Experimentally characterized embedded Mckibben muscle as a nastic material for biomedical applications



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This study presents the experimental results that characterize a nastic sheet material?s performance. We defined nastic sheet as a McKibben muscle designed from a foundation that would be embedded as an array in an elastomer matrix. The goal is to be able to utilize the embedded McKibben sheets in the biomedical industry as an improvement to the synthetic devices and/or processes. One mechanism that might produce these improvements is to mimic the biological materials that form functional organs, biological structures, and active tissues. Linking human technology and natural structures is and will continue to be important to society for several reasons. It would improve: (1) the lifestyle of humans in regards to artificial parts that mimic human parts (which will allow us to live longer), (2) artificial limb functionality, and (3) comfort and aesthetics. The objective is focused on characterizing and evaluating McKibben muscles as an embedded muscle sheet by building McKibben muscles and testing them alone and in sheets with one, two, three, and five muscles. The sheets would be known as a single, double, triple and quintuple embedded sheet. Another objective is to determine the performance penalty that embedding puts on the material. The experiments performed used several different approaches, such as analytical models, tensile test analysis, and prototype construction of the specimens. All specimens were designed to have a constant final length of 120mm, being embedded in a polyurethane matrix. We characterized the fundamental performance of a McKibben muscle and each specific embedded sheet. We measured the specimens? work-density and quantified the inactive matrix?s impact on work-density. Based on the results, several improvements were suggested on the fabrication of the specimens. The experiment shows positive potential outcome that could be utilized in the biomedical field, but the results would improve with the suggestions provided in the study. A sample of the results - the actual work-density for both the single and doubleembedded sheets showed an increase to 7.82% and 2.96% consecutively. Once the specimens are removed from the mold, the McKibben muscle automatically tries to retract to its initial state while the polyurethane matrix tries to stay at its initial state.