Phononic crystals (PnC) consist of two or more materials arranged in a spatially periodic manner. Introduction of a defect into the crystal lattice is a technique to create resonant modes. The idea behind the application of a PnC as sensor element is the dependence of the characteristic features of those modes on speed of sound. Currently the sensor designs are based on common 2D phononic crystal geometries. A liquid-filled defect in the crystal lattice creates a resonant mode used for the determination of sound velocity of the confined analyte. This (complex) value allows the determination of thermodynamic values which are linked to molecular properties of (bio)chemical samples. The objective of our current research is two-fold: a new geometry considering disposable elements containing the analyte while keeping the high sensitivity of the acoustic sensor signal and suppressing influences of unavoidable inaccuracies when replacing the analyte container.