Improved synthesis and growth of graphene oxide for field effect transistor biosensors.

Reduced graphene oxide (RGO) has many advantages over graphene such as low-cost, aqueous processable and industrial-scalable. However, two main limitations that prevent the use of RGO in electronics are the high electrical resistance and large electrical resistance deviation between fabricated devices. This limits RGO's use in biosensors, capacitors and other electronic devices. Herein, we present (1) a modified Hummer's method to obtain large RGO flakes via in-situ size fractionation and (2) the novel growth of RGO which can bridge the gaps in-between existing RGO flakes. Together, these two processes reduced the electrical resistance drastically from 1.99E + 06 to 4.68E + 03 Ω/square and the standard deviation decreased from 80.5 % to 16.5 %. The RGO was then fabricated into a field-effect transistor biosensor. A 1 pmol to 100 nmol change in Cytochrome C protein corresponded to a 3 % change in electrical resistance. The reported improved RGO synthesis method and subsequent growth enable large-scale application of RGO in practical electronic devices such as biosensors.