Figure 1.

Schematic of the electrode and ac-EHD mechanism. (a) Optical image of the asymmetric electrode pair containing an inner circular small electrode and a large outer ring electrode with an edge to edge distance of 1000 μm between the electrodes. The diameter of the inner electrode and the width of the outer ring electrode were 250 and 30 μm, respectively. Scale bar = 200 μm. (b) Schematic representation of the mechanism of ac-EHD induced surface shear forces for rapid capture and detection of E. histolytica antigen (not drawn to scale). Under an ac-EHD field, the charges induced within the electrical double layer of an electrode experience an electrical body force that drives the bulk fluid onto the inner circular electrode. This fluid flow transports target molecules or detection antibody in the bulk fluid and can continuously supply target molecules (i.e., increase sensor-target affinity interactions) onto the capture domain. Further, the fluid flow can be tuned using the applied ac field to achieve optimal fluid flow that can maximize device performance. This ability of ac-EHD flow can enable rapid capture and detection of target antigens.