How a butterfly’s scales are born
蝴蝶鳞片是如何诞生的

A butterfly’s wing is covered in hundreds of thousands of tiny scales, like miniature shingles on a paper-thin roof. A single scale is as small as a speck of dust yet surprisingly complex, with a corrugated surface that helps wick away water, manage heat, and reflect light to give a butterfly its signature shimmer.
蝴蝶的翅膀覆盖着成千上万的微小鳞片，就像纸薄屋顶上的微型瓦片。单个鳞片小如尘埃，却出奇地复杂，具有波纹表面，有助于排水、管理热量，并反射光线，使蝴蝶呈现出标志性的闪光。

MIT researchers have now captured the moments when an individual scale begins to develop this ridged pattern. The researchers used advanced imaging techniques to observe the microscopic features on a developing wing as a painted lady butterfly emerged in its chrysalis.
麻省理工学院的研究人员现在捕捉到了单个鳞片开始形成这种脊状图案的时刻。研究人员使用先进的成像技术观察到一只彩绘夫人蝴蝶在蛹中发育时翅膀上的微观特征。

Using a special microscopic technique to peer through an opening they created in the chrysalis itself, the team continuously imaged individual scales as they grew out from the wing’s membrane during a crucial time window in the butterfly’s development. These images reveal for the first time how a scale’s initially smooth surface begins to wrinkle to form microscopic, parallel undulations like the ridges in corduroy. The ripple-like structures eventually grow into more finely patterned ridges, which make many functions of the adult wing scales possible.
研究团队使用一种特殊的显微技术，通过他们在蛹中创建的开口窥视，连续拍摄了在蝴蝶发育的关键时间窗口中从翅膀膜上长出的单个鳞片。这些图像首次揭示了鳞片最初光滑的表面如何开始起皱，形成像灯芯绒脊一样的微观平行波纹。这些波纹状结构最终会发展成更精细的脊状图案，使成年翅膀鳞片的许多功能成为可能。

The transition to a corrugated surface is likely a result of “buckling”—a mechanical process by which a material bows in on itself as it is subjected to compressive forces or constrained within a confined space. In this case, as they confirmed with the help of a theoretical model describing the general mechanics of buckling, actin bundles—long filaments that run under a growing membrane and support the scale as it takes shape—pin the membrane in place like ropes around an inflating hot-air balloon.
表面转变为波纹状可能是“屈曲”的结果——一种材料在受到压缩力或被限制在狭小空间内时向内弯曲的机械过程。在这种情况下，正如他们通过描述屈曲一般力学的理论模型所确认的那样，肌动蛋白束——在生长膜下运行并在鳞片成形时支撑鳞片的长丝——像热气球周围的绳索一样将膜固定在适当位置。

“Buckling is an instability, something that we usually don’t want to happen as engineers,” says Mathias Kolle, an associate professor of mechanical engineering and coauthor of a study on the work. “But in this context, the organism uses buckling to initiate the growth of these intricate, functional structures.”
“屈曲是一种不稳定性，作为工程师，我们通常不希望它发生，”机械工程副教授兼该研究的合著者 Mathias Kolle 说。“但在这种情况下，生物体利用屈曲来启动这些复杂、功能性结构的生长。”

The team is working to visualize more stages of butterfly wing growth that could inspire advanced functional materials in the future.
该团队正在努力可视化更多的蝴蝶翅膀生长阶段，这些阶段可能会在未来启发先进的功能材料。

“These materials would exhibit tailored optical, thermal, chemical, and mechanical properties for textiles, building surfaces, vehicles—really, for generally any surface that needs to exhibit characteristics that depend on its micro- and nanoscale structure,” Kolle says.
“这些材料将展示为纺织品、建筑表面、车辆——实际上是任何需要展示其微观和纳米结构特性的表面的定制光学、热学、化学和机械特性，”Kolle 说。

“We want to learn from nature, not only how these materials function, but also how they’re formed,” says Anthony McDougal, SM ’15, PhD ’22, an MIT postdoc and another coauthor. “If you want to, for instance, make a wrinkled surface, which is useful for a variety of applications, this gives you two really easy knobs to tune to tailor how those surfaces are wrinkled. You could either change the spacing of where that material is pinned, or you could change the amount of material that you grow between the pinned sections. And we saw that the butterfly is using both of these strategies.”
“我们想从自然中学习，不仅是这些材料如何运作，还包括它们是如何形成的，”Anthony McDougal 说，他是 MIT 的博士后，也是另一位合著者。“例如，如果你想制造一个皱纹表面，这对各种应用都很有用，这给了你两个非常简单的调节旋钮来定制这些表面的皱纹。你可以改变材料固定点的间距，或者你可以改变在固定点之间生长的材料量。我们发现蝴蝶正在使用这两种策略。”