Correlation Between Structural Parameters and Piezoelectric Performance of PVDF Heart Sound Sensors

The exceptional flexibility, piezoelectric properties, and biocompatibility of polyvinylidene fluoride (PVDF) make it an ideal material for flexible heart sound sensors. This study systematically investigates how the key sensor design parameters of area, aspect ratio, thickness, and encapsulation layer influence piezoelectric output performance, establishing the underlying governing relationships.

Beginning with a formalization of the direct piezoelectric mechanism and constitutive equations for PVDF, we developed a parametric COMSOL Multiphysics model to probe the influence of sensor design. This model informed the fabrication of multiple sensor samples, whose performance was then benchmarked against simulations via a custom mechanical test system. Ultimately, a dedicated heart sound simulation setup assessed the acquisition fidelity of our proprietary D-type sensor.

Simulation and experiment confirmed the direct piezoelectric mechanism. Sensitivities on the order of 10^-15 to 10^-14 C/Pa were measured, with a linearity characterized by a coefficient of determination (R²) exceeding 0.978. Output increased with sensor area. Polydimethylsiloxane (PDMS) encapsulation enhanced performance compared to unencapsulated variants. Notable deviations arose between simulation and experiment concerning the effects of thickness and aspect ratio. The proprietary D-type sensor produced a root mean square (RMS) output voltage (V_RMS) approximately 1.79 times that of its commercial counterpart.

This study establishes a validated framework for optimizing PVDF heart sound sensors, demonstrating that output performance is enhanced by augmenting the effective area, minimizing film thickness, maintaining a moderate aspect ratio, and utilizing a PDMS encapsulation layer. The close agreement between simulation and experiment underpins this guidance, providing a direct pathway for engineering sensor design.