Reminding about tagged objects using passive RFIDs

People often misplace objects they care about. We present a system that generates reminders about objects left behind by tagging those objects with passive RFID tags. Readers positioned in the environment frequented by users read tags and broadcast the tags' IDs over a short-range wireless medium. A user's personal server collects the read events in real-time and Processes them to determine if a reminder is warranted or not. The reminders are delivered to a wristwatch-sized device through a combination of text messages and audible beeps. We believe this leads to a practical and scalable approach in terms of system architecture and user experience as well as being more amenable to maintaining user privacy than previous approaches. We present results that demonstrate that current RFID tag technology is appropriate for this application when integrated with calendar information.