The goal of the proposal is to fundamentally study and subsequently pioneer a radically different graphene sensing mechanism based on detection of vapor molecules diploe moments.
Chemical Vapor sensor technologies are crucial for several applications which can bring fundamental changes to environmental protection and personalized healthcare. Unfortunately, current generation of nanoelectronic vapor sensors is too slow for practical use, and the challenge lies intrinsically in its sensing mechanism. To address this fundamental challenge, the proposal aims to pioneer a dipole-detection based sensing mechanism which can offer orders of magnitude improvement in both speed and sensitivity compared to the current state-of-the-art. The success of the proposed project will open a door to developing a plethora of vapor sensing technologies with a broad range of applications in environmental protection, industry safety, biomedicine, and homeland security. In addition, the knowledge and techniques acquired through the proposed research can readily be extended to study and detect biomolecules (such as DNAs and proteins) in the aqueous environment. More broadly, the proposed project is highly interdisciplinary and should advance science and technology in areas of nanomaterials, nanoelectronics, sensing technology, and device physics. The project also includes a prominent outreach and education program, which promotes awareness of and interest in nanoscience and nanotechnology among K-12 and undergraduate students. The knowledge and research findings resulting from this project will be integrated into a number of new nanotechnology courses currently under development that are related to carbon nanotechnology, biomedical instrumentation, and biological/chemical sensing. This project will be further enhanced by proactively recruiting underrepresented students, which can significantly improve the diversity of science, technology, engineering, and mathematics (STEM) disciplines and workforce.
The goal of the proposed project is to fundamentally study and subsequently pioneer a radically different graphene sensing mechanism based on detection of vapor molecules diploe moments. In contrast to the existing nanoelectronic sensors where the direct current (DC) signal is used, this approach utilizes the graphene transistor as a high-frequency mixer with surface-absorbed molecules functioning as an electrostatic gate. The molecular dipole is excited by alternating current (AC) driving voltage; the oscillating dipole in turn generates an AC conductance modulation on the graphene transistor, which can be detected by measuring the mixing current. By going into higher frequencies, the slow sensing response in the conventional nanoelectronic sensor can be overcome when the AC field switching outpaces the slow dynamics of interface states, thus resulting in 2-3 orders of magnitude faster sensing speed (~0.1 s) and >10-fold better sensitivity (~1 pg) than the state-of-the-art. The specific tasks include: 1) Fundamental study of high-frequency graphene nanoelectronic sensing mechanism; 2) Design, fabrication, characterization, and optimization of the proposed graphene vapor sensors; 3) On-chip integration of graphene vapor sensor with micro-gas chromatography (micro-GC) device. The project will generate fundamental and detailed understanding at the nanometer scale about how molecules behave under high-frequency excitation and how they interact with the graphene. In addition, the integration of graphene vapor sensor array with an on-chip micro-GC device will truly showcase the advantages of a nanoelectronic sensor that not only has high speed and high sensitivity, but also is non-destructive and highly compatible with on-chip fabrication/integration technologies.