Retention of copper(II) metal ions in a silicon-glass microfluidic device

This work describes the construction of a silicon microchip for retention of copper(II) metal ions. Conventional photolithographic process was applied to transfer the generated pattern to silicon wafers. Using Reactive Ion Etching (RIE), SF6 based, channels 50 mu m wide and 10 mu m deep were produced. The channels were sealed with borosilicate glass using anodic bonding process. The surface of the channels were modified with N-(beta-aminoethyl)-gamma-aminopropyl-trimetoxysilane through a silanization reaction to promote the adsorption of copper(II) ions. An amperometric detector was placed at the microchip outlet and copper(II) ions were detected by a gold electrode at 0 V (against Ag/AgCl(KCl sat.) reference electrode). Copper(II) ions were retained and eluted with HCl 50 mu mol L-1 in a micro-flow system at a flow rate about 100 mu L min(-1). Reproducibility in the peak area and height were about 4.6 % and 10 %, respectively, for three consecutive injections of 600 mu L of 10 mu mol L-1 copper(II) sample.