Mid-Infrared Narrow Band Plasmonic Perfect Absorber for Vibrational Spectroscopy

•We experimentally offer a new narrowband perfect absorber operating in the mid-IR frequency regime that is relevant to analysis of biomolecules.•The engineered design demonstrates higher sensitivity on detection of 10 nm thick polymeric film due to its lower optical losses compared to regular plasmonic nanoantenna.•The multiple narrow band resonances makes it a prime candidate for the study of complex biosystems such as a cell membrane.