Stress measurement using diameter changes in artery of forearm and evaluation of ultrasonic blood vessel diameter sensor system

Several stress load influences our body as stress reaction. In the case of artery, contraction of smooth muscle of arterial wall is dynamically influenced by stress load as changes in vascular tone. Stress measurement system using diameter changes in artery of forearm has been developed. Changes of blood vessel diameter in radial artery was measured using ultrasound. Firstly, changes in radial arterial diameter of human were measured during stress load by a commercial ultrasonic equipment. Two kinds of stress were loaded, one is physical stress load (cold water load) and the other is mental stress load (mental arithmetic load). Arterial stiffness which reflects vascular tone was calculated using measured blood pressure and measured arterial diameter as inflation difficulty of blood vessel wall. Arterial stiffness was dynamically changed according to stress load. In the case of using commercial ultrasonic equipment, blood vessel diameter was derived from ultrasonic B-mode image of blood vessel and the ultrasonic probe and the system are relatively big, complicated and expensive. Simple and small size ultrasonic blood vessel diameter measurement sensor and system have been developed using MEMS process. To evaluate accuracy of the developed sensor and the system, comparison between measured data from fabricated sensor system and measured data from the commercial ultrasonic equipment was performed using blood vessel model. Acquired diameters were well correlated according to diameter change of the vessel model by changing internal pressure of the vessel model during step change and pulsatile change of internal pressure of the vessel model. © 2020 The Institute of Electrical Engineers of Japan.