Microfluidic methods are frequently used to produce
cell-laden microgels for various biomedical purposes. Such
microfluidic methods generally employ oil-water systems.
The poor distribution of crosslinking reagents in the oil phase
limits the available gelation strategies. Extracting the microgel
from the oil-phase also reduces its production efficiency. In this
study, an aqueous two-phase system (ATPS) involving dextran
(DEX) and polyethylene glycol (PEG) was used to prepare
cell-laden microgel. This avoided the problems associated with
an oil phase. The microgel precursor polymers and crosslinking
reagents were dispersed in the DEX and PEG phases, respec-
tively. The ultra-low interfacial tension of the ATPS hindered
droplet formation. A co-flow microfluidic device was fabricat-
ed to overcome this problem. The device incorporated a square-
wave-changing injection force, to improve the efficiency of
droplet formation. The microgel precursor (including alginate
and carboxymethyl cellulose derivatives possessing phenolic
hydroxyl moieties) could be dispersed in the DEX solution at
various concentrations. Uniform droplets were formed with

• Cell-laden microgel prepared using a biocompatible aqueous two-phase strategy