Thanks to technology and advancements in medicine, people are living longer, and due to a change in the family unit many are living independently. This trend leads towards a growing elder population who have the desire to "age in place." With the high cost of nursing homes and related services, there is a significant need for more efficient and affordable home monitoring solutions. Today there are 35 million people over the age of 65, and by the year 2030 this number will grow to 70 million people based on data collected by the US Census Bureau. Only 4% currently reside somewhere other than their own home, with 90% of Americans, 60 years and older, wanting to remain in their own homes and communities as they age. Of this 90%, it has been determined that 75% of these adults have at least one chronic condition.
Researchers at the University of Virginia, Department of Computer Science have been developing a wireless sensor network for assisted-living and residential monitoring. ALARM-NET provides pervasive and adaptive health-care for continuous monitoring using environmental and wearable sensors. ALARM-NET is a wireless sensor network for smart healthcare. While preserving resident comfort and privacy, the network creates a continuous medical history. Unobtrusive area and environmental sensors combine with wearable interactive devices to evaluate the health of spaces and the people who inhabit them. Authorized care providers may monitor resident health and activity patterns, such as circadian rhythm changes, which may signify changes in healthcare needs. High costs of installation and retrofitting are avoided by using ad hoc, self-managing networks.
The AlarmNet architecture for smart healthcare possesses the essential elements of future medical applications such as integration with existing medical practices and technology, real-time, long-term monitoring, miniature, wearable sensors, and assistance to the elderly and chronic patients. It
extends healthcare from the traditional clinic or hospital setting to
assisted-living and retirement homes, enabling 'telecare' without the
prohibitive costs of retrofitting existing structures. In AlarmNet, the WSN collects data according to a physician's
specifications, removing some of the cognitive burden from the patient
(who may suffer age-related memory decline) and providing a continuous
record to assist diagnosis. Health-related tasks are also made easier
for the patient, for example, medication reminders, object location,
and emergency communication.The architecture is multi-tiered, with lightweight sensors, mobile components, and more
powerful stationary devices. Sensors are heterogeneous, and all
integrate into the network. Multiple patients and their resident family
members are differentiated for sensing tasks and access privileges.
As researchers at UVA point out, wireless sensor networks are ideally suited as a foundation for smart healthcare in AlarmNet, due to these several inherent qualities:
Portability and unobtrusiveness.
Small devices collect data and communicate wirelessly, operating with
minimal patient input. They may be carried on the body or deeply
embedded in the environment. Unobtrusiveness helps with patient
acceptance and minimizes confounding measurement effects. Since
monitoring is done in the living space, the patient travels less often,
which is safer and more convenient.
Ease of deployment and scalability.
Devices can be deployed in potentially large quantities with
dramatically less complexity and cost compared to wired networks.
Existing structures, particularly dilapidated ones, can be easily
augmented with a WSN network whereas wired installations would be
expensive and impractical. Devices are placed in the living space and
turned on, self-organizing and calibrating automatically.
Real-time and always-on.
Physiological and environmental data can be monitored continuously,
allowing real-time response by emergency or healthcare workers. The
data collected form a health journal, and are valuable for filling in
gaps in the traditional patient history. Even though the network as a
whole is always-on, individual sensors still must conserve energy
through smart power management.
Reconfigurability and self-organization.
Since there is no fixed installation, adding and removing sensors
instantly reconfigures the network. Doctors may re-target the mission
of the network as medical needs change. Sensors self-organize to form
routing paths, collaborate on data processing, and establish
hierarchies.
Researchers at UVA have adapted a low-cost sensor module that is capable of
detecting motion and light intensity changes. The module also has a
simple one-button and one-LED user interface for testing and
diagnostics. The module is interfaced to a MicaZ wireless sensor
node that processes the sensor data and forwards the information to the
rest of the wireless network. The picture shows a MicaZ detached from its normal battery-pack and interfaced to the motion sensor (X-10 RF circuits were removed, making this a truly low-power sensor) via the 51-pin connector. A
set of such modules (MotionMote) is used to track human presence and to monitor the
lighting conditions in various locations of the living space. This
activity data is used to maintain location context, and are fed to the
back-end software.
AlarmNet has also implemented a wearable body network with MicaZ motes embedded
in a jacket, which can record human activities and
location using a
2-axis accelerometer and GPS. The components are shown (w/out jacket). The recorded activity data is uploaded subsequently through
an access point for archival, from which past human activities and
locations can be reconstructed. One mote is placed on the back so that the y-axis (either positive or
negative) is always pointing downward. It may also possess GPS
capability if the tracking aspect is to be used. The other two motes
are placed one on each arm so that when the arm is in a vertical
position pointing down, the y-axis (either positive or negative) also
points down. A web-server interface has also been implemented to make some SQL
requests of a DBMS through a localized user interface which is a user
view for this sub-system. This module allows the user to query the data
collected and identify various activities that the user performed in
the past and his or her location information of the past.
SolarDust, a sensor board for Mica motes shown on the left was also designed to provide the mote's microprocessor with a UART interface
to a bluetooth transceiver. This enables the body network to communicate
with other commercially available sensor devices, as well as
communicate with a resident's cell phone for emergency response! The backbone network connects traditional systems, such as PDAs, PCs,
and databases, to the sensor network. It also connects
discontiguous sensor nodes by a high-speed relay for efficient routing. The backbone may communicate wirelessly or may overlay
onto an existing wired infrastructure. In a previous posting, we discussed the LCD interface board for the MicaZ that is suitable
for wearable applications, called the SeeMote. It presents sensor
readings, reminders and queries, and can accept rudimentary input from
the wearer. It has a five-button interface and a Secure Digital flash
memory expansion port.
A wireless sensor network solution like AlarmNet benefits both the healthcare providers and their patients. For the providers, an automatic monitoring system is valuable for many reasons as it frees humans from 24/7 physical monitoring, reducing labor costs and increasing efficiency. The wearable sensor devices can sense even small changes in vital signals that humans might overlook, such as heart rate and blood oxygen levels, boosting accuracy. The quick notification of these changes may save human lives, and the data collected from the wireless sensor network can be stored and integrated into a comprehensive health record of each patient, which helps physicians make more informed diagnoses. Eventually, the analyzing, diagnosis, treatment process may also be semi-automated, so a human physician can be assisted by an electronic physician.
Healthcare patients benefit from improved health as a result of faster diagnosis and treatment of diseases. Other quality-of-life issues, such as privacy, dignity, and convenience, are supported and enhanced by the ability to provide services in an environment more comfortable for the patient. Though 24/7 physical presence of caregivers is reduced, the patient is not isolated from contact with the outside world—an important component of mental health. Family members and the system itself become part of the healthcare team. Finally, memory aids and other patient-assistance services can restore some lost independence, while preserving safety.
This implementation of wireless sensor networks will enable us to create a world that can improve the quality of life for through continuous monitoring of those needing as 'Assisted Living and Residential Monitoring Network.'
