Microfabrication of a Multiplexed Device for Controlled Deposition of Miniaturised Copper-Structures for Glucose Electro-Oxidation in Biological and Chemical Matrices

The electrochemical multiplexed sensing has been gaining attention since this approach allows one to merge several sensing areas into a single compact chip. Here, we show several routes for the successful wafer scale microfabrication of a multiplexed silicon chip consisting of six ultramicro single gold (Au) bands (1 × 45 μm) as sensing electrodes. We have also developed a simple, low cost method to increase the roughness of the ultramicro sensing electrode surfaces (the roughness factor –RMS– increased from 1.6 to 2.3 nm) with high reproducibility via an electrochemical potassium hydroxide treatment. We show the application the fabricated ultramicro sensing surface via hydrogen bubble template to achieve copper foam (CuFoam) depositions. The resulting CuFoam microarchitectures were used to demonstrate a multi-purpose multiplexed platform, which was capable of catalysing glucose from serum samples and from river water to determine the chemical oxygen demand (COD). We also show the impact of the CuFoam as reference electrode to improve the electroanalytical performance of the device. The resulting sensing platform showed a superior sensitivity of 121 mA/mM cm2 and a wide linear range, 0.05 mM–22.15 mM. Herein, we clearly demonstrate the intimate link between microfabrication and engineering micro-interfaces for high performance sensing tools in fields of chemical and biological applications.