Introducing interactive components into furniture has proven difficult due to the different lifespans of furniture and digital devices. We present Foxels, a modular, smart furniture concept that allows users to create their own interactive furniture on demand by simply snapping together individual building blocks. The modular design makes the system flexible to accommodate a variety of interactive furniture setups, making it particularly well-suited for re-configurable spaces. Considering the trade-off between ease-of-use and high versatility, we explored a number of interaction methods that can be applied to modular interactive furniture, thereby extending the well-known tangible programming paradigm. After explaining our implementation, we demonstrate the validity of the proposed concepts by presenting how Foxels can be used in an ideation workshop along with many additional real-world examples.

We present RESi (Resistive tExtile Sensor Interfaces), a novel sensing approach enabling a new kind of yarn-based, resistive pressure sensing. The core of RESi builds on a newly designed yarn, which features conductive and resistive properties. We run a technical study to characterize the behaviour of the yarn and to determine the sensing principle. We demonstrate how the yarn can be used as a pressure sensor and discuss how specific issues, such as connecting the soft textile sensor with the rigid electronics can be solved. In addition, we present a platform-independent API that allows rapid prototyping. To show its versatility, we present applications developed with different textile manufacturing techniques, including hand sewing, machine sewing, and weaving. RESi is a novel technology, enabling textile pressure sensing to augment everyday objects with interactive capabilities.

FlexCase is a novel flip cover for smartphones, which brings flexible input and output capabilities to existing mobile phones. It combines an e-paper display with a pressure- and bend-sensitive input sensor to augment the capabilities of a phone. Due to the form factor, FlexCase can be easily transformed into several different configurations, each with different interaction possibilities. Users can use FlexCase to perform a variety of touch, pressure, grip and bend gestures in a natural manner, much like interacting with a sheet of paper. The secondary e-paper display can act as a mechanism for providing user feedback and persisting content from the main display. In this paper, we explore the rich design space of FlexCase and present a number of different interaction techniques. Beyond, we highlight how touch and flex sensing can be combined to support a novel type of gestures, which we call Grip & Bend gestures. We also describe the underlying technology and gesture sensing algorithms. Numerous applications apply the interaction techniques in convincing real-world examples, including enhanced e-paper reading and interaction, a new copy and paste metaphor, high degree of freedom 3D and 2D manipulation, and the ability to transfer content and support input between displays in a natural and flexible manner.

Today's commercially available prosthetic limbs lack tactile sensation and feedback. Recent research in this domain focuses on sensor technologies designed to be directly embedded into future prostheses. We present a novel concept and prototype of a prosthetic-sensing wearable that offers a non-invasive, self-applicable and customizable approach for the sensory augmentation of present-day and future low to mid-range priced lower-limb prosthetics. From consultation with eight lower-limb amputees, we investigated the design space for prosthetic sensing wearables and developed novel interaction methods for dynamic, user-driven creation and mapping of sensing regions on the foot to wearable haptic feedback actuators. Based on a pilot-study with amputees, we assessed the utility of our design in scenarios brought up by the amputees and we summarize our findings to establish future directions for research into using smart textiles for the sensory enhancement of prosthetic limbs.

In this paper, we present Presstures, an extension to current multi-touch operations that enriches common multi-finger gestures with pressure information. By using the initially applied pressure level for implicit mode switching, a gesture can be enhanced with different functionalities to enlarge the interaction space for multi-touch. To evaluate the feasibility of our concept, we conducted an experiment, which indicates good human sensorimotor skills for performing multi-touch gestures with a few number of pressure levels and without any additional feedback. Based on the experimental results, we discuss implications for the design of pressure-sensitive multi-touch gestures, and propose application scenarios that make optimal use of our concept.

We present FlexSense, a new thin-film, transparent sensing surface based on printed piezoelectric sensors, which can reconstruct complex deformations without the need for any external sensing, such as cameras. FlexSense provides a fully self-contained setup which improves mobility and is not affected from occlusions. Using only a sparse set of sensors, printed on the periphery of the surface substrate, we devise two new algorithms to fully reconstruct the complex deformations of the sheet, using only these sparse sensor measurements. An evaluation shows that both proposed algorithms are capable of reconstructing complex deformations accurately. We demonstrate how FlexSense can be used for a variety of 2.5D interactions, including as a transparent cover for tablets where bending can be performed alongside touch to enable magic lens style effects, layered input, and mode switching, as well as the ability to use our device as a high degree-of-freedom input controller for gaming and beyond.

Triggering commands on large interactive surfaces is less efficient than on desktop PCs. It requires either large physical movements to reach an interaction area (e.g., buttons) or additional operations to call context menus (e.g., dwell). There is a lack of efficient ways to trigger shortcuts. We introduce Kolibri - a pen-based gesture system that allows fast access of commands on interactive whiteboards. Users can draw tiny gestures (approx. 3 mm) anywhere on the surface to trigger commands without interfering with normal inking. This approach does neither require entering a gesture mode, nor dedicated gesture areas. The implementation relies on off-the-shelf hardware only. We tested the feasibility and explored the properties of this technique with several studies. The results from a controlled experiment show significant benefits of Kolibri comparing to an existing approach.

When multiple users are simultaneously sharing a workspace, it is not always clear what should happen when a user invokes an undo action. In this paper we explore different user interfaces for undo/redo for co-located collaborative workspaces, such as large interactive whiteboards. A preliminary study revealed that users expect neither a global nor personal undo, but rather a regional undo. We propose and evaluate three automatic regional undo/redo techniques (clustering, workspace, field of view) designed for a large interactive whiteboard. The results of the evaluation showed that an undo technique based on users' field of view was most preferred, while the content-based clustering technique produced most errors. We conclude with potential improvements to the developed techniques, and propose a set of design recommendations for implementing regional undo/redo on large interactive surfaces.

Ferroelectric material supports both pyro- and piezoelectric effects that can be used for sensing pressures on large, bended surfaces. We present PyzoFlex, a pressure-sensing input device that is based on a ferroelectric material. It is constructed with a sandwich structure of four layers that can be printed easily on any material. We use this material in combination with a high-resolution Anoto-sensing foil to support both hand and pen input tracking. The foil is bendable, energy-efficient, and it can be produced in a printing process. Even a hovering mode is feasible due to its pyroelectric effect. In this paper, we introduce this novel input technology and discuss its benefits and limitations.