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Updated: Apr 7, 2026

Nanopore DNA Sequencing for Metagenomic Soil Analysis
Published on: December 14, 2017
Label-free DNA sequencing using Millikan detection
Roger Dettloff1, Danielle Leiske1, Andrea Chow2
1Caerus Molecular Diagnostics, Mountain View, CA 94043, USA.
Abstract:
A label-free method for DNA sequencing based on the principle of the Millikan oil drop experiment was developed. This sequencing-by-synthesis approach sensed increases in bead charge as nucleotides were added by a polymerase to DNA templates attached to beads. The balance between an electrical force, which was dependent on the number of nucleotide charges on a bead, and opposing hydrodynamic drag and restoring tether forces resulted in a bead velocity that was a function of the number of nucleotides attached to the bead. The velocity of beads tethered via a polymer to a microfluidic channel and subjected to an oscillating electric field was measured using dark-field microscopy and used to determine how many nucleotides were incorporated during each sequencing-by-synthesis cycle. Increases in bead velocity of approximately 1% were reliably detected during DNA polymerization, allowing for sequencing of short DNA templates. The method could lead to a low-cost, high-throughput sequencing platform that could enable routine sequencing in medical applications.
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