High-Speed Graphene Field Effect Transistors on Microbial Cellulose Biomembrane

For the goal of developing biocompatible sensors and electronics for in vivo applications, we report the first graphene field effect transistors (GFETs) fabricated on microbial cellulose (MBC), a biointegrative and ultraflexible biopolymer membrane. GFETs on MBC are fabricated in a wafer-scale using a transferred CVD graphene with a mobility of ${\rm{> 1700\,cm}}^{2}{\rm{/ Vs}}$ . With an excellent ohmic contact resistance of below ${\rm{0.1\,\Omega \,mm}}$, and a high transconductance of ${\rm{G}}_{{\rm{m}}}\sim 260$ mS/mm with ${\rm{I}}_{{\rm{ds}}}\sim 380$ mA/mm at ${\rm{V}}_{{\rm{ds}}}\,= \,{\rm{1\,V}}$, very promising RF performance was demonstrated. With a gate length of $2\,\mathrm{\mu} {\rm{m}}$, a cut-off frequency of ${\rm{f}}_{{\rm{T}}}\sim 2.5$ GHz and a maximum oscillation frequency of ${\rm{f}}_{{\rm{max}}}\sim 7.2$ GHz were obtained without de-embedding. This corresponds to an extrinsic ${\rm{f}}_{{\rm{T}}}{\rm{\cdot L}}_{{\rm{g}}}$ of ${\rm{5\,GHz\cdot }}\mu {\rm{m}}$, comparable to those reported for GFETs on other well-known flexible substrates. RF GFETs on the biointegrative MBC therefore show great promise for high-sensitivity and high-speed in vivo sensors and electronics applications.