# DesignWIKI

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2015.01.09 11:13
design:change_physical_phenomena

# Change Physical Phenomena

Given an existent design that uses one physical phenomenon, a new, creative design may arise by trying to use a different phenomenon.

Consider the transformations provided of a particular device and look for different ways of achieving the same transformation.

The device might change one kind of motion into another (e.g. rotational motion into linear motion). Look for different phenomena that achieve that same transformation (e.g. a slider-crank mechanism versus a rack and pinion gear system).

Alternatively, the device might change one kind of energy into another. For example, sonar systems typically use a microphone that turns pressure waves in water into an electrical signal. In a recent patent, however, fibre optics are used to replace the microphone. A standing light wave is established in the optical fibre; any variation in the length of fibre will change the characteristic of the standing wave in a measurable way. Underwater pressure waves make the cable vibrate, which causes detectable changes in the standing wave pattern of the light in the fibre. Whereas a regular microphone turns sound into an electrical signal, this new method turns sound into a light signal.

Related to this is the technique of using different states of matter. For example, consider a conventional toothbrush, with bristles. This uses a solid state of matter (the bristles) to rub dirt off your teeth. Can you identify a known way to brush your teeth with these other states of matter:

• a liquid?
• a gas or vapour?
• energy?1)

Example: Putting out fire with sound Two undergraduate electrical engineering students at George Mason University have figured out how to put fires out with sound. They found that at certain frequencies, air vibrates in a way that prevents oxygen from staying in contact with a combusting material. There's a YouTube clip of the device in action, and you can read more about it at treehugger and The Washington Post.

Desalinating water with a shock wave Desalinating water is important to provide drinking water. Conventionally, one boils and then condenses salt water - the salt is left behind from the boiling process. It's easy, but energy intensive. Another method is reverse osmosis, where salt is basically filtered out of water by passing it through a special membrane that traps salt. This uses a little less energy, but is more “high-tech” and therefore complex, unreliable, and expensive. Researchers at MIT have come up with another way: generating a shockwave in a flow of water that literally separates the salt out of the flow. This method, though still complex, uses a lot less energy. In this case, the original phenomenon was a change of state (liquid to vapour). The osmosis method is strictly physical. The shockwave method, on the other hand, uses vibration (physical energy transmission) to achieve the same goal more efficiently. (The research has been published in the scientific literature.)

1)
Okay, this isn't really a state of matter, but remember $E=mc^2$.