Description
The development of sensitive point-of-care (POC) diagnostics is often hindered by low target analyte concentrations and matrix interference. This work presents a comprehensive microfluidic framework leveraging Ion Concentration Polarization (ICP) to overcome these challenges through two primary pathways: integrated on-chip and off-chip preconcentration of biomolecules for several biosensing methodologies.
ICP exploits the formation of ion-depleted and ion-enriched zones near ion-selective membranes, such as Nafion, under an applied electric field. This phenomenon triggers a symmetry breaking in ion concentration, leading to an intensified electric field at the depletion layer. Charged biomolecules are trapped at the edge of this depletion zone due to a field-gradient-focusing effect, where the electrophoretic velocity of the analyte is balanced by counteracting advection—driven by pressure or electroosmosis. This mechanism enables continuous accumulation of analytes, significantly increasing local concentrations.[1]
For on-chip biosensing applications, we integrated ICP-preconcentration directly with local electrochemical sensing. This platform supports both coupled and decoupled operation modes, facilitating the continuous detection of bioanalytes such as Homovanillic acid (HVA) in artificial sweat with enhancement factors ranging from 10 to 100. [2] Additionally, a dynamic buffer exchange operation using a Y-junction design effectively removes neutral inhibitory species—reducing them to 0.015 of initial levels—while retaining the preconcentrated analyte plug.
To enhance existing diagnostic infrastructure, we developed a customized, pump-free ICP-based device compatible with commercially available immunoassays. Utilizing built-in hydraulic pressures, the device captures targets from large sample volumes and facilitates the on-demand extraction of preconcentrated microliter-sized droplets. Validated with standard ELISA and Lateral Flow Assay (LFA) kits, this pre-step improved the limit of detection (LOD) for IgG antibodies by one order of magnitude without requiring modification of original assay protocols.[3]
The results demonstrate that ICP-based preprocessing effectively bridges the gap between fundamental electrokinetics and practical clinical application. By unifying sample purification, programmable plug manipulation, this framework provides a robust solution for the next generation of sensitive, portable diagnostic tools capable of operating in complex biological environments.
Keywords: Ion Concentration Polarization; ample Preprocessing; Electrochemical Sensing; Immunoassay Enhancement; Microfluidics.
[1] S. Park, B. Sabbagh, G.Yossifon, Lab-on-a-chip, 22, 814, 2022.
[2] S. Park, D.Kaufman, H. Ben-Yoav, and G. Yossifon, Anal. Chem., 96, 6501, 2024.
[3] B. Sabbagh, S. Park, and G. Yossifon, Lab-on-a-chip, 25,4765, 2025.