Current Directions in Biomedical Engineering (Sep 2023)
Analysis of stretch distribution of high compliant elastomers within folded lumen vessels
Abstract
Elastomer based high compliant balloons containing strain sensing element(s) (SEs) is currently under development intended for in-vivo biomechanical diagnostics of vessels. It could potentially reveal local lumen features based on patterns derived from the sensing elements. A Finite Element based, simulation study in COMSOL® (v5.6) focusses on in-vivo inflation behavior of an elastomeric balloon being equipped with SE, whose compliance is ideally magnitudes higher than the surrounding tissue in an idealized 2D setup. We hypothesized the vessel’s inner wall as a closed convexconcave 4-fold structure correlated to surface structures found in urethrae and parameterized the fold depth. A set of SEs consisted of one SE over the inner surface of balloon while the other over the outer wall. Out of the three adjacent placed sets, The first set was closer to the tissue lumen while the third set the farthest. We assessed the stretch of balloon over its inner circumference through SEs. At conformal contact with the tissue wall, The first SE shows a higher value, while the third element undergoes the least stretch within the three sensing elements. The SE’s over the outer circumference show the exact opposite relation. The differences between the sensing elements over the inner and outer circumferences show a correlation with the curvature of the tissue it conforms to. With use of balloon that was 10x thicker (10μm vs 1μm), around 10x larger stretch differences were captured suggesting possibility to use less sensitive measuring system. For the ideal situations performed, the curvature and depth information may be comprehended by observing differences between inner and outer SEs while thicker balloons prove to be more useful to generate differences that are easier to capture in practical situations. This semiquantitative study suggests that simulation studies are powerful tools to obtain new analytical techniques for shape characterization.
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