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Table 5 External gelation with off-chip introduction of cross-linkers

From: Preparation of alginate hydrogel microparticles by gelation introducing cross-linkers using droplet-based microfluidics: a review of methods

References

Hu et al., 2012 [20]

Zhang et al., 2020 [59]

Present review

Droplet generation

Na-alginate

1.5 wt%

0.006–1 wt%

0.006–1 wt%

Continuous fluid

N-decanol

DMCa

DMCa

Use of surfactant

Span 80

NO

NO

Geometry

Flow-focusing

Cross-flowing

Cross-flowing

Microfluidic material

Glass chip

Fluoropolymer tubing and junctions

Fluoropolymer tubing and junctions

External gelation by introducing Na-alginate and cross-linkers off-chip during collection

Number of phases or steps

2 phases - 1 collection bath

1 phase - 1 collection bath

2 phases - 2 successive collection baths

Description of phases or steps

Phase 1

CaCl2 (15 wt%) in n-decanol

CaCl2

(0.1–1 wt%)

Step 1

DMC and evaporation of DMC

Phase 2

Ba (CH3COO)2 (15 wt%)

in water and glycerol

Step 2

CaCl2 (0.5–10 wt%) in water

Surfactant

Span 80

NO

NO

  1. aContinuous and dispersed fluids partially miscible