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(NH ₃ ) ₆ ³⁺ 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 (H ₂ O ₂ ) 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 H ₂ O ₂ 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 H ₂ O ₂ and could be a promising sensor for H ₂ O ₂ measurement.