Enhancement sensing of biomarkers by acoustic graphene plasmonic mode

Abstract

The sensitivity and accuracy of molecular detection using THz technology are limited due to the weak interaction between THz waves and biomolecules. An acoustic graphene plasmons (AGP) resonator could have ultra-compressed light fields and provide strong light-matter interactions at the microscopic level. In the paper, the AGP construction for bio-molecules sensing with high sensitivity is proposed, which consists of a continuous graphene and nano-gap separated metal strip, and a continuous gold layer separated by silica. By coupling free-space light to the nanogap to form a sonic graphene plasma, the gold reflector further improves the excitation efficiency of the sonic graphene plasma and achieves good free-space incident light absorption (97.2%). Adjusting the width of the metal band to achieve four absorption peaks in the range of molecular vibration frequency, adding the test molecule, the absorption rate at the molecular vibration frequency of 13 µm is increased from the original 5%–40%, which allows precise analysis of molecular structure information. In the mid-infrared and terahertz range, the system can offer promising applications for light-matter interactions and efficient coupled sensing of long spectra compared to conventional graphene plasma structures.