Development of plasmonic substrates for biosensing

Abstract

The transmission of normally incident light through arrays of subwavelength holes (nanoholes) in gold thin films is enhanced at the wavelengths that satisfy the surface plasmon resonance (SPR) condition. Our group has been active on the implementation of schemes for the application of this phenomenon for chemical sensing. For instance, we have shown that the interaction between adsorbates with nanoholes modified the SP resonance conditions, leading to a shift in the wavelength of maximum transmission. The output sensitivity of this substrate was found to be 400 nm RIU-1 (refractive index units), which is comparable to other grating-based surface plasmon resonance devices. The array of nanoholes was also integrated into a microfluidic system and the characteristics of the solution flow and detection systems were evaluated. In this work, we will concentrate on improving the efficiency of the nanohole arrays for applications in chemical in chemical sensing. Attempts to improve the sensitivity of the device will be discussed. In-hole sensing is suggested as an alternative to decrease the number of probe molecules, and enhance sensitivity. A biaxial sensing scheme will also be introduced. The biaxial scheme allows for polarization-modulation detection that can account for background fluctuations. A flow-through approach should lead to an optimized transport situation of the analytes to the immobilized species at the surface, which should significantly improve the time and sensitivity of the analysis. Finally, we will discuss the implementation of multiplexing detection using these arrays. Multiplexing detection in zero-order transmission is simpler to implement than the common multiplexing imaging from angle-resolved SPR.