An ingenious new use for liquid crystal displays being developed at the University of California, Davis, might one day make complex chemical analyses almost as easy as checking the time on your wristwatch. The only supplies needed would be the chemical sample, the stamp-size test chip, a few drops of liquid crystal and enough ambient light for the person running the test to read the result. The test doesn't even require electricity. What we're proposing is comparable to the level of sophistication in a liquid-crystal watch and, as we all know, that technology has been very successful. In this Friday's issue of the journal Science, Abbott and his colleagues will report their construction of a prototype liquid crystal assay and describe the chemical and physical principles that make it work.
Liquid crystals are a state of matter, just like the better-known states of liquid, solid and gas.
Like solid crystals, liquid crystals can bend light and change its color. And as their name suggests, they can flow like a liquid. Wristwatch displays and computer screens employ this light-bending yet fluid quality. With electrical fields, they direct the orientation of the rod-shaped molecules within liquid crystals. The orientation determines how the crystals will transmit light, and that in turn produces the images we perceive as numbers on a watch face or pictures on a computer screen.