Multimodal Molecular Sensing Using Freestanding Two-dimensional Material Structures

Measurement technologies that enable simple and rapid diagnosis have become increasingly important due to the experience of COVID-19 pandemic. The use of graphene in ion sensitive field effect transistor (ISFET)-based biosensors is expected to result in highly sensitive biosensing. However, the problem of Debye shielding limits the measurement range of FET sensors, making it difficult to detect biopolymers in solutions with physiological salt concentrations. In this paper, we introduce a graphene-based biosensor with molecular recognition capabilities by functionalizing the surface of suspended graphene. The graphene resonant mass sensor quantifies molecules by measuring the change in their resonant frequency associated with molecular adsorption. High sensitivity can be achieved in such mass sensors by thinning the vibrating membrane. The proposed technology is expected to be applied to measurement systems that can detect chemical substances and viruses in the environment, as well as disease-causing gas components in exhaled gases with ultra-high sensitivity.