Kirigami Transistors...

On the left is a paper model of the kirigami-inspired graphene pyramid, which is the square object in the microscope image on the right. Also shown in the microscope image are a spiral spring (top) and a number of cantilevers (right). The scale bar in the microscope image is 10 μm long. (Courtesy: McEuen Group, Cornell University)

Topics: Consumer Electronics, Electrical Engineering, Nanotechnology, Semiconductor Technology

A stretchable and bendable transistor has been made by researchers in the US by applying the principles of kirigami – the Japanese art of paper cutting – to graphene. The researchers have also made tiny graphene-based hinges and pyramids, and they are confident that they could reduce the size of their devices to the nanometre scale. The team also points out that the current micro-scale devices could be useful for biocompatible electronics, including probes for the study of neurons.

The mainstay of the electronics industry, silicon, is rigid and brittle, and is therefore not appropriate for making deformable electronics. The ability to deform is particularly useful for electronic devices that interface with biological organisms, for example sensitive prosthetic skin and subcutaneous sensors, which must bend and stretch with surrounding tissue. Graphene is a flexible sheet of carbon just one atom thick, and could offer a way to create deformable electronics because of its high electrical conductivity. One problem with graphene, however, is that it stretches very little.

Nanoscientist Paul McEuen and colleagues at Cornell University in Ithaca, New York, were inspired to try graphene kirigami after they investigated the bending stiffness of the material. They used an infrared laser beam to press on a gold pad located on the tip of a graphene cantilever that is about 10 μm long. By measuring the displacement in response to the known force of the laser photons, they calculated the bending stiffness of the material. They also monitored the thermal oscillations of a graphene cantilever and calculated the stiffness from the oscillation amplitude.

Physics World: Stretchable graphene transistors inspired by kirigami, Tim Wogan