Fig. 1.

Schematic representation of the preconcentration protocol. A 2-mL droplet of solution containing the miRNA solution to be preconcentrated is placed on the disk via drop casting, followed by air drying. This procedure can be repeated N times. The disk is then transferred into a vial containing buffer solution and manually shaken for 1 min. Subsequently, the solution containing the preconcentrated target is measured via SWV at the paper-based electrode