Some people are just begging for attention. Marketers are constantly trying to find ways to build brand awareness, often with clothing -- it's a common practice to make shirts and hats featuring ­company logos and slogans. To really grab your attention, some companies are using fabric displays -- techniques and systems designed to make dynamic images and text on clothes and other things made of fabric.

Sam Yeh/AFP/Getty Images Two Taiwanese models wear LED costumes at a photonics festival in Taipei.

There are many different kinds of fabric displays. Some use a still image as a starting point, relying on fabric with special properties to make the design more eye-catching. Other fabric displays can show full video with sound. Each method relies on different technologies, and all have their advantages and disadvantages.

A few fabric display techniques are readily available to the consumer market. Creative individuals have used fabric display technology to build elaborate costumes. Jay Maynard used electroluminescent wire (EL wire) in the costume he built based on the Disney film "Tron" -- his Web page describes how made the costume. His efforts gained national attention, and before long Maynard was making the talk show circuit as "the Tron guy."

In this article, we'll look at the different ways inventors have modified clothing to make a bigger impact on audiences. We'll learn about an idea for fur displays that use electrostatic charges to shocking effect. We'll see how a heat-sensitive dye can turn a normal T-shirt into a very large mood ring. After that, we'll explore the world of electroluminescent clothing. Then we'll see how LED and PLED displays can turn a normal outfit into an eye-catching light display. Finally, we'll learn about companies that have created clothing with built-in television and PC displays.

In the next section, we'll look at a way some engineers plan to use fur to create a dynamic fabric display.

Fur Fabric Displays

There has been some confusion about what, exactly, a fur fabric display is. Philips Electronics filed a patent application with the simple title "Fabric Display," though some science blogs and magazines have referred to it as "furry television." At its most basic level, this fur fabric display relies on a very simple technology. Patches of fur cover an image, and when the fur moves, it reveals the image underneath. It's a simple way to conceal and reveal designs.

The fabric display has three layers. The bottom layer is conductive, which means it can carry electricity from a power source -- like a small battery pack -- to the rest of the fabric to create an electrostatic field across the fur, which gives each strand of fur the same electrical charge.

The next layer in a fur fabric display is the fabric's base color or design. This could be a company logo, a picture or just a particular color. The furry display doesn't change the design on the cloth; it just hides or reveals portions of the design at a given time.

The third layer is the fur. It can be any color, but it must be short enough so that when the user turns on the electrostatic field, the strands stand on end and reveal the design or color of the fabric underneath. For example, in a simple fur fabric display, you could use red fur to cover a blue shirt. When you turn on the power for the conductive layer, the red fur would stand on end, revealing the blue shirt underneath. To a distant observer, it would appear that the shirt had just magically changed colors.

The patent application refers to each small, visible section of the base fabric as a "pixel," which may be why some articles refer to the display as furry television. While it might be possible to approximate primitive animation techniques by printing one image across the fur layer and a slightly adjusted image on the fabric underneath, it's not quite the same as watching television on someone's jacket.

Thermochromic Fabric Displays

The word "thermochromic" looks a little intimidating at first, but the concept itself is pretty simple. Thermo comes from the Greek word "thermos," which means warm or hot. Chromic comes from "chroma," meaning color. A thermochromic substance changes color as it changes temperature. In fabrics, a special dye acts as the thermochromic agent.

Some thermochromic dyes change from colorful to clear, revealing the color of the fabric underneath. Companies can use thermochromic dyes in shirts that slowly reveal a company slogan or logo as the shirt heats up. When the shirt cools down, the logo seems to disappear.

There are two widely used elements in thermochromic dyes, and both rely on chemical reactions:

• Liquid crystals: These thermochromic dyes rely on liquid crystals contained in tiny capsules. The liquid crystals are cholestric, also known as chiral nematics, which means that its molecules arrange themselves in a very specific helical structure. These structures reflect certain wavelengths of light. As the liquid crystals heat up, the orientation of the helices changes, which causes the helices to reflect a different wavelength of light. To our eyes, the result is a change in color. As the crystals cool down, they reorient themselves into their initial arrangements and the original color returns.
• Micro-encapsulate thermochromic system: In this system, the thermochromic dye contains millions of tiny capsules that look a little like an organic cell. Each capsule has an outer membrane and contains an organic, hydrophobic solvent, which makes it less likely that water will dilute or wash out the chemicals in the dye. The solvent contains particles of a color developer and a dye precursor. As the capsule heats up, the solvent melts and a chemical reaction causes the color developer to donate a proton to the dye precursor. In turn, this causes the precursor to develop into the dye itself and change color. When the dye cools down, the developer and precursor separate, the solvent resolidifies and the color returns to its original state.
• Like fur fabric displays, thermochromic fabrics aren't animated -- they can only conceal and reveal designs or colors based on environmental conditions. While that might be enough for some people, others want even more dynamic clothing.

Electroluminescent Fabric Displays

If wearing a furry display or heat-sensitive clothing doesn't seem appealing, you might want to look into electroluminescent fabric displays. Electroluminescent substances give off light after being exposed to electricity. For fabric displays, designers use electroluminescent wire (EL wire) to create amazing, vibrant effects.

EL wires have several layers:

• The core layer is a copper wire that acts as a conductor in the EL wire's alternating current (AC) power system.
• On top of the copper is a coating of electroluminescent phosphor. This is the material that will emit light after encountering an AC electric field.
• The next layer consists of two wires wrapped around the phosphor. These wires complete the second half of a circuit, the first half consisting of the copper conductor.
• Last comes a pair of plastic sheaths, which protects both the phosphor material (moisture can ruin some phosphors) and the user from electric shocks.

EL wire needs a high voltage -- around 100 volts -- to glow brightly. Lower voltages result only in a dull glow. Some EL wires can produce a range of light wavelengths depending on the frequency of applied power. Elwire.com offers an "aqua" EL wire with a color that varies from deep green to deep blue as the user alters the power frequency from 60 hertz (Hz) to 6 Hz. Also, because EL wire needs an AC power system, any outfit that has EL wire will need a battery pack and an inverter -- a device that converts direct current (DC) power to AC power. To learn more about AC and DC power, read our article on How Electricity Works.

Jay Maynard -- the Tron guy -- constructed his costume with EL wire.

Because the core of EL wire is copper, it's flexible but holds its shape. You can bend EL wire into all sorts of designs. When it's turned off, EL wire looks like a colorful plastic tube, but when the power comes on, EL wire looks like thin strands of neon lights. An outfit with EL wire could have several different strands emitting different colors, and might even include a sequencer -- a special circuit board -- connected to the power source that manages each strand's power supply. By alternating power to various strands, the wire can appear to be animated as different strands flash on and off.

Clothes with EL wire require careful maintenance and cleaning procedures. If the wire is permanently affixed to the clothing, the wearer will need to carefully wash it by hand and let it dry on a flat surface, or rely on spot cleaning. Throwing electroluminescent clothes into the washing machine is a good way to ruin a special outfit, and could even damage other clothes or the washing machine itself if the plastic tubing around the copper core tears.

Electroluminescent clothes are bright and vibrant, and with the right equipment they can display lights in patterns and sequences, but they're still fairly static -- you're limited by the shapes into which you've bent the EL wire.