Enhancing fluorescent response of immunosensing by a dielectrophoresis chip with transparent electrodes and microcavities array

Microelectrodes used in dielectrophoresis (DEP) chips are mostly made of metal materials; however, the metal electrodes can induce extra background noise as observed in a fluorescence microscope. Currently, the fluorescent response still dominates the indicators of immunoassays; therefore it is important to eliminate the extra background noise of the fluorescence response generated by metal electrodes for an immunosensor. In this reported study, a transparent conductive material, indium tin oxide (ITO), was employed in the fabrication of DEP electrodes, and the fluorescent responses of a DEP chip with transparent electrodes were compared with an identical DEP chip with conventional Au electrodes during an immunoassay. According to the experimental results, the enhancement of the fluorescent response of the DEP chip with ITO electrodes was greater than the values of the DEP chip with Au electrodes; about 1.57 times and 1.44 times for the immunosensing of 10 and 1 nm bovine serum albumin (BSA), respectively. In addition, by applying the DEP force during the immunosensing, the fluorescent response was also enhanced because of the condensation ability to BSA by the DEP force. Consequently, a DEP chip with transparent ITO electrodes and a microcavities array has been demonstrated, and the background noise of the fluorescence response can be eliminated to enhance the sensitivity of immunosensing.