Microfluidic device for coupling isotachophoretic sample focusing with nanopore single-molecule sensing
Nanopore sensing remains challenging at low target concentrations, where the detection rate is limited by slow diffusion of analytes into the sensing volume. In this work, we show that an electrokinetic preconcentration method called isotachophoresis (ITP) can be used to deliver a highly concentrated zone of analytes to a solid-state nanopore. The key to ITP-nanopore sensing lies in the ability to electrically decouple the two modes to avoid damaging the fragile dielectric membrane. By choosing electrolyte conditions that enable both efficient focusing and sensing, and by implementing electrical switching in a custom microfluidic device, we show that ITP focusing can enhance the event rate by over 300 times compared to free diffusion.
