Static force transducer based on resonant piezoelectric structure: root cause investigation

The aim of this paper is to investigate the design and the integration of a static force sensor based on a resonant bulk acoustic wave piezoelectric transducer. Experimental measurements of the electrical admittance spectrum show its dependence on the applied force. We noticed that the quality of the frequency response for a given vibration mode degrades with the increase of the applied force, which limits the force measuring range. The root cause of the response-stress dependence is investigated by means of the developed analytical model and a finite element analysis. The analysis results show that the selected operating vibration mode, the components of the structure on which the piezoelectric specimen is positioned and the boundary conditions at the contact interfaces between all the components have a direct effect on the electrical admittance spectrum. A modified structure was proposed to enhance the quality of the frequency response. The experimental tests show higher measuring range (up to 1500 N).