Evaluation of a new instrument for measuring segmented radial force of SE-stents implemented in the LGF
Sammanfattning: Endovascular surgery is a relatively new, rapidly growing, clinical technique and research area. A new endovascular tool has been developed by Endovascular Development AB, the Liungman Guidewire Fixator (LGF) that secures the distal position of a guidewire. The design of the LGF resembles a nitinol (Nickel-Titanium) stent and exerts a radial force against the blood vessel wall. It is desirable to have a well-founded understanding of all the mechanical characteristics of the product from a medical technology safety perspective. There are different methods for uniformly measure the radial force of an object, i.e. where one single total radial force represents the entire object. This report investigates the possibility for segmented radial force measurement by the development of a new measuring instrument. A prototype of the measuring instrument has been produced to test if the proposed method can be implemented or not. The prototype has been designed, developed and constructed to measure the radial force of individual segments of the stent. The stent segments were created using iris diaphragms and their resistance to radial change were measured using strain gauges. The concept was to measure the radial force differences between each segment with respect to the diameter of the stent. The results show a large and high intensity variation of data due to the strain gauge application. The variation is due to disturbances and flaws in the manufacturing process. On the other hand, one can see that the values for the radial forces of the segments for them different LGFs provide reasonable magnitudes. Some experiments also presents results similar to previous experiments. However, at the same time, no statistically significant conclusion can be drawn. The concept and the theory should work if the errors are changed. In summary, the proposal is to further develop the prototype and complement the experiment using finite element analysis.
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