Fabrication of Low Noise Borosilicate Glass Nanopores for Single Molecule Sensing

Abstract

We describe low-cost fabrication, size control and characterization of borosilicate glass nanopores for sensing of single biomolecules. Nanopores with pore diameters down to ∼100nm were fabricated in borosilicate glass capillaries using table-top carbon-di-oxide laser assisted glass capillary puller. We further achieve controlled reduction in pore diameter by sculpting of glass capillaries under constant electron beam exposure of a scanning electron microscope. We confirm successful fabrication of sub-10nm pores by SEM imaging. We further show electrical characterization and low-noise behavior of these borosilicate nanopores and compare various geometries of pulled conical glass nanopores. We show, for the first time, a comprehensive characterization of glass nanopore conductance across a wide range (1M-1μM) of salt conditions. We show the conditions for the conical pore conductance model to fit to this extended salt range. We also experimentally show, for the first time, the role of buffer conditions in this wide salt range measurement. Finally, we demonstrate single molecule sensing capabilities of these devices with real-time translocation experiments of individual λ-DNA molecules. We observe distinct current blockage signatures of single and multiply folded DNA molecules as they undergo voltage-driven translocation through the glass nanopores. We find increased signal to noise for single molecule detection for higher trans-nanopore driving voltages.