Majority of existing nanoelectronic sensors are based on charge detection, where molecular binding changes the charge density of the sensor and leads to sensing signal. However, there are several fundamental limitations to the charge-detection based electronic sensors. In this talk, I will discuss our group’s recent works on a new paradigm of electronic sensing by exploring the heterodyne mixing response between the molecular dipole and a nanoscale transistor. First, we successfully demonstrated that the fundamental ionic screening effect can be mitigated by operating single-walled carbon nanotube field effect transistor as a high-frequency heterodyne biosensor. Second, we demonstrated the concept of nanoelectronic heterodyne sensor for vapor detection in a graphene device. Simultaneous rapid (down to 0.1 s) and sensitive (down to 1 ppb) detection of a wide range of vapor analytes are achieved, representing orders of magnitude improvement over state-of-the-art nanoelectronics sensors. Third, we demonstrated electrical probing and tuning of the non-covalent physisorption of polar molecules on graphene surface by using graphene nanoelectronic heterodyne sensors. Finally, I will present our recent work on a new type of universal graphene vapor sensor that can detect both polar and non-polar molecules.
Zhaohui Zhong is currently an Associate Professor of Electrical Engineering and Computer Science at the University of Michigan. He received his B.S. and M.S. in Chemistry from Nanjing University in 1998 and 2000, and his Ph.D. in Chemistry from Harvard University in 2005. From 2005 to 2008, he was a postdoctoral associate at Cornell University Center for Nanoscale Systems. He joined the faculty of EECS at the University of Michigan in 2008. He is a recipient of ACS Petroleum Fund Doctoral New Investigator and NSF CAREER award, and the co-founder of Arborsense Inc, a start-up company working on wearable graphene sensor. His research lies at the frontier of nanoelectronics and nanophotonics.