A Bi-modal Probe Integrated with A-mode Ultrasound and Force Sensor for Single-site Assessment of Arterial Pressure-Diameter Loop

There is an ever-increasing interest in the research community towards the development of advanced in-vivo diagnostic and screening tools for cardiovascular diseases. Various methodologies often do not account for potential errors in arterial pressure and diameter measurements. This paper highlights these pitfalls through the design and instrumentation of a bi-modal probe integrated with A-scan ultrasound and force sensor. This probe is used for simultaneous and single-site assessment of pressure – diameter (PD) loop of superficial arteries. In-vivo measurement of PD loop is a gateway to study the mechanical properties of artery, design and development of vascular grafts and clinically significant for measurement of arterial stiffness, local pulse wave velocity, and central blood pressure. The novelty comes with the usage of an image free A-scan mode of ultrasound, which makes it possible to keep the force sensor and ultrasound transducers very close, solving one of the challenges faced by state-of-the-art techniques in single site measurement. In addition to this, in-house-developed acquisition hardware and software ensures matched frequency response and time synchronization for both pressure and diameter signals. Signals were reliably recorded with an SNR of 20 dB and constructed PD loop is in the clockwise direction with pressure signals leading diameter signals.