The rapid growth of wireless technologies and
personal area networks has enabled the continuous healthcare monitoring of
mobile patients using compact sensors that collect and evaluate body parameters
and movements. These sensors constitute a body area network (BAN) where
patients’ vital signs are collected and reported wirelessly to a base station.
Once the data is received, it is displayed or stored in a database for future
use. The use of BANs is to provide the users with logging of patients’ critical
vital signs, and also to provide primary healthcare providers a snapshot of the
wearer’s health.
The goal of this project was to investigate
the feasibility of the inexpensive construction, and use of a BAN. A BAN,
consisting of two nodes and a base station was successfully built and tested
using open source and inexpensive hardware to measure pulse rate body
temperature and patient’s location. Each node consisted of a pulse sensor, a
temperature sensor, a GPS module and a Zigbee wireless modem packaged together.
The nodes were designed to incorporate other sensors, such as an accelerometer,
in the future. The base station consisted of a receiving Zigbee modem and
a Wi-Fi module. The captured data was inserted into a MySQL database
where a webpage with a graphing application programming interface (API) was
used to display the data. The system has been successfully tested in real time
where data was successfully obtained and displayed. Future enhancements to
safeguard the data, including the encryption of the patient data is under
investigation.
Network Architecture
The
Wireless Body Area Network (WBAN) was implemented using a single hop star
topology in beacon mode (data being sent continuously without interruption)
where sensors collect data and send it to the base station which is the task
manager of the network. The proposed WBAN architecture is shown in the figure
below. Two individual body sensor nodes serving as transmitters have been
designed to collect, process, and transmit the pulse rate, body temperature,
and the patient’s location signals in real time. The system operates within a range
of 30m from the base station.
The base station
which is the network coordinator manages the activities of individual nodes by
periodically requesting data. In addition to data integration and analysis, the
base station also relays processed data to display devices and PDAs. The base
station is equipped with an Arduino Uno Microcontroller for system
coordination, a receiving ZigBee module and a Wi-fi module for wireless
communication and data transmission over the 802.11b/g wireless networks which make it possible to
access the collected data via the internet.
Transmitter
To
achieve a power efficient network, open source and low power consumption
hardware were used to implement the transmitter. Each transmitting node
comprises one off-the shelf XBee wireless module, one pulse sensor, one
temperature sensor, and one GPS module. The XBee wireless module operates on
the 802.15.4 protocol at a frequency of 2.4GHz with a power output of 1mW and a
data transmission rate of 250kbps which ensures the wireless nature of the
network. One pulse sensor wearable on the ear or on a finger with a current
consumption of 4mA at 5V , 16mm of diameter, 3mm of thickness, and a cable
length of 609mm. The pulse sensor collects data from the pulse rate. One TMP36
analog temperature sensor with a voltage output of 1.75V at 125°C to
measure the body temperature. One GTPA013 ultimate GPS module with a -165dBm
sensitivity and only 20mA current draw; this determines the location of the
subject at all time. Each transmitting node is powered up using a 9V battery
and the data collected is wirelessly sent to the base station for processing,
display, and storage.
Transmitting Node
User's Interface
The User interface
which is a display website was designed using the php and html code. The
software intended to be easy for medical personnel to use and provides enough
details on patient Pulse rate, blood pressure and location. The sensor device
on the patient transmits raw data to the receiver which in turn sends the
data wirelessly to the MySQL database using a wifi shield. Whenever,
the database gets new data from the device, it refreshes the page
and displays the new data in the format that the user can understand. And also,
include is a feature to store all the Data in server so it can be used future
reference.
Experimental Results
To check the functionality of the devices, the following
experiments were made. As shown on the figure below, the comparison between the
industrial and the experimental pulse sensors was performed. The results
obtained from both sensors are almost similar, that is a good indication for
the functionality of the project. The graph also shows the result received from
the temperature sensor.
Body Temperature Data
Pulse Variation with Different Activities
Conclusion & Future Work
The system was built and successfully tested in real time where data was
successfully captured and displayed. At this stage the project mainly focused
on the collection of the data for pulse rate, temperature, and location from
patient. The captured data is made available to the user through a graphing
application programming interface (API). Future enhancements
to safeguard the data, including the encryption of the patient data is under investigation. The communication between the transmitter and the base station is
crucial to collect the data without any interruption. The network works within
the range of 30 meters to have the best result. Power consumption of the
devices is one of the most important phases of the project. Production of power
using body temperature or from physical movements of the patient is the second
phase of the project. For the now, the base station is powered up using a USB
cable that connects with computer, but the transmitter uses a 9V battery to
operate. Finally, the design was completed
using the low cost or off-the-shelf hardware.
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