OBJECTIVE: While non-invasive, cuffless blood pressure (BP) measurement has demonstrated relevancy in controlled environments, ambulatory measurement is important for hypertension diagnosis and control. We present both in-lab and ambulatory BP estimation results from a diverse cohort of participants. METHODS: Participants (N=1125, aged 21-85, 49.2% female, multiple hypertensive categories) had BP measured in-lab over a 24-hour period with a subset also receiving ambulatory measurements. Radial tonometry, photoplethysmography (PPG), electrocardiography (ECG), and accelerometry signals were collected simultaneously with auscultatory or oscillometric references for systolic (SBP) and diastolic blood pressure (DBP). Predictive models to estimate BP using a variety of sensor-based feature groups were evaluated against challenging baselines. RESULTS: Despite limited availability, tonometry-derived features showed superior performance compared to other feature groups and baselines, yieldingprediction errors of 0.32 ±9.8 mmHg SBP and 0.54 ±7.7 mmHg DBP in-lab, and 0.86 ±8.7 mmHg SBP and 0.75 ±5.9 mmHg DBP for 24-hour averages. SBP error standard deviation (SD) was reduced in normotensive (in-lab: 8.1 mmHg, 24-hr: 7.2 mmHg) and younger (in-lab: 7.8 mmHg, 24-hr: 6.7 mmHg) subpopulations. SBP SD was further reduced 15-20% when constrained to the calibration posture alone. CONCLUSION: Performance for normotensive and younger participants was superior to the general population across all feature groups. Reference type, posture relative to calibration, and controlled vs. ambulatory setting all impacted BP errors. SIGNIFICANCE: Results highlight the need for demographically diverse populations and challenging evaluation settings for BP estimation studies. We present the first public dataset of ambulatory tonometry and cuffless BP over a 24-hour period to aid in future cardiovascular research.

There is a dearth of appropriate tools for young learners with mixed visual abilities to engage with computational learning. Addressing this gap, Torino is a physical programming language for teaching computational learning to children ages 7–11 regardless of level of vision. To create code, children connect physical instruction pods and tune their parameter dials to create music, audio stories, or poetry. Currently, the uptake of novel educational technologies to support inclusive education of children with disabilities continues to be limited at scale. We consider how the Torino Learning Environment supports non-specialist teachers to teach computational learning to children with mixed visual abilities in a UK-wide evaluation with 75 children and 30 teachers over a period of three months. We demonstrate how children can successfully learn with a novel physical programming language. We articulate how key design constructs such as persistent program overview and liveness supported non-specialist teachers to co-produce learning for children of different ages, visual and cognitive abilities. We conclude with reflective guidance on evaluating inclusive educational technologies at scale.CCS CONCEPTSHuman-centered computing → Accessibility → Empirical studies in accessibility

Across the world, policy initiatives are being developed to engage children with computer programming and computational thinking. Diversity and inclusion has been a strong force in this agenda, but children with disabilities have largely been omitted from the conversation. Currently, there are no age appropriate tools for teaching programming concepts and computational thinking to primary school children with visual disabilities. We address this gap through presenting the design and implementation of Torino, a tangible programming language for teaching programming concepts to children age 7–11 regardless of level of vision. In this paper, we: (1) describe the design process done in conjunction with children with visual disabilities; (2) articulate the design decisions made; and (3) report insights generated from an evaluation with 10 children with mixed visual abilities that considers how children are able to trace (read) and create (write) programs with Torino. We discuss key design trade-offs: (1) readability versus extensibility; and (2) size versus liveness. We conclude by reflecting upon how an inclusive design approach shaped the final result.

We present Project Zanzibar: a flexible mat that can locate, uniquely identify and communicate with tangible objects placed on its surface, as well as sense a user's touch and hover hand gestures. We describe the underlying technical contributions: efficient and localised Near Field Communication (NFC) over a large surface area; object tracking combining NFC signal strength and capacitive footprint detection, and manufacturing techniques for a rollable device form-factor that enables portability, while providing a sizable interaction area when unrolled. In addition, we detail design patterns for tangibles of varying complexity and interactive capabilities, including the ability to sense orientation on the mat, harvest power, provide additional input and output, stack, or extend sensing outside the bounds of the mat. Capabilities and interaction modalities are illustrated with self-generated applications. Finally, we report on the experience of professional game developers building novel physical/digital experiences using the platform.

We investigate how technology can support collaborative learning by children with mixed-visual abilities. Responding to a growing need for tools inclusive of children with vision impairments (VI) for the teaching of computer programing to novice learners, we explore Torino -- a physical programing language for teaching programing constructs and computational thinking to children age 7-11. We draw insights from 12 learning sessions with Torino that involved five pairs of children with vision ranging from blindness to full-sight. Our findings show how sense-making of the technology, collaboration, and learning were enabled through an interplay of system design, programing tasks and social interactions, and how this differed between the pairs. The paper contributes insights on the role of touch, audio and visual representations in designs inclusive of people with VI, and discusses the importance and opportunities provided through the 'social' in negotiations of accessibility, for learning, and for self-perceptions of ability and self-esteem.

We present Picco, a tiny situated display for drawings and simple animations, which are created on a dedicated tablet app. Picco was designed to support playful messaging in the workplace through a glanceable desktop device that would place minimal demands on users. Two studies of the device at work demonstrated how crafting was an expression of intimacy when the device was used to connect the workplace to the home, and a way of demonstrating skill and humor to a broad audience when messages were sent amongst co-workers. However, the level of skill needed to produce these messages became a barrier to entry for some co-workers. Our findings suggest that visible ownership of a situated device, which can be personalized in other ways, can underpin a secondary level of participation that is crucial in supporting a sense of involvement when the level of crafting required can stifle more direct participation.

We present a novel approach to the construction of electronic prototypes which can support a variety of interactive devices. Our technique, which we call circuit stickers, involves adhering physical interface elements such as LEDs, sounders, buttons and sensors onto a cheap and easy-to-make substrate which provides electrical connectivity. This assembly may include control electronics and a battery for standalone operation, or it can be interfaced to a microcontroller or PC. In this paper we illustrate different points in the design space and demonstrate the technical feasibility of our approach. We have found circuit stickers to be versatile and low-cost, supporting quick and easy construction of physically flexible interactive prototypes. Building extra copies of a device is straightforward. We believe this technology has potential for design exploration, research proto-typing, education and for hobbyist projects.

Personal fabrication machines, such as 3D printers and laser cutters, are becoming increasingly ubiquitous. However, designing objects for fabrication still requires 3D modeling skills, thereby rendering such technologies inaccessible to a wide user-group. In this paper, we introduce MixFab, a mixed-reality environment for personal fabrication that lowers the barrier for users to engage in personal fabrication. Users design objects in an immersive augmented reality environment, interact with virtual objects in a direct gestural manner and can introduce existing physical objects effortlessly into their designs. We describe the design and implementation of MixFab, a user-defined gesture study that informed this design, show artifacts designed with the system and describe a user study evaluating the system's prototype.

In this paper we explore a new type of wearable computing device, an interactive identity badge. An embedded LCD presents dynamic information to the wearer and interaction is facilitated by sensing movement of the retractable string which attaches the unit to the wearer's belt. This form-factor makes it possible to interact using a single hand, providing lightweight and immediate access to a variety of information when it's not convenient to pick up, unlock and interact directly with a device like a smartphone. In this paper we present our prototype interactive badge, demonstrate the underlying technology and describe a number of usage scenarios and interaction techniques

We describe the SAWUI architecture by which smartphones can easily show user interfaces for nearby appliances, with no modification or pre-installation of software on the phone, no reliance on cloud services or networking infrastructure, and modest additional hardware in the appliance. In contrast to appliances? physical user interfaces, which are often as simple as buttons, icons and LEDs, SAWUIs leverage smartphones? powerful UI hardware to provide personalized, self-explanatory, adaptive, and localized UIs.

In this paper we present the features of a new physical device prototyping platform called Microsoft .NET Gadgeteer along with our initial experiences using it to teach computer science in high schools. Gadgeteer makes it easy for newcomers to electronics and computing to plug together modules with varied functionality and to program the resulting system's behavior. We believe the platform is particularly suited to teaching modern programming concepts such as object-oriented, event-based programming and it could be a timely addition to established teaching tools given the current interest in improving high school computer science education in some regions. We have run a number of pilot studies in the US and in the UK with students of varying age and ability. Our results indicate that the tangible and expressive nature of Gadgeteer helps to engage and motivate a diverse set of students. We were also pleasantly surprised by the level of polish and sophistication of the devices which were built. We hope to further explore the potential of Gadgeteer for teaching in future work and we encourage others to build on our experiences.

In this paper we present a number of different physical construction techniques for prototyping functional electronic devices. Some of these approaches are already well established whilst others are more novel; our aim is to briefly summarize some of the main categories and to illustrate them with real examples. Whilst a number of different tools exist for building working device prototypes, for consistency the examples we present here are all built using the Microsoft .NET Gadgeteer platform. Although this naturally constrains the scope of this study, it also facilitates a basic comparison of the different techniques. Our ultimate aim is to enable others in the field to learn from our experiences and the techniques we present.

DIYbio (Do It Yourself Biology) aims to 'open source', tinker and experiment with biology outside of professional settings. In this paper, we present the origins, practices, and challenges of DIYbio initiatives around the world. Our findings depict DIYbio as operating across intersections ('seams') between a range of stakeholders, materials and concerns. To map out the role of Human Computer Interaction (HCI) across these seams, we present design exercises (functional prototypes) that explore three areas for future work: internal collaboration tools within the DIYbio and professional community; mechanisms for external communication with stakeholders from the general public; and bio-electronic assemblies of organic and digital materials. In doing so, we hope to critically re-envision the role of HCI at the emerging intersection of biology, computation and DIY.

Lifelogging is a technically inspired approach that attempts to address the problem of human forgetting by developing systems that ‘record everything’. Uptake of lifelogging systems has generally been disappointing, however. One reason for this lack of uptake is the absence of design principles for developing digital systems to support memory. Synthesising multiple studies, we identify and evaluate 4 new empirically motivated design principles for lifelogging: Selectivity, Embodiment, Synergy and Reminiscence. We first summarise 4 empirical studies that motivate the principles, then describe the evaluation of 4 novel systems built to embody these principles. The design principles were generative, leading to the development of new classes of lifelogging system, as well as providing strategic guidance about how those systems should be built. Evaluations suggest support for Selection and Embodiment principles, but more conceptual and technical work is needed to refine the Synergy and Reminiscence principles.

We present Interactive Generator (InGen), a self-powered wireless rotary input device capable of generating haptic or force feedback without the need for any external power source. Our approach uses a modified servomotor to perform three functions: (1) generating power for wireless communication and embedded electronics, (2) sensing the direction and speed of rotation, and (3) providing force feedback during rotation. While InGen is rotating, the device is capable of providing the sensation of detents or bumps, changes in stiffness, and abrupt stops using only power that is harvested during interaction. We describe the device in detail, demonstrate an initial 'TV remote control' application, and end with a discussion of our experiences developing the prototype and application. To the best of our knowledge, InGen is the first self-powered device, which also provides haptic feedback during operation. More broadly, this work demonstrates a new class of input sys-tems that uses human-generated power to provide feedback to the user and wirelessly communicate sensed information.

The complexities and costs of deploying Ubicomp applications seriously compromise our ability to evaluate such systems in the real world. To simplify Ubicomp deployment we introduce the robotic pseudopod (P.Pod), an actuator that acts on mechanical switches originally designed for human control only. P.Pods enable computational control of devices by hijacking their mechanical switches -- a term we refer to as mechanical hijacking. P.Pods offer simple, low-cost, non-destructive computational access to installed hardware, enabling functional, real world Ubicomp deployments. In this paper, we illustrate how three P.Pod primitives, built with the Lego MindStorm NXT toolkit, can implement mechanical hijacking, facilitating real world Ubicomp deployments which otherwise require extensive changes to existing hardware or infrastructure. Lastly, we demonstrate the simplicity of P.Pods by observing two middle school classes build working smart home applications in 4 hours.

There are a number of mobile shopping aids and recommender systems available, but none can be easily used for a weekly shop at a local supermarket. We present a minimal, mobile and fully functional lambent display that clips onto any shopping trolley handle, intended to nudge people when choosing what to buy. It provides salient information about the food miles for various scanned food items represented by varying lengths of lit LEDs on the handle and a changing emoticon comparing the average miles of all the products in the trolley against a social norm. When evaluated in situ, the lambent handle display nudged people to choose products with fewer food miles than the items they selected using their ordinary shopping strategies. People also felt guilty when the average mileage of the contents of their entire shopping trolley was above the social norm. The findings are discussed in terms of how to provide different kinds of product information that people care about, using simple lambent displays.

Home heating is a major factor in worldwide energy use. Our system, PreHeat, aims to more efficiently heat homes by using occupancy sensing and occupancy prediction to automatically control home heating. We deployed PreHeat in five homes, three in the US and two in the UK. In UK homes, we controlled heating on a per-room basis to enable further energy savings. We compared PreHeat's prediction algorithm with a static program over an average 61 days per house, alternating days between these conditions, and measuring actual gas consumption and occupancy. In UK homes PreHeat both saved gas and reduced MissTime (the time that the house was occupied but not warm). In US homes, PreHeat decreased MissTime by a factor of 6-12, while consuming a similar amount of gas. In summary, PreHeat enables more efficient heating while removing the need for users to program thermostat schedules.

This work describes the design process and installation of three speculative, rudimentary machines, or rudiments. Through careful iterations in their design, the rudiments are intended to provoke curiosity and discussion around the possibility of autonomy in interactive systems. The design of the rudiments is described in detail, alongside the design decisions that were made to suggest a machine autonomy and to provoke discussion. Some preliminary reflections from installing the rudiments in two separate households are also reported. Widely divergent opinions of the rudiments from the two households are used to discuss a number of themes for thinking about autonomy and interactive systems design. Overall, the presented work adopts a perspective strongly oriented towards guiding future research, but, importantly, aims to do so by opening up and exposing the design possibilities rather than constraining them.

Microsoft .NET Gadgeteer is a new prototyping platform that makes it easier to construct, program and shape new kinds of computing objects. It is comprised of modular hardware, software libraries and 3D CAD support. Together, these elements support the key activities involved both in the rapid prototyping and the small-scale production of custom embedded, interactive and connected devices. We propose to organize and run a studio at TEI 2010 where participants are introduced to the platform and its capabilities. Participants will work in groups, assembling electronic modules, writing software and designing a case or enclosure for their device. The end-result will be that each group develops a fully functional device, which can be exhibited at the TEI demo session.

In spite of many advances in GUI workstations, the keyboard has remained limited to text entry and basic command invocation. In this work, we introduce the Touch-Display Keyboard (TDK), a novel keyboard that combines the physical-ergonomic qualities of the conventional keyboard with dynamic display and touch-sensing embedded in each key. The TDK effectively transforms the keyboard into an interactive surface that is seamlessly integrated with the interaction space of GUIs, extending graphical output, mouse interaction and three-state input to the keyboard. This gives rise to an entirely new design space of interaction across keyboard, mouse and screen, for which we provide a first systematic analysis in this paper. We illustrate the emerging design opportunities with a host of novel interaction concepts and techniques, and show how these contribute to expressiveness of GUIs, exploration and learning of keyboard interfaces, and interface customization across graphics display and physical keyboard.

Researchers have explored pointing devices operated by a single finger, but their advantage was not clear compared to conventional mice controlled by the whole hand. To incorporate the benefits of both, we prototyped hybrid pointing devices that combined both finger and hand movement to control the cursor, and experimentally compared their performance with single-finger and whole-hand devices. Results showed that such hybrid devices have the potential to improve pointing performance in terms of time, error, and bandwidth, especially for precise pointing.

People now routinely carry radio frequency identification (RFID) tags - in passports, driver's licenses, credit cards, and other identifying cards - from which nearby RFID readers can access privacy-sensitive information. The problem is that people are often unaware of security and privacy risks associated with RFID, likely because the technology remains largely invisible and uncontrollable for the individual. To mitigate this problem, we introduce a collection of novel yet simple and inexpensive tag designs. Our tags provide reader awareness, where people get visual, audible, or tactile feedback as tags come into the range of RFID readers. Our tags also provide information control, where people can allow or disallow access to the information stored on the tag by how they touch, orient, move, press or illuminate the tag.

Digital mementos are increasingly problematic, as people acquire large amounts of digital belongings that are hard to access and often forgotten. Based on fieldwork with 10 families, we designed a new type of embodied digital memento, the FM Radio. It allows families to access and play sonic mementos of their previous holidays. We describe our underlying design motivation where recordings are presented as a series of channels on an old fashioned radio. User feedback suggests that the device met our design goals: being playful and intriguing, easy to use and social. It facilitated family interaction, and allowed ready access to mementos, thus sharing many of the properties of physical mementos that we intended to trigger.

A human-powered user interface device sources its power from the physical effort required to operate it. This paper describes a technique by which a geared DC motor and a simple circuit can be used to enable interaction-powered rotary input devices. When turned, the circuit provides a temporary power source for an embedded device, and doubles as a sensor that provides information about the direction and rate of input. As a proof of concept, we have developed a general-purpose wireless input device -- called the Peppermill -- and illustrate its capabilities by using it as a remote control for a multimedia-browsing application.

We present a novel hardware device based on ferromagnetic sensing, capable of detecting the presence, position and deformation of any ferrous object placed on or near its surface. These objects can include ball bearings, magnets, iron filings, and soft malleable bladders filled with ferrofluid. Our technology can be used to build reconfigurable input devices – where the physical form of the input device can be assembled using combinations of such ferrous objects. This allows users to rapidly construct new forms of input device, such as a trackball-style device based on a single large ball bearing, tangible mixers based on a collection of sliders and buttons with ferrous components, and multitouch malleable surfaces using a ferrofluid bladder. We discuss the implementation of our technology, its strengths and limitations, and potential application scenarios. ACM Classification: H5.2 [Information interfaces and

In this paper we present novel input devices that combine the standard capabilities of a computer mouse with multi-touch sensing. Our goal is to enrich traditional pointer-based desktop interactions with touch and gestures. To chart the design space, we present five different multi-touch mouse implementations. Each explores a different touch sensing strategy, which leads to differing form-factors and hence interactive possibilities. In addition to the detailed description of hardware and software implementations of our prototypes, we discuss the relative strengths, limitations and affordances of these novel input devices as informed by the results of a preliminary user study.

Threshold devices present information gathered from the home's surroundings to give new views on the domestic situation. We built two prototypes of different threshold devices and studied them in field trials with participant households. The Local Barometer displays online text and images related to the home's locality depending on the local wind conditions to give an impression of the sociocultural surroundings. The Plane Tracker tracks aircraft passing overhead and imagines their flights onscreen to resource an understanding of the home's global links. Our studies indicated that the experiences they provided were compelling, that participants could and did interpret the devices in various ways, that their form designs were appropriate for domestic environments, that using ready-made information contributed to the richness of the experiences, and that situating the information they provided with respect to the home and its locality was important for the ways people engaged with them.

We present a system that extends a typical workstation environment with a malleable physical interface for working with digital clips. It allows users to pick digital clips, give each its own dedicated key for direct access, and combine keys dynamically on a physical surface in a way that inherently reflects the state of an extended clipboard. The system affords copying and pasting of multiple clips each directly accessible through its own key shortcut. The keys can also be dynamically re-arranged to organize clips, and taken from workstation to another to transport clips, acting simultaneously as token and as copy-paste-interface for a digital object.

In most work environments people archive both the real and digital versions of their documents. But unlike the digital world, in the physical world locating a document can become a very time consuming task. The reason for this is the lack of a direct connection between the physical and digital versions of documents.

We introduce a new type of interactive surface technology based on a switchable projection screen which can be made diffuse or clear under electronic control. The screen can be continuously switched between these two states so quickly that the change is imperceptible to the human eye. It is then possible to rear-project what is perceived as a stable image onto the display surface, when the screen is in fact transparent for half the time. The clear periods may be used to project a second, different image through the display onto objects held above the surface. At the same time, a camera mounted behind the screen can see out into the environment. We explore some of the possibilities this type of screen technology affords, allowing surface computing interactions to extend 'beyond the display'. We present a single self-contained system that combines these off-screen interactions with more typical multi-touch and tangible surface interactions. We describe the technical challenges in realizing our system, with the aim of allowing others to experiment with these new forms of interactive surfaces.

Design tools that integrate hardware and software components facilitate product design work across aspects of physical form and user interaction, but at the cost of requiring designers to work with other than their accustomed programming tools. In this paper we introduce VoodooFlash, a tool designed to build on the widespread use of Flash while facilitating design work across physical and digital components. VoodooFlash extends the existing practice of authoring interactive applications in terms of arranging components on a virtual stage, and provides a physical stage on which controls can be arranged, linked to software components, and appropriated with other physical design materials.

Rather than existing as a computer input device with a rigid shape, a predetermined selection of controls and a fixed layout, a malleable control structure is made up of a set of controls that can be freely arranged on control areas. The structure is physically adaptable by users during operation: control areas and controls can be introduced, organized and removed to suit interaction requirements and personal preference.We present an implementation of a malleable control structure called VoodooIO. Our design contributes a novel material -- the network substrate - that can be used to transform everyday surfaces into control areas, and the concept of implementing basic control units (such as buttons, sliders or dials) as ad hoc network nodes.VoodooIO does not constitute an application interface in itself. Like any input device, it only becomes concrete as an interface component in the context of a particular application. We introduce the concept of softwiring as a collection of techniques and practices that allow users to benefit from malleable control interfaces in a number of concrete scenarios of use.

The History Tablecloth is a flexible substrate screen-printed with electroluminescent material forming a grid of lace-like elements. When objects are left on the table, cells beneath them light to form a halo that grows over a period of hours, highlighting the flow of objects in the home. The Tablecloth explores an approach to design that emphasises engaging, open-ended situations over defined utilitarian purposes. Long-term deployment of the History Tablecloth in a volunteer household revealed complex ways that people experienced and interacted with the Tablecloth. Beyond evoking reflection on the flow of objects over a particular table, the Tablecloth served as a ground for interpretative reflection about technology, an asset for social interaction, and an aesthetic object. Even behaviours we saw as system errors were interpreted by the users as interactively rich. Their experience highlights the subtlety of domestic ubiquitous computing, illustrating alternatives to traditional views of technology's domestic role.

This paper presents a low-cost and practical approach to achieve basic input using a tactile cube-shaped object, augmented with a set of sensors, processor, batteries and wireless communication. The algorithm we propose combines a finite state machine model incorporating prior knowledge about the symmetrical structure of the cube, with maximum likelihood estimation using multivariate Gaussians. The claim that the presented solution is cheap, fast and requires few resources, is demonstrated by implementation in a small-sized, microcontroller-driven hardware configuration with inexpensive sensors. We conclude with a few prototyped applications that aim at characterizing how the familiar and elementary shape of the cube allows it to be used as an interaction device.