手术夹钳是外科手术中常用的夹持器具，传统的手术夹钳主要通过齿形结构使湿滑的软体器官变形产生机械互锁来提高夹持稳定性，这往往会带来严重的组织损伤。为了降低夹钳夹持损伤，需要发展以强湿黏附增摩来取代强夹持增摩的技术，实现湿环境下"松夹而不滑脱"功能。树蛙经过千万年的进化，其脚掌形成了优异的湿摩擦功能。通过表征发现树蛙脚掌表面结构多为密排六棱柱。且随着界面间液量减少，树蛙脚垫由湿变干过程中液膜会出现碎化分散，摩擦力出现近百倍增大的现象，即称为边界强摩擦状态。通过对仿生表面的测试发现，液膜的碎化现象由其特殊的密排棱柱结构所决定，液膜碎化会使液膜更为均匀铺展，产生极强表面张力，从而能够在无任何外界压力的情况下仍能产生极高的摩擦力，有助于达到手术夹钳"松夹而不滑脱"的效果。此外，棱柱结构的各向异性与沟槽的方向性分布使得摩擦力表现出各向异性，鲜猪肝夹持测试发现，与传统齿形夹钳相比仿生六棱柱表面具有更优异的摩擦性能，更适合于仿生手术夹钳表面。基于树蛙脚垫强摩擦机制，提出了仿生手术夹钳设计制造方法，并验证了其降低组织损伤的有效性。
张力文
,
陈华伟
,
王炎
,
张鹏飞
,
张国凯
,
张德远
. 基于树蛙脚掌湿黏附的仿生手术夹钳表面研究[J]. 机械工程学报, 2018
, 54(17)
: 14
-20
.
DOI: 10.3901/JME.2018.17.014
Surgical grasper is one of the most common used tools in surgery. To effectively grasp soft slippery tissues, traditional surgical graspers are usually constructed with sharp teeth to deform tissue and form mechanical interlock between interfaces, which easily leads to strong tissue damages. Improvement of wet friction properties at the interface between the surgical grasper and soft tissue can greatly reduce the holding force required and the soft tissue damage. To design a surface with strong wet attachment performance, the wet attachment mechanisms of tree frog has been studied. Here we find that its toe pad is constructed with micropillar array, which mainly are hexagon. With liquid volume decreasing, the uniform liquid self-splitting effect has been observed on micropillar array surface, and the boundary friction appears on both tree frog's toe pad and bioinspired surface. This boundary friction mainly comes from the thin liquid film induced strong capillary force and leads to strong friction without any normal force. Besides, the anisotropic pillars and channels' distribution on toe pad leads to its directional dependent friction. By testing the friction of different pillar structure surfaces and traditional surgical grasper surfaces with macroscale teeth, the hexagonal pillar pattern exhibited improved wet frictional performance, which is appropriate for bioinspired surgical graspers. Finally, the soft tissue damage of these patterns was evaluated, and the effectiveness of biomimetic surface patterns when applied in surgical graspers is confirmed.
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