Abstract
The combination of bipolar electrochemistry (BE), as a wireless electrochemical approach, and of electrochemiluminescence (ECL) as an imaging readout is a successful strategy with a wide range of analytical applications. However, small conductive entities such as micrometric and nanometric objects are particularly difficult to polarize by BE since they require extremely high electric fields. In order to circumvent this issue due to intrinsic limitations of BE, we elaborated a solid-state micropore, decorated with a rhombus-shaped gold microelectrode. The electric field strength was concentrated inside the solid-state micropore where the conductive gold microelectrode was precisely located and acted as a bipolar light-emitting device. This original configuration allowed achieving adequate polarization of the gold microelectrode in a wireless manner, which led locally to ECL emission. ECL imaging shows that light was generated by the bipolar microelectrode in the center of the micropore. ECL emission could be achieved by imposing a potential value (10 V) to the feeder electrodes that is more than 2 orders of magnitude lower than those required without the micropore. The reported ECL approach opens exciting perspectives for the development of original wireless bioanalytical applications and dynamic bipolar experiments with small objects passing through the pores.
Highlights
To cite this version: Silvia Voci, Abdulghani Ismail, Pascale Pham, Jing Yu, Ali Maziz, et al
Fabrication of the microfluidic device with the micropore and the rhombus-shaped Au surface.—We designed a microfluidic device comprising the following main components: a planar solidstate micropore, a single rhombus-shaped Au microelectrode and two feeder Au electrodes. These spatial restrictions are considered as planar because they are at the surface of the substrate and not drilled through the silicon chips
After, removing the residual photoresist layer by acetone and plasma O2, dry thermal oxidation was performed in a furnace to grow 300 nm of an insulating SiO2 layer. This layer is thick enough to prevent any electrochemical reactions between the silicon substrate and the ECL reagents dissolved in solution
Summary
To cite this version: Silvia Voci, Abdulghani Ismail, Pascale Pham, Jing Yu, Ali Maziz, et al. ECL was generated using the model [Ru(bpy)3]2+/TPA system at very low potentials considering the effective length of the rhombus-shaped Au microelectrode along the axis of the electric field vector (i.e. 3 μm). ECL imaging shows that emission occurs in the middle of the micropore at the level of the bipolar Au microelectrode.
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