Design Of The Quadru-Signal Physiological Monitor

The electrocardiogram (ECG),blood pressure(BP),sphygmus and blood oxygensaturation(SO₂) are the most fundamental bio-indicators of human beings. It's helpfulfor doctors to measure these biology signals in the first-aid outside the hospital.However, most of the existing monitor systems are inconvenient to be carried andcontrolled. Therefore, an intelligentized, portable, low dissipation multi-parametersmonitor system is presented in this paper.Based on the experience of biology signal acquisition circuit, this system isdesigned according to the respective characteristics of ECG,BP and SO2 signals.The system has three modules: pre-amplifier based on common mode drivingtechnique is applied in ECG module;the Oscillometric method is used in BP module;Photo Plethysmo Graphy (PPG) is applied in SO₂ module. All the modules are basedon ADμC84× which has 24-bits ∑-ΔA/DC.Since the signal detected are vulnerable to the environment noise and patient'smovement, several signal processing methods are employed this paper: morphologyoperators is used for the first time to remove the power line interference and baselineexcursion in BP module;the dynamic spectroscopy is applied firstly to remove theinfluence of individual discrepancy and measuring condition in the SO2 module;thesmoothness method is used to remove power line interference in ECG acquisition.The results of experiments verify the validity of these methods. Moreover, we appliedtwo new methods in BP module: parabola mensuration and unitary proportioncriterion. And accumulative average method is used to calculate the pulsation, toreduce the stochastic error.Designed on modularization technique, the system is divided into severalmodules with specific function and clear frame, facilitating its modification,optimization and maintenance in the future. ADμC84× as the core MCU of thesystem, its strong analog and digital function make the monitor simple but powerful,and reliable.