There is currently a demand for flexible biomedical sensors. Characteristics as soft, thin, elastic, flexible and comfortable to the contact with skin should be matched with performance and ultimately made of sustainable, and biocompatible materials. In this work, chitosan as a flexible biodegradable polymeric matrix was combined with ferroelectric BaTiO3 particles obtained by hydrothermal synthesis to prepare flexible films. The biocomposites have high flexibility and the addition of particles improves the elasticity of pristine chitosan films. Of relevance towards the targeted application, the biocomposites exhibit a better resistance to water than chitosan. The dielectric permittivity increases with the addition of BaTiO3 particles. The observation of d33 and d15 by PFM, confirms the presence of piezoelectric domains corresponding to the location of BaTiO3 particles. These results contribute to the understanding of the role of functional oxides on the chemical and physical behavior of biobased polymers, creating opportunities to design optimized and more sustainable flexible piezoelectric sensor films.

The Front Cover shows a flexible functional biocomposite film composed of chitosan biopolymer and BaTiO3 particles, which was prepared by environmentally benign methodologies. This film is flexible, and its elasticity can be tailored by the addition of BaTiO3 particles. The dielectric permittivity increases with the barium titanate content. The evidence of piezoelectricity turns this material promising for the design of flexible piezoelectric sensor films. More information can be found in the Full Paper by P. Ferreira and co‐workers.