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Abstract: tracheal stents are an important form of treatment for benign or malignant central airway obstruction. However, the mechani-cal behavior of current tracheal stents is signifcantly diferent from that of the native trachea, which leads to a variety of serious complications. In this study, inspired by the structure of the native trachea, a wavy non-uniform ligament chiral tracheal stent is proposed, in which J-shaped stress–strain behavior and negative Poisson's ratio response are achieved by replacing the tangential ligament of tetrachiral and anti-tetrachiral hybrid structure with a wavy non-uniform ligament. Through the combination of theoretical analysis, fnite element analysis and experimental tests, a wide range of desired J-shaped stress–strain curves are explored to mimic the native porcine trachea by tailoring the stent geometry. Besides, the negative Poisson's ratio and auxetic diameter curves versus axial strain of the stent are also studied in detail, thus contribut-ing to the enhancement of cross-section ventilation and reducing the migration of the stent. This novel tracheal stent with a unique microstructure shows a potential to perfectly match the physiological activities of the native trachea and thereby reduce potential complications.

浙大刘加朋、姚鑫骅、杭州市第一人民医院叶健等 | 一种模拟真实气管J形应力-应变行为的新型非均匀韧带手性结构气管支架

本研究论文聚焦能够适应人体气管动态行为的功能支架设计。气管支架是针对气管狭窄或塌陷的患者所采用的一类气管内部环形网状支撑物，以此来扩张和支撑气管，达到解除狭窄的治疗目的。支架植入术是除手术外治疗气管狭窄较为理想的方法。然而，目前临床上常用的气管支架难以达到完全理想的治疗效果，主要缺陷表现在批量生产的支架无法适应不同患者、不同病灶、不同阶段的治疗需求，其主要原因包括：①由于人体呼吸运动的多样性和复杂性，导致支架在气管内移位甚至脱位；②对于儿童患者，现有的支架由于无法适应人体生长变化而导致失效。因此，设计并制造一种形状、性能可变，能够适应人体气管动态行为的功能支架，已成为决定气管狭窄治疗效果最为关键的因素之一。

鉴于此，论文提出了一种波浪形非均匀韧带手性结构气管支架。该支架基于手性拉胀机械超材料的负泊松比特性，采用波浪形非均匀韧带（W-N-L）替换四手性和反四手性混合结构的切向韧带，实现了支架的J形应力-应变行为和负泊松比特性。通过调控韧带几何参数和晶格拓扑模拟原生气管力学特性，且支架表现出负泊松比效应，轴向拉伸形变条件下，径向适度膨胀以适应气管动态行为，对保证气道畅通和消除支架移位起到重要作用。