The Development of CMOS Amperometric Sensing Chip with a Novel 3-Dimensional TiN Nano-Electrode Array

An electrochemical sensing chip with an 8 × 8 array of titanium nitride three-dimensional nano-electrodes (TiN 3D-NEA) was designed and fabricated via a standard integrated complementary metal oxide semiconductor process. Each nano-electrode in 3D-NEA exhibited a pole-like structure with a radius of 100 nm and a height of 35 nm. The numeric simulation showed that the nano-electrode with a radius of around 100 nm exhibited a more uniformly distributed electric field and a much higher electric field magnitude compared to that of the microelectrode. Cyclic voltammetry study with Ru(NH₃)₆³⁺ also revealed that the TiN 3D-NEA exhibited a much higher current density than that obtained from the microelectrode by two orders of magnitude. Further studies showed that the electrocatalytical reduction of hydrogen peroxide (H₂O₂) could occur on a TiN 3D-NEA-based sensing chip with a high sensitivity of 667.2 mA⋅mM^-1⋅cm^-2. The linear detection range for H₂O₂ was between 0.1 μM and 5 mM with a lowest detection limit of 0.1 μM. These results indicated that the fabricated TiN 3D-NEA exhibited high catalytic activity and sensitivity to H₂O₂ and could be a promising sensor for H₂O₂ measurement.