Crumpling of graphene optimizes graphene field effect transistors (GFETs) as ultrasensitive biosensors

Biosensors are devices that translate biological responses into electrical signals. They have many applications in various fields, however biosensors are especially useful for early detection of diseases such as cancer and other genetic disorders. This could be done, for example, via detection of specific proteins or nucleic acids in body fluids. For the case of DNA and RNA, detection of genetic mutations or specific sequences in DNA can be indicative of the state of a disease. Biosensors with high sensitivity and specificity are essential to the future of the aforementioned fields, however current biosensor technology does not meet the demands of high sensitivity, low cost, and ease of use by the patients. Graphene field effect transistors (GFETs) provide a refreshing alternative to biosensing with benefits including easy integration as biomolecular sensors, low fabrication costs,and most notably they have the ability to lower the biomarker detection limit to the femto-molar range. In this paper, we present a prototype for the new class of GFETs where the channel consists of a layer of crumpled graphene that yields extreme sensitivity for detection of DNA in the sub-atto-molar range. Furthermore, we find that increasing the crumpling ratio of the graphene increases the device’s sensitivity for nucleic acid detection. We hypothesize this is due to two main mechanisms:formation of ’electrical hot spots’ due to variations in the Debye length above the sensor layer and the presence of a more significant band gap for the deformed graphene channel which in turn affects its conductivity. Continuing the work of this project would take the form of further increasing the sensitivity to be able to detect historically scarce molecules that can then lead to more effective biosensing tools in medicine.