Decroly Gilles, Lambert Pierre, Delchambre Alain
TIPs Dpt CP 165/67, Université Libre de Bruxelles, Brussels, Belgium.
BEAMS Dpt CP 165/56, Université Libre de Bruxelles, Brussels, Belgium.
Front Robot AI. 2021 Nov 11;8:768236. doi: 10.3389/frobt.2021.768236. eCollection 2021.
The rise of soft robotics opens new opportunities in endoscopy and minimally invasive surgery. Pneumatic catheters offer a promising alternative to conventional steerable catheters for safe navigation through the natural pathways without tissue injury. In this work, we present an optimized 6 mm diameter two-degree-of-freedom pneumatic actuator, able to bend in every direction and incorporating a 1 mm working channel. A versatile vacuum centrifugal overmolding method capable of producing small geometries with a variety of silicones is described, and meter-long actuators are extruded industrially. An improved method for fiber reinforcement is also presented. The actuator achieves bending more than 180° and curvatures of up to 0.1 mm. The exerted force remains below 100 mN, and with no rigid parts in the design, it limits the risks of damage on surrounding tissues. The response time of the actuator is below 300 ms and therefore not limited for medical applications. The working space and multi-channel actuation are also experimentally characterized. The focus is on the study of the influence of material stiffness on mechanical performances. As a rule, the softer the material, the better the energy conversion, and the stiffer the material, the larger the force developed at a given curvature. Based on the actuator, a 90 cm long steerable catheter demonstrator carrying an optical fiber is developed, and its potential for endoscopy is demonstrated in a bronchial tree phantom. In conclusion, this work contributes to the development of a toolbox of soft robotic solutions for MIS and endoscopic applications, by validating and characterizing a promising design, describing versatile and scalable fabrication methods, allowing for a better understanding of the influence of material stiffness on the actuator capabilities, and demonstrating the usability of the solution in a potential use-case.
软机器人技术的兴起为内窥镜检查和微创手术带来了新机遇。气动导管为传统的可操纵导管提供了一种有前景的替代方案，可在自然通道中安全导航，而不会造成组织损伤。在这项工作中，我们展示了一种优化的直径为6毫米的两自由度气动致动器，它能够在各个方向弯曲，并包含一个1毫米的工作通道。描述了一种通用的真空离心包覆成型方法，该方法能够用各种硅树脂制造小尺寸部件，并且可以在工业上挤出米长的致动器。还提出了一种改进的纤维增强方法。该致动器可实现超过180°的弯曲，曲率可达0.1毫米。施加的力保持在100毫牛以下，并且设计中没有刚性部件，从而降低了对周围组织造成损伤的风险。致动器的响应时间低于300毫秒，因此不受医疗应用的限制。还通过实验对工作空间和多通道驱动进行了表征。重点是研究材料刚度对机械性能的影响。通常，材料越软，能量转换越好；材料越硬，在给定曲率下产生的力就越大。基于该致动器，开发了一种携带光纤的90厘米长的可操纵导管演示器，并在支气管树模型中展示了其在内窥镜检查中的潜力。总之，这项工作通过验证和表征一种有前景的设计、描述通用且可扩展的制造方法、更好地理解材料刚度对致动器性能的影响以及在潜在用例中展示该解决方案的可用性，为用于微创手术和内窥镜应用的软机器人解决方案工具箱的开发做出了贡献。
