Three dimensional microelectrode array device integrating multi-channel microfluidics to realize manipulation and characterization of enzyme-immobilized polystyrene beads

We microfabricated a novel device consisting of a 4 × 4 array microchamber sandwiched with the two microband electrode array. This device allows dielectrophoretic (DEP) manipulation of microbeads to introduce into and release out a certain address of the V-shaped microchamber, by applying AC voltage (10 Vpp, 10 kHz) on the basis of DEP forces. The design and the position of the two electrodes (row and column electrodes) at each microchamber were optimized by simulation based on a finite element method. More importantly, electrochemical generation-collection measurement was possible to evaluate enzymatic activity. After microbeads immobilized with glucose oxidase (GOD) was entrapped in the V-shaped microchamber with DEP, a measuring solution containing 3 mM ferrocenemethanol (FcCH2OH) and 0.1 M glucose was introduced. The medium in the V-shaped microwell was immediately exchanged into the measuring solution whereas microbeads stayed within the microwell without applying DEP voltage, because the flow within the microchamber was isolated from that of the main channel. Then the potential of the row and column electrodes were set at 0.5 and 0.1 V vs Ag/AgCl. The GOD activity can be monitored as the decrease in the [FcCH2OH]+ reduction current.