Researchers at the Georgia Institute of Technology have used nanowires to make force sensors and force-based digital logic.
The sensors replace the conductive gate of a FET with a ZnO nanowire..
And the same nanowire also acts as the FET's channel.
"ZnO is unique because of its coupled piezoelectric and semiconductor properties," Professor Zhong Lin Wang told Electronics Weekly.
The whole FET is a length of ZnO wire with metal connections at either end for the source and drain.
Deformation of the wire creates strain, generating an electric field which affects carriers travelling along the wire.
"When we apply a strain to a nanowire placed across two metal electrodes, we create a field, which is strong enough to serve as the gating voltage," said Wang. "This type of device would allow mechanical action to be interfaced with electronics, and could be the basis for a new form of logic device that uses the piezoelectric potential in place of a gate voltage."
'Strain-gated transistors' fabricated on a flexible polymer substrate have been combined by the team to make basic logic operations - including NOR, XOR NAND, multiplexer and demultiplexer functions - by applying different types of strain to the wires.
There is also an inverter, created by placing strain-gated transistors on both sides of a flexible substrate.
"Using the strain-gated transistor as a building block, we can build complicated logic," said Wang. "This is the first time that a mechanical action has been used to create a logic operation."
His team has previously used similar wires in voltage generators, and pH and UV detectors, and has dubbed the technology 'piezotronics'.
"The family of devices we have developed can be joined together to create self-powered, autonomous and intelligent nanoscale systems," Wang said. "We can create complex systems totally based on zinc oxide nanowires that have memory, processing, and sensing capabilities powered by electrical energy scavenged from the environment."
The devices are slow "and would not challenge traditional CMOS transistors for speed in conventional applications", said the university.
Wang's has also created hybrid logic devices that use zinc oxide nanowires to control current moving through single-walled carbon nanotubes.
Photo: a Georgia Tech researcher manipulates ZnO nanowire devices fabricated on a flexible polymer substrate.