Conditioning of the signal to be acquired from a photoplethysmographic sensor

Abstract

The subject of the paper is devoted to noninvasive acquisition of parameters specifying a photoplethysmographic signal (PPG) to which the pulse waveform contributes as the major component. Continuous monitoring ofphotoplethysmograms is of great importance in clinical practice. An optoelectronic sensor based either on reflection or transmission variant of lighttissue interaction can be used to detect the PPG signal, however, there are a lot of difficult measurement problems. Reliability of noninvasive optical sensing depends on specific factors, including physiological as well as technical interferences. In the paper, application of selected manners of digital filtration, which were used to process the raw signals acquired from an optoelectronic sensor placed on the fmgertip, is presented. The transmission variant oflight penetration is considered. The proposed procedures of signal conditioning allow making possible effective acquisition of useful parameters of a raw noisy PPG signal. Measurable quantitative changes caused by qualitative changes in a given pulse waveform shape and disturbances may be evaluated.