Defence Kejun Shi: "Flexible Piezoelectric Composite Materials and Devices for Self-Powered Sensing"

Promotors: First promotor: Prof M.I. Acuautla Meneses, Second promotor Prof J. Scherpen

Abstract: Flexible piezoelectric materials offer a promising route toward self-powered sensing systems that are lightweight, mechanically compliant, and compatible with wearable and curved-surface applications. However, polymeric piezoelectrics such as PVDF-TrFE still face challenges in achieving high electromechanical performance while maintaining flexibility, processability, and practical device integration.

This thesis develops PVDF-TrFE-based flexible piezoelectric composites through coordinated material, interfacial, structural, and processing design. Heterostructured MWCNTs@BaTiO3 fillers and core-shell PANI@BaTiO3 particles are introduced to enhance polarization, interfacial coupling, and piezoelectric response. These material platforms are further translated into self-powered sensing devices for tactile perception, wearable biomechanical monitoring, and human-machine interaction. In addition, ultrasonic spray deposition is developed as a scalable route for fabricating large-area, conformal, and directly patterned C@BaTiO3/PVDF-TrFE films, enabling applications in plantar-pressure mapping and curved-surface vibration monitoring.

Overall, this work establishes an integrated design approach that connects polymeric piezoelectric fundamentals with practical self-powered sensing systems, providing a pathway toward flexible, scalable, and intelligent sensing technologies.

Dissertation