There are various non-destructive techniques for determining the internal properties of materials in fluids, semi-solids, solids, and biological tissue. One of these techniques is low intensity ultrasonic testing. In this proceeding, a study on the architecture of a piezoelectric acoustic detector (PAD) is presented, from which the analysis for design, development and construction of the acoustic wave detector in the ultrasonic spectrum has emerged. Its aim is to apply it to soft matter and tissue. The 110 μm thick polyvinylidene fluoride (PVDF) piezoelectric element was used as the active element in the thickness mode configuration. Piezoelectric constitutive equations were applied to a one-dimensional model for the analysis. A cylindrical iron-nickel backing was used, and the parts were bonded with silver conductive epoxy glue. The results are presented. The equation for the output voltage of the piezoelectric acoustic detector is described. Functional testing of the PAD is demonstrated using the pulse-echo technique, in which an acoustic wave generator excited an ultrasonic immersion sensor in emission configuration and the DAP was connected to a digital oscilloscope to observe the received signal. Finally, pulsed photoacoustic spectroscopy was applied to a biological tissue emulator and yielded significant results in detection of a ruby sphere embedded in the emulator. It is proposed to further investigation the DAP models in multilayer structural configurations to increase their sensitivity.