Our physiological activity reflects our inner workings. However, we are not always aware of it in full detail. Physiological devices allow us to monitor and create adaptive systems and support introspection. Given that these devices have access to sensitive data, it is vital that users have a clear understanding of the internal mechanisms (extrospection), yet the underlying processes are hard to understand and control, resulting in a loss of agency. In this work, we focus on bringing the agency back to the user, by using design guidelines based on principles of honest communication and driven by positive activities. To this end, we conceived a tangible, modular approach for the construction of physiological interfaces that can be used as a prototyping toolkit by designers and researchers, or as didactic tools by educators and pupils. We show the potential of such an approach with a set of examples, supporting introspection, dialog, music creation, and play.

Single-hand microgestures have been recognized for their potential to support direct and subtle interactions. While pioneering work has investigated sensing techniques and presented first sets of intuitive gestures, we still lack a systematic understanding of the complex relationship between microgestures and various types of grasps. This paper presents results from a user elicitation study of microgestures that are performed while the user is holding an object. We present an analysis of over 2,400 microgestures performed by 20 participants, using six different types of grasp and a total of 12 representative handheld objects of varied geometries and size. We expand the existing elicitation method by proposing statistical clustering on the elicited gestures. We contribute detailed results on how grasps and object geometries affect single-hand microgestures, preferred locations, and fingers used. We also present consolidated gesture sets for different grasps and object size. From our findings, we derive recommendations for the design of microgestures compatible with a large variety of handheld objects.

Spatial Augmented Reality (SAR) transforms real-world objects into interactive displays by projecting digital content using video projectors. SAR enables co-located collaboration immediately between multiple viewers without the need to wear any special glasses. Unfortunately, one major limitation of SAR is that visual content can only be projected onto its physical supports. As a result, displaying User Interfaces (UI) widgets such as menus and pop-up windows in SAR is very challenging. We are trying to address this limitation by extending SAR space in mid-air. In this paper, we propose Drone-SAR, which extends the physical space of SAR by projecting digital information dynamically on the tracked panels mounted on a drone. DroneSAR is a proof of concept of novel SAR User Interface (UI), which provides support for 2D widgets (i.e., label, menu, interactive tools, etc.) to enrich SAR interactive experience. We also describe the implementation details of our proposed approach.

Traditional computer systems based on the WIMP paradigm (Window, Icon, Menu, Pointer) have shown potential benefits at school (e.g. for web browsing). On the other hand, they are not well suited as soon as hands-on and collaborative activities are targeted. We present CARDS, a Mixed-Reality system that combines together physical and digital objects in a seamless workspace to foster active and collaborative learning. We describe the design process based on a participatory approach with researchers, teachers, and pupils. We then present and discuss the results of a user study that tends to show that CARDS has a good educational potential for the targeted activities.

Despite the increasing popularity of soft interactive devices, their fabrication remains complex and time consuming. We contribute a process for rapid do-it-yourself fabrication of soft circuits using a conventional desktop inkjet printer. It supports inkjet printing of circuits that are stretchable, ultrathin, high resolution, and integrated with a wide variety of materials used for prototyping. We introduce multi-ink functional printing on a desktop printer for realizing multi-material devices, including conductive and isolating inks. We further present DIY techniques to enhance compatibility between inks and substrates and the circuits' elasticity. This enables circuits on a wide set of materials including temporary tattoo paper, textiles, and thermoplastic. Four application cases demonstrate versatile uses for realizing stretchable devices, e-textiles, body-based and re-shapeable interfaces.

Mixed Reality systems combine physical and digital worlds, with great potential for the future of HCI. It is possible to design systems that support flexible degrees of virtuality by combining complementary technologies. In order for such systems to succeed, users must be able to create unified mental models out of heterogeneous representations. In this paper, we present two studies focusing on the users' accuracy on heterogeneous systems using Spatial Augmented Reality (SAR) and immersive Virtual Reality (VR) displays, and combining viewpoints (egocentric and exocentric). The results show robust estimation capabilities across conditions and viewpoints.

Single-hand thumb-to-finger microgestures have shown great promise for expressive, fast and direct interactions. However, pioneering gesture recognition systems each focused on a particular subset of gestures. We are still in lack of systems that can detect the set of possible gestures to a fuller extent. In this paper, we present a consolidated design space for thumb-to-finger microgestures. Based on this design space, we present a thumb-to-finger gesture recognition system using depth sensing and convolutional neural networks. It is the first system that accurately detects the touch points between fingers as well as the finger flexion. As a result, it can detect a broader set of gestures than the existing alternatives, while also providing high-resolution information about the contact points. The system shows an average accuracy of 91% for the real-time detection of 8 demanding thumb-to-finger gesture classes. We demonstrate the potential of this technology via a set of example applications.

Digital technology has been completely integrated into our daily lives, yet the potential of technology to improve its users' life satisfaction is still largely untapped. Mindfulness, the act of paying a deliberate and non-judgmental attention to the present moment, has been shown to have a positive impact on a person's health and subjective well-being--commonly called "happiness". Based on an iterative process with meditation teachers and practitioners, we designed a new tool to support mindfulness practices. This tool takes the shape of an augmented sandbox, designed to inspire the user's self-motivation and curiosity. By shaping the sand, the user creates a living miniature world that is projected back onto the sand. The natural elements of the garden are connected to real-time physiological measurements, such as breathing, helping the user to stay focused on the body. Moreover, using a Virtual Reality headset, they can travel inside their garden for a dedicated meditation session. Preliminary results seem to indicate that the system is well suited for mindfulness and induces a calm and mindful state on the user. The meditation teachers envisioned the use of Inner Garden in their practice.

Most of our daily activities take place in the physical world, which inherently imposes physical constraints. In contrast, the digital world is very flexible, but usually isolated from its physical counterpart. To combine these two realms, many Mixed Reality (MR) techniques have been explored, at different levels in the continuum. In this work we present an integrated Mixed Reality ecosystem that allows users to incrementally transition from pure physical to pure virtual experiences in a unique reality. This system stands on a conceptual framework composed of 6 levels. This paper presents these levels as well as the related interaction techniques.

Virtual Reality allows rapid prototyping and simulation of physical artefacts, which would be difficult and expensive to perform otherwise. On the other hand, when the design process is complex and involves multiple stakeholders, decisions are taken in meetings hosted in the physical world. In the case of aerospace industrial designs, the process is accelerated by having asymmetric collaboration between the two locations: experts discuss the possibilities in a meeting room while a technician immersed in VR tests the selected alternatives. According to experts, the current approach is not without limitations, and in this work, we present prototypes designed to tackle them. The described artefacts were created to address the main issues: awareness of the remote location, remote interaction and manipulation, and navigation between locations. First feedback from experts regarding the prototypes is also presented. The resulting design considerations can be used in other asymmetric collaborative scenarios.

Spatial augmented reality and tangible interaction enrich the standard computer I/O space. Systems based on such modalities offer new user experiences and open up interesting perspectives in various fields. On the other hand, such systems tend to live outside the standard desktop paradigm and, as a consequence, they do not benefit from the richness and versatility of desktop environments. In this work, we propose to join together physical visualization and tangible interaction within a standard desktop environment. We introduce the concept of Tangible Viewport, an on-screen window that creates a dynamic link between augmented objects and computer screens, allowing a screen-based cursor to move onto the object in a seamless manner. We describe an implementation of this concept and explore the interaction space around it. A preliminary evaluation shows the metaphor is transparent to the users while providing the benefits of tangibility.

We present a prototype of an augmented sandbox where the sand is used to create a miniature living world, designed as an ambient display for contemplation and self-reflection. The landscape can be reshaped at any time. Once the sand is left still for a moment, the world starts evolving -- vegetation grows, water flows and creatures move around -- according to the user's internal state. We use a consumer-grade EEG and breathing sensors to reflect on frustration and meditative states of users, which they can monitor by looking at the sandbox.