An effect of AC electrothermal flow on a carbon nanotube network based biosensor

Abstract

The mechanism of various kinds of biosensors mainly depends on the chemical affinity between probe molecules immobilized on the sensor surface and the target molecules in the solution. The amount of target molecules can be inferred from the mechanical, optical, or electrical signal generated by probe-target binding events. The binding process proceeds through two steps: the mass transport process and the surface reaction process. It is known that under the low target concentration condition, the binding rate is limited by the slow diffusive transport process. To increase the probe-target binding rate, AC electrokinetics can be used to assist the transport process. Various methods such as AC electroosmosis, dielectrophoresis, AC electrothermal flow are suggested by other groups. Among them, AC electrothermal flow can have a significant effect in the conductive biological solution. In this thesis, the effect of AC electrothermal flow on the biosensor performance is analyzed by both simulation and experiments. The carbon nanotube network based biosensor consists of concentric electrodes is used for identifying the effect of AC electrothermal flow. Simulation results indicate that AC electrothermal flow can assist the transport of target molecules toward the sensor surface and enhance the probe-target binding rate. For experiments, a biomarker for acute myocardial infarction, cardiac troponin-I, is selected. Experimental results demonstrate AC electrothermal flow can boost the probe-target binding speed and significantly enhance the biosensor performance.