ZigBee Comes to the Aid of Overtaxed Health-care Providers
Wireless developer Cambridge Consultants is demonstrating how ZigBee's unique networking attributes can be exploited to implement sophisticated monitoring networks for the elderly and vulnerable. This emerging wireless application offers a major market opportunity for OEMs, as well as being a powerful aid that could reduce the load on stretched health-care resources while helping people preserve their independence.
The demonstration illustrates a concept mobile node in such a network. Worn by the elderly or vulnerable, the wireless node monitors physiological signs and additionally provides zonal location sensing to identify which room the wearer is in. Combined with a few other fixed ZigBee nodes--a load sensor on the bed, for example--pictures of typical daily activity can be constructed. These could be used by relatives, building supervisors and caregivers to monitor vulnerable people and identify deviations to patterns in advance of problems, as well as providing the familiar panic button facility.
"ZigBee is seen as a key technology for home automation and sensor networks, but its characteristics can be extremely valuable in some health-care applications as well,” notes Cambridge Consultants' Paul Williamson. "Research is establishing how modern wireless networks can enhance today's panic-button type systems. Our demonstration of personal monitoring combined with position sensing illustrates that ZigBee provides a practical platform for every aspect of such systems, including sophisticated body sensor nodes."
For mobile nodes attached to people, ZigBee has the data rates to allow “person down” alarms to be complemented by sophisticated functions ranging from monitoring blood pressure to breathing or heart rate.
Cambridge Consultants' demonstration uses 250 millisecond updates to monitor breathing, in addition to transmitting the data required for position updates. In conjunction with data from simple sensors such as load cells on beds and chairs, and current flow sensors on electronic appliances, typical behavior patterns in the home can be readily constructed--as research from ImperialCollege is showing.
Raw data can be transmitted to a central location using a broadband line, or analyzed and stored locally for review on demand. This information can then be used by social services or doctors to monitor when intervention might be required, or to notify care staff of significant changes in activity patterns.
ZigBee's support for ultra-low power-devices that can operate for years from a small cell makes it ideal for wireless networking such devices. The designed-for-purpose nature of ZigBee means that all the sensor nodes can be implemented using single-chip radio-plus-microcontroller devices costing a few dollars.
In conjunction with ZigBee's support for ad hoc mesh topologies, which allows installation without any specialized skills, these factors make it possible to design easy-install home monitoring networks, with consumer resale prices starting at a few hundred dollars.
The zonal location capability is based on a proprietary Cambridge Consultants algorithm that runs on standard ZigBee hardware and uses the standard ZigBee protocol stack. Zonal location can be used in the home, or professional care environments, to monitor behavior and allow rapid response to alarms, and can be added to existing ZigBee infrastructure, at low cost to the developer.