The external scent efferent system of selected European true bugs (Heteroptera): a biomimetic inspiration for passive, unidirectional fluid transport

Abstract

In this work, we present structured capillaries that were inspired by the microstructures of the external scent efferent system as found in different European true bug species (Pentatomidae and Cydnidae). These make use of small, orientated structures in order to facilitate fluid movement towards desired areas where defensive substances are evaporated. Gland channels and microstructures were investigated by means of scanning electron microscopy and abstracted into three-dimensional models. We used these models to create scent channel replicas from different technical substrates (steel and polymers) by means of laser ablation, laser structuring and casting. Video analysis of conducted fluid-flow experiments showed that bug-inspired, artificial scent fluid channels can indeed transport different fluids (water solutions and oils/lubricants) passively in one direction (velocities of up to 1 mm s−1), while halting the fluid movement in the opposite direction. At the end of this contribution, we present a physical theory that explains the observed fluid transport and sets the rules for performance optimization in future work.

Continuous Directional Water Delivery on the 3D-Printed Arrowhead Microstructure Array

“…The liquids driven by gradient Laplace force have favorable velocities and transport distances. However, the structures used for these studies are complex, and their preparation is difficult [6,9,45,46,47,48,49]. The average velocity of liquids driven by various anisotropic structures is below 0.1 mm/s, and the transport distance (L/R) is generally less than 20 [26,49,50,51].…”

“…Spider silk can effectively capture water from the morning fog in arid regions via directional droplet motion on its one-dimensional thread-like natural form [4]. With its unique back structure, the fogstand beetle can harvest fog [5,6]. The famous Nepenthes alata plant can induce oriented capillarity, which spontaneously delivers liquid up to the peristome to form a trap in which small insects are caught [7,8,9,10].…”

“…This is typically observed on spider silk, cactus spines, and Nepenthes alata structures. Systems that employ gradient Laplace force are characterized by high transport speeds and can ensure transport over certain distances [3,6,27]. However, the preparation of gradient Laplace structures is complex and costly.…”

Bio-inspired microneedle design for efficient drug/vaccine coating

“…Nature inspired surfaces with special wetting properties range from ultra-hydrophobic self-cleaning applications of the lotus-effect (Barthlott and Neinhuis 1997) up to hydrophilic polymer anti-fouling coating applications inspired by marine mussels (Hamming and Messersmith 2008). In the context of MN coating, bio-inspired microfluidic devices and structured surfaces which, coming in contact with different liquids, promote a directional movement of the liquids (Comanns et al 2014; Buchberger et al 2015; Comanns et al 2015; Comanns et al 2016; Kirner et al 2017; Plamadeala et al 2017; Buchberger et al 2018; Hischen et al 2018), are of great interest.…”

AMROBS: All-Metal Replicas of Biological Surfaces—A Novel Approach Combining Established Techniques

“…Casting, three-dimensional (3D) printing, lithography, laser etching or micromilling in technical surfaces like polymers and metals are just a few commonly used procedures. Successful examples for this kind of processing are various [12,13,14,15], however they all share a certain loss of detail in the final product—usually due to the reduction of information in the abstraction process or technical limitations. Such replicas can be good enough (and reasonable with concern to production cost and effort), however in many cases a true 1:1 copy is needed.…”