The present disclosure provides a method and a microfluidic device for producing one or more combinatorial microcompartment comprising at least two sample species within a carrier phase, the microfluidic device comprising a target channel, a first sample species reservoir comprising a first sample species and at least a second sample species reservoir comprising a second sample species, a first sample injection channel comprising a sample injection channel reservoir end connected to the first sample species reservoir and a sample injection channel junction end connected to the target channel, and at least a second sample injection channel comprising a sample injection channel reservoir end connected to the second sample species reservoir and a sample injection channel junction end connected to the target channel; wherein the sample injection channel junction end of the first sample injection channel and/or the second sample injection channel are valvelessly connected to the target channel and comprise at least one hydrodynamic resistor. The present disclosure also provides a method for co-localizing an entity with a barcode oligonucleotide or set of components thereof in a microfluidic device according to the invention.