Expansion microscopy (ExM) is a novel super-resolution imaging technique. Biological samples can be isotropically expanded through expandable hydrogels,allowing for significantly improved resolution. This technique is compatible with various biological molecules and can be implemented using wide-field and confocal microscopes. For example, the resolution of wide-field microscopy can be improved from 250 nm to 60nm, and that of confocal microscopy from 120nm to 30nm. The uniform expansion preserves the spatial information of biomolecules.