Abstract: The method to measure blood pressure via pulse wave transit time(PWTT)requires monitoring ECG and pulse wave signals simultaneously， which has no portability. A new noninvasive method of measuring systolic blood pressure(SBP)continuously is therefore proposed， in which the PWTT can be obtained simply through volume pulse waves. The volume pulse waves were acquired by a blood oxygen probe with red light emitting diode， and then the accelerated pulse waves were gotten through filtering， amplifying and processing the signals. The PWTT between the progressive and reflected waves of the accelerated pulse waves was calculated and the SBP was calibrated. The system was implemented using the Android cell phone and ATmega128 MCU. The experimental results indicate that there is no obvious difference between the SBP measured by the new system and by an electronic sphygmomanometer with error less than 10 mmHg.

Key words: volume pulse wave, PWTT(pulse wave transit time), SBP(systolic blood pressure), noninvasive blood pressure measuring, Android cell phone