Performance evaluation of biosignal measurement at the wheelchair system

The purpose of this study is to measure both ECG and BCG(Ballistocariograph) signal of a subject on moving or resting wheelchair and detect the heart rate and respiratory rate and transmit an event message to remote server on emergent situation. To acquire ECG and BCG data, amplifier circuits were composed to be suitable for their characteristics. 3-axial accelerometer was built in the developed device to measure the mechanical noise that can be generated on moving wheelchair.The output signals were converted to digital data and stored in bio-signal archiving media(SD card). CDMA module was used to transmit the event data on ECG electrode detachment and the received data was monitored by the developed C# application program. 8 volunteers participated in the experiment to evaluate the validity of the developed device. When the event occurs in each subject, 48 Kbyte data, stored for 32 seconds from that point, was transmitted to remote server through CDMA cellular phone network correctly. The received data of ECG , BCG, and 3-axial acceleration could be archived in server and the heart rate and respiratory rate could be measured and analyzed. The correlation coefficients of respiratory rate in resting and moving with the real value were 0.9636 and 0.9237, respectively. The correlation coefficient ofR-R intervals between the developed and reference device was 0.999.In conclusion, the developed device in this study could acquire the ECG and BCG data of subjects on wheelchair simultaneously and measure their heart rate and respiratory rate. In addition, event data was verified to be transmitted to remote server without any errors.