A Bilateral In Vitro Model for Cardiovascular Disease Investigations Using Photoplethysmography Sensors

Photoplethysmography (PPG) is a noninvasive optical sensing technique utilised widely for the assessment of cardiovascular disease (CVD). As CVD is the leading cause of mortality globally, there is a significant interest in the innovation of new and robust noninvasive technologies for the early detection of CVD. This work aimed to develop and evaluate vascular tissue phantoms using the techniques of PPG. The paper describes the fabrication process of custom vessels and the formation of tissue phantoms. In addition, PPG measurement protocols utilising the developed tissue phantoms in an in vitro cardiovascular flow rig were also employed. Following analysis of the acquired PPGs, including feature extraction and statistical analysis, the results demonstrated for the first time that PPGs can be successfully acquired from two identical tissue phantoms placed in a bilateral configuration. This research paves the way for investigating PPGs in a controlled in vitro environment including examining the effect of vascular ageing (arterial stiffness) on the PPG signals.