Development of a load cell-based Bluetooth device for Pulse Wave Velocity estimation

With 17.9 million deaths per year, approximately 32% of all annual deaths, cardiovascular disease (CVD) is the world’s largest cause of death. Early detection and treatment of CVD can significantly lower the risk of premature death and ensure that patients lead normal lives. Among the several predictive factors, arterial stiffness has been found to be a useful indicator of cardiovascular risk and has a close relationship with Pulse Wave Velocity (PWV). Pulse Wave Velocity (PWV), which is often measured between the carotid and femoral sites, measures the speed of propagation of the pressure wave inside the arteries. For this reason, this thesis aims to develop a low-cost, non-invasive Bluetooth device for PWV estimation. The sensitive elements used are digital micro force load cells produced by Honeywell, which behave like force sensors: placed on the skin in proximity of an artery, they can detect the smallest force variations caused by the artery pulse wave. These sensors are also chosen for their dimensions to find an alternative to tonometers used in the probes of ATHOS, an experimental device developed by the MiNES research group in Politecnico di Torino where this work has been conducted. Firstly, an analysis of the state of the art about load cells and force sensors on the market was carried out. After choosing the sensor, the focus was shifted to implementing a read-out firmware to extract data collected by the sensor and, secondly, its characterization. After implementing the Bluetooth Low Energy data transmission among sensors and the laptop, the sensors have been integrated within a modified version of the ATHOS probe holder. For the real-time visualization of the pulse wave signal, a Graphic User Interface of the experimental system has been adjusted to the sensor in use.