Nanoaperture array-based plasmonic sensors of dangerous substances using transparent conductive oxides

Abstract

Detection of dangerous substances like explosives, pathogenic microorganisms and toxic chemical is of utmost interest for homeland defense and anti-terrorist actions. Among the devices of choice for that purpose are surface plasmon resonance (SPR) chemical-biological sensors since they are ultra-fast, highly sensitive and label-free. We consider one of the advanced types of SPR sensors, those with ordered arrays of subwavelength apertures in plasmonic material. Such sensors show high sensitivity in transmission readout mode, are useful for both liquid and gaseous analytes and can be used as a building block for complex microfluidic systems for multianalyte detection. Simultaneously, high electromagnetic field concentrations in nanoapertures enhance nonlinear effects, thus further facilitating detection of complex molecules of dangerous substances. We performed finite element simulation of the performance of such devices for various materials and nanoaperture sizes and shapes. We dedicated special attention to the case when the subwavelength array is formed in transparent conductive oxide (TCO) host. An example of TCO is tin oxide, routinely used in thin layers for window defrosting and defogging elements in armored vehicles. We show that compared to conventional nanoaperture array sensors based on metal hosts the TCO-based devices simultaneously offer enhanced selectivity and retain high sensitivity.