Method and system of monitoring respiratory signal by radio
A method and system is provided for monitoring a respiratory signal by radio. The method includes the steps of: converting a change in electric resistance, which is caused by a change in abdominal circumference measured through a rubber waistband that is made of conductive rubber and is mounted on a lower garment of a testee during respiration, into a voltage signal, performing A/D conversion on the voltage signal, and transmitting the converted digital signal to a short distance by radio using a wireless communication protocol for ZigBee; and receiving the respiratory signal transmitted by radio, transmitting it to a computer unit by wire through an RS-232 port that is a serial communication port, and enabling a tester to monitor the respiratory signal through a screen.
1. A method of monitoring a respiratory signal by radio, the method comprising:
attaching a single rubber waistband that is made of a conductive rubber to a lower garment of a testee so that the waistband completely surrounds the testee's body;
a respiratory signal measuring and transmitting step of converting a change in electric resistance, which is caused by a change in abdominal circumference measured through the rubber waistband during respiration, into a voltage signal, performing analog/digital (A/D) conversion on the voltage signal, and transmitting the converted digital signal to a short distance by radio using a wireless communication protocol for ZigBee; and
a respiratory signal receiving and monitoring step of receiving the respiratory signal transmitted by radio, transmitting it to a computer unit by wire through an RS-232 port that is a serial communication port, and enabling a tester to monitor the respiratory signal through a screen.
2. The method as claimed in claim 1 , wherein the rubber waistband is produced by mixing conductive particles into rubber so as to have the electric resistance from tens of Ω to several kΩ.
3. The method as claimed in claim 1 , wherein the rubber waistband in the respiratory signal measuring and transmitting step is operated by one of four resistors constituting a Wheatstone bridge circuit, and undergoes the conversion of the electric resistance change thereof into the voltage signal.
4. The method as claimed in claim 1 , wherein the voltage signal converted by the electric resistance change of the rubber waistband corresponds to the respiratory signal that is amplified through a differential amplifier circuit and minimizes high-band noise through a low pass filter circuit.
5. The method as claimed in claim 1 , wherein, prior to the respiratory signal receiving and monitoring step, a calibration procedure of performing a CO 2 inhalation test on each testee once, analyzing correlation between an abdominal respiratory signal and a tidal volume of the testee to calculate a regression line, and substituting the abdominal respiratory signal, measured in the respiratory signal measuring and transmitting step, into the regression line to measure the lung volume.