Research Topics

· Electron Microscopy for Fluidics · Condensation on Superhydrophobic Surfaces · 3D Nanofabrication · EBID/CNT Interconnects

Scalable Three Dimensional Nanofabrication

I am interested in development of scalable and cost effective three dimensional nanofabrication techniques for variety of applications. Currently I am particularly interested in development of methods which combine fabrication approaches like deposition (CVD, ALD, EBID/FIBID, etc.), etching, casting, printing, and so on with self-assembly processes. My current projects in this area are summarized below.

·3D silicon fabrication using metal-assisted chemical etching (MaCE)

In the MaCE process etching is confined to a small region surrounding a metal catalyst template, which can travel in three dimensions as it etches into silicon and other semiconductor materials. This method is emerging as a scalable low cost alternative to traditional microfabrication techniques and has been successfully applied to produce tilted and zigzag nanowires, helical holes, and cycloidal and spiral trenches. In this project we explore different strategies for achieving fully 3D MaCE nanofabrication through mechanical control of the catalyst motion during etching. So far we have demonstrated that:
-Thin insulator patterns underneat the metal catalyst can locally block the etching process
-The motion of the catalyst during etching can be controlled mechanically through pinning with insulator patterns. Controllable out-of-plane rotational catalyst motion was achieved.
-Relationship between catalyst geometry and etching rate was determined experimentally.
-2D catalyst divided into regions with different etching rates can self-assemble into 3D object during etching.

Collaboration: Dr. Owen Hildreth (former GT, current NIST Boulder), Dr. CP Wong (GT), and Dr. Andrei Fedorov (GT)



·Nanoparticle Self-assembly into Superhydrophobic Liquid Marbles

Nanoparticles adsorbed onto the surface of a drop can fully encapsulate the liquid, creating a robust and durable soft solid with superhydrophobic characteristics referred to as a liquid marble. Artificially created liquid marbles have been studied for about a decade but are already utilized in some hair and skin care products and have numerous other potential applications. These soft solids are usually formed in small quantity by depositing and rolling a drop of liquid on a layer of hydrophobic particles but can also be made in larger quantities in an industrial mixer. In this project, we demonstrated that microscale liquid marbles can also form through self-assembly during water condensation on a superhydrophobic surface covered with a loose layer of hydrophobic nanoparticles.

Collaboration: Dr. John Henry Scott (NIST), Dr. Jeff Chinn (IST), and Dr. Marlon Walker (NIST)