Session: 07-08-03: Biomedical Devices, Sensors, and Actuators III

Paper Number: 174031

Measurement System for Continuous Blood Pressure by Using Camera and Impinging Jet Flow 

Introduction: Recently, as each beat and long-term measurement of blood pressure in daily life can lead to the prevention of cerebrovascular and cardiovascular diseases, not only maximum and minimum blood pressure, but also continuous measurement of blood pressure changes is required. We have proposed pressure measurement by using an impinging air jet and camera to measure continuous blood pressure without a cuff. In our previous investigations[1][2], the effect of the impinging jet pressure on the pulsating elastic tube on the pressure in the tube and the amount of deformation was investigated, and it was found that the proper jet pressure can be obtained to choose mode of no deformation for the tube. But it is not clarified to find out the effects of pulse timing of the jet pulse on the deformation process.

 

Methodology: In this investigation, by using the principle of the tonometry method, which can detect the continuous internal pressure of blood vessels, an experimental model with an elastic tube and pulsatile flow are used to observe the deformation of the elastic tube by an air jet. In the experimental apparatus, the internal pressure of the tube between the pump and the experimental section is measured by a pressure sensor. The deformation process of the tube is observed by a video camera, and it is determined as deformation.

 

Results: From the measurement of internal pressure, it is found that the tube is deformed significantly and the internal pressure in the tube is disturbed with increasing jet pressure. It suggests that it is possible to obtain the deformation of the tube without significantly affecting the pressure inside the tube by selecting an appropriate jet pressure, and that the internal pressure can be obtained from the tube deformation. But the pulsation cannot be captured due to the long ejection time of air jet comparing with pressure fluctuation. By shortening the ejection time, it should be possible to estimate the internal pressure waveform in more detail by using displacement of the tube.

 

Conclusions: In this presentation, by applying an air jet with proper strength to a pulsating elastic tube, it is concluded that (1)By optimizing the jet pressure, deformation of the tube without affecting the pressure inside the tube can be obtained, (2)Effect of delay of valve timing on the internal pressure in the tube is large, and effect of delay on the displacement of tube deformation is low. 

 

[1] A.Yamamoto et.al., Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 19(2), pp.149-159, 2024, [2] A.Yamamoto et.al., ICIC Express Letters, 19(5), pp.527-534, 2025

 

 

Presenting Author: Masaaki Tamagawa Kyushu Institute of Technology

Presenting Author Biography: 2010- Professor , Kyushu Institute of Technology, Japan

Authors:

Kota Taoka Kyushu Institute of Technology
Ayumu Yamamoto Kyushu Institte of Technlogy
Yuko Miyamura Teikyo University
Yohji Yamamoto National Institute of Technology, Kitakyushu Collage,
Takeshi Tachibana National Institute of Technology, Kitakyushu Collage,
Tetsuya Kimura Kobe University
Masaaki Tamagawa Kyushu Institute of Technology