螳螂虾启发了一种由细菌制成的新材料

温馨提示:全文约4439字,阅读全文大约需要5分钟

对人类来说,螳螂虾被称为“拇指劈开器”,因为它倾向于打倒不幸的渔民。螳螂虾海底被捕食,被称为“死亡的化身” —甲壳类动物将其两个锤子状的附件退回其表面之下,并用力释放它们,使lam壳消失。螳螂虾更喜欢螃蟹,从战略上首先将其爪子吹掉,这样猎物就无法自卫。因此,当螳螂虾的锤子砸成拇指,蛤或螃蟹的脸时,其结构中的任何裂纹都会以扭曲的方式传播,从而将能量耗散到整个材料中。

对人类来说,螳螂虾被称为“拇指劈开器”,因为它倾向于打倒不幸的渔民。螳螂虾海底被捕食,被称为“死亡的化身” —甲壳类动物将其两个锤子状的附件退回其表面之下,并用力释放它们,使lam壳(自然界中最坚硬的材料之一)消失。螳螂虾更喜欢螃蟹,从战略上首先将其爪子吹掉,这样猎物就无法自卫。

所有的打击都会给锤子本身带来很大的压力。因此,为了应对不断的猛击,进化使这些武器的材料呈“ Bouligand”形状。而不是将材料层整齐地堆叠一起,而是像DNA的螺旋结构一样扭曲这些层。因此,当螳螂虾的锤子砸成拇指,蛤或螃蟹的脸时,其结构中的任何裂纹都会以扭曲的方式传播,从而将能量耗散到整个材料中。结果,锤子不会劈成两半。

整洁的人说,南加州大学和加州大学欧文分校的工程师已经发明了一种以螳螂虾的虾皮为基础的聪明材料。 (如果您是个正式的人,那么它们技术上被称为dactyls。)这是一个转折点:细菌的帮助下,它们已经能够使矿物质3D打印的虾类Bouligand结构中生长。 ,所有事物中。

研究人员首先从聚合物中3D打印出简单的晶格结构,基本上是网格。如您上图中所看到的,所得到的脚手架内部有足够的空白空间,可以认为它就像支撑建筑物的梁。然后,他们将整个结构浸入细菌溶液中,放置12至24小时。溶液中的巴斯德氏菌属细菌附着聚合物晶格上,并开始分泌一种称为脲酶的酶。

当研究人员将结构浸入尿素和钙离子的第二浴槽中时,尿素酶开始了化学反应,生成碳酸钙。这是赋予蛤壳以及自己的骨骼和牙齿强度的材料。它也是螳螂虾​​锤的组成部分。实验室中,当研究人员将支架留溶液中时,碳酸钙不断积累,并10天内完全填满了晶格,并为研究人员提供了由聚合物骨架和矿物内脏制成的超韧材料。您可以上图中看到结构的进度。

研究人员能够3D打印具有各种内部形状的格子,从波浪形到十字形,如上图所示。 C行显示了矿物填充聚合物骨架中空隙的位置。D行的彩色图像中,您可以看到碳酸钙矿床的刚度得分较高(以红色表示),而晶格排名较低(以蓝色和绿色表示)。

但是研究人员真正追求的是Bouligand结构,这种结构使螳螂虾的锤子具有韧性。下图中,有四种不同类型的晶格。图像A显示了这些3D打印结构的外观,其中I型只是材料的线性堆叠,而IV型是Bouligand结构-每层偏移45度,从而产生一种漩涡。C行中,图像显示了填充有白色碳酸钙的聚合物暗带。类型I杂货店里像过道一样排列,而类型IV看起来更混乱。

碰巧是一种很好的混乱。当研究人员测试每个晶格的强度时,IV型Bouligand结构吸收的能量是I型的20倍。“这种微观结构可确保这种复合材料非常坚硬,”南加州大学工程师王启明说共同撰写了一篇新论文,描述了《高级材料》杂志上的发现。 “当您有裂纹时,该裂纹将以扭曲的方式传播,以耗散材料内部的能量。”王和他的同事说,实际上,这种材料比天然珍珠母(珍珠母)吸收更多的能量,这使某些贝壳具有强度,并且还击败了现有的人造材料。

就像螳螂虾的锤子吸收拳头的能量而不会折断一样,用这种新方法开发的材料也可以。为了潜的用途,王说要考虑防弹衣,这需要消散子弹的能量。 Wang说,碳酸钙的重量也相当轻,因此科学家们也许还可以为飞机甚至是机器人的表皮制作更坚固的面板。

普渡大学土木工程师Pablo Zavattieri说:“对我来说,这是将来制造制造业的一种方式,而我并不是唯一这样说的人。”传统的制造业中,缺陷可能会潜入。另一方面,大自然已经数百万年的螳螂虾锤中开发出奇妙的Bouligand结构,并且可以通过简单的格子和细菌浴来复制这种模式。 Zavattieri说:“以这种方式,自然是无可挑剔的。” “自然是3D打印机。”

使这种细菌构建的材料与众不同的另一件事是其再生能力。就像,如果我们没有建造道路,而是建造道路呢? Wang说:“如果我们受到损害,您只需将细菌引入内部,细菌就会重新生长。” “这些结构非常坚固,坚固,并且有可能自我修复。”

研究人员还没有到位-他们让细菌实验室中受控条件下生长矿物质,即使那时也只是少量。扩大道路建设规模将带来更多工程挑战;例如,获得正确的支撑支架与硬化材料的比例。但是Zavattieri实际上已经研究3D打印混凝土。他说:“我认为这并不疯狂。” “我们完全可以让机器人打印经典的支架,将细菌留那里,然后让它们使材料生长10天。”


英文译文:

To humans, the mantis shrimp is known as the “thumb splitter,” due to its propensity to punch the digits of unfortunate fishers. To its prey on the seafloor, the mantis shrimp is known as “death incarnate”—the crustacean cocks back its two hammer-like appendages under its face, releasing them with such force that they obliterate clam shells, one of the toughest materials in nature. The mantis shrimp has even more fun with crabs, strategically blowing off their claws first so the prey can’t defend itself.

All that bashing puts serious stress on the hammers themselves. So to deal with the constant punching, evolution gave the material of these weapons a “Bouligand” shape. Instead of the layers of material neatly stacking one on top of another, the layers are twisted, almost like the helical structure of DNA. So when a mantis shrimp’s hammer smashes into a thumb or a clam or a crab’s face, any crack in its structure will propagate in a twist pattern, dissipating the energy throughout the material. As a result, the hammer doesn’t snap in half.

Neat, said engineers at the University of Southern California and the University of California, Irvine, who’ve invented a clever kind of material based on the mantis shrimp’s clobber-sticks. (If you’re one for formality, they’re technically known as dactyls.) It’s a twist within a twist: They’ve been able to get minerals to grow within a 3D-printed shrimp-inspired Bouligand structure with the help of bacteria, of all things.

The researchers began by 3D printing a simple lattice structure, basically a grid, out of a polymer. As you can see in the image above, the resulting scaffold had plenty of empty space within—think of it as being like the beams that support a building. They then dipped the whole structure in a bacterial solution and let it sit for 12 to 24 hours. The Sporosarcina pasteurii bacteria within the solution attached to the polymer lattice and started secreting an enzyme called urease.

When the researchers dipped the structure into a second bath of urea and calcium ions, the urease kicked off a chemical reaction that created calcium carbonate. This is the same material that gives a clam’s shell—as well as your own bones and teeth—their strength. It’s also a component of the mantis shrimp’s hammer. In the lab, as the researchers left the scaffolding in the solution, the calcium carbonate kept on accumulating, filling in the lattice entirely within 10 days, and giving the researchers a super-tough material made of a polymer skeleton and mineral innards. You can see the structure’s progress in the image above.

The researchers were able to 3D print lattices with a variety of interior shapes, from wave patterns to crosses, as shown in the images above. Row C shows where the mineral filled in gaps in the polymer skeleton. In the colorful images of row D, you can see that calcium carbonate mineral deposits score high in stiffness (indicated in red), while the lattice ranks lower (shown in blue and green).

But what the researchers were really after was the Bouligand structure, which gives the mantis shrimp’s hammer its resilience. In the image below, there are four different types of lattices. Image A shows what those 3D printed structures look like, with Type I being just a linear stack of material, while Type IV is the Bouligand structure—each layer shifts 45 degrees, creating a kind of swirl. In row C, the images show the dark bands of polymer filled in with white calcium carbonate. Type I is arranged like aisles in the grocery store, whereas Type IV looks more chaotic.

A good kind of chaotic, as it happens. When the researchers tested the strength of each lattice, the Type IV Bouligand structure absorbed 20 times as much energy as Type I. “This kind of microstructure makes sure that this kind of composite is very tough,” says University of Southern California engineer Qiming Wang, coauthor on a new paper describing the findings in the journal Advanced Materials. “When you have a crack, that crack will propagate in the twist pattern to dissipate the energy inside the material.” In fact, the material absorbs more energy than natural nacre (mother of pearl), which gives some shells their strength, and also beats existing artificial materials, Wang and his colleagues say.

Just as the mantis shrimp’s hammer absorbs the energy of its punches without snapping, so too might materials developed with this new method. For potential uses, Wang says to think of body armor, which needs to dissipate a bullet’s energy. Calcium carbonate is also fairly lightweight, so scientists might also be able to grow tougher panels for aircraft, or even skins for robots, Wang says.

“This is, for me, a way to do manufacturing in the future, and I'm not the only one saying that,” says Purdue University civil engineer Pablo Zavattieri, who wasn’t involved in this research. In traditional manufacturing, defects can sneak in. Nature, on the other hand, has over millions of years developed the wondrous Bouligand structure in the mantis shrimp’s hammer, and it’s a pattern that can be replicated with a simple lattice and a bacterial bath. “Nature is, in that way, impeccable,” Zavattieri says. “Nature is a 3D printer.”

Another thing that makes this bacteria-built material special is its ability to regenerate. Like, what if instead of building roads, we grew them? “If we have damage, you just introduce bacteria inside, and it can grow it back,” says Wang. “These structures are very tough, very strong, and can potentially repair themselves.”

The researchers aren’t there quite yet—they got the bacteria to grow minerals in controlled conditions in the lab, and even then it was only in small quantities. Scaling up for constructing roads would bring additional engineering challenges; for instance, getting the right ratio of supporting scaffold to hardening material. But Zavattieri is actually already working on 3D printing concrete. “I don't think it's super crazy,” he says. “We can totally have robots print the classic scaffold, leave the bacteria there, and then let them grow the material for 10 days.”


Share this Post:

相关资讯: