Hernandez Alyssa M, Sandoval Jessica A, Yuen Michelle C, Wood Robert J
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Boston, MA, 02134, USA.
Project CETI, New York, NY, 10003, USA.
Sci Rep. 2025 Jan 6;15(1):960. doi: 10.1038/s41598-024-82221-0.
Many aquatic organisms utilize suction-based organs to adhere to diverse substrates in unpredictable environments. For multiple fish species, these adhesive discs include a softer disc margin consisting of surface structures called papillae, which stabilize and seal on variable substrates. The size, arrangement, and density of these papillae are quite diverse among different species, generating complex disc patterns produced by these structures. Considering papillae arrangements in three fish species, the Northern Clingfish (Gobiesox maeandricus), Tidepool Snailfish (Liparis florae), and Chilean Clingfish (Sicyases sanguineus), we fabricated physical disc models that tested relevant surface pattern parameters under shear loading conditions. Parameters of interest included the area of papillae-like structures, the spacing between adjacent structures (channel spacing), and the percent coverage of elements relative to the total disc area. To create our models, a soft silicone elastomer was added to a stiff circular suction cup, which was then "stamped" using a laser-etched and thermoformed mold base to create the desired surface patterning. Discs were tested using a robotic arm equipped with a force sensor, which sheared them across smooth and rough surfaces at a fixed speed and distance. The arm was also used to vary the initial compression to test performance under both suction-dominant and friction-dominant preloads. For our designs, patterns with smaller papillae-like structures and channel spacing often produced higher peak forces than those with larger features. However, the design that withstood the highest shear load featured an intermediate pad size and channel spacing, potentially highlighting a balance between overall surface area and fluid channeling. Additionally, discs with surface patterns often outperformed the control discs (no pattern) on both smooth and rough surfaces, but performance was highly dependent on preload, with patterned discs exhibiting benefits with the higher "friction-dominant" preloads.
许多水生生物利用基于吸力的器官在不可预测的环境中附着于各种基质。对于多种鱼类来说，这些吸盘包括一个较软的盘边缘，由称为乳突的表面结构组成，这些结构可在可变基质上实现稳定和密封。这些乳突的大小、排列和密度在不同物种之间差异很大，形成了由这些结构产生的复杂盘状图案。考虑到三种鱼类——北方喉盘鱼（Gobiesox maeandricus）、潮汐池狮子鱼（Liparis florae）和智利喉盘鱼（Sicyases sanguineus）的乳突排列，我们制作了物理盘模型，在剪切载荷条件下测试相关的表面图案参数。感兴趣的参数包括乳突状结构的面积、相邻结构之间的间距（通道间距）以及元素相对于盘总面积的覆盖率。为了制作我们的模型，将一种柔软的硅橡胶弹性体添加到一个坚硬的圆形吸盘上，然后使用激光蚀刻和热成型的模具底座进行“冲压”，以创建所需的表面图案。使用配备有力传感器的机械臂对盘进行测试，该机械臂以固定的速度和距离在光滑和粗糙表面上对其进行剪切。该机械臂还用于改变初始压缩量，以测试在吸力主导和摩擦主导的预载荷下的性能。对于我们的设计，具有较小乳突状结构和通道间距的图案通常比具有较大特征的图案产生更高的峰值力。然而，承受最高剪切载荷的设计具有中等的垫尺寸和通道间距，这可能突出了总表面积和流体通道之间的平衡。此外，具有表面图案的盘在光滑和粗糙表面上通常都比对照盘（无图案）表现更好，但性能高度依赖于预载荷，有图案的盘在较高的“摩擦主导”预载荷下表现出优势。
