Fig. 1: FTIR spectrum of bovine serum albumin (BSA) & schematic of the QCLD device.
From: A mid-infrared lab-on-a-chip for dynamic reaction monitoring
a Attenuated total reflection Fourier-transform infrared spectrometer (ATR-FTIR) reference measurement of the thermal denaturation process of BSA, analyzed in the range of the amide I\(^{\prime}\) band between 50 ∘C (blue) and 90 ∘C (red). The temperature-induced transition from α-helix (1651 cm−1, blue) to β-sheet (1615 cm−1, red) is indicated. b On-chip sensor concept including indicated plasmonic mode. Emitter (QCL, 10 μm wide) and detector (QCD, 15 μm wide) are connected through a 48 μm long tapered SiN-based plasmonic waveguide. The whole sensor is submerged into the sample solution (D2O + BSA), which is shown by the blue transparent layer on the chip. The gold layer (plasmonic waveguide and electrical contacts) is indicated in gold color, the SiN passivation and dielectric loading layer are shown in brown and the InP substrate is indicated in dark gray.
