Custom Silicone Vessels for In Vitro Investigations on Vascular Ageing using Photoplethysmography

Cardiovascular diseases (CVD) remain a major health challenge, affecting millions of individuals. Alongside the impact of CVD, the natural process of vascular ageing contributes to changes in the vascular system, potentially compromising cardiovascular health by causing arterial stiffness. Current clinical methods for vascular health assessment often require referrals from General Practitioners, leading to delays and patient anxiety. Photoplethysmography (PPG), an optical sensing technique employed in numerous wearables, holds promise for assessing cardiovascular health, particularly in the context of vascular ageing. This paper presents a study where novel customisable vessel-tissue phantoms to simulate the vascular system in vitro were implemented. Various additives in the silicone elastomer were explored for their impact on vessel wall thickness and elasticity. The results demonstrate that changes in silicone elastomer formulation significantly affect the mechanical properties of the developed vessels. In vitro PPG signals were acquired from the customised phantoms. Tests have shown statistical difference between two vessel-tissue phantoms with vessels of varying elasticity. This study paves the way in investigating further the potential of PPG as an indicator of vascular ageing.