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Numerical prediction and measurement of the piezoelectric transducer response to laser generated stress waves

One milestone achievement of HYMNOS subproject 1 features the collaboration of the projects HYMNOS and MeDiOO at HOT in order to complement optoacoustic signals detected in the lab by means of numerical simulations. This collaboration is ultimately aimed at predicting and understanding optoaocustic (OA) signal generation in biological tissue.

Recently, we created a software tool that implements a simple electromechanical finite difference model to study the response of a piezoelectric polyvinylidenflourid (PVDF) transducer to trespassing optoacoustic pressure waves in the acoustic nearfield prior to thermal relaxation of the OA source volume. Complementing transducer signals measured in a controlled laboratory experiment with numerical simulations of an adequate model of the experimental setup, we find that, bearing in mind the apparent limitations of the one-dimensional approach, the simulated transducer signals can be used very well to predict and interpret the experimental findings.

The figure below illustrates (a) the numerical simulation of the transducer response using our finite difference model for one of the source volume configurations studied in the context of the thesis, (b) the verification of our results via an elaborate finite-volume implementation of an acoustic 1D Riemann solver (provided by the open source PyClaw CLAWPACK tool), and, (c) a measured curve recorded using a PVDF transducer. In either subfigure the dashed curve indicates the low-pass blurring of the full experimental setup.

Overview subproject 1