A transistor has three connectors. Two for the flow of electrons and a third for regulating such a flow. It works like a tap with the third connector working like the lever you use to open, increase, decrease and stop the flow of water. A tiny signal applied on the third connector can modulate the flow of electrons across the other two, hence the transistor can work as an amplifier.
Now scientists have found a way to apply some properties of smart materials to the construction of a transistor made by just two connectors, the one used for the flow of electrons. This flow gets regulated (modulated) by the degree of bending of the material between the two connectors. The more it bends, the higher the resistance and the less flow of electrons…
It is nothing new, in the sense of discovery of a property. It is now many years that scientists have discovered the piezoelectric effect, the displacements of charges as consequence of mechanical strain applied to a material.
But it is the first time that this effect is put to use (solving the engineering challenges) to create a transistor, actually a multitude of transistors on a surface.
This has been done by researchers at Georgia Tech who have created piezotronic arrays of transistors (inventing also the name for it…).
You can also see these “taxels” as sensors able to detect strain variation in a material at a microscopic level (at the dimension of the gap between the two connector -the strain gate in the schematics). Since they operate at microscopic level they are also very precise in terms of location and of measure, provided you have several of them to provide you with individual measurement.
Since this is the case one can imagine to use this array as a sort of skin to sense the strength of the interaction with another object and indeed this is the first application the researchers are working on: provide tactile sensation (feedback) to robots.
In their post they list as potential applications:
Multidimensional signature recording, in which not only the graphics of the signature would be included, but also the pressure exerted at each location during the creation of the signature, and the speed at which the signature is created.
Shape-adaptive sensing in which a change in the shape of the device is measured. This would be useful in applications such as artificial/prosthetic skin, smart biomedical treatments and intelligent robotics in which the arrays would sense what was in contact with them.
Active tactile sensing in which the physiological operations of mechanoreceptors of biological entities such as hair follicles or the hairs in the cochlea are emulated.
As you can see it really goes beyond robots, opening up yet another way to cyber interfaces.