Toward Flexible Piezoelectrets with High Environmental Stability: A Hybrid Approach

Abstract

In this work, an effective and low-cost method to fabricate hybrid piezoelectrets based on cyclic olefin copolymer (COC) and polypropylene (PP). The electromechanical properties of the hybrid piezoelectrets were characterized. In the hybrid piezoelectrets, PP constituted the overall structure while COC was used as surface layers for charge storage. The hybrid piezoelectrets exhibited good piezoelectric properties, flexibility, and significantly improved environmental stability. The hybrid piezoelectrets had a piezoelectric coefficient d33 up to 1200 pC/N. The PP piezoelectrets lost all piezoelectric activity after annealing for 16 hours at 70 °C. By comparison, even after 200 hours of annealing at 110 °C, the hybrid COC/PP piezoelectrets still retained 25% of the activity. The hybrid piezoelectrets also showed excellent stability under high humidity. The performance of the hybrid piezoelectrets as force sensors were demonstrated.