Nanowire mesh sensor for SERS breath analysis

We report a quick and low-cost method for the fabrication of a label-free gas nanosensor for breath analysis, based on surface enhanced Raman spectroscopy (SERS), using nanowires (NWs) as a backbone. We followed a fully solution-processed method for the decoration of TiO₂ NWs with plasmonic gold (Au) nanoparticles (NPs), and their subsequent dielectrophoretic (DEP) self-assembly on predefined substrate locations. This approach produces a 3D NW mesh that maximizes the SERS-active surface of the device, while achieving signal reliability and reproducibility. The sensor's performance was tested using 4-aminothiophenol (4-ATP) in gas phase, at concentrations as low as 0.01 parts-per-million (ppmv). These findings demonstrate the applicability of the NW mesh sensor for the development of breath analysis platforms for diagnostic and medical screening applications.