Scanning Probe-Shaped Nanohole Arrays with Extraordinary Optical Transmission as Platform for Enhanced Surface Plasmon-Based Biosensing

We analyzed the use of subwavelength ordered nanohole patterns for detection of miniscule amounts of biological analytes. Owing to their surface plasmon resonance (SPR) operation, such structures show an extraordinarily high optical transmission in visible spectrum, at the same time concentrating the illumination to the very small area of the nanoholes and being much more sensitive to refractive index changes than the conventional SPR sensors. We applied an approximate analytical approach to design our V-shaped, nanometer-sized hole arrays. We utilized scanning-probe nanolithography to fabricate the designed nanoholes in silver substrate. We investigated the topography of the obtained patterns by atomic force microscopy. Compared to conventional SPR optical sensors, the nanohole array-based structures allow for the detection of smaller quantities of analytes, enhance nonlinear effects and ensure improved sensitivities to different analytes