Integrated electrochemical sensor based on electrowetting-on-dielectric microfluidic chip

In this work, we describe the design and study of a novel electrochemical microsensor integrated with electrowetting-on-dielectric (EWOD) microfluidic chip for automatic, rapid and microscale detection. The microsensor was based on the parallel plate EWOD chip. The pretreatment of microliter analyte including dispensing, transporting, mixing and colleting was realized mainly by EWOD electrodes on the bottom plate. The top plate consists of the ground wires for EWOD microfluidics and an on-chip electrochemical cell with gold three-electrode system. The structure and fabrication process were optimized to improve the reliability and stability of integrated chip. The chip can simultaneously realize multifunctional manipulation and online electrochemical detection for reagent droplets. It shows a wide linear range of 10.0 μM-1.0 mM ferrocenemethanol (FcM). The sensitivity of anodic and cathodic peak current was about 5.47 nA/μM (R²=0.99994) and 5.21 nA/μM (R²=0.99904), respectively. This work shows a great promise for microliter biosensing based on smart microfluidic unit and integrated electrochemical cell in the future.