Abstract
This thesis investigates the design and fabrication of novel soft, passive interfaces, focusing on the affordances that emerge from their geometry, surface, and material properties. The design exploration spans across textile materials and 3D-printed smart structures capable of detecting touch and pressure, while providing soft and deformable surfaces for everyday interaction. As interactive systems become increasingly integrated into daily environments, this work examines how the overall interface form, together with the visual and tactile characteristics of the surface, and the structural qualities of materials such as flexibility, influence and support various forms of gestural interaction. The first part of this thesis examines how users interact with a three-dimensional surface, such as a touch-sensitive middle console for in-car use. A series of experiments evaluates the geometry of the 3D-surface in terms of usability and the types of gestural patterns users can perform on such 3D interfaces. This is followed by an exploration of how specific surface properties, such as visual and tactile features, guide on-surface gestures, including the design and prototyping of both functional and non-functional textile-based interfaces. The next part of the thesis focuses on the conceptualization and fabrication of soft, flexible structures that support out-of-plane interactions, such as pressure-based gestures. These structures are realized through deformable 3D-printed designs combined with ferromagnetic filaments that leverage inductive sensing, and are evaluated in terms of their mechanical properties, sensing performance, and long-term stability. Furthermore, by varying the configurations of ferromagnetic components within these 3D-printed structures, different application scenarios are demonstrated, including controllers, weight measurement systems, and smart wearables such as shoes. Together, these contributions form a design-driven approach to creating soft interfaces, demonstrating how form and soft materials such as textiles and 3D-printed deformable structures shape and influence the affordances of user interaction in everyday contexts.