From a physics point of view, biological cells are mechanical objects that generate forces, withstand stresses and deformation, and react flexibly to their environment. This talk will focus on the role of intermediate filaments (IFs) which together with actin filaments and microtubules form the cytoskeletal network in eukaryotes. In the cell, IFs form complex higher-order structures: small subunits hierarchically assembly into extended filaments, which then form bundles and networks. We approach the biological system from two sides, combing in vitro work on simplified model systems and work on living cells. We use microfluidic tools for in situ investigations at high spatial and temporal resolution. Combining these methods with visible light microscopy (such as fluorescence of phase contrast) has long been established, and recently we have succeeded to employ x-ray imaging on living cells using microfluidic devices. I will give an overview of the role of IFs for cell mechanics and show examples of experimental strategies we have recently developed.