The Design Of Noninvasive Blood Pressure Instrument Based On Oscillometric Method

Blood pressure is the important physiological parameter which indicates the enginery of human's circulating system. From the blood pressure we can know about the heart's ability to pump blood,pulse rate,blood vessel's resistance,main artery and big artery's elasticity ,the blood capacity of whole body,blood's physical state,etc.So the mesurement of the blood pressure is very importment to clinic diagnose.How ever,how to get the exact and credible blood pressure parameter by the no invasion and economical method is still the problem of the biomedicine field.Oscillometric method is the advanced method for the no invasion blood pressure measurement. It qualitatively provides the order of the pulse pressure signal's changing with the cuff pressure and quantificationally points out the relationship between the mean blood pressure value and the pulse wave signal. So this method gives us a more scientific way to find other blood pressure parameters. With the rapid development of eletronics and computer technology,no invasion blood pressure instrument based on Oscillometric method begin to come out.We have successfully designed an experiment system for the no invasion blood pressure measurement with our own IP.In our research and develop task we have done a lot work to study foreign instrumen and design ideas.This experiment system is based on MSP430 series MPU with excellent erformance and applies advanced digital signal process and intelligent technology.In hardware design,the following means were applied:After a lot of experment and fully knowing about the characteristic of the pulse wave signal,we have designed the accurate and credible circuit to collect the pulse wave signal;Power circuit,communicaion circuit,power drivers circuit have been disigned for the instrument.In software design,the following arithmetic were applied:1. Applying several digital signal process method to make the pulse wave signal more smoothness;2. Applying LMS self-adaptive filter to eleminating the noise of the pusle wave signal;3. Applying differential and limen method to improve the gain of ture pusle signal and effictively abandon the artifact wave resulted from movement;4. Bringing forward exact and feasible arthmetic to identify the systolic and diastolic blood pressures based on the keystone of oscillometric method and lots of experiment.5. Besides the blood pressure pusle rate is measured in the system and progression average means is applied to optimize the result.