November 12, 2014Scallop microbots designed to swim through your bodily fluids

Researchers have been experimenting with real micro-sized robots that literally swim through your bodily fluids (Image: Max Planck Institute)

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In the 1960s science fiction film Fantastic Voyage, audiences thrilled to the idea of shrinking a submarine and the people inside it to microscopic dimensions and injecting it into a person’s bloodstream. At the time it was just fantasy and as fantastic an idea as its title suggested. Today, however, micro-miniature travelers in your body have come one step closer to reality. Researchers from the Max Planck Institute have been experimenting with real micro-sized robots that literally swim through your bodily fluids and could be used to deliver drugs or other medical relief in a highly-targeted way.

The microrobots being designed by the team literally are swimmers; they are scallop-like devices designed to paddle through non-Newtonian fluids like blood and plasma (even water behaves in this way at a microscopic level). This means that, unlike swimming in water at a macro-level, these microbots need to move through fluid that has a changing viscosity depending on how much force is exerted upon it.

To do this, the microbots need a method of propulsion that can fit in their tiny bodies as well as take advantage of the non-Newtonian fluid in which they are moving. Importantly, the team is using a reciprocal method of movement to propel their microscallops; but generally this doesn’t work in such fluids, which is why organisms that move around in a biological system use non-reciprocating devices like flagella or cilia to get about.

However these robotic microswimmers actually take advantage of this property and use a scallop swimming motion to move around. The researchers call this process "modulation of the fluid viscosity upon varying the shear rate." In simple terms, the micro scallops open and close their "shells" to compress the fluid and force it out behind them, which then propels them along.

"The shell is only a few times larger than the thickness of a human hair," said Professor Peer Fischer, leader of the Micro, Nano and Molecular Systems Research Group. "A liquid like water is about as viscous for these devices as honey or even tar is for us."

The research team used ferromagnetic actuators (basically magnetically-operated hinges) to open and close their shells under the influence of an applied external alternating magnetic field – on to close, off to open. Do this often enough and quickly enough, and the microrobot scallop can swim at speed across – say – your eyeball.

The fact that the microrobot scallop has no motor to drag around contributes to its exceptionally small size – around 800 microns. This makes it miniscule enough to make its way through your bloodstream, around your lymphatic system, or across the slippery goo on the surface of your eyeballs. And, not only are they small, but their simplicity makes them ideal to be printed on a 3D printer.

Apart from the obvious use in delivering a product in a targeted way to parts of the body inaccessible by conventional methods, the team has yet to elucidate any other uses for their swimming microscallop robots. However, if they get the devices small and agile enough, it’s fairly likely that many in the medical world will find a way to exploit their properties to the benefit of patients.

The video below shows some animations and descriptions of the microscallop swimmers and their unique propulsion system.

The research was published in the journal Nature Communications.

微型扇贝机器人 可在人体内游泳

11月12日，旨在通过你的身体fluids

研究员游泳2014Scallop microbots一直在尝试真正的微小尺寸的机器人，从字面上通过你的体液游泳（图片：马克斯·普朗克研究所）

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20世纪60年代科幻片神奇旅程，兴奋萎缩潜艇和里面的人到微观层面，并注射到人的血液的想法观众。在当时这只是幻想和梦幻般的一个想法，它的标题建议。然而，今天，在你的身体微缩的旅客都来一步步接近现实。从马克斯普朗克研究所的研究人员一直在尝试真正的微小尺寸的机器人，从字面上通过你的体液游泳，可用于输送药物或其他医疗救助的具有高度针对性的方法。

的微型机器人被设计被球队从字面上是游泳;它们设计成桨通过非牛顿流体如血液和血浆（甚至水行为方式以这种方式在微观水平）扇贝状装置。这意味着，与在宏观层面游动在水中，这些microbots需要移动通过流体，其具有变化的粘度取决于于它是多大的力施加。

为了做到这一点，microbots需要推进的方法，其能适应他们的小团体，以及采取它们被移动非牛顿流体的优势。重要的是，球队用运动的倒数的方法来推动他们microscallops;但一般这在这些流体不起作用，这就是为什么四处移动的在生物系统中的生物体使用像鞭毛或纤毛非往复式设备获取有关。

然而，这些机器人microswimmers实际采取此属性的优点，并使用一个扇贝游泳运动走动。研究人员“在不同的剪切速率的调制流体粘度。”称这个过程简单来说，微扇贝打开和关闭自己的“壳”，以压缩流体，并迫使它在他们身后，然后沿推动他们。

“的外壳仅比人的头发丝的厚度大几十倍， “教授说同行菲舍尔，微纳米分子系统研究组组长。 “像水一样的液体大约是粘稠的，这些设备如蜂蜜，甚至焦油是我们的。”

该研究小组利用铁致动器（基本磁式铰链）来打开和关闭的应用外部的影响下，他们的炮弹交变磁场 - 在关闭，关闭到开启。经常这样做不够，速度不够快，而微型机器人扇贝可以在速度跨越游泳 - 说 - 你的眼球

该微型机器人扇贝有没有电机拖动周围的事实，有助于其超小的尺寸 - 约800微米。这使得它微不足道足够的通过你的血液，以做它的方式，在你的淋巴系统，或在湿滑咕你的眼球的表面上。并且，不仅是它们小，但它们的简单性使得它们理想要打印在三维打印机。

除了在提供产品有针对性的方式向身体难以接近通过常规方法的部件的明显的用途，该球队有尚未阐明任何其他用途的游泳microscallop机器人。但是，如果他们得到的设备小巧而灵活，这是相当有可能，许多医学界将找到一种方法来利用其特性，以病人的利益。