The field of optofluidics aims at the study of light/fluid interaction and has a particularly strong impact in the field of bioanalytics [1]. To meet the technological requirements of future applications, optofluidic devices are increasingly being integrated into monolithic on-chip environments with the aim of reducing the use of bulk optical components to an absolute minimum. In addition to examples such as particle trapping [2] or energy harvesting [3], optofluidics enables precise control of light/fluidic interaction, which in the vast majority of cases is realized by coupling optical waveguides with microfluidics, resulting in highly integrated devices with ultra-small geometric footprints [4]. Two promising applications that are particularly challenging in the context of integrated microfluidics are single nano-object tracking and surface-enhanced Raman spectroscopy (SERS). Tracking individual nano-objects is very important as it enables measurement of the dynamics of diffusing nanoparticles (NPs) within biomolecular solutions and reveals critical information about, for example, molecular-level interactions [5], self-assembly pathways [6], and the activity of nanoscale components such as molecular motors [7]. The combination of microfluidics and SERS based on an integrated waveguide is a promising approach to address applications that are not achievable with current technology. Initial attempts to integrate planar waveguides into microfluidic environments are based on antiresonant optical waveguides (ARROWS) [17, 18], while complex fabrication processes and difficult access to the core region have prevented their widespread use.
The project is supported by the DFG joint proposal number SCHM 2655/15-1; AOBJ 665732.