Accurate measurements of blood pressure, a major indicator of multiple health risks, and its continuous monitoring are extremely important for personal health care. Invasive methods, which are unpractical for daily use, are the most accurate way to measure blood pressure (BP). Thus, there is a growing need for more accurate and convenient non-invasive measurement wearables that allow the users to monitor their BP continuously. Current wearables (such as smart watches) are still immature, and its performance has not been validated at the level for clinical use. In order to improve the sensor technology embedded in wearables for accurate BP measurements, the “skin effect” must be considered. The skin is located between the sensor in the wearables and the blood vessel. It can act as a physical filter, affecting the sensor measurements. Since using human subjects to study the effect of skin stiffness is resource intensive and costly, this project proposes to use artificial skin samples to study the effect of skin on BP. The primary goals of this study are to fabricate skin samples based on silicones that can represent a range of human skin properties, perform characterization testing of the samples using a Dynamic Mechanical Analyzer (DMA), and evaluate how skin samples affect the pulse measurements. The characterization testing results show that the modulus of the samples can represent a range of human skin. The findings of this project are anticipated to pave the way to develop mathematical models (transfer functions) that can relate the actual pulse pressure in arteries and the measured pulse data with respect to a range of skin properties as well as the development of non-invasive radial pulse monitoring systems. Developing a transfer function would improve the accuracy of wearable devices for continuous BP monitoring, thus providing a practical alternative to invasive BP measuring.
Author: Miranda Eaton
Faculty Advisor: Dr. Jeong-Hoi Koo, Department of Mechanical and Manufacturing Engineering
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