Plasmonic optical sensors printed from Ag–PVA nanoinks†
In this paper we report on the use of a nanocomposite based on silver nanoparticles embedded in PVA as a plasmonic optical sensor to detect and quantify trace amounts of amines in gas and water, respectively. The transduction mechanism of the sensor is based on the changes of the LSPR band of Ag NPs when analyte molecules are chemisorbed on their surface. The Ag–PVA sensors are fabricated by means of a high-precision microplotter, a direct-write technology developed for printing materials from solution. The nanoink is formulated with a metal precursor (AgNO3) and a polymer (PVA) using an adequate mixture of solvents to meet the rheological requirements for the fluid dispensing process. The LSPR intensity is the most sensitive magnitude to follow the interaction between Ag NPs embedded in PVA and amines. Ag–PVA patterns are tested as a plasmonic optical sensor for the detection of ethylenediamine in solution showing a limit of detection as low as 0.1 nM. Moreover Ag nanocomposite patterns are also used for sensing vapours of several biogenic (cadaverine and putrescine) and synthetic (ethylenediamine and methylenediamine) amines, where shorter amines exhibit the largest sensor response. This plasmonic optical sensor is also tested in real-time monitoring of chicken meat spoilage at room temperature. We believe that the Ag–PVA nanocomposite can be the basis for the development of sensor spots, bar-codes and other labels for smart packaging technology, among other sensing applications.