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About "Ask A Scientist!"

On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 28 September, 2005 Next Week's Question
Science behind mood rings, laptops screens is similar
Question
What causes a heat sensitive material, such as a mood ring, to change color when it's temperate is altered? What is this material made of, and where else might it be used?

Question
In school you learn that "matter" comes in three phases: solid, liquid, and gas. A well-known example is water. If you take water (a liquid) and put it in the freezer, you will form ice (a solid). Or if you heat water on the stove, you will observe steam (a gas). In all three phases of water, the molecules are the same (H2O). However, the way that those H2O molecules are arranged is different. In the solid phase the water molecules are very close together, in the gaseous phase they are far apart, and in the liquid phase they are somewhere in between.

Did you know that some special materials have four phases of matter? This fourth phase is called the "liquid crystalline" phase (LC). The LC phase has properties that make it both liquid-like and solid-like. A mood ring is an example of an object that takes advantage of the special properties of liquid crystals.

Here is a brief explanation of how mood rings work. The ring is a glass shell filled with molecules that are in the LC phase. When light shines on the ring, certain colors of light will be reflected depending on how the molecules are arranged. The arrangement of molecules depends on your body temperature. When your body temperature changes, the arrangement of molecules also changes, causing a different color of light to be reflected. To the extent that your body temperature indicates your "mood," you can then "see" your mood by the color of light that is reflected.

The liquid crystalline phase was first observed in 1888 by Austrian chemist Friedrich Reinitzer. Surprisingly, nearly 80 years passed before the first commercial products were realized. Today you will find LCs in many electronic display applications (LCD) like laptop computers, digital watches, calculators, and cell phones. These LC phases operate as shutters and can be switched on (light) and off (dark) by the action of an electric current.

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