Wireless developer Cambridge Consultants Inc, Boston, (cambridgeconsultants.com) demonstrated how a ZigBee network can provide home monitoring for the elderly and vulnerable. This emerging wireless application can reduce the load on healthcare resources while helping people preserve their independence. “ZigBee is a key technology for home automation and sensor networks, but its characteristics can be useful in healthcare as well,” says Cambridge Consultants' Paul Williamson.

The demonstration illustrated a mobile-node concept in such a network. A wireless node worn by an elderly person monitors physiological signs while also providing the wearer's location. The mobile node would also give wearers a panic button that would call for help.

The network, when combined with fixed ZigBee nodes, such as a load sensor on the bed, lets supervisors sketch a picture of the wearer's typical daily activity. The activity profile could then be used to monitor vulnerable people and identify changes in the patterns in advance of problems.

ZigBee's ultra-low power devices can operate for years on small batteries. Sensor nodes can be made of single-chip, radio-plus-microcontroller devices costing a few dollars.

For nodes attached to people, Williamson says ZigBee has data rates that allow adding ‘person down’ alarms as well as monitor blood pressure, breathing, and heart rate. The demonstration used 250-msec updates to monitor breathing, for example, in addition to transmitting data for position updates.