Department: Electrical & Computer Engineering
Research Institute Affiliation: California Institute for Telecommunications and Information Technology (Calit2)
Faculty Advisor(s): Michael Heller

Primary Student
Name: Youngjun Song
Email: yos001@ucsd.edu
Phone: 858-822-1276
Grad Year: 2014

Scaling is always a challenging engineering issue, and the fabrication of nanoscale components into macroscopic size devices and materials will be no exception. In the case of cost effective flexible hybrid energy conversion and storage devices, the key challenge is the development of a viable manufacturing technology that allows rapid and controlled integration of a number of different conductive polymers and nanocomponents into higher-order materials and devices. In previous work, the Heller lab used a microelectronic array device with 400 microelectrodes (55 microns in diameter) to carry out the electric field directed (EFD) layer by layer (LBL) assembly of nanoparticles into higher order structures (NanoLetters 8, pp.4053-60, 2008; SMALL v3, #7, pp. 1237-44, 2007; J. Assc. Lab Automation, v12, #5, pp. 267-276, 2007 ). Using these microdevices, various DNA, biotin/streptavidin and enzyme derivatized nanoparticles could be fabricated in 55 micron diameter lift-off structures with up to 40 layers of different nanoparticles. We have now designed, fabricated and tested 4? silicon wafer EFD devices with a 5 cm x 5 cm active area containing 400 electrodes (2.5mm x 2.5mm) with 8um spacing. These new EFD-LBL "macrodevices" are now being used to carry out the layering of conductive polymers, micron size particles and nanoparticles. The EFD-LBL devices and process have major advantages over classical LBL self-assembly processes. First, the single nanoparticle layers can be deposited in under a minute at a rate 100-1000 times faster than passive assembly. Second, EFD-LBL allows the concentrations of polymers/nanocomponents to be significantly reduced, increasing specificity and reducing impurities. Third, the integrity of binding reactions between these nanocomponents, such as electrostatic, covalent, biological DNA, and protein ligands, are maintained throughout the process, granting a vast number of potential material combinations. Fourth, EFD-LBL process also has the intrinsic ability to allow for near instantaneous X-Y reconfigurability, providing maskless X-Y patterning in real time. Fifth, the completed products can be removed via a simple lift-off procedure, making the EFD-LBL device a true manufacturing platform. EFD-LBL devices represent a true synergy of combining the best aspects of a top-down and bottom-up technologies for nano, micro and macrofabrication and heterogeneous integration of different materials and components. In addition to photovoltaic/battery materials and devices, the EFD-LBL process has potential for the fabrication of fuel cells, smart materials, and miniaturized chemical or biosensor lab-on-a-chip devices.

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