Wearable devices offer promising avenues for health monitoring by potentially integrating heart rate patterns for diagnostic purposes. Watch-like devices are poised to achieve this by monitoring the pulse of the radial artery. Traditionally, this site has been assessed in Oriental medicine, where different pulse fluctuations signify various health conditions. The properties of the skin play a crucial role in accurately measuring radial pulses, as they are transmitted through the skin layer for assessment. In essence, the transmitted pulses depend on the mechanical properties of the skin, such as stiffness and damping, which vary with age. Studying the role of skin in radial pulse measurement necessitates the development of skin models that simulate the mechanical properties of human skin. Previous research has utilized elastomers like Ecoflex, but with limited success. Therefore, this study proposes to investigate new polymeric materials using 3D printing technology. The goal is to create patterns within Polydimethylsiloxane (PDMS) samples to modify their material properties. The Cellink BIO X printer is employed to fabricate ASTM standard samples with two matrix patterns (grid and hexagonal) and infill densities of 30%, 60%, and 90%. Subsequently, a dynamic mechanical analyzer (DMA) is used to conduct a series of sample tests. The results indicate that stiffness or modulus increases with higher infill density. Furthermore, the hexagonal pattern samples exhibit higher stiffness compared to the grid pattern samples at equivalent infill densities. These initial findings suggest that PDMS samples with a grid pattern and lower infill density (<30%) may demonstrate mechanical properties compatible with human skin.
For the careers of the authors, Madeline Webber is pursuing medical school, where this research has been crucial in exposure to the mechanical side of medical technology. As Cory Webber will soon be joining the workforce as a mechanical engineer, this research helped apply the engineering principles learned in class to the design and analysis of future products.
Author(s): Madeline Webber and Cory Webber
Advisor(s): Jeong-Hoi Koo, Mechanical and Manufacturing Engineering
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