Drift-corrected nanoplasmonic hydrogen sensing by polarization†
Accurate and reliable hydrogen sensors are an important enabling technology for the large-scale introduction of hydrogen as a fuel or energy storage medium. As an example, in a hydrogen-powered fuel cell car of the type now introduced to the market, more than 15 hydrogen sensors are required for safe operation. To enable the long-term use of plasmonic sensors in this particular context, we introduce a concept for drift-correction based on light polarization utilizing symmetric sensor and sensing material nanoparticles arranged in a heterodimer. In this way the inert gold sensor element of the plasmonic dimer couples to a sensing-active palladium element if illuminated in the dimer-parallel polarization direction but not the perpendicular one. Thus the perpendicular polarization readout can be used to efficiently correct for drifts occurring due to changes of the sensor element itself or due to non-specific events like a temperature change. Furthermore, by the use of a polarizing beamsplitter, both polarization signals can be read out simultaneously making it possible to continuously correct the sensor response to eliminate long-term drift and ageing effects. Since our approach is generic, we also foresee its usefulness for other applications of nanoplasmonic sensors than hydrogen sensing.