| 摘要 |
<p>A surface acoustic wave (SAW) sensor comprises a transducer (24) provided on a substrate (23), wherein the transducer (24) is orientated on the substrate (23) so that the direction of acoustic wave propagation is such that the variation of sensor output with temperature, associated with the variation of the substrate third-elastic constants with temperature, substantially equal but opposite to the sum total of the variation of sensor output with temperature associated with the substrate linear temperature coefficient of expansion and with the variations with temperature of the substrate non-zero third-order elastic constants, the substrate first-order elastic constants and the substrate density. The effect of temperature variation on sensor output is thereby minimised. This is achieved with a 35 degree arrangement or with reflective gratings inclined at an angle of 3.1 degree to the normal. Additionally a robost package with a dish is given. Particular application is the measurement of torque.</p> |
