From a polymer with shape memory made moving cilia

Scientists have made artificial moving cilia that are controlled by the magnetic field and light. They keep their shape when bent, but, at the same time, they can be made to solidify in a temporary position from which they signal themselves back will return to permanent. It is based on a polymer with shape memory, which involved magnetic and light-absorbing components. Article published in the journal Advanced Materials Technologie.

Living organisms to move liquids or solid particles are often used moving cilia. It’s a thin organelles, like hairs or fibers. If the cilia are located along a duct or channel, then simultaneously bending and unbending they will move along it moisture, food, or waste. For example, this clears the respiratory epithelium of man, where the cilia gradually push pulmonary slizg up into the throat where it is swallowed.

If you create artificial analogues of these organelles, they can be used in places which are too narrow to accommodate a full of pumps, e.g. for water circulation in thin tubes. In addition, it will allow to create effective macroconveyor for fine particles like sand and dust.

Jessica Liu (Jessica Liu) from the University of North Carolina and her colleagues made the cilia, which can not only move on command, but also firmly set in the desired position. To do this, scientists had based elastic polymer with memory shape, complicit in his fine magnetic particles based on iron and light-absorbing components made of gold. For the manufacture of the cilia is not required nor the casting of form or thread. Flat not cured workpiece is placed in a strong magnetic field, and the composite is pulled along its lines of force, then cools and hardens. The length of the fibers can be varied from 500 microns to three millimeters, adding plastics additives in the casting.

Manufactured cilia can be controlled in several ways. For giving a permanent form, they must be heated to 180 degree, and then mechanically pressed in the right direction. After that, the cilia can bend or straighten with a magnet, and in the opposite direction they will return due to the elastic forces. If in the folded state to cover the led for about four minutes, the polymer is slightly heated, will soften and harden in a new form.

However, the used plastic has shape memory. Materials of this type can memorize multiple States, which are switched by triggers: heat, magnetic field or chemical action. The trigger for the selected polymer is to increase the temperature and when heated to about 80 degrees, it seeks to restore the form, which was set at 180 degrees, which when switched off, the magnet does not interfere.

Due to this potentially will be possible not only the movement of materials sent by the cilia channel, but, for example, localization of the movement. Assume that the underlying form of all of the villi — folded, and their rectification is switched on the magnet. We can fix the brush in the extended position, to take a narrow led, and to consolidate them at some point. After that fell under the diode fibers are fixed in an extreme position, and the magnet will not activate this area.

Chemists regularly made of plastics with unusual properties. For example, some of them may be samozahvata, or be transparent conductors. As entertainment they can be used to inflate a giant soap bubbles with area a in the container.

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