Abstract

Mid-infrared (MIR) spectroscopy is an extremely powerful method to study biomolecules, since it combines chemical specificity and sensitivity with almost non-destructive probing. MIR vibrational spectroscopy (500 to 3500 cm⁻¹; 3–20 µm) is based on the excitation of fundamental molecular vibrations, which are characteristic for each species, as well as its molecular structure. Recently nanocrystaline diamond (NCD) has been compared with traditional bioanalytical test formats (polystyrene microtiter plates) using an antibody based ELISA targeting C-reactive protein, and showed superior signal-to-noise ratios for NCD surfaces [1]. The detection of an organic substance with evanescent field absorption has been demonstrated in slab diamond waveguide (DWG) with significant sensitivity improvement compared to conventional MIR slab/strip waveguides [2]. We aim to combine these two findings into a miniaturized MIR-spectroscopic measurement technique based on diamond waveguides with a NCD surface that enable super sensitive, label-free detection of chemicals and biomolecular interactions. Here, the characterization of an 8 mm long multimode diamond strip waveguide is presented.

© 2015 IEEE