Author(s):
In-kwon Kim - Ulsan University Medical School
The Need for a Telemetry System
Hospital staff must frequently record incubator internal data, such as temperature and humidity. However, when recording this data, it is inconvenient for doctors and nurses to go in front of the incubator each time to check. Therefore, the necessity arises for a telemetric system. In the past, people have attempted telemetric transmissions using Web-based, or Bluetooth communication. However, there were problems with incubator mobility and limits in the number of channels. In order to solve these problems, we developed this system using the low-power RF sensor network.
We used NI LabVIEW to measure system data because we could easily construct much of the code using controls and functions already developed through other development tools. Also, concerning the PDA program, the system we developed using the usual development tool EVC++ had difficulty displaying graphs in real time due to limited functionality. However, we solved this problem by using the LabVIEW PDA Module.
Developing a Complex Solution Using LabVIEW
We first applied LabVIEW to the system when data was received through RS232 communication from a PC connected to the receiver of the RF sensor network. We set data transmission speed at 19,200 bps. We received data through RF communication in the form of a data packet of 36 bytes. Then, the system sorted through the large amount of information.
First, we used a case statement to determine the accuracy of incoming data. Then, from the 36 bytes of data packet, we derived only the data necessary to be shown to users. In addition, since the upper byte and lower byte of each data value were reversed, we used a simple function to restore the order. The system displayed the separated data in the form of a graph after temperature and humidity were calculated. Concerning the temperature and humidity, the system displayed a histogram for 30 different data points. The system also stored data as text so that the files could be automatically copied for later examination or when the PDA was connected to the PC. Finally, because different ranges were represented by temperature and humidity, we arranged the data to be expressed in one chart using two different y-axes.
In principle, temperature within the incubator is kept at a similar level with body temperature; however, because our system was tested in a general laboratory, we set the temperature for alarm warning at 30˚. If the temperature exceeded the set limit, the LED in the front panel turned red, and the alarm sounded.
The system used property nodes for real-time update of the x-axis in the graph for each channel. In addition, the system was arranged so that all channels could be monitored in the main menu screen, and each channel could be monitored separately using the tab control. Also, we used TCP/IP communication to transmit data concerning channels, temperature, and humidity to the PDA. We used iPAQ h2210 as the PDA for the system, the most recent one using Pocket PC 2003 as its operating system. With regards to TCP/IP communication, we used the SD type wireless LAN card because there was no built-in wireless LAN. On the PDA interface, only one graph on temperature was provided due to the limits of PDA screen and problems with charts.
New System Provides Mobility and Future Possibilities
At first, we applied Bluetooth communication using VISA function to the system. However, due to problems with distance, we used TCP/IP communication. Currently, using TCP/IP communication, doctors and nurses can obtain data anywhere the Internet can be used. In the future, we hope to improve the system using the tab control of the LabVIEW 7.1 PDA Module, as well as other improved chart functions as provided. The system now provides simple data on temperature and humidity, but in the future, more diversified data may be available based on vital signs and used for a network of data. In addition, hospitals could use this system for ubiquitous health care using PDA or other types of mobile handsets and for home automation.
For more information, contact:
In-kwon Kim
Ulsan University Medical School
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