Provided herein is a sensing apparatus comprising, at least one LSPR light source, at least one detector, and at least one sensor for LSPR detection of a target chemical. The sensor comprises a substantially transparent, porous membrane having nanoparticles immobilized on the surface of its pores, the nanoparticles being functionalized with one or more capture molecules. There is further provided a self-referencing sensor for distinguishing non-specific signals from analyte binding signals. The self-referencing sensor comprising one or more nanoparticles having at least two distinct LSPR signals.