Electrothermal stirring for heterogeneous immunoassays.
A technique is proposed to enhance microfluidic immuno-sensors, for example, immunoassays, in which a ligand immobilized on a microchannel wall specifically binds analyte flowing through the channel. These sensors can be limited in both response time and sensitivity by the diffusion of analyte to the sensing surface. In certain applications, the sensitivity and response of these heterogeneous immunoassays may be improved by using AC electrokinetically-driven microscale fluid motion to enhance antigen motion towards immobilized ligands. Specifically, the electrothermal effect is used to micro-stir analyte near the binding surface. Numerical simulations of antigen in a microchannel flow subjected to the electrothermal effect show that 6 V(rms) applied to electrodes near a binding region can increase binding in the first few minutes by a factor of seven. The effectiveness of electrothermal stirring is a strong function of the Damköhler number. The greatest binding enhancement is possible for high Damköhler numbers, where the reaction is limited by diffusion. Based on these results, the utility of this technique for diffusion-limited microfluidic sensor applications is demonstrated.
Sigurdson
Marin
M
Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106, USA.
Wang
Dazhi
D
Meinhart
Carl D
CD
D000936:Antigen-Antibody Complex / Q000032:analysis*; D017076:Computer-Aided Design; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods; D006358:Hot Temperature; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods
D000936:Antigen-Antibody Complex