The group is divided up in to four main research thrusts:
- Carbon Mechanics
- Carbon electronics
- Nano-Bio Interfaces
- Molecular Assembly
- Carbon Mechanics
RF-NEMS are important for both fundamental research (e.g. pushing the limits of mass, charge, magnetic sensing) and technology (e.g.transceivers for wireless communications, biosensing, etc). Graphene NEMS represent the ultimate limit of such devices. In our group, we develop novel fabrication techniques to create large arrays of graphene NEMS for large-scale on-chip nanomechanical signal processing. We develop novel readout techniques to overcome the challenges associated with the electrical detection of small displacements (of the level of a few angstroms) at high frequencies and apply these to develop novel devices such as tunable filters, voltage-controlled oscillators and other nanomechanical radio frequency integrated circuits (RFICs). We are also interested in using mechanical motion to probe the fundamental physics of graphene e.g. in the quantum Hall regime.
"Frictional Characteristics of Atomically Thin Sheets," Science 328, 76 - 80(2010) [ pdf format ] [ supporting material ]
"Performance of Monolayer Graphene Nanomechanical Resonators with Electrical Readout," Nature Nanotechnology, 4 , 861 - 867 (2009) [ pdf format ] [ supplementary infromation ]
- Carbon Electronics
Using mechanical techniques to manipulate and transfer materials at the nano-scale, we fabricate layered heterostructures utilizing single-layer graphene and carbon nanotubes as building blocks. This allows us to better isolate and study the intrinsic electronic properties of 2D and 1D systems (e.g. quantum Hall effect and Luttinger liquid behaviour, respectively) while also enabling us to engineer new layered, meta-materials with new device functionality (e.g high performance field effect transistors for high frequency analog applications).We are also interested in studying bilayer graphene where the existence of a dynamically variable bandgap, a unique feature not found in conventional semiconductors, allows the possibility of realizing tunable digitial devices and novel opto-electronic applications. Finally, we maintain a continued effort on realizing scalability in graphene devices through the development of improved wafer-scale growth techniques.
"Boron nitride substrates for high-quality graphene electronics," Nature Nanotechnology 5 , 722 - 726 (2010) [ pdf format ] [ supplementary infromation ]
- Nano-Bio Interfaces
Transparent and conducting films are used in modern technologies like video displays, solar cells, lasers, optical communication devices and solid state lighting. Carbon nanotube films are also a class of conducting materials that are gaining a lot of attention due to their extraordinary optical transparency as well as low sheet resistance. These conducting nanotube films are a potential candidate for usage in dye sensitized solar cells as well as fuel cells, where they can be used both as conducting electrode materials as well as catalyst support for enhacing the electrochemical reaction. - Molecular Assembly
We are developing strategies to control the immobilization of nanostructures and biomolecules onto lithographically defined features on solid substrates with precise control over position and orientation, so that they can be integrated into functional devices and circuits.
The combined use of lithographic patterning and (bio)molecular self-assembly allows the production of highly ordered arrangements of nano-objects, ranging from proteins to DNA nanostructures, as well as organic (e.g. CNTs) and inorganic assemblies (e.g Quantum Dots), for a variety of (nanoscale) investigations.
We have shown how by specific design of biomolecular nanoarrays (Palma et al Methods in Molecular Biology 2011), it is possible to simultaneously monitor hundreds of protein/DNA binding events at the single-molecule level (Palma et al JACS 2011). We have employed similar approaches to control the self-assembly of Quantum Dots in nanoarrays with single-particle control and resolution (Abramson, Palma et al, submitted to Advanced Materials).
We are currently working on the self-assembly of DNA nanostrucutres (such as DNA-origami) and CNT segments, on properly functioanlized nanodots.
The high density and resolution achievable with our platform/s can find general application in the fabrication of nanoscale functional devices“Selective biomolecular nanoarrays for parallel single-molecule investigations” Journal of the American Chemical Society (2011), ASAP [ pdf format ] [ supporting information ]
“Controlled confinement of DNA at the nanoscale: nanofabrication and surface bio-functionalization”, Methods in Molecular Biology, Vol. 749 (2011) ISBN: 978-1-61779-141-3
"Adjacent Assembly of Self-Assembled Monolayers for the Construction of Selective Bio-Platforms, "Sensor and actuators B, 2011, [ pdf format ]
New approach for measuring protrusive forces in cells, "Journal of Vacuum Science and Technology B, Vol.29,No.6,Nov/Dec 2011, [ pdf format ]
