title: U3
design: Harvested cells at the required densities were combined with gel beads containing the barcoded information along with a mixture of cells and enzymes. Oil surfactant droplets in a microfluidic double-cross system were used for encapsulation to generate Gel Beads-In-Emulsions (GEMs). GEMs were passed through a reservoir and collected while the gel beads were lysed to release the barcode sequence. The cDNA fragment was then reverse transcribed before the sample was labeled. The gel beads and the oil droplets are ruptured and PCR amplification was performed using the generated cDNA as a template. The products of all GEMs were mixed and a standard sequencing library is constructed. The cDNA was first enzymatically digested into fragments of about 200300 base pairs (bp), together with the library building process of traditional secondgeneration sequencing such as sequencing junction and primers. Finally, the DNA library was generated by PCR amplification