title: Fabrication of metallized nanopores in silicon nitride membranes for single-molecule sensing.
abstract: The fabrication and characterization of a metallized nanopore structure for the sensing of single molecules is described. Pores of varying diameters (>10 nm) are patterned into free-standing silicon nitride membranes by electron-beam lithography and reactive ion etching. Structural characterization by transmission electron microscopy (TEM) and tomography reveals a conical pore shape with a 40 degrees aperture. Metal films of Ti/Au are vapor deposited and the pore shape and shrinking are studied as a function of evaporated film thickness. TEM tomography analysis confirms metalization of the inner pore walls as well as conservation of the conical pore shape. In electrical measurements of the transpore current in aqueous electrolyte solution, the pores feature very low noise. The applicability of the metallized pores for stochastic sensing is demonstrated in real-time translocation experiments of single lambda-DNA molecules. We observe exceptionally long-lasting current blockades with a fine structure of distinct current levels, suggesting an attractive interaction between the DNA and the PEGylated metallic pore walls.
authors.affiliation: Walter Schottky Institut Technische Universität München Am Coulombwall 3, 85748 Garching, Germany.
authors.forename: Ruoshan
authors.initials: R
authors.lastname: Wei
authors.forename: Daniel
authors.initials: D
authors.lastname: Pedone
authors.forename: Andreas
authors.initials: A
authors.lastname: Zürner
authors.forename: Markus
authors.initials: M
authors.lastname: Döblinger
authors.forename: Ulrich
authors.initials: U
authors.lastname: Rant
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics; D015374:Biosensing Techniques / Q000379:methods*; D004279:DNA, Viral / Q000378:metabolism; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D004560:Electricity; D008567:Membranes, Artificial; D008670:Metals / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D010316:Particle Size; D016062:Porosity; D017655:Silicon Compounds / Q000737:chemistry*
chemical_list: D004279:DNA, Viral; D004129:Dimethylpolysiloxanes; D008567:Membranes, Artificial; D008670:Metals; D017655:Silicon Compounds; C032734:silicon nitride