Abstract: A feedback photoplethysmography measuring device is provided, including: a measuring device that measures a human body to obtain a photoplethysmography signal; an analog/digital conversion unit that converts the photoplethysmography signal measured by the measuring device to a photoplethysmography value which is a digital value; a variation-degree calculation unit that calculates a photoplethysmography variation value according to the photoplethysmography value converted by the analog/digital conversion unit; and a feedback emitted light amplitude adjustment unit that controls the measuring device according to a plurality of preset control values or the adjusted photoplethysmography variation value calculated by the variation-degree calculation unit, and adjusts the photoplethysmography variation value to a minimum variation value.

Abstract: An apparatus and a method for noninvasive and caffless blood pressure measurement are provided. The apparatus includes: a photoplethysmography (PPG) amplitude calculation unit, a time difference calculation unit, a velocity calculation unit, and a calculation unit. The method includes the following steps: calculating amplitude differences between characteristic points of a PPG waveform; calculating differences between a time point of a peak of an electrocardiography (ECG) waveform and a time point of each of the characteristic points of the PPG waveform; calculating differences between time points of the characteristic points of the PPG waveform; performing calculation according to the length of a hand and an ECG-PPG time difference to obtain a pulse wave velocity (PWV); and performing calculation according to the PWV, one of the characteristic point amplitude difference, and one of the characteristic point time difference to obtain a systolic/diastolic blood pressure estimate.