CVD Multilayer Boron Nitride-encapsulated graphene Solution-Gated Field-Effect Transistors for wearable and implantable biosensors

Great efforts are currently devoted to the development of graphene Solution-Gated Field-effect transistors (gSGFET) as sensors for biosensing applications and particularly, neural implants. Indeed, with the high carrier mobility of graphene, graphene-based sensors exhibit very high sensitivity and the easy integration of graphene in flexible devices is a clear advantage for implantable technologies by reducing rejection from biological tissues. However, despite the great performances already exhibited by gSGFETs for biosensing, this technology has not shown its full potential yet. This is due to the fact that since the graphene channel is in direct contact with the liquid medium, the carrier mobility, and consequently the sensitivity of a gSGFET, stays below its theoretical value and the sensors performances are subjected to stability issues. Hexagonal Boron Nitride (hBN) has been proved to be a key two-dimensional material that will enable to overcome carrier mobility limitations. Because the access to highly pure large scale-hBN is challenging, we tested here whether more accessible lower-quality commercial Chemical Vapor Deposited Multilayer BN could still be successfully used to improve gSGFETs sensitivity for neural recordings. We demonstrate that even when using a commercial multilayer BN, the performances of gSGFET sensors can be improved to enable neural recording.