Graphene transistors compatible with living cells

Posted by Kate Taylor

A team at at the Technische Universitaet Muenchen says it's built the foundation for devices to communicate directly with the human brain.

The researchers' new graphene-based transistor array is compatible with living biological cells and can, for the first time, record the electrical signals they generate.

Silicon's problematic for use with living cells - it doesn't take well to getting wet, for example, and it's expensive.

However, the scientists say that graphene, which is is chemically stable and biologically inert, offers outstanding electronic performance, can easily be processed on flexible substrates, and should lend itself to large-scale, low-cost fabrication.

The researchers started with an array of 16 graphene solution-gated field-effect transistors (G-SGFETs) fabricated on copper foil by chemical vapor deposition and standard photolithographic and etching processes.

"The sensing mechanism of these devices is rather simple," says Dr Jose Antonio Garrido.

"Variations of the electrical and chemical environment in the vicinity of the FET gate region will be converted into a variation of the transistor current."

The researchers grew a layer of biological cells similar to heart muscle right on top of this array. And they found that it was easy to distinguish the signals transmitted by individual cells from the  intrinsic electrical noise of the transistors.

"Much of our ongoing research is focused on further improving the noise performance of graphene devices, and on optimizing the transfer of this technology to flexible substrates such as parylene and kapton, both of which are currently used for in vivo implants," says Garrido.

"We are also working to improve the spatial resolution of our recording devices."

In the meantime, the team's working with scientists at the Paris-based Vision Institute to investigate whether graphene layers are biocompatible with cultures of retinal neuron cells.

They're also working with an EU team working on developing brain implants based on flexible nanocarbon devices.