OBJECTIVE: In parts of the developing world traditionally modeled healthcare systems do not adequately meet the needs of the populace. This can be due to imbalances in both supply and demand--there may be a lack of sufficient healthcare and the population most at need may be unable or unwilling to take advantage of it. Home-based care has emerged as a possible mechanism to bring healthcare to the populace in a cost-effective, useful manner. This study describes the development, implementation, and evaluation of a mobile device-based system to support such services. MATERIALS AND METHODS: Mobile phones were utilized and a structured survey was implemented to be administered by community health workers using Open Data Kit. This system was used to support screening efforts for a population of two million persons in western Kenya. RESULTS: Users of the system felt it was easy to use and facilitated their work. The system was also more cost effective than pen and paper alternatives. DISCUSSION: This implementation is one of the largest applications of a system utilizing handheld devices for performing clinical care during home visits in a resource-constrained environment. Because the data were immediately available electronically, initial reports could be performed and important trends in data could thus be detected. This allowed adjustments to the programme to be made sooner than might have otherwise been possible. CONCLUSION: A viable, cost-effective solution at scale has been developed and implemented for collecting electronic data during household visits in a resource-constrained setting.

This paper presents Open Data Kit (ODK), an extensible, open-source suite of tools designed to build information services for developing regions. ODK currently provides four tools to this end: Collect, Aggregate, Voice, and Build. Collect is a mobile platform that renders application logic and supports the manipulation of data. Aggregate provides a "click-to-deploy" server that supports data storage and transfer in the "cloud" or on local servers. Voice renders application logic using phone prompts that users respond to with keypad presses. Finally, Build is a application designer that generates the logic used by the tools. Designed to be used together or independently, ODK core tools build on existing open standards and are supported by an open-source community that has contributed additional tools. We describe four deployments that demonstrate how the decisions made in the system architecture of ODK enable services that can both push and pull information in developing regions.

In 2007, approximately 30% of US adults were obese, with related health care costs exceeding 100 billion dollars. Clearly, the obesity epidemic represents a growing societal concern. One challenge in weight control is the difficulty of tracking food calories consumed and calories expended by activity. This paper presents a system for automatic monitoring of calories expended using a single body-worn accelerometer. Our system uses activity inference combined with signal analysis to estimate calories expended in real-time using regression formulas developed by the American College of Sports Medicine. To validate our system, we have collected data from 51 subjects in a laboratory setting using a treadmill and a more natural field test. Actual caloric expenditure was determined using the medical "gold standard" measurement, of oxygen consumption. We are able to achieve 89% accuracy with lab data and 79% with field data -- both high enough to be useful in practice.

Organizations in low income regions need tools for collecting and reporting on data. Existing paper-based approaches are often slow and incomplete when compared to data collection tools on mobile devices. In this demonstration, we present the authors Android-based system in addition to broader work by the OpenRosa Consortium - a community dedicated to building open source, standards-based tools for mobile data collection, aggregation, analysis, and reporting.

Embedded systems are increasingly becoming connected through wireless networking. These devices now form the basis of many of today's consumer products including cell phones and video game controllers. In the "Software for Embedded Systems" class in the Department of Computer Science & Engineering at the University of Washington, we used the design of a multi-player video game as motivation for the principal concepts in wireless embedded systems. Each student in the class designed an accelerometer-based game controller and then, the class as a whole, developed a multi-player video game that allowed 28 players (the number of students in the course) to play simultaneously. In this paper, we first describe the context of the course and its goals followed by the hardware/software platform we used to realize the game controller. We then detail the pedagogical approach we used to collectively design the video game (loosely based on soccer) and conclude with the lessons learned from this group design experience and how we would enhance the project and course in the future.

In this paper we present FireWxNet, a multi-tiered portable wireless system for monitoring weather conditions in rugged wildland fire environments. FireWxNet provides the fire fighting community the ability to safely and easily measure and view fire and weather conditions over a wide range of locations and elevations within forest fires. This previously unattainable information allows fire behavior analysts to better predict fire behavior, heightening safety considerations. Our system uses a tiered structure beginning with directional radios to stretch deployment capabilities into the wilderness far beyond current infrastructures. At the end point of our system we designed and integrated a multi-hop sensor network to provide environmental data. We also integrated web-enabled surveillance cameras to provide visual data. This paper describes a week long full system deployment utilizing 3 sensor networks and 2 web-cams in the Selway-Salmon Complex Fires of 2005. We perform an analysis of system performance and present observations and lessons gained from our deployment.

The irregularities of a low cost wireless communication interface, changing environmental conditions, in-situ deployment and scarce resources make management, monitoring and troubleshooting performance of a sensor network a challenging task. In this paper we present the design of a decentralized fault diagnosis system for a wireless sensor network. Our system distinguishes between multiple root causes of degraded performance and provides efficient feedback into the network to troubleshoot the fault

Establishing secure links between pairs of directly connected sensor nodes is an important primitive for building secure wireless sensor networks. This paper systematically identifies two important security requirements of pairwise key setup in wireless sensor networks, namely opaqueness and inoculation. Transitory master key schemes, such as the LEAP protocol, can satisfy both requirements if the master key has not been compromised. However, if the master key is compromised, every key in the network is exposed to an adversary. To prevent the master key from becoming a single point failure of the whole system, we propose a new opaque transitory master key (OTMK) scheme for pairwise key setup in sensor networks. In OTMK, even if the master key is compromised, an adversary can only exploit a small number of keys nearby the compromised node, while other keys in the network remain safe. To further investigate key establishment schemes, we experimented with a way to compromise a sensor node, and tested our key establishment time in a real sensor network environment.