Liquid crystals are strange things indeed. Beyond just making your TV crystal clear or iPhone look pretty, liquid crystals can be made to grow into tiny, flower-like lenses, according to a study from the University of Pennsylvania at Philadelphia published last month in Physical Review X.
New Scientist reports that the group found they could manipulate the way the liquid crystal particles arranged themselves by dropping a tiny, transparent silicon bead into the solution. With the bead in place, the rod-like particles that make up the liquid crystal solution would arrange themselves into a regular pattern, forming a bulge over the bead. That bulge was covered in tiny “petals” that focus light inward towards a focal point within the bead.
In the past, playing with liquid crystal orientation had produced lenses, but the process had required very complicated trellis-like scaffolding. The lenses produced with liquid crystal can be much smaller than those made with glass, and with this simpler means of making them, these lenses could make their way into things like solar arrays and liquid crystal displays in the next decade or so.
This story got me interested in precisely how liquid crystals work and what they are, so I did a bit of reading and here are the basics of what I found. Liquid crystals are, as their name suggests, substances that can behave like liquids and like crystals. When you run a current through them, the molecules arrange themselves into certain patterns depending on the voltage used and the chemical composition of the crystal solution, which is how LCD displays work. Different voltages will elicit different textures in the crystals, which then bend polarized light in different ways. When a crystal’s shape is altered with electricity, it will twist light passing through it which changes the color we perceive. By regulating the voltage run through the crystal, you can regulate the shades of color created.
This group did not manipulate their crystal’s conformation though. They simply allowed the crystals to arrange themselves over top of the bead and the result was remarkable. Regardless of whether or not we see liquid crystal lenses being grown for mass production any time soon, this is an important discovery in the study of liquid crystals, and it just looks damn cool too.