Scientists around the world are working on tiny machines that will revolutionize medicine. Because the microrobots, often only a fraction of the diameter of a hair, can bring medical active ingredients to specific problem areas in the body and carry out the smallest surgical interventions. The miniature machines are driven and steered with external energy, mostly acoustic or magnetic fields.
When it comes to the shape of the floating bodies, researchers are often inspired by micro-organisms such as bacteria or algae. A research group at ETH Zurich has now for the first time developed a microrobot that imitates the swimming and feeding technique of a starfish larva.
Push away or suck in liquid with hairs
Depending on whether it swims or eats, the starfish larva creates different eddies.
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Quelle: Prakash Lab/Stanford University
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At first glance, the similarity between microrobots and starfish larvae is small. The larva of the five-armed marine animal is a few millimeters in size and has a lobed body. The microrobot, on the other hand, is a simple rectangle and around ten times smaller – it measures only a quarter of a millimeter. However, they both have one important feature in common: the fine, mobile hairs on the surface of the body, so-called cilia.-
The starfish larva is covered with hundreds of thousands of such hairs. Arranged in rows, they beat back and forth in the sea water in a coordinated manner, creating eddies in the process. A few years ago, researchers showed that the animal uses the complex flow patterns alternately as a swimming drive or to suck in food particles.
In order to switch from eating mode to swimming mode, the starfish larva changes, among other things, the orientation of the rows of hairs to one another. Two rows inclined towards each other create a vortex with a thrust effect, with which the larva moves forward in the water. If, on the other hand, the rows of hairs are oriented in the opposite direction, a vortex is created that sucks in liquid and the food particles it contains.
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