When the block is compressed,
individual carbon nanotubes start
to buckle, which in turn decreases
the block’s electrical resistance
© Rensselaer, Pushparaj
Taking advantage of the material’s unique electrical and mechanical properties, researchers repeatedly squeezed a 3-millimeter nanotube block and discovered it was highly suitable for potential applications as a pressure sensor. No matter how many times or how hard they squeezed the block, it exhibited a constant, linear relationship between how much force was applied and electrical resistance.
A sensor incorporating the carbon nanotube block would be able to detect very slight weight changes and would be beneficial in any number of practical and industrial applications, Sreekala said. Two potential applications are a pressure gauge to check the air pressure of automobile tires, and a microelectromechanical pressure sensor that could be used in semiconductor manufacturing equipment.
Over the course of the experiment, the researchers placed the carbon nanotube block in a vice-like machine and applied different levels of stress. They took note of the stress applied and measured the corresponding strain put on the nanotube block. As it was being squeezed, the researchers also sent an electrical charge through the block and measured its resistance, or how easily the charge moved from one end of the block to the other.
The research team discovered that the strain they applied to the block had a linear relationship with the block’s electrical resistance. The more they squeezed the block, the more its resistance decreased. On a graph, the relationship is represented by a neat, straight line. This means every time one exposes the block to a load of X, they can reliably expect the block’s resistance to decrease by Y.
The pressure sensor would function similarly to a typical weight scale. By placing an object with an unknown weight onto the carbon nanotube block, the block would be squeezed down and its electrical resistance would decrease. The sensor would then send an electrical charge through the nanotube block, and register the resistance. The exact weight of the object could then be easily calculated, thanks to the linear, unchanging relationship between the block’s strain and resistance.
COMPAMED.de; Source: Rensselaer Polytechnic Institute