A pumpless solution exchange system for nanopore sensors.

This paper proposes a nanopore-based sensor exploiting the solution exchange of a droplet-based lipid bilayer driven by a superabsorbent polymer. Biological nanopores are candidates for use in portable sensors because of their potential to recognize and detect single molecules. One of the current challenges in the development of portable nanopore sensors is the inability to achieve continuous detection. To achieve continuous detection, we have exploited the suction force of a superabsorbent polymer to drive the continuous microfluidic flow required to wash the analyte out of the droplet. The superabsorbent polymer drives the microfluidic flow without electricity, and the developed solution exchange system remains compact. To demonstrate solution exchange in the droplet containing the lipid bilayer, the concentration of heptakis(6--sulfo)-β-cyclodextrin was monitored in a time-dependent manner using α-hemolysin nanopores. A reduction in the concentration, attributable to solution exchange, was successfully observed. We believe that the proposed system will increase the portability and usability of nanopore sensors.