Development of Hybrid Piezoelectric Materials for Tactile Sensing

As the robotics is moving its interest from the machine tools for industrial production to biomimetic, even human-like systems, the need for materials that fulfill skin role arises. Skin presents a structure that has multiple roles such as protection and tact. The basic requirements for a skin mimetic material are flexibility and a measurable physical property triggered by the pressure. In this work hybrid piezoelectric materials are prepared and characterized. The flexibility of materials is assured by the polymeric matrices while ceramic oxide fillers grant a piezoelectric response. Polyvinilidene fluoride (PVDF) is used both in its piezoactive β-form and piezopassive α-form, in order to investigate the contribution of the organic phase to the overall response. Polymethylmethacrylate (PMMA) is also used in order to compare the behavior of an amorphous and a semi-crystalline polymer. Lead-based ceramics were avoided, despite they are known to be the most effective piezoelectric materials, to prevent complications in terms of toxicity. Ceramic materials with lower piezoelectric coefficient, but more suitable for human robotics such as barium titanate and zinc oxide are preferred. Organic matrices and ceramic powders are then employed for preparing composites with different compositions, microstructures and mechanical behaviors, in order to evaluate their piezoelectric response in view of their application as sensing skin for robots.