Microfluidics Lab, Department of Aerospace and Mechanical Engineering, University of Liège, Liège, Belgium.
Functional and Evolutionary Morphology Laboratory, FOCUS, University of Liège, Liège, Belgium.
J R Soc Interface. 2020 May;17(166):20200024. doi: 10.1098/rsif.2020.0024. Epub 2020 May 6.
Many insects can climb on smooth inverted substrates using adhesive hairy pads on their legs. The hair-surface contact is often mediated by minute volumes of liquid, which form capillary bridges in the contact zones and aid in adhesion. The liquid transport to the contact zones is poorly understood. We investigated the dynamics of liquid secretion in the dock beetle by quantifying the volume of the deposited liquid footprints during simulated walking experiments. The footprint volume increased with pad-surface contact time and was independent of the non-contact time. Furthermore, the footprint volume decreased to zero after reaching a threshold cumulative volume (approx. 30 fl) in successive steps. This suggests a limited reservoir with low liquid influx. We modelled our results as a fluidic resistive system and estimated the hydraulic resistance of a single attachment hair of the order of MPa · s/fl. The liquid secretion in beetle hairy pads is dominated by passive suction of the liquid during the contact phase. The high calculated resistance of the secretion pathway may originate from the nanosized channels in the hair cuticle. Such nanochannels presumably mediate the transport of cuticular lipids, which are chemically similar to the adhesive liquid.
许多昆虫可以利用腿部的粘性毛垫在光滑的倒置基板上爬行。毛发与表面的接触通常是由微小体积的液体介导的，这些液体在接触区域形成毛细桥，有助于附着。液体向接触区域的输送还了解甚少。我们通过量化模拟行走实验中沉积的液体足迹的体积，研究了码头甲虫 中液体分泌的动力学。足迹体积随垫面接触时间的增加而增加，与非接触时间无关。此外，在连续步骤中达到累积体积（约 30fl）的阈值后，足迹体积减小到零。这表明储液器有限，液体流入量低。我们将我们的结果建模为一个流体阻力系统，并估计单个附着毛发的液压阻力约为 MPa·s/fl。甲虫毛垫中的液体分泌主要是在接触阶段通过液体的被动抽吸来实现的。分泌途径的高计算阻力可能源于毛表皮中的纳米通道。这些纳米通道可能介导了与粘性液体化学性质相似的角质层脂质的运输。
