Graphene Transistor Reads Electrical Signals of Biological Cells

A team of scientists from Technical University Munich (Munich, Germany) and the Juelich Research Center have demonstrated a graphene-based transistor array that can record electrical signals generated by living biological cells. Because of a unique combination of characteristics, graphene has been identified as a material that will be used in the future in biomedical applications which require a direct interface between nerve cells and microelectronic devices. Such sensors could be placed inside an eye, ear or brain to help compensate for neural damage, and unlike the silicon microelectronics that do not perform well in wet biologic environments, graphene's biologically inert carbon atoms are chemically stable and offer outstanding electronic performance.

The researchers used an array of 16 graphene solution-gated field-effect transistors. By using standard photolithographic, etching, and chemical vapor deposition processes, the transistors were fabricated on copper foil. A layer of biological cells similar to heart muscle was then grown directly on top of this array. While electrical noise can be an issue with reliable communication in similar silicon devices, with the graphene array, the action potentials of individual cells were detectable above the electrical noise of the transistors and could be recorded with high temporal and spatial resolution. The transistor array sensed a series of spikes that moved across the array in a way action potentials would move across the cell layer, and when introducing the stress hormone norepinephrine, the array recorded a higher frequency of spikes.

The team is now trying to transfer the technology to flexible parylene and kapton substrates, which are frequently used for in vivo implants. The biocompatibility of graphene layers in retinal neuron cell cultures is also being tested in a collaboration with the Paris-based Vision Institute. The proof of concept study results were published in the Advanced Materials journal.