MyHealthAssistant: an event-driven middleware for multiple medical applications on a smartphone-mediated body sensor network.

An ever-growing range of wireless sensors for medical monitoring has shown that there is significant interest in monitoring patients in their everyday surroundings. It however remains a challenge to merge information from several wireless sensors and applications are commonly built from scratch. This paper presents a middleware targeted for medical applications on smartphone-like platforms that relies on an event-based design to enable flexible coupling with changing sets of wireless sensor units, while posing only a minor overhead on the resources and battery capacity of the interconnected devices. We illustrate the requirements for such middleware with three different healthcare applications that were deployed with our middleware solution, and characterize the performance with energy consumption, overhead caused for the smartphone, and processing time under real-world circumstances. Results show that with sensing-intensive applications, our solution only minimally impacts the phone's resources, with an added CPU utilization of 3% and a memory usage under 7 MB. Furthermore, for a minimum message delivery ratio of 99.9%, up to 12 sensor readings per second are guaranteed to be handled, regardless of the number of applications using our middleware.