Design, development, and validation of a soft electronic skin based on piezoelectric polymers

This thesis explores the design, development, and validation of a soft electronic skin based on piezoelectric polymers. The electronic skin incorporates spatially distributed sensory elements that function as artificial mechanoreceptors, enabling the detection of tactile stimuli in robotic and prosthetic applications. The research focuses on two main aspects: the design and fabrication of bioinspired artificial skin that emulates the mechanical properties of human skin to support effective haptic perception, and the influence of the soft protective layer on signal transduction. First, the thesis outlines the fabrication process of the electronic skin, focusing on the tactile sensing layer, which is based on PVDF (polyvinylidene fluoride) transducers. These transducers were chosen for their capability to detect dynamiccontactsandtransientevents, effectivelycoveringthefull frequency range of all human mechanoreceptors. A soft protective layer, made of Dragon Skin silicone, emulates the softness of human skin and protects the embedded sensors. This layer was carefully optimized in terms of thickness to enhance the functionality of the electronic skin. Additionally, the thesis presents a mathematical and finite element model to study indentation on the electronic skin surface. The model evaluates how the elastomeric protective layer transmits distributed normal and tangential forces to the PVDF transducer. This dimensionless approach develops a flexible framework for predicting mechanical-to-electrical signal conversion, supporting the optimization of soft electronic skin designs across different transducer types and configurations. Also, the thesis investigates the properties of the protective layer, examining its viscoelastic and hyperelastic characteristics through finite element simulations and a pilot experimental campaign. This analysis aims to understand how these material properties influence the tactile response of the skin. Finally, a FEM analysis is presented to study the slippage phenomenon between a rigid surface and a Dragon Skin fingertip, aiming to characterize this behavior towards the development of slip detection algorithms.