24-hour Finger Typer Ambulatory Blood Pressure Monitoring Based On CF Card

Blood Pressure ( BP ), which received wide attention in clinical and medical research, is one of the most important physiological parameters of human body. Due to the characteristic of variability, it is of great importance for us to detect BP in long time.The significance of the research on the 24 hours Ambulatory Blood Pressure Monitoring (ABPM) reflects in several aspects:(1) Long time continuous monitoring is more beneficial to the research of the fluctuations of BP in one day compared with the traditional dynamic interrupted measurement;(2) It makes people more comfortable by using the photoelectric technology but not based on the cuff, which is also helpful to the monitoring of BP during the night.(3) It is small size and portability.This paper focus on the design of the 24 hours finger ambulatory blood pressure monitoring system based on CF card. The pulse wave signal from the finger tip is amplified and sampled firstly, and then the A/D result is transmitted to the CF card. The system is well designed with many characteristics as follows. The Common Mode Rejection Ratio (CMRR) of the amplifier is greater than 80dB, the sampling frequency is 2000Hz for each lead with a high resolution of 12-bit and the analog-to-digital converter is embedded in the MCU.The data of pulse wave signals are read on PC from CF card using the card reader. The IIR filter and wavelet are then used to eliminate noise and baseline drift. We use the stepwise regression method to extract the significant parameters of the pulse wave, and find the correlations between the pulse wave and BP. The experimental results show that the system can be able to realize the long time continuous monitoring.