Pavlović Danica, Salatić Branislav, Ćurčić Srećko, Milovanović Petar, Pantelić Dejan V
Institute of Physics, University of Belgrade, Pregrevica 118, 11080, Belgrade, Serbia.
Institute of Zoology, University of Belgrade - Faculty of Biology, Studentski Trg 16, 11000, Belgrade, Serbia.
Front Zool. 2024 Nov 14;21(1):28. doi: 10.1186/s12983-024-00552-0.
All living organisms exist in a world affected by many external influences, especially water and light. Photonic nanostructures present in certain insects, have evolved over time in response to diverse environmental conditions, facilitating communication within and between species, camouflage, thermoregulation, hydration, and more. Up to now, only a few insect species have been discovered whose elytron changes its color due to permeation of water (or its vapor) through cuticle.
Here we report on a scarabaeid beetle Hoplia argentea remarkable in its ability to shift from green to brownish-red when exposed to water, demonstrating reversible changes. Here we show that elytron and scales form a complex and efficient micro/nano-optofluidic system. Water is channeled into the elytral lacunae, then transported internally to the petals of the scales, where it is wicked inside each scale, pushing the entrapped air out. Wicking is a very fast process, occurring during a few seconds. The advantage of this principle is in extremely high pressure (approximately 15 bar) produced by capillary forces, which expediates permeation of air. We present optical models that explain the physical mechanisms behind the coloration, detailing how superhydrophilic properties influence optical behavior.
Species within the genus Hoplia exhibit diverse coloration strategies, likely linked to their specific ecological niches. These organisms have evolved intricate optical and microfluidic systems that facilitate rapid alterations in body coloration, potentially serving purposes such as environmental camouflage and thermoregulation. Studying microfluidic and optical properties of the elytra will not only enhance our understanding of the biological purposes behind color change but also inspires design of artificial biomimetic devices. Dynamic fluid flow patterns, described in this paper, are fairly constant and unique and can be used in security applications as a, so called, physically unclonable functions (PUF). More broadly, this kind of microfluidic system can be used for controlled drug release, sensing, hydraulic and pneumatic pumping.
所有生物都存在于一个受多种外部影响的世界中，尤其是水和光。某些昆虫身上存在的光子纳米结构，随着时间的推移，已经根据不同的环境条件进化，促进了物种内部和物种之间的交流、伪装、体温调节、水合作用等。到目前为止，只发现了少数几种昆虫，其鞘翅会因水（或其蒸汽）透过角质层而改变颜色。
在此，我们报道了一种金龟子科甲虫——银纹花金龟，它在接触水时能够从绿色转变为棕红色，呈现出可逆变化，十分引人注目。我们在此表明，鞘翅和鳞片形成了一个复杂且高效的微纳光流体系统。水被引导至鞘翅腔，然后在内部输送到鳞片的瓣片处，在那里水被吸入每个鳞片内部，将被困的空气挤出。吸湿过程非常迅速，在几秒钟内即可完成。这一原理的优势在于由毛细作用力产生的极高压力（约15巴），这加速了空气的渗透。我们提出了光学模型，解释了变色背后的物理机制，详细说明了超亲水特性如何影响光学行为。
花金龟属的物种表现出多样的着色策略，这可能与它们特定的生态位有关。这些生物进化出了复杂的光学和微流体系统，有助于体色的快速变化，可能具有环境伪装和体温调节等作用。研究鞘翅的微流体和光学特性不仅能增进我们对变色背后生物学目的的理解，还能启发人造仿生装置的设计。本文所描述的动态流体流动模式相当稳定且独特，可作为一种所谓的物理不可克隆功能（PUF）用于安全应用。更广泛地说，这种微流体系统可用于控制药物释放传感、液压和气动泵。
