Directly printed plasmonic substrates of gold micro-flake array for plasmonically-enhanced infrared absorption-spectroscopic biodetection

Abstract

Infrared absorption-spectroscopy (IRAS) is an essential tool for identifying molecular species with specific spectral fingerprints and widely used to characterize and identify known or unknown chemical substances in scientific research and industry. Recently, plasmonic substrates that can dramatically enhance local light field have greatly boosted the performance of IRAS technology, which is generally called plasmonically-enhanced infrared absorption-spectroscopy (PEIRAS), for high-sensitivity biochemical detection. However, the fabrication of micro/nano-structures of noble metals, such as gold and silver, is still challenging and costly, which thus hinders the broad use and further development of PEIRAS technologies. Here, we present a precision photoreduction and replacement reaction combined technology to directly print plasmonic substrates of periodic gold micro-flake array for PEIRAS biodetection. Such a periodic gold micro-flake array exhibits a strong plasmonic surface-lattice resonance whose reflection spectra can be precisely tailored to desired wavelength for PEIRAS biodetection. It has been experimentally demonstrated that the directly printed plasmonic substrate of PEIRAS can be utilized to detect bovine serum albumin via IRAS at the limit of concentration level at 10 nM. The additive printing nature of its fabrication technology makes such a plasmonic substrate promising for widespread IRAS biodetection applications.