Investigation of the interaction between graphene membranes suspended and liquid by nano-infrared spectroscopy*

The chemical properties of biological systems in their native living environment has been a constant ambition in life sciences. Infrared spectroscopy is a unique analytical tool that enables identification of chemical compounds by their natural molecular-vibrational signatures in a label-free mode. Here we report the development of a robust fluidic platform specifically designed for nanoscale resolved infrared spectroscopy of biomaterials in liquid environments. An advantage of our proposed fluidic chip is the use of an atomic-thin graphene layer as an optical window for accessing the liquid stream inside the micro-channels written in the silicon wafer. We demonstrate the feasibility of the platform for scattering scanning near-field optical microscopy for measuring the infrared fingerprint of typical biological fluids based on Dimethyl Sulfoxide, Phosphate, Citric Acid, and Human Serum Albumin. We foresee our development to serve as a template for future studies involving fundamental questions on the chemistry of in-solution nanoscale bio-systems.