Real-time dual-loop electric current measurement for label-free nanofluidic preconcentration chip

• Published in: Lab on a chip Vol. 15; no. 1; pp. 319 - 33
• Main Authors: Chung, Pei-Shan, Fan, Yu-Jui, Sheen, Horn-Jiunn, Tian, Wei-Cheng
• Format: Journal Article
• Language: English
• Published: England 07.01.2015
• Subjects: Biomolecules; Chips; Devices; Electric current; Electricity; Electrochemical Techniques - instrumentation; Equipment Design; Microfluidic Analytical Techniques - instrumentation; Monitoring; Nanofluids; Nanostructure; Nanotechnology - instrumentation; Real time; Volt-ampere characteristics
• ISSN: 1473-0197; 1473-0189
• DOI: 10.1039/c4lc01143k

An electrokinetic trapping (EKT)-based nanofluidic preconcentration device with the capability of label-free monitoring trapped biomolecules through real-time dual-loop electric current measurement was demonstrated. Universal current-voltage ( I - V ) curves of EKT-based preconcentration devices, consisting of two microchannels connected by ion-selective channels, are presented for functional validation and optimal operation; universal onset current curves indicating the appearance of the EKT mechanism serve as a confirmation of the concentrating action. The EKT mechanism and the dissimilarity in the current curves related to the volume flow rate ( Q ), diffusion coefficient ( D ), and diffusion layer (DL) thickness were explained by a control volume model with a five-stage preconcentration process. Different behaviors of the trapped molecular plug were categorized based on four modes associated with different degrees of electroosmotic instability (EOI). A label-free approach to preconcentrating (bio)molecules and monitoring the multibehavior molecular plug was demonstrated through real-time electric current monitoring, rather than through the use of microscope images. A label-free approach to preconcentrating (bio)molecules and monitoring the multibehavior molecular plug through real-time dual-loop electric current monitoring.