Introducing Contextual Information to Mobile Phones by External and Embedded Sensors

This paper introduces the opensensor platform. The idea is to build a wireless sensor platform that is inspired by the idea of open source. The material to build, to program and to teach the opensensor is freely available. The opensensor platform can be used for all kind of wireless sensor network research, but in this paper the focus is on contextual information retrieval for the mobile phone. After introducing and motivating the opensensor platform, some first examples and projects for contextual information retrieval are introduced.