Nanofluidics
A new tool for sensing and manipulating molecules in solution

Mr. Rohit Karnik, PhD Candidate
Department of Mechanical Engineering
University of California - Berkeley

Abstract
The range of electrostatic interactions in ionic solutions is characterized by the Debye length, which is typically 1-100 nm in aqueous solutions. When a fluidic channel is scaled down to dimensions comparable to the Debye length, electrostatic interactions govern the ionic environment in such nanofluidic channels. Based on this unique property, we have developed a nanofluidic transistor for electrokinetic flow control of ions and molecules. Analogous to a field-effect transistor, the gate voltage in a nanofluidic transistor controls the concentration of ions and biomolecules in the nanofluidic channel, and hence controls their transport. While the nanofluidic transistor can dynamically control flow, we have also developed a new technique to pattern surface charge for spatially modulating electrokinetic flow. In addition, we have demonstrated that biological binding reactions inside nanofluidic channels block the channel and change its charge environment, which can be sensed by simply measuring the channel conductance. With the capabilities of dynamic flow control and sensing combined with ease of fabrication, our system is a promising tool for processing and analysis of complex solutions.

Monday, February 20, 2006
11 AM, 337 Towne Bldg.