The present invention relates to the field of microfluidics and in particular to methods for detecting microfluidic droplets and particles within droplets, as well as sorting the droplets. These methods allow for quantifying properties and activities of the particles within the droplets. For this purpose, the invention provides microfluidic droplets comprising suitably labelled particles. The invention also provides microfluidic devices and systems having properties which make them particularly suitable for use in the methods of the invention.