Enabling accurate condition monitoring with embedded nanoparticle sensing

Elastico-mechano-luminescent (EML) properties of Europium-doped Molybdenum Aluminate (MoAl₂O₃:Eu) were trialed as a method to identify position and magnitude of localised high-stress component values and discrete material damage in a pseudorock sample subjected to uniaxial compression. The deformed pseudorock sample is translucent and is used to represent a geomaterial mimic, with the EML emission generated in response to dynamic loading of the embedded nanoparticle sensors. In this work, we focus on the evaluation of EML nanoparticles and the use of pseudorocks, mimics of geomaterials, for deformation analysis. Typically, such experiments collect sparsely distributed data, often collated from post-experiment analysis. Within this research MoAl₂O₃:Eu EML nanoparticles were incorporated within an epoxy thermoset resin with mechanical properties analogous to rocks. A mixing ratio of 1:200 nanoparticle/resin (by weight) has been found to yield optimal emission while retaining sample translucence and a 1:5 mixing ratio yields maximum emission with a reduction in translucence. The inclusion of the EML nanoparticles within the epoxy resin significantly alters the mechanical properties of the sample, with the lowest nanoparticle ratio (0.5% by weight) producing a brittle sample prone to rapid failure/fragmentation. The highest nanoparticle ratio (20% by weight) exhibits higher yield strain with little or no sign of brittle fracture, more representative of sandstone (geomaterial) under triaxial load. This paper will introduce nanoparticle sensing and expand on the potential of EML for pseudorock deformation monitoring. A summary of the fabrication process and experimental procedure used to observe the stress conditions within a luminescent nanoparticle-polymer resin mixture under uniaxial load conditions are also presented. Emission spectra for MoAl₂O₃:Eu samples mixed at 20% by weight are presented, with emission peaks consistently observed at ∼520 nm for a uniaxial load up to 4.9 MPa. These results indicate that EML nanoparticle-polymer resin compounds act as useful analogues for studying dynamic and quasi-static behaviour in rocks.