid (5) to define a hermetically sealed chamber (6). The lid (5) is of flexible metal material and the major surface (5A) of the lid forms a diaphragm which will deflect in response to changes in the pressure surrounding the device. A substrate (7) upon which a plurality of SAW devices are laid down is supported on a rigid frame (3A) of the base so that the central region thereof is unsupported between edges (11, 12). A dimple (10) is formed in the lid (5) and presses on a central region of the substrate (7). Changes in pressure will accordingly cause distortion of the central region of the substrate. The end regions (8, 9) of the substrate (7) carry further SAW devices so that, by analyzing the changes in characteristics of all the SAW devices a temperature compensated indication of pressure change, together with an indication of absolute temperature, may be provided by interrogating the SAW devices.

Abstract: A wheel, particularly for a vehicle, includes at least a portion formed from non-metallic material which incorporates at least one sensor indicative of a condition sensed. A wheel is molded from a fiber reinforced plastics material and incorporates passive sensors capable of indicating conditions of the wheel or the tire associated with it (e.g., tire pressure or torque transmitted). The sensor output is processed by an ASIC device to provide an output signal to a communications device also mounted on the wheel. The ASIC and communications device are powered by a virtual battery which is charged by, e.g., using electrical pulses generated by strain within the wheel itself. An id tag may be provided to identify the wheel in question.

Abstract: A pressure monitoring device comprises a rigid base (2) which has secured thereto a lid (5) to define a hermetically sealed chamber (6). The lid (5) is of flexible metal material and the major surface (5A) of the lid forms a diaphragm which wil deflect in response to changes in the pressure surrounding the monitor. A substrate (7) upon which a plurality of SAW devices are laid down is supported on a rigid frame (3A) of the base so that the central region thereof is unsupported between edges (11, 12). A dimple (10) is formed in the lid (5) and presses on a central region of the substrate (7). Changes in pressure will accordingly cause distortion of the central region of the substrate. The end regions (8, 9) of the substrate (7) carry further SAW devices so that, by analysing the changes in characteristics of all the SAW devices a temperature compensated indication of pressure change, together with an indication of absolute temperature, may be provided by interrogating the SAW devices.