Remote Blood Pressure Monitoring Using a Wireless Sensor Network - Proceedings of All India Seminar on Biomedical Engineering 2012 (AISOBE-2012) - page 150

Network Description
The topology of our wireless network is that of a static routing infrastructure with
mobile sensor nodes. Energy scavenging is employed at the router nodes so that
connection to a permanent power supply is not needed [ 3 ]. The need for batteries is
eliminated. Scavenging energy from indoor light sources is an inefficient process
and results in limited amounts of energy to power the router nodes. To compensate
for this, the router nodes operate in synchronized pairs and at a 50 % duty cycle.
This allows sufficient time during the off-cycle for each node to scavenge the
energy required for its next on-cycle.
The process of the router node in the network is as:
• Initialize Router Node Parameters
• Locate the Network
• Shortest path to base station is determined
• If ID is received and route partner is available, then Wake a Routine
• If not, then acquire ID from base station and find a route partner
• Message is forwarded
• If network connection is lost, then locate the network again.
Once the routing infrastructure is set up, a sensor node can easily access the
network by choosing the shortest path. The sensor node processes as follows:
• Sensor node parameters are initialized
• Reading is taken
• Network is located
• Shortest path to base station is determined
• Sensor reading is sent to base station
• Sensor goes to sleep mode
• When it wakes, again reading is taken.
Sensor nodes are designed to be mobile to allow patient movement. Thus, each
subsequent reading requires the sensor node to reconnect to the network in a
potentially different location. This pattern also allows the sensor node to sleep
between readings, thereby extending battery life [ 4 ].
Future Work
Future enhancements to the system may possess a graphical display of the
incoming data replacing the text display. Additional medical instruments like a
portable ECG, temperature measuring transducer can be interfaced. Increased
integration with existing hospital systems and databases can be done. Apart from
the medical field, it has wide applications in sensing forest fire, etc.