This poster from the Kjærgaard lab at Aarhus University demonstrates how Flow Induced Dispersion Analysis (FIDA) was used to evaluate de novo designed protein binders, measuring the hydrodynamic radius of fluorescently labelled targets to detect and rank binding directly in unpurified bacterial lysates. FIDA identified high-affinity, thermally stable binders against ALFA-tag and GK-domain targets at nanomolar affinity, with a simple dilution step removing false positives. It is an example of using FIDA to screen and characterise designed protein binders in solution without purification.