Impacts of substrate materials on microstructure and electrochemical properties of Ti/TiN/TiON laminated films for gene sequencing chips

•In situ deposition of Ti/TiN/TiON laminated films by simple direct current (DC) reactive magnetron sputtering•Insights into the internal stress effects on the microstructure and electrochemical properties of electrode films•Demonstration of polymer as promising substrate material for upper cover plate electrode in nanopore-based DNA sequencing chips Nanopores have attracted significant attention in the past decade for their rapid deoxyribonucleic acid (DNA) detection. For nanopore-based DNA sequencing chips, single-crystal Si and glass substrates are appropriate for the deposition of microelectrode films and subsequent patterning. However, these fragile materials face difficulties in precision machinery processing fluid flow channels on the surface. Therefore, in this study, titanium/titanium nitride/titanium oxynitride (Ti/TiN/TiON) laminated films are grown in situ on polyamide (PA), glass, and Si substrates using direct current (DC) magnetron sputtering technology, capitalizing on the disparities in surface states and thermal expansion coefficients of the various substrates. The results demonstrate that the films deposited on the PA substrate exhibit high effective surface area due to enlarged porosity between columnar grains, resulting in exceptional specific capacitance (16.2 mF·cm-2, 2.3 times that of Si substrate electrode). In addition, the film has favorable electrochemical cycling stability (86.5% capacitance retention rate after 2000 cycles). These features make the film exhibit enough driving force in DNA sequencing chips, represented by a clear reorganization of the base signal. Ti/TiN/TiON laminated films were deposited on polyamide (PA) substrate, large compressive stress enhanced the porosity, oxidation and specific capacitance. [Display omitted]