So far this is a neat toy that has ample promise. Blocking sunlight
is actually an excellent application. After all we can simply make
sure that the window tracks the location of the sun and blocks it
from that direction while optiomizing general visibility.
I also like to see something that can move a layer of fluid up a
slope continously. That may be valuable as hell particularly if it
can be tuned to a specific molecule that is mixed with another
molecule or even dissolved. How about water out of sea water?
It is certainly a neat trick and easily manipulated.
By Ben Coxworth
August 8, 2014
What if your house's
windows could automatically reduce the amount of hot sunlight passing
through them, or your car's windshield could cause rain droplets to
bead off to its edges? These things and more could soon be possible,
thanks to a new animal hair-inspired material developed at MIT.
The material consists
of a base layer of transparent flexible silicone, studded with a
dense array of tiny nickel microhairs (or "micropillars").
At around 70 microns in height and 25 microns in width, each one is
approximately a quarter the diameter of a human hair.
When an external
magnetic field is applied at one side of the array, all of the hairs
simultaneously bend towards it. The degree to which they bend can be
controlled by varying the intensity of the field.
Firstly, this
response can be used to alter how much light passes through the
material. While the microhair array is pretty much clear when viewed
top-down while the hairs are standing straight up, its opacity
increases as the hairs bend over – they're essentially working like
the slats in a set of window blinds.
Secondly, water
droplets resist rolling "against the grain" of the
bent-over hairs, but will readily roll in the direction that the
hairs are pointing. Utilizing this characteristic, it's possible to
guide the path of water droplets moving across the surface of the
material. They can even be made to roll uphill, by
bending the hairs underneath a droplet in that direction.
With these two
qualities in mind, the material could be used in applications such as
smart windows that block excess sunlight from overheating buildings
during the day, windshields that direct moisture away from the
driver's line of sight, rain-repellant clothing, or even
lab-on-a-chip devices that precisely guide the flow of liquid samples
through their microchannels.
The research is being
led by mechanical engineering grad student Yangying Zhu, and is
described in a paper that was recently published in the
journal Advanced Materials.
The microhairs can be
seen in action, in the video below.
Source: MIT
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