Microfabrication atomic layer deposited Pt NPs/TiN thin film on silicon as a nanostructure signal Transducer: Electrochemical characterization toward neurotransmitter sensing

Titanium nitride (TiN) is widely utilized in microelectrode array fabrication for electrophysiological recordings due to its relatively low noise levels, long term stability, and exceptional biocompatibility. Atomic layer deposition (ALD) is a well-established approach for the fabrication of TiN thin films, offering great control over the thickness and properties of the films. Although, advanced procedures have been reported to develop micro and nanostructured electrodes, TiN thin film has yet not been widely applied as electrode material for electrochemical sensing, and characterization of these ALD fabricated TiN films is lacking. Here, we study the use of TiN thin films as electrochemical signal transducer for neurotransmitter dopamine (DA) detection with emphasis on investigation the effect of oxygen functionalities on the electrochemical performance of the films. We find that in order to have high enough sensitivity and selectivity the electrode material used to realize the measurements must be modified. In this work, we described TiN thin film surface modification through hybridization of microfabrication and nanocomposite approaches. Because of its good adhesion, TiN is considered as a high interesting support for Pt catalyst. Therefore, ALD was used to deposit TiN thin films and to design Pt nanoparticles (Pt NPs) on highly conductive boron-doped silicon. Further modification was done through multiwalled carbon nanotubes (MWCNTs), which were immobilized on Pt NPs/ TiN hybrid electrode by Nafion film. Synergistic effect of Pt NPs, MWCNTs, and Nafion film caused significant increase in the electrocatalytic activity towards DA electrooxidation. The proposed sensor material was characterized by focused ion beam milling combined with scanning electron microscopy (FIB-SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), spectroscopic ellipsometry, contact angle measurement and its electrochemical behavior was studied by cyclic voltammetry (CV). CV technique was applied for sensing DA in the range of 0.05-35 mu M (R-2 = 0.990) with a good sensitivity (16.31 mu A/mu M) and a low detection limit of 40 nM (for S/N = 3). The developed sensor exhibited reasonable response time and good stability.