In recent years, statistical studies have highlighted an increase in the incidence of cardiovascular diseases (CVDs). Therefore, detecting and diagnosing these conditions in advance is crucial to ensure appropriate treatment and prevent further complications. Since the elastic properties of arteries change with aging or in the presence of diseases, arterial stiffness is a key indicator of vascular health and a significant risk factor for CVDs. A physical model commonly used is based on the Moens Korteweg equation, which correlates the Pulse Wave Velocity (PWV), the speed at which the pressure wave propagates along a blood vessel, to the Young's Modulus. The PWV, in turn, can be calculated from the Pulse Transit Time (PTT), which is the temporal delay required for a pressure wave to travel a specific distance between two sites. To study the relationship between PWV and arterial stiffness, an experimental in vitro system was created to simulate the cardiovascular apparatus under controlled velocity and pressure conditions. Four different silicone models were used, each with different mechanical properties, simulating blood vessels in terms of geometry and mechanical characteristics. Two photoplethysmographic (PPG) sensors were used for PTT measurements. These are extremely small and low-cost devices that utilize a LED light source and a photodetector to detect volumetric changes. Currently, these sensors are widely used in wearable devices such as smartwatches and smartbands to provide the user with important vital parameters, such as heart rate and blood oxygenation. The pair of PPG sensors was positioned in each phantom models at three specific distances to determine the optimal distance for detecting arterial stiffness. The purpose of this study is to enhance the use of PPG sensors for monitoring the mechanical properties of blood vessels and, thus, to prevent potential cardiovascular pathologies.