Author Topic: Piezoresistive effect  (Read 3098 times)

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Piezoresistive effect
« on: November 06, 2009, 13:59:00 pm »
"The piezoresistive effect describes the changing electrical resistance of a material due to applied mechanical stress. The piezoresistive effect differs from the piezoelectric effect. In contrast to the piezoelectric effect, the piezoresistive effect only causes a change in resistance; it does not produce an electric potential"

"History
The change of resistance of metal devices due to an applied mechanical load was first discovered in 1856 by Lord Kelvin. With single crystal silicon becoming the material of choice for the design of analog and digital circuits, the large piezoresistive effect in silicon and germanium was first discovered in 1954 (Smith 1954)."

"Piezoresistive effect in silicon
The resistance of silicon changes not only due to the stress dependent change of geometry, but also due to the stress dependent resistivity of the material. This results in gauge factors to orders of magnitudes larger than those observed in metals (Smith 1954). The resistance of n-conducting silicon mainly changes due to a shift of the three different conducting valley pairs. The shifting causes a redistribution of the carriers between valleys with different mobilities. This results in varying mobilities dependent on the direction of current flow. A minor effect is due to the effective mass change related to changing shapes of the valleys. In p-conducting silicon the phenomena are more complex and also result in mass changes and hole transfer."

i bring this into the equation for a few simple facts.. stan meyer says the reason why people like faraday were not able to produce such systems like stans is because of technology.. in their time there wasnt knowledge nor the technonogly of modern day metals such as stainless steel... for those that dont know stainless has silicon in it.. the silicon plays one of the major role that keep stainless from stainling.. the silicon has be but under mechenical stress and has become crystal defects.. they have a way of using i think light energy to maintain a constant atomic skin of ionized oxygen. the uxy is what keeps it from corroding..



http://en.wikipedia.org/wiki/Piezoresistive_effect