Conceptual design of a multi-functional sphygmus detection system

From the energy point of view, obtaining simultaneous blood pressure and flow rate of the radial artery at the wrist is very important for sphygmic diagnosis in medicine. This work depicts the conceptual design for a noninvasive multi-functional sphygmus detection system. According to Y. C. Fung's flow rate equation, flow rate is a function of the diameter of the blood vessel, two adjacent pressures, arterial compliance, the distance between the two adjacent pressures and the viscosity of the blood. Because the distance between the two adjacent pressures is preset and the viscosity is obtained from either a data bank or viscometer, four measuring techniques are proposed to realize the calculation of the flow rate. First, use thermal array sensors and a thermal image identification technique to locate the artery for positioning the sphygmus detection head at wrist and to estimate the diameter of blood vessel as well. Second, detect the delay time between the two adjacent pressures, and then compute the downstream pressure in accordance with the sampled upstream pressure and delay time. Third, employ pressure feedback control to determine the variation of the vessel diameter that in turn can be used to compute the dynamic arterial compliance. Finally, use the nonlinear flow rate equation to calculate the blood flow rate.