Last improvements in the analysis of resonant strip sensors

The paper proposes new improvements to a previously established two-dimensional model of 29.3 MHz NLC-cut strip resonators used as temperature sensors. Starting from that previous model, we present a model which takes into account the dependence of the vibration mode along the third coordinate i.e. along the length of the strip, by means of Hamilton´s principle. Thereafter, an estimation of the C₁ parameter is numerically achieved by performing additional simplifications, which have little effect onto the accuracy in the circumstance. We also present the results of a force-sensitivity experiment applying a compressive load equal to - 1N at the end of the sensor narrow plate. The measured frequency shift was close to 1.3 kHz. Simple calculations show that the frequency shift predicted by the acousto-elastic effect is much larger than the shift arising from the action of rigid stiffening onto the flexural branch coupled with thickness shear. These first investigations indicate that the force-frequency effect in strip resonators seems to be large enough to make them usable as force sensors.