Optimization of structural and poling strategies in piezoelectric elastomer composites for soft sensing applications

• Flexible PDMS/BaTiO 3 composites were designed for biomedical applications. • Dielectric and piezoelectric properties were analyzed. • Properties were optimized by dielectrophoresis and bimodal particle distribution. • d 33 and d 31 increased by ≈10 and ≈5 times compared to monomodal random composite. • Innovative poling strategy enabled further improvement of piezoelectric coupling. Piezoelectric flexible sensors are emerging as key components in medical applications, offering unique electromechanical properties for various diagnostic and therapeutic purposes. In this study, ceramic-filled silicone composites were developed as high-performance piezoelectric materials suitable for soft biomedical sensing applications. To enhance their electromechanical response, a multi-parametric design strategy was adopted, combining three approaches: the use of bimodal particle size distribution and the dielectrophoretic alignment of these particles within the matrix, supported by an optimized poling process. Results revealed that composites with an oriented particle distribution, consisting of 25 % of micro-sized particles and 75 % of nano-sized particles exhibited significant improvements in piezoelectric coefficient (d 33 ) compared to composites with randomly distributed particles. Additionally, the piezoelectric transverse coefficient (d 31 ) was significantly improved under in situ poling conditions, particularly in nano-rich and hybrid systems. These findings underline the potential of combining particle alignment, size hybridization, and poling optimization in enhancing the performance of piezoelectric composites for innovative medical sensor applications.