Scale-down effects: Towards miniaturization of an electrochemical sensor using biomolecules

This work studies miniaturization effects of an electrochemical sensor for TNT detection modified with Tobacco mosaic virus-like particles (VLPs). VLPs have been genetically modified to express peptides that show high binding affinity to TNT. When immersed in a solution containing TNT, modified VLPs bind to the TNT molecules, changing their diffusion coefficient. This change generates a differential reduction current compared with control measurements. To investigate the scale-down effects of this novel sensing mechanism, experiments were conducted in a millimeter scale platform as well as fully integrated, microfabricated electrochemical cells. Specifically, the effects of working electrode surface area, electrode spacing, and electrode interface area were studied, with a focus on improving sensor sensitivity at the microscale. Experimental results suggest that the sensitivity of the sensor can be enhanced by increasing electrode interface area and reducing electrode spacing. These results can serve as a design guide for performance optimization of miniaturized Lab-on-a-chip devices.