- Category: Technologies
- Published: Wednesday, 18 July 2012
Transense Technologies has developed two distinct sensors, one measures torque and temperature the other pressure and temperature, and the requisite electronics to interrogate and read them. These sensors utilise Surface Acoustic Wave (SAW) technology.
A SAW is an acoustic wave that travels along the surface of an elastic material. This kind of wave is commonly used in piezoelectric devices in electronic circuits. These piezoelectric devices will convert electrical pulses into mechanical vibrations and, conversely, mechanical vibrations into electrical pulses. A SAW resonant sensor is designed to resonate at a certain frequency, but if its piezoelectric substrate distorts through heat, mechanical stress or pressure, it will resonate at a different frequency. When a radio wave is directed at this device to interrogate its properties, it will, in the absence of any external forces, reflect (back scatter) a wave of the same frequency to the source. If, however, the device is subject to external force, e.g. heat or stress, the reflected wave will be of a different frequency and that change in frequency can be measured. The Company has developed a way of measuring the difference in frequency between these waves in a range of sensors, which can be used to accurately calculate torque, temperature and pressure. In order to read this change in frequency, the Company has developed associated interrogation electronics and software. These SAW devices are fabricated utilising common processes employed in the manufacture of silicon integrated circuits.
The Triple SAW Torque Device represents a breakthrough in quartz die technology, permitting temperature compensated strain measurement in 2 orthogonal directions for torque measurement in power steering and driveline applications
The Triple SAW Pressure Device is at the heart of Transense's TPMS technology, providing temperature compensated pressure measurement from a single quartz die operating in a simple bending mode
There are numerous automotive applications for our patented technology. Applications such as Tyre Pressure Monitoring Systems (TPMS), Electrical Power Assisted Steering (EPAS) and driveline management, we are now expanding into industrial markets. The diagram below shows how multiple SAW sensors can be incorporated into a single vehicle