Modulation techniques of the SAW sensor's echo in accordance with the physical phenomena

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It is already known that the centre frequency of the surface acoustic wave is determined by the shape and spacing of the IDT and its fingers. For a simple IDT structure the centre wavelength and thus frequency is determined by the spacing between consecutive positive and negative electrodes. Thus by straining the material in the direction perpendicular to the electrodes, measurable frequency modulation will occur. It is yet to be researched and understood how other physical phenomena allow wave modulation. Moreover, various transducer techniques shall be examined (e.g. 3-phase IDT, finger withdrawal,varying finger overlap etc.) to achieve the best results. It is known that by converting EM wave into acoustic one the IDT excites more modes than it is desired. More specifically bulk waves can be observed, however they are undesired as they contribute to energy loss. Other modes will also be excited and the key challenge will be to minimize the effect of the slowest ones on the overall system accuracy. Moreover, guided acoustic waves shall be considered and examined to evaluate their sensitivity to the aforementioned stimuli, and whether mode spreading (due to most likely laminated structure) can be contained. Finally, other sensing options shall be considered, e.g. slow wave structures. To achieve all of the above simulation models shall be built and tested.