A Novel Sphygmogram Sampling and Self-Adjusting Scheme for e-Home Healthcare

Pulse wave transmit time method has been used to estimate blood pressure by simultaneously measuring electrocardiogram & pulse signals [1]. Most researchers use photo reflective sensor to capture photoplethysmograph (PPG) signal by attaching sensor on finger tip. However, such a way would interfere hands in operating further the e-home healthcare system, plus PPG has flatter morphological shape [2] which is not adequate for searching feature points. Thus the piezoelectric ceramics is selected to acquire sphygmogram (SPG) signal with sharp morphological shape from wrist. Using such a way can free fingers to operate the e-home healthcare system. A SPG sampling scheme with signal conditioning circuit and relevant software for realizing signal amplitude and baseline-shift self-adjustment are proposed in this paper. A close-loop control is constructed between computer and micro control unit (MCU) such that to acquire the self-adjusted stable SPG signal. The testing results show out superior features of this scheme.