… For smart dust to be useful engineers must figure out how to build a global view from the information provided by millions or billions of individual sensors.

For example, suppose that agricultural researchers scatter a million battery-powered, smart-dust sensors by helicopter to monitor water levels across a cornfield. Without knowing where each sensor has landed, how would the researchers determine whether the sensors’ combined range leaves gaps? Or imagine that engineers have deployed a sensor network to keep track of boats in a harbor. If each sensor reports how many boats it detects, how can the engineers keep an accurate tally without knowing how many sensors have counted the same boat?

To tackle these questions and others, researchers are drawing on techniques from topology, the study of shapes. Analyzed by mathematicians for more than a century, topology has until recently had few real-world applications.

More info here.

From Crossbow’s blog:

Crossbow’s Japan office is working with a customer to develop a system based on Crossbow’s MICAz Mote to demonstrate how wireless sensor network products can be used to ensure safety for children and others using ubiquitous networking technologies. The initial system was featured on the news and can be seen in the video below. The Motes were used on school children who had a MICAz Mote attached. The school property was outfitted with MICAz Motes fixed in various locations to provide location data on the child based on the signal strength from their attached Mote. This setup also allowed the teachers to monitor whether a child left the school premises. The perimeter was equipped with MICAz Motes so that if a child left the school property and their signal was detected to have moved in a direction away from the school, the gateway would detect the activity and automatically send an email or text alert to the parent/teacher informing them that their child had exited the school. This was also tested by a group of children on a school field trip. If any student moved out of range from the teacher, there would be a display or sound alert so that the teacher was notified instantly.

A video is availabe on YouTube.