Ultrahigh Throughput On-Chip Synthesis of Microgels with Tunable Mechanical Properties

Microgels, 1-100 mu m sized hydrogel particles, have emerged as versatile materials for constructing injectable tissue scaffolds, with superb control over various properties. Microfluidic synthesis of microgels offers significant advantages over conventional batch synthesis such as high uniformity and precise control over emulsion size. Despite these positive attributes, the gelation of microfluidic droplets is typically performed off-chip, compromising the particle homogeneity, and confounding the ability to control their mechanical properties. To address this, a multistep microgel synthesis line is developed, comprising of a flow focusing droplet generator followed by a UV-curing stage that delivers a precise UV dosage to each droplet, allowing precise control of the mechanical properties of hydrogel microparticles. Furthermore, parallel operation of 4080 identical synthesis lines on a single chip is demonstrates, generating precisely defined microgels at a throughput appropriate for commercial and clinical translation. The system is validated by generating poly(ethylene glycol) diacrylate microgel particles with a diameter down to 40 mu m at a throughput above 1 kg h(-1) (10(6) particles s(-1)), with a coefficient of variation of 3%. It is demonstrated that the stiffness of the microgels can be precisely controlled from 10(3) to 10(4) Pa by varying the UV dosage.