Suspended Graphene Nanoribbon Ion-Sensitive Field-Effect Transistors Formed by Shrink Lithography for pH/Cancer Biomarker Sensing

Low-cost and facile shrink lithography is utilized to form suspended graphene nanoribbon (GNR) for an ion-sensitive field-effect transistor (ISFET) with pH/cancer marker sensing applications. By combining shrink thermoplastic film with hot embossing process, GNR patterns 50 nm wide are achieved in a low-cost and simple way. Ambipolar characteristics of a suspended GNR ISFET after annealing presents an enhanced ambipolar effect. Different pH solutions are introduced to characterize the performance of GNR ISFET. For cancer biomarker sensing, the suspended GNR functionalized with specific anti-PSA antibodies as bio-receptor are capable of detecting prostate specific antigen down to 0.4 pg/mL. In comparison, the unsuspended GNR and microscale graphene sheet based ISFETs through the same design and fabrication are characterized under the same measurement conditions, showing that suspended GNR ISFET is superior in sensitivity and detection limit.