UTAP - Unique Topographies for Acoustic Propagation: Designing Algorithmic Waveguides for Sensing in Interactive Malleable Interfaces.

Construction and sensing within malleable interfaces is usually limited by a number of constraints. Building the interface from diverse combinations of conductive and nonconductive soft materials, such as fabrics or foams combined with various sensors, complicates the manufacturing process and offers limited options in shaping. In this paper we propose \"Unique Topologies for Acoustic Propagation\" (UTAP), a novel approach for algorithmic design of malleable tangible interfaces. A fundamental feature of our approach is the implementation of algorithmically generated topologically distinct lattices that, attached to piezoelectric (PZT) transducers, allow us to sense and recognize changes in a modulated acoustic signal on deformation and classify it into different interaction states. Our systematic approach to manufacturing malleable interfaces opens possibilities to design shapes that allow implementation in a wide range of potential use cases. We demonstrate the UTAP approach on multiple interfaces assembled using laser cut and 3D printed lattices in conjunction with silicon compound moulding. Finally, we present a technical evaluation of our method based on studies of four distinct interface designs, assessing performance in sensing and localising simple deformations such as pressing on single and multiple spots, as well as different force levels and actions, including bending and twisting.