Engineering adjustable two-pore devices for parallel ion transport and DNA translocations

Area of Science:

• Nanotechnology
• Biophysics
• Materials Science

Background:

• Solid-state nanopores offer precise control over molecular transport.
• Parallel analysis of analytes requires scalable and reliable multi-pore systems.
• Existing nanopore fabrication methods present challenges in creating uniform, parallel structures.

Purpose of the Study:

• To develop and characterize a two-pore solid-state nanopore device for parallel ionic current and DNA translocation measurements.
• To investigate the relationship between pore geometry (diameter and thickness) and conductance.
• To demonstrate the feasibility of parallel analyte detection and pore-specific event identification.

Main Methods:

• Fabrication of silicon nitride membranes with precisely controlled nanopore dimensions using electron beam lithography (EBL) and focused ion beam (FIB) drilling.
• Ionic current measurements to determine pore conductance and characterize pore geometry.
• Simultaneous translocation measurements of double-stranded DNA (dsDNA) through parallel nanopores.
• Analytical, numerical, and experimental validation of conductance additivity for widely separated pores.

Main Results:

• Successfully fabricated two parallel nanopores with similar diameters (~3 nm) but varying thicknesses (2.6-10 nm), yielding distinct conductance levels.
• Demonstrated that the total conductance of two widely separated pores is the sum of individual pore conductances, validated across analytical, numerical, and experimental approaches.
• Achieved simultaneous detection of over 12,000 dsDNA translocation events within 2 minutes, with high accuracy in assigning events to specific pores.
• Successfully monitored translocations through one pore even when the other was clogged, highlighting device robustness.

Conclusions:

• The developed two-pore device enables parallel translocation reading, significantly enhancing throughput for nanopore sensing.
• Precise control over nanopore thickness via EBL is crucial for tuning conductance and achieving distinct signal levels.
• This parallel architecture represents a fundamental advancement for solid-state nanopore systems and can be extended to multi-pore configurations.