  Ionic concentration-polarization (CP)-based biomolecule preconcentration is
an established method for enhancing the detection sensitivity of target
biomolecules. However, the formed preconcentrated biomolecule plug rapidly
sweeps over the surface-immobilized antibodies, resulting in a short-term
overlap between the capture agent and the analyte, and subsequently suboptimal
binding. To overcome this, we designed a setup allowing for periodic formation
of a preconcentrated biomolecule plug by activating the CP for predetermined
on/off intervals. This work demonstrated the feasibility of the cyclic CP
actuation and optimized the sweeping conditions required to obtain maximum
retention time of a preconcentrated plug over a desired sensing region and
enhanced detection sensitivity. The ability of this method to efficiently
preconcentrate different analytes and to successfully increase immunoassay
sensitivity, underscore its potential in immunoassays serving the clinical and
food testing industries.
