Ph.D., City University of New York, 1999

Post-doctoral Fellow, Department of Physics, Harvard University, 1999-2002.

Assistant Professor, 2002-present.

Research Interests: nanoscale materials science and their applications in biological systems. This includes: (1) Molecular scale solid-state nanopore fabrication; (2) Nanoscale materials science related to nanopore fabrication; (2) Single DNA and protein detection with a solid-state nanopore device; (5) artificial biosolar systems to serve as fuel supplies to nanodevices.

NANOFABRICATION, NANOSCALE MATERIALS SCIENCE, AND SINGLE DNA AND PROTEIN DETECTION

Nanoscale pores function as membrane channels in all living systems, where they serve as sensitive electro-mechanical devices that regulate electrical potential, ionic flow, and molecular transport through the cell membrane. Studies of nanopore construction and their characterization for single molecule transport through solid-state membranes will lead to man-made cell membranes and single molecule detectors. Currently, there are two major aspects of this research include studies involving:

I. Molecular Size Solid State Nanopore Fabrication and Nanoscale Materials Science Study. A combination of semiconductor device fabrication techniques: photolithography, reactive ion etching, and wet chemical etching are used to create a free standing silicon nitride membrane supported by silicon substrate. To make 1 to 10 nanometer pores in the membrane, focused Ion Beam machine or e-beam lithography, followed by newly developed ways of controlling the lateral mass transport of matter across a surface on nanometer length scales, called ion beam sculpting are used (Fig.1). This Ion Beam Sculpting system not only provide a tool for making nanopores, it also allow us to conduct basic materials sciences studies on how the thickness, electrical properties and chemical activity of the nanopores depend on: 1) ion beam flux,2) ion beam species, 3) ion beam energy, 4) sample temperature and surface treatment.

II. Developing solid state nanopore based single biopolymer detectors. Solid-state nanopores are mechanically robust, have tunable dimensions, tolerate broad temperatures, pH, and chemical variations, and are therefore ideally suitable for DNA and protein detection as well as integrated electronic device development. The principle of nanopore detection is: a single nanopore in an insulating membrane separates two ionic solution filled compartments; a voltage across the membrane is applied by a pair of electrodes. When polymers are added to the solution, translocation of an individual molecule through the pore will partially block the nanopore, a characteristic current blockage will be recorded (Fig.2). Each event is characterized by its current blockade amplitude, ¥Ib, and its time duration td. The research we are interested in studying: 1) employing a combination of electrical and fluorescence techniques to observe single biopolymers in real time, 2) studying the physics of charged molecules driven through the nanopore by an electrical field, 3) characterizing, counting and sizing charged DNA and protein molecules moving through the nanopores, 4) study DNA-protein interactions, and 5) developing new techniques to improve the time and space resolution of single molecule detection.