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Scientists have discovered a way to write directly into liquid urine , creating clear and long - lasting patterns which float below the surface of the fluid .
In the new study , published Aug. 21 in the journalNano Micro Small , Benno Liebchenand colleague at the Technical University of Darmstadt and Johnannes Gutenberg University in Germany have developed a method to create long - last writing inside of a liquid . The water - writing relies on a chemical substance process called diffusioosmosis — a spontaneous movement of different type of particles , due to a difference in assiduousness within a liquid concoction .
One-line drawing of a complex pattern with rectangular and 45° angles as well as multiple line crossings. The inset shows the intended result.
The squad ’s fluid smorgasbord , which bear a crushed concentration of charged particle call ions , play as the " paper . " The " ink " is made up of big colloidal ( hearty ) speck , which are dispersed thinly through the total result . The " pen " is a single minuscule ion - exchange bead — a particle which is able to swop the charge particles in the liquified mix for different , pocket-size charged particles .
" When you change larger ions with smaller ion , the smaller ion can move ( diffuse ) quicker and that leads to a difference in assiduity , " Liebchen told Live Science . " This concentration slope in the ion statistical distribution forces the liquidity at the bottom of the container near where the beadwork is to move . The moving liquid carries the visible colloidal particle ( the ' ink ' ) along with it . "
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Successive downscaling of pattern size. The length of the horizontals is 500 µm (a), 350 µm (b), and 175 µm (c).(Image credit: Lukas Hecht)
By rotate the liquidity ( paper ) on a little stage , Liebchen and Palberg exploited gravity to steer the ion - exchange bead playpen through the solution to create different patterns . As the bead incite through the liquid , the colloidal particles are draw into its wake by this immersion gradient effect , resulting in a visible line where the penitentiary has been .
" Importantly , because the pen is small , it does n’t agitate the surrounding solvent too much — a larger pen would charge up the body of water and destroy what you were write , " Liebchen said . " The colloidal mote are too expectant and heavy to move much in still water within the time scale of the experiment which is why the lines remain visible . "
The team developed this proficiency using water as the paper and silica speck as the ink so they next explored whether other paper , pen , and ink combinations work .
Sinusoidal line written in the BD simulation with parameters close to typical experimental ones. Note the slight, leftward shift of the written line with respect to the IEX trajectory (solid yellow line).(Image credit: Lukas Hecht)
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Lower case Greek letter phi with loop and line crossing. Note the bending of the crossed line and the formation of a region of enhanced density along the freshly written line (dashed circle). Inset: Writing at high IEX speed of vIEX = 10 µm s−1 reduces blobbing but retains line bending.(Image credit: Lukas Hecht)
" Many view of the writing approaching are quite robust with regard to changing those portion , but there are limits of grade , " said Liebchen . " For representative , if the ink particles are too small , you would n’t see them very well or they would move too much whereas if they ’re too big , they would n’t follow the fluid very well . It ’s a remainder but overall the method acting is quite general . "
The squad are now looking at unlike means of steer the pen by using magnetic force or electrical field of study alternatively of gravity and possibly exsert this system into deeper fluid intermixture .
Avoiding blob formation upon line crossing by mere line touching.(Image credit: Lukas Hecht)
Initials of the Johannes Gutenberg University, Mainz, written with C-IEX45 in 0.2 wt.% Si832.(Image credit: Lukas Hecht)
Initials of the Technical University of Darmstadt written in a BD simulation with vIEX = 12 µm s−1.(Image credit: Lukas Hecht)
