Monolithic integration of three-material microelectrodes for electrochemical detection on PMMA substrates

• Au–Ag–Pt and C–Ag–Pt three-electrode systems were demonstrated.
• An electrochemical sensing microchip was constructed.
• The excellent performance of the microchip was evaluated.
• The microchip holds great potential for a variety of electrochemical analyses.

Monolithic integration of three-material microelectrodes for electrochemical detection on poly (methyl methacrylate) (PMMA) substrates is presented. Au–Ag–Pt three-material electrodes were all fabricated based on polymer compatible photolithography processes, and the fabrication sequence of the electrodes was optimized. The C–Ag–Pt three-electrode system was also demonstrated. To reduce the electrical resistance, the carbon electrode was made on a silver intermediate layer which was simultaneously fabricated with Ag electrodes. A PMMA/poly(dimethylsiloxane) electrochemical sensing microchip with the Au–Ag–Pt three-electrode systems was constructed. The reproducibility of the three-electrode system from single and different microchips was characterized. The performance of the microchip was evaluated by two kinds of electrochemical probes (Ru(bpy)3Cl2 and dopamine).

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