Nanofluidic system for single molecule manipulation and analysis

Abstract

This thesis focuses on characterizing and controlling the translocation of single 48.5 kbp [lambda]-DNA molecules through an artificial nanopore with the objective of enabling multiple measurements on the same molecule. This approach may enable nanopore sensors with enhanced size or charge resolution through statistical averaging over multiple detection events. Nanopores with dimensions of 200 nm x 500 nm x 5 pm connected by microfluidic channels were fabricated using soft lithography in polydimethylsiloxane (PDMS). The PDMS nanopore could successfully detect translocation events of single [lambda]DNA molecules. Factors such as applied voltage bias, DNA concentration, and dimensions of the channel were found to affect the frequency of translocation events and signal-to-noise ratio, which are critical factors for implementing multiple measurements on the same molecule with feedback control. Noise contributions from each part of the experimental apparatus and device were also characterized. Feedback control using Labview was implemented to reverse the direction of applied voltage bias upon detection of a translocation event. The direction of travel of single DNA molecules could be successfully reversed and two measurements on the same molecule were realized. This work lays the foundations for a nanofluidic device for enhanced measurement resolution through statistical averaging over multiple measurements on the same molecule.