This study aims to investigate the potential of using polymer multi-material additive manufacturing (MMAM) to produce miniature hydraulic piston actuators combining rigid structures and flexible seals. Such actuators offer great potential for medical robots in X-ray and magnetic resonance environments, where conventional piston actuators cannot be used because of safety issues caused by metal components.,Hydraulic pistons with two different integrated flexible seal shapes are designed and manufactured using MMAM. Design 1 features a ring-shaped seal made from a flexible material that is printed on the surface of the rigid piston shaft. Design 2 appears identical from the outside, yet an axial opening in the piston shaft is added to enable self-reinforced sealing as fluid pressure increases. For both designs, samples with three different outer diameters are fabricated leading to a total of six different piston versions. The pistons are then evaluated regarding leakage, friction and durability.,Measurement results show that the friction force for Design 2 is lower than that of Design 1, making Design 2 more suitable for the intended application. None of the versions of Design 2 shows leakage for pressures up to 1.5 MPa. For Design 1, leak-tightness varies with the outer diameter, yet none of the versions is consistently leak-tight at 1.5 MPa. Furthermore, the results show that prolonged exposure to water decreases the durability of the flexible material significantly. The durability the authors observe may, however, be sufficient for short-term or single-use devices.,The authors investigate a novel design approach for hydraulic piston actuators based on MMAM. These actuators are of particular interest for patient-specific medical devices used in radiological interventions, where metal-free components are required to safely operate in X-ray and magnetic resonance environments. This study may serve as a basis for the development of new actuators, as it shows a feasible solution, yet pointing out critical aspects such as the influence of small geometry changes or material performance changes caused by water absorption.

中文翻译：

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用于医疗机器人的多材料 3D 打印液压执行器

本研究旨在研究使用聚合物多材料增材制造 (MMAM) 生产结合刚性结构和柔性密封件的微型液压活塞执行器的潜力。这种执行器为 X 射线和磁共振环境中的医疗机器人提供了巨大的潜力，在这些环境中，由于金属部件引起的安全问题而无法使用传统的活塞执行器。使用 MMAM 设计和制造具有两种不同集成柔性密封形状的液压活塞。设计 1 具有由柔性材料制成的环形密封件，该密封件印在刚性活塞轴的表面上。设计 2 从外观上看是相同的，但在活塞轴上增加了一个轴向开口，以便在流体压力增加时实现自增强密封。对于这两种设计，制造了三种不同外径的样品，导致总共有六种不同的活塞版本。然后对活塞的泄漏、摩擦和耐久性进行评估。测量结果表明，设计 2 的摩擦力低于设计 1，使设计 2 更适合预期应用。设计 2 的所有版本均未显示压力高达 1.5 MPa 的泄漏。对于设计 1，密封性随外径而变化，但没有一个版本在 1.5 MPa 下始终保持密封。此外，结果表明，长时间暴露在水中会显着降低柔性材料的耐用性。然而，作者观察到的耐用性可能足以用于短期或一次性设备。作者研究了一种基于 MMAM 的液压活塞执行器的新设计方法。这些执行器特别适用于放射介入中使用的患者特定医疗设备，其中需要无金属部件才能在 X 射线和磁共振环境中安全运行。这项研究可以作为开发新执行器的基础，因为它展示了一个可行的解决方案，同时指出了一些关键方面，例如由吸水引起的微小几何变化或材料性能变化的影响。