Ultra-sensitive suspended graphene nanocomposite cancer sensors with strong suppression of electrical noise.

The cancer sensor based on suspended layer-by-layer self-assembled graphene reported in the paper exhibits an ultra high sensitivity due to graphene material properties in nature. By simply immersing the substrate alternatively into charged graphene suspensions and polyions, graphene nanoplatelets are self-assembled in the channel as the sensing region, followed by SF(6) dry etching to suspend the structure. Conductance shift curves demonstrate that the suspended graphene sensors functionalized with specific anti-PSA antibodies as bioreceptor are capable of detecting prostate specific antigen down to 0.4 fg/ml (11 aM), at least one order of magnitude lower than unsuspended devices. The noise spectra analysis confirms the lower level of 1/f noise in suspended graphene devices. Carbon nanotube sensor under the same conditions of design, manufacture, and measurement are implemented to compare with graphene devices, showing the prominent advantages of graphene as a sensing material.