Wearable haptic technologies for applications in rehabilitation and robotics

The aim of the thesis is to present two distinct approaches (High and Low TRL) to the design of wearable haptic technologies leading to different research challenges in the field of rehabilitation and robotics. Specifically, the High TRL approach consists in the integration of commercial components into a physical interface (system-level integration of components), while the Low TRL approach involves the merging of multiple disciplines from biology and medicine to engineering, electronics, physics, chemistry and materials science, to develop novel materials and functional devices (component-level design). A wearable tactile display, namely the VT belt was developed following the High TRL approach, through the integration of commercial vibrating motors (VT units) into a textile belt. The belt has been interfaced to sensorized shoes to deliver augmented sensory feedback to lower-limb amputees. The thesis reports on the design and validation of the VT belt through experiments involving both able-bodied subjects and transfemoral amputees. Along with the design of the VT belt, the Low TRL approach was explored in the field of robotics to fabricate flexible devices to be integrated into robotics platforms. Functionalization of flexible surfaces was achieved through the bottom-up synthesis and integration of nanomaterials onto flexible substrates, enabling the exploitation of the physical and chemical properties of the nanostructures to a macro scale. Following this approach, the piezoelectric properties of ZnO nanorods (NRs) and their fast response to dynamic loads, mimicking the behavior of human skin mechanoreceptors have been harnessed in the fabrication of tactile sensors able to detect pressures and vibrations and suitable for application as electronic skin. A similar fabrication concept was adopted to develop CNTs-based flexible adhesives that showed robustness and adhesion to smooth and rough surfaces in preliminary experiments, proving to be promising materials for improving grasping and manipulation abilities of robotic systems both at micro- and macroscale.