  Graphene solution-gated field-effect transistors (SGFETs) are a promising
platform for the recording of cell action potentials due to the intrinsic high
signal amplification of graphene transistors. In addition, graphene technology
fulfils important key requirements for for in-vivo applications, such as
biocompability, mechanical flexibility, as well as ease of high density
integration. In this paper we demonstrate the fabrication of flexible arrays of
graphene SGFETs on polyimide, a biocompatible polymeric substrate. We
investigate the transistor's transconductance and intrinsic electronic noise
which are key parameters for the device sensitivity, confirming that the
obtained values are comparable to those of rigid graphene SGFETs. Furthermore,
we show that the devices do not degrade during repeated bending and the
transconductance, governed by the electronic properties of graphene, is
unaffected by bending. After cell culture, we demonstrate the recording of cell
action potentials from cardiomyocyte-like cells with a high signal-to-noise
ratio that is higher or comparable to competing state of the art technologies.
Our results highlight the great capabilities of flexible graphene SGFETs in
bioelectronics, providing a solid foundation for in-vivo experiments and,
eventually, for graphene-based neuroprosthetics.
