Droplet microfluidics: Enabling the tailored fabrication of hydrogel particles

Abstract

Hydrogel particles are attracting increasing interest as tunable microscale platforms that combine precise architectures with diverse chemical, biological, and physical functionalities. Among fabrication strategies, droplet microfluidics has emerged as a powerful technology for producing monodisperse hydrogel particles with controllable size, composition, and internal structure via precise regulation of microscale fluid dynamics. This review first outlines the fundamental principles of droplet microfluidics, including chip fabrication, channel design, droplet generation dynamics, energy input modes, and fluidic compositions, which collectively underpin reliable particle production. We then highlight compatible hydrogel precursor systems, gelation methods, and functionalization strategies for engineering tailored hydrogel particles. The versatility of such particles is further emphasized, supporting applications in cell culture, 3D bioprinting, drug delivery, and diagnostics. Finally, we provide an outlook on future directions, including system parallelization, process automation, and artificial intelligence integration, anticipated to expand the scalability, functionality, and multidisciplinary impact of droplet-microfluidic hydrogel platforms.

References

[1] Daly AC, Riley L, Segura T, Burdick JA. Hydrogel microparticles for biomedical applications. Nat Rev Mater. 2020; 5: 20-43.

[2] Nakamura K, Di Caprio N, Burdick JA. Engineered shape-morphing transitions in hydrogels through suspension bath printing of temperature-responsive granular hydrogel inks. Adv Mater. 2024; 36:e2410661.

[3] Rojek KO, Cwiklinska M, Kuczak J, Guzowski J. Microfluidic formulation of topological hydrogels for microtissue engineering. Chem Rev. 2022; 122: 16839-16909.

[4] Yuan Y, Zhang Q, Lin S, Li J. Water: the soul of hydrogels. Prog Mater Sci. 2025; 148:101378.

[5] Liu T, Du Y, Yan Y, et al. pH-responsive dual-functional hydrogel integrating localized delivery and anti-cancer activities for highly effective therapy in PDX of OSCC. Mater Today. 2023; 62: 71-97.

[6] Tang L, Wang L, Yang X, Feng Y, Li Y, Feng W. Poly(N-isopropylacrylamide)-based smart hydrogels: design, properties and applications. Prog Mater Sci. 2021; 115:100702.

[7] Liu Y, Yu Z, Zhang K, Chen X, Zhang W, Ge F. Cellulose-based hydrogel with controllable structure for selective, quantitative and sensitive silver ion colorimetric detection. Chem Eng J. 2025; 521:167083.

[8] Chen W, Wang C, Liu W, et al. A matrix-metalloproteinase-responsive hydrogel system for modulating the immune microenvironment in myocardial infarction. Adv Mater. 2023; 35:2209041.

[9] Yue J, Liu Z, Wang L, Wang M, Pan G. Recent advances in bioactive hydrogel microspheres: material engineering strategies and biomedical prospects. Mater Today Bio. 2025; 31:101614.

[10] Wang X, Zeng J, Gan D, et al. Recent strategies and advances in hydrogel-based delivery platforms for bone regeneration. Nanomicro Lett. 2024; 17: 73.

[11] Wen F, Lee C. Water droplets play a role in Internet of Things applications. Droplet. 2024; 3:e133.

[12] Long F, Guo Y, Zhang Z, et al. Recent progress of droplet microfluidic emulsification based synthesis of functional microparticles. Glob Chall. 2023; 7:2300063.

[13] Shang L, Cheng Y, Zhao Y. Emerging droplet microfluidics. Chem Rev. 2017; 117: 7964-8040.

[14] Liu X, Gao W, Lu Y, Wu L, Chen Y. High-throughput microfluidic production of carbon capture microcapsules: fundamentals, applications, and perspectives. Int J Extreme Manuf. 2024; 6:032010.

[15] Huang J, Fu D, Wu X, et al. One-step generation of core-shell biomimetic microspheres encapsulating double-layer cells using microfluidics for hair regeneration. Biofabrication. 2023; 15:025007.

[16] Zheng Y, Wu Z, Khan M, et al. Multifunctional regulation of 3D cell-laden microsphere culture on an integrated microfluidic device. Anal Chem. 2019; 91: 12283-12289.

[17] Kaminski TS, Garstecki P. Controlled droplet microfluidic systems for multistep chemical and biological assays. Chem Soc Rev. 2017; 46: 6210-6226.

[18] Gérard A, Woolfe A, Mottet G, et al. High-throughput single-cell activity-based screening and sequencing of antibodies using droplet microfluidics. Nat Biotechnol. 2020; 38: 715-721.

[19] Mesquita CRS, Charelli LE, Baptista LS, Naveira-Cotta CP, Balbino TA. Continuous-mode encapsulation of human stem cell spheroids using droplet-based glass-capillary microfluidic device for 3D bioprinting technology. Biochem Eng J. 2021; 174:108122.

[20] Wang J-X, Wang H, Lai H, et al. A machine vision perspective on droplet-based microfluidics. Adv Sci. 2025; 12:2413146.

[21] Mirshafiei M, Rashedi H, Yazdian F, Mahmoudi Z. Microfluidic-assisted fabrication of cell-laden GelMA/SilMA microspheres incorporated dexamethasone-loaded MSNs for promoting osteogenic differentiation. Chem Eng J. 2025; 520:166221.

[22] Zhang P, Su D, Shen X, Xie P, Jiang Z. Preparation and evaluation of microcapsules of sodium alginate based on microfluidic technology. Food Hydrocoll. 2024; 154:110113.

[23] Mohamadzade Sani H, Falahi M, Aieneh K, Hosseinalipour SM, Salehi S, Asiaei S. Performance optimization of droplet formation and break up within a microfluidic device – Numerical and experimental evaluation. Int J Heat Fluid Flow. 2024; 106:109266.

[24] Zhang J, Xu W, Xu F, et al. Microfluidic droplet formation in co-flow devices fabricated by micro 3D printing. J Food Eng. 2021; 290:110212.

[25] Shao L, Pan B, Hou R, Jin Y, Yao Y. User-friendly microfluidic manufacturing of hydrogel microspheres with sharp needle. Biofabrication. 2022; 14:025017.

[26] Shakeri A, Khan S, Didar TF. Conventional and emerging strategies for the fabrication and functionalization of PDMS-based microfluidic devices. Lab Chip. 2021; 21: 3053-3075.

[27] Kwak B, Lee Y, Lee J, Lee S, Lim J. Mass fabrication of uniform sized 3D tumor spheroid using high-throughput microfluidic system. J Control Release. 2018; 275: 201-207.

[28] Ma L, Zhao X, Hou J, et al. Droplet microfluidic devices: working principles, fabrication methods, and scale-up applications. Small Methods. 2024; 8:e2301406.

[29] Jeong HH, Yelleswarapu VR, Yadavali S, Issadore D, Lee D. Kilo-scale droplet generation in three-dimensional monolithic elastomer device (3D MED). Lab Chip. 2015; 15: 4387-4392.

[30] Ghosh S, Ghosh A, Pati F, Duraiswamy S. Chipless millifluidics device for rapid fabrication of hepatic spheroids with decellularized liver matrix. ACS Biomater Sci Eng. 2025; 11: 6684-6700.

[31] Moragues T, Arguijo D, Beneyton T, et al. Droplet-based microfluidics. Nat Rev Methods Prim. 2023; 3: 32.

[32] Shi J, Zhang Y, Fan Y, Liu Y, Yang M. Recent advances in droplet-based microfluidics in liquid biopsy for cancer diagnosis. Droplet. 2024; 3:e92.

[33] Chiarello E, Gupta A, Mistura G, Sbragaglia M, Pierno M. Droplet breakup driven by shear thinning solutions in a microfluidic T-junction. Phys Rev Fluids. 2017; 2:123602.

[34] Gan Z, Liu H, Wang Y, Tao T, Zhao M, Qin J. One-step generation of porous GelMA microgels by droplet-based chaotic advection effect. Adv Mater Technol. 2022; 8:2201102.

[35] Ashikhmin A, Piskunov M, Kochkin D, Ronshin F, Chen L. Droplet microfluidic method for estimating the dynamic interfacial tension of ion-crosslinked sodium alginate microspheres. Langmuir. 2024; 40: 15906-15917.

[36] Utada AS, Fernandez-Nieves A, Stone HA, Weitz DA. Dripping to jetting transitions in coflowing liquid streams. Phys Rev Lett. 2007; 99:094502.

[37] Zhu P, Wang L. Passive and active droplet generation with microfluidics: a review. Lab Chip. 2017; 17: 34-75.

[38] Xu JH, Li SW, Tan J, Wang YJ, Luo GS. Controllable preparation of monodisperse O/W and W/O emulsions in the same microfluidic device. Langmuir. 2006; 22: 7943-7946.

[39] Nooranidoost M, Izbassarov D, Muradoglu M. Droplet formation in a flow focusing configuration: effects of viscoelasticity. Phys Fluids. 2016; 28:123102.

[40] Babkin IA, Udepurkar AP, Van Avermaet H, et al. Encapsulation of cadmium-free InP/ZnSe/ZnS quantum dots in poly(LMA-co-EGDMA) microparticles via co-flow droplet microfluidics. Small Methods. 2023; 7:2201454.

[41] Pan D, Zhang Y, Zhang T, Li B. Flow regimes of polymeric fluid droplet formation in a co-flowing microfluidic device. Colloids Interface Sci Commun. 2021; 42:100392.

[42] Fu T, Wu Y, Ma Y, Li HZ. Droplet formation and breakup dynamics in microfluidic flow-focusing devices: from dripping to jetting. Chem Eng Sci. 2012; 84: 207-217.

[43] Nunes JK, Tsai SSH, Wan J, Stone HA. Dripping and jetting in microfluidic multiphase flows applied to particle and fibre synthesis. J Phys D: Appl Phys. 2013; 46:114002.

[44] Mastiani M, Mosavati B, Kim M. Numerical simulation of high inertial liquid-in-gas droplet in a T-junction microchannel. RSC Adv. 2017; 7: 48512-48525.

[45] Baroud CN, Gallaire F, Dangla R. Dynamics of microfluidic droplets. Lab Chip. 2010; 10: 2032-2045.

[46] Moiré M, Peysson Y, Herzhaft B, et al. Ultralow interfacial tension measurement through jetting/dripping transition. Langmuir. 2017; 33: 2531-2540.

[47] Barker B, Bell JB, Garcia AL. Fluctuating hydrodynamics and the Rayleigh–Plateau instability. Proc Natl Acad Sci USA. 2023; 120:e2306088120.

[48] Sheng L, Ma L, Chen Y, Deng J, Luo G. A comprehensive study of droplet formation in a capillary embedded step T-junction: from squeezing to jetting. Chem Eng J. 2022; 427:132067.

[49] Liu HT, Wang H, Wei WB, Liu H, Jiang L, Qin JH. A microfluidic strategy for controllable generation of water-in-water droplets as biocompatible microcarriers. Small. 2018; 14:1801095.

[50] van Loo S, Stoukatch S, Kraft M, Gilet T. Droplet formation by squeezing in a microfluidic cross-junction. Microfluid Nanofluid. 2016; 20: 146.

[51] Squires TM, Quake SR. Microfluidics: fluid physics at the nanoliter scale. Rev Mod Phys. 2005; 77: 977-1026.

[52] Liu X, Ji Y, Deng Y, Wu Y. Advection of droplet collision in centrifugal microfluidics. Phys Fluids. 2019; 31:032003.

[53] Cubaud T, Mason TG. Capillary threads and viscous droplets in square microchannels. Phys Fluids. 2008; 20:053302.

[54] Ho TM, Razzaghi A, Ramachandran A, Mikkonen KS. Emulsion characterization via microfluidic devices: a review on interfacial tension and stability to coalescence. Adv Colloid Interface Sci. 2022; 299:102541.

[55] Qi C, Zhou T, Wu X, et al. Micro-nano-fabrication of green functional materials by multiphase microfluidics for environmental and energy applications. Green Energy Environ. 2024; 9: 1199-1219.

[56] Chong ZZ, Tan SH, Gañán-Calvo AM, Tor SB, Loh NH, Nguyen N-T. Active droplet generation in microfluidics. Lab Chip. 2016; 16: 35-58.

[57] Park S, Ryu J, Han K-H. Reusable EWOD-based microfluidic system for active droplet generation. Lab Chip. 2025; 25: 225-234.

[58] Kichatov B, Sudakov V, Kalyuzhnaya D, Korshunov A, Ryapolov P. Active droplet generation in flow-focusing microfluidics under influence of transverse magnetic field. Lab Chip. 2025; 25: 6306-6313.

[59] Li D, Cao Y, Huang B, et al. Active femtoliter droplet generation in microfluidics by confined interface vibration. Langmuir. 2021; 37: 1297-1305.

[60] Park S-Y, Wu T-H, Chen Y, Teitell MA, Chiou P-Y. High-speed droplet generation on demand driven by pulse laser-induced cavitation. Lab Chip. 2011; 11: 1010-1012.

[61] Zhu K, Yu Y, Cheng Y, Tian C, Zhao G, Zhao Y. All-aqueous-phase microfluidics for cell encapsulation. ACS Appl Mater Interfaces. 2019; 11: 4826-4832.

[62] Michelon M, Huang Y, de la Torre LG, Weitz DA, Cunha RL. Single-step microfluidic production of W/O/W double emulsions as templates for β-carotene-loaded giant liposomes formation. Chem Eng J. 2019; 366: 27-32.

[63] Zhi Z, Liu R, Wang W, Dewettinck K, Van Bockstaele F. Recent progress in oil-in-water-in-oil (O/W/O) double emulsions. Crit Rev Food Sci Nutr. 2023; 63: 6196-6207.

[64] Kamperman T, Trikalitis VD, Karperien M, Visser CW, Leijten J. Ultrahigh-throughput production of monodisperse and multifunctional janus microparticles using in-air microfluidics. ACS Appl Mater Interfaces. 2018; 10: 23433-23438.

[65] Jeyhani M, Thevakumaran R, Abbasi N, Hwang DK, Tsai SSH. Microfluidic generation of all-aqueous double and triple emulsions. Small. 2020; 16:1906565.

[66] Chao Y, Shum HC. Emerging aqueous two-phase systems: from fundamentals of interfaces to biomedical applications. Chem Soc Rev. 2020; 49: 114-142.

[67] Moon BU, Jones SG, Hwang DK, Tsai SS. Microfluidic generation of aqueous two-phase system (ATPS) droplets by controlled pulsating inlet pressures. Lab Chip. 2015; 15: 2437-2444.

[68] Ding Y, Howes PD, deMello AJ. Recent advances in droplet microfluidics. Anal Chem. 2020; 92: 132-149.

[69] Sun Z, Zhou J, Sheng L, et al. Microfluidic engineering of microgels: fabrication methods, structural design, assembly strategies, and biomedical applications. Acta Biomater. 2025; 207: 142-173.

[70] Liu F, Yang Y, Wan X, et al. Space-confinment-enhanced fluorescence detection of DNA on hydrogel particles array. ACS Nano. 2022; 16: 6266-6273.

[71] Tran VV, Phung V-D, Do HH. Advances and innovations in hydrogel particles for sustainable purification of contaminants in aqueous solutions. Chem Eng J. 2024; 486:150324.

[72] Parida D, Moreau E, Nazir R, et al. Smart hydrogel-microsphere embedded silver nanoparticle catalyst with high activity and selectivity for the reduction of 4-nitrophenol and azo dyes. J Hazard Mater. 2021; 416:126237.

[73] Zheng D, Chen W, Chen T, et al. Hydrogen ion capturing hydrogel microspheres for reversing inflammaging. Adv Mater. 2024; 36:2306105.

[74] Guo Y, Bae J, Fang Z, Li P, Zhao F, Yu G. Hydrogels and hydrogel-derived materials for energy and water sustainability. Chem Rev. 2020; 120: 7642-7707.

[75] Gan Z, Qin X, Liu H, Liu J, Qin J. Recent advances in defined hydrogels in organoid research. Bioact Mater. 2023; 28: 386-401.

[76] Hu Y, Kim Y, Hong I, Kim M, Jung S. Fabrication of flexible pH-responsive agarose/succinoglycan hydrogels for controlled drug release. Polymers. 2021; 13: 2049.

[77] Mukundan LM, Das S, Rajasekaran R, et al. Photo-annealable agarose microgels for jammed microgel printing: transforming thermogelling hydrogel to a functional bioink. Int J Biol Macromol. 2024; 278:134550.

[78] Capeling MM, Czerwinski M, Huang S, et al. Nonadhesive alginate hydrogels support growth of pluripotent stem cell-derived intestinal organoids. Stem Cell Rep. 2019; 12: 381-394.

[79] Geuens T, Ruiter FAA, Schumacher A, et al. Thiol-ene cross-linked alginate hydrogel encapsulation modulates the extracellular matrix of kidney organoids by reducing abnormal type 1a1 collagen deposition. Biomaterials. 2021; 275:120976.

[80] Devina N, Eriwati Y, Santosa A. The purity and viscosity of sodium alginate extracted from Sargassum brown seaweed species as a basic ingredient in dental alginate impression material. J Phys Conf Ser. 2018; 1073:052012.

[81] Crispim JF, Ito K. De novo neo-hyaline-cartilage from bovine organoids in viscoelastic hydrogels. Acta Biomater. 2021; 128: 236-249.

[82] Cassel de Camps C, Aslani S, Stylianesis N, et al. Hydrogel mechanics influence the growth and development of embedded brain organoids. ACS Appl Bio Mater. 2022; 5: 214-224.

[83] Wang Y, Liu H, Zhang M, Wang H, Chen W, Qin J. One-step synthesis of composite hydrogel capsules to support liver organoid generation from hiPSCs. Biomater Sci. 2020; 8: 5476-5488.

[84] Elcin YM, Dixit V, Gitnick G. Hepatocyte attachment on biodegradable modified chitosan membranes: in vitro evaluation for the development of liver organoids. Artif Organs. 1998; 22: 837-846.

[85] Liu H, Wang Y, Cui K, Guo Y, Zhang X, Qin J. Advances in hydrogels in organoids and organs-on-a-chip. Adv Mater. 2019; 31:1902042.

[86] Khademhosseini A, Eng G, Yeh J, et al. Microfluidic patterning for fabrication of contractile cardiac organoids. Biomed Microdevices. 2007; 9: 149-157.

[87] Wang D, Guo Y, Zhu J, et al. Hyaluronic acid methacrylate/pancreatic extracellular matrix as a potential 3D printing bioink for constructing islet organoids. Acta Biomater. 2023; 165: 86-101.

[88] Bejoy J, Wang Z, Bijonowski B, et al. Differential effects of heparin and hyaluronic acid on neural patterning of human induced pluripotent stem cells. ACS Biomater Sci Eng. 2018; 4: 4354-4366.

[89] Sachs N, Tsukamoto Y, Kujala P, Peters PJ, Clevers H. Intestinal epithelial organoids fuse to form self-organizing tubes in floating collagen gels. Development. 2017; 144: 1107-1112.

[90] Sandilya S, Singh S. Development of islet organoids from human induced pluripotent stem cells in a cross-linked collagen scaffold. Cell Regen. 2021; 10: 38.

[91] Agarwal T, Celikkin N, Costantini M, Maiti TK, Makvandi P. Recent advances in chemically defined and tunable hydrogel platforms for organoid culture. Bio-Design and Manufacturing. 2021; 4: 641-674.

[92] Buchmann B, Engelbrecht LK, Fernandez P, et al. Mechanical plasticity of collagen directs branch elongation in human mammary gland organoids. Nat Commun. 2021; 12: 2759.

[93] Broguiere N, Isenmann L, Hirt C, et al. Growth of epithelial organoids in a defined hydrogel. Adv Mater. 2018; 30:1801621.

[94] de Melo BAG, Jodat YA, Cruz EM, Benincasa JC, Shin SR, Porcionatto MA. Strategies to use fibrinogen as bioink for 3D bioprinting fibrin-based soft and hard tissues. Acta Biomater. 2020; 117: 60-76.

[95] Klotz BJ, Oosterhoff LA, Utomo L, et al. A versatile biosynthetic hydrogel platform for engineering of tissue analogues. Adv Healthc Mater. 2019; 8:1900979.

[96] Bernal PN, Bouwmeester M, Madrid-Wolff J, et al. Volumetric bioprinting of organoids and optically tuned hydrogels to build liver-like metabolic biofactories. Adv Mater. 2022; 34:2110054.

[97] Ng S, Tan WJ, Pek MMX, Tan M-H, Kurisawa M. Mechanically and chemically defined hydrogel matrices for patient-derived colorectal tumor organoid culture. Biomaterials. 2019; 219:119400.

[98] Yu X, Wang L, Xu B, et al. Conjugation of CMCS to silk fibroin for tuning mechanical and swelling behaviors of fibroin hydrogels. Eur Polym J. 2021; 150:110411.

[99] Nili E, Harkin DG, Dawson RA, Richardson NA, Suzuki S, Chirila TV. Membranes prepared from recombinant RGD-silk fibroin as substrates for human corneal cells. Molecules. 2021; 26: 6810.

[100] Drumheller PD, Hubbell JA. Densely crosslinked polymer networks of poly(ethylene glycol) in trimethylolpropane triacrylate for cell-adhesion-resistant surfaces. J Biomed Mater Res. 1995; 29: 207-215.

[101] Vallmajo-Martin Q, Broguiere N, Millan C, Zenobi-Wong M, Ehrbar M. PEG/HA hybrid hydrogels for biologically and mechanically tailorable bone marrow organoids. Adv Funct Mater. 2020; 30:1910282.

[102] Hayashi S, Sasaki Y, Kubo H, et al. Construction of hybrid cell spheroids using cell-sized cross-linked nanogel microspheres as an artificial extracellular matrix. ACS Appl Bio Mater. 2021; 4: 7848-7855.

[103] Ng SS, Saeb-Parsy K, Blackford SJI, et al. Human iPS derived progenitors bioengineered into liver organoids using an inverted colloidal crystal poly (ethylene glycol) scaffold. Biomaterials. 2018; 182: 299-311.

[104] Hernandez-Gordillo V, Kassis T, Lampejo A, et al. Fully synthetic matrices for in vitro culture of primary human intestinal enteroids and endometrial organoids. Biomaterials. 2020; 254:120125.

[105] Wilson RL, Swaminathan G, Ettayebi K, et al. Protein-functionalized poly(ethylene glycol) hydrogels as scaffolds for monolayer organoid culture. Tissue Eng Part C Methods. 2021; 27: 12-23.

[106] Jung N, Moreth T, Stelzer EHK, Pampaloni F, Windbergs M. Non-invasive analysis of pancreas organoids in synthetic hydrogels defines material-cell interactions and luminal composition. Biomater Sci. 2021; 9: 5415-5426.

[107] Wang M, Bai J, Shao K, et al. Poly(vinyl alcohol) hydrogels: the old and new functional materials. Int J Polym Sci. 2021; 2021:2225426.

[108] Gregg A, De Volder M, Baumberg JJ. Kinetics of light-responsive CNT/PNIPAM hydrogel microactuators. Small. 2024; 20:2305034.

[109] Hauck M, Saure LM, Zeller-Plumhoff B, et al. Overcoming water diffusion limitations in hydrogels via microtubular graphene networks for soft actuators. Adv Mater. 2023; 35:2302816.

[110] Han C, Cao M, Yu J, et al. Carboxymethyl cellulose-based composite polymer hydrogels cross-linked with epichlorohydrin and application for Cu(II) removal. ACS Appl Polym Mater. 2023; 5: 2070-2078.

[111] Milos F, del Campo A. Polyacrylamide hydrogels as versatile biomimetic platforms to study cell-materials interactions. Adv Mater Interfaces. 2024; 11:2400404.

[112] Okay O. Polymeric Cryogels: Macroporous Gels with Remarkable Properties. Vol 263. Springer International Publishing; 2014: 199-222.

[113] Zhang Y, Tang C, Span PN, et al. Polyisocyanide hydrogels as a tunable platform for mammary gland organoid formation. Adv Sci. 2020; 7:2001797.

[114] Ye S, Boeter JWB, Mihajlovic M, et al. A chemically defined hydrogel for human liver organoid culture. Adv Funct Mater. 2020; 30:2000893.

[115] Op ’t Veld RC, Joosten L, van den Boomen OI, et al. Monitoring (111)In-labelled polyisocyanopeptide (PIC) hydrogel wound dressings in full-thickness wounds. Biomater Sci. 2019; 7: 3041-3050.

[116] Song W, Li L, Liu X, et al. Hydrogel microrobots for biomedical applications. Review Front Chem. 2024; 12:1416314.

[117] Razavi S, Janfaza S, Tasnim N, Gibson DL, Hoorfar M. Microencapsulating polymers for probiotics delivery systems: preparation, characterization, and applications. Food Hydrocoll. 2021; 120:106882.

[118] Shi Y, Gao X, Chen L, et al. High throughput generation and trapping of individual agarose microgel using microfluidic approach. Microfluid Nanofluid. 2013; 15: 467-474.

[119] Schindler M, Siriwardena D, Kohler TN, et al. Agarose microgel culture delineates lumenogenesis in naive and primed human pluripotent stem cells. Stem Cell Rep. 2021; 16: 1347-1362.

[120] Lee KY, Mooney DJ. Alginate: properties and biomedical applications. Prog Polym Sci. 2012; 37: 106-126.

[121] Xu M, Qin M, Cheng Y, et al. Alginate microgels as delivery vehicles for cell-based therapies in tissue engineering and regenerative medicine. Carbohydr Polym. 2021; 266:118128.

[122] Liu M, Zhang F, Xiao J, Liu B, Cespedes CL, Meng X. The M/G ratio of alginate oligosaccharides: the key to enhance the coloration of strawberries. Carbohydr Polym. 2024; 323:121422.

[123] Bojorges H, López-Rubio A, Fabra MJ, Martínez-Abad A. Estimation of alginate purity and M/G ratio by methanolysis coupled with anion exchange chromatography. Carbohydr Polym. 2023; 321:121285.

[124] Xu Y, Qi R, Zhu H, et al. Liquid-liquid phase-separated systems from reversible gel-sol transition of protein microgels. Adv Mater. 2021; 33:e2008670.

[125] Zhou J, Tian Z, Tian QY, et al. 3D bioprinting of a biomimetic meniscal scaffold for application in tissue engineering. Bioact Mater. 2021; 6: 1711-1726.

[126] He J, Sun Y, Gao Q, et al. Gelatin methacryloyl hydrogel, from standardization, performance, to biomedical application. Adv Healthc Mater. 2023; 12:2300395.

[127] Sun X, Wu Q, Li W, et al. Facile fabrication of drug-loaded PEGDA microcapsules for drug evaluation using droplet-based microchip. Chin Chem Lett. 2022; 33: 2697-2700.

[128] Hakim Khalili M, Zhang R, Wilson S, Goel S, Impey SA, Aria AI. Additive manufacturing and physicomechanical characteristics of PEGDA hydrogels: recent advances and perspective for tissue engineering. Polymers. 2023; 15: 2341.

[129] Dendukuri D, Pregibon DC, Collins J, Hatton TA, Doyle PS. Continuous-flow lithography for high-throughput microparticle synthesis. Nat Mater. 2006; 5: 365-369.

[130] Martino C, Vigolo D, Solvas XCi, Stavrakis S, deMello AJ. Real-time PEGDA-based microgel generation and encapsulation in microdroplets. Adv Mater Technol. 2016; 1:1600028.

[131] Lee S, Hamonangan WM, Kim JH, Kim SH. Soft and tough microcapsules with double-network hydrogel shells. Adv Funct Mater. 2022; 32:2203761.

[132] Zheng F, Tian R, Lu H, et al. Droplet microfluidics powered hydrogel microparticles for stem cell-mediated biomedical applications. Small. 2024; 20:e2401400.

[133] Chen Q, Utech S, Chen D, Prodanovic R, Lin JM, Weitz DA. Controlled assembly of heterotypic cells in a core-shell scaffold: organ in a droplet. Lab Chip. 2016; 16: 1346-1349.

[134] Chen J, Shen H, Heng Y, et al. Droplet microfluidics-assisted fabrication of shape controllable iron-alginate microgels with fluorescent property. Macromol Rapid Commun. 2024; 45:2400084.

[135] Krutkramelis K, Xia B, Oakey J. Monodisperse polyethylene glycol diacrylate hydrogel microsphere formation by oxygen-controlled photopolymerization in a microfluidic device. Lab Chip. 2016; 16: 1457-1465.

[136] Husch JFA, Araujo-Gomes N, Willemen NGA, et al. Upscaling osteoclast generation by enhancing macrophage aggregation using hollow microgels. Small. 2024; 20:e2403272.

[137] Pareja Tello R, Wang S, Fontana F, et al. Fabrication of hydrogel microspheres via microfluidics using inverse electron demand Diels–Alder click chemistry-based tetrazine-norbornene for drug delivery and cell encapsulation applications. Biomater Sci. 2023; 11: 4972-4984.

[138] Liu H, Wang Y, Wang H, et al. A droplet microfluidic system to fabricate hybrid capsules enabling stem cell organoid engineering. Adv Sci. 2020; 7:1903739.

[139] Li B, Zhang L, Yin Y, et al. Stiff hydrogel encapsulation retains mesenchymal stem cell stemness for regenerative medicine. Matter. 2024; 7: 3447-3468.

[140] Chen J, Li P, An R, et al. Droplet microfluidics-assisted fabrication of Fe-alginate microgels with complex morphology: effect of the composition of droplets. Lab Chip. 2025; 25: 3270-3286.

[141] Huang X, Li J, Luo J, Gao Q, Mao A, Li J. Research progress on double-network hydrogels. Mater Today Commun. 2021; 29:102757.

[142] Wang H, Liu H, Liu H, Su W, Chen W, Qin J. One-step generation of core–shell gelatin methacrylate (GelMA) microgels using a droplet microfluidic system. Adv Mater Technol. 2019; 4:1800632.

[143] Keller S, Teora SP, Hu GX, Nijemeisland M, Wilson DA. High-throughput design of biocompatible enzyme-based hydrogel microparticles with autonomous movement. Angew Chem Int Ed. 2018; 57: 9814-9817.

[144] Li Y, Chen Y, Xue Y, et al. Injectable hydrogel delivery system with high drug loading for prolonging local anesthesia. Adv Sci. 2024; 11:e2309482.

[145] Decker C, Jenkins AD. Kinetic approach of oxygen inhibition in ultraviolet- and laser-induced polymerizations. Macromolecules. 2002; 18: 1241-1244.

[146] Xia B, Krutkramelis K, Oakey J. Oxygen-purged microfluidic device to enhance cell viability in photopolymerized PEG hydrogel microparticles. Biomacromolecules. 2016; 17: 2459-2465.

[147] Nagase K, Yamato M, Kanazawa H, Okano T. Poly(N-isopropylacrylamide)-based thermoresponsive surfaces provide new types of biomedical applications. Biomaterials. 2018; 153: 27-48.

[148] Li Z, Lu F, Liu Y. A review of the mechanism, properties, and applications of hydrogels prepared by enzymatic cross-linking. J Agric Food Chem. 2023; 71: 10238-10249.

[149] Chen M, Bolognesi G, Vladisavljevic GT. Crosslinking strategies for the microfluidic production of microgels. Molecules. 2021; 26: 3752.

[150] Li X, Xiong Y. Application of “click” chemistry in biomedical hydrogels. ACS Omega. 2022; 7: 36918-36928.

[151] Yang S-H, Song W-L, Fan L-L, et al. Microfluidic fabrication of monodisperse microcapsules with gas cores. Lab Chip. 2024; 24: 3556-3567.

[152] Seiffert S. Functional microgels tailored by droplet-based microfluidics. Macromol Rapid Commun. 2011; 32: 1600-1609.

[153] Heida T, Neubauer JW, Seuss M, Hauck N, Thiele J, Fery A. Mechanically defined microgels by droplet microfluidics. Macromol Chem Phys. 2017; 218:1600418.

[154] Kumachev A, Greener J, Tumarkin E, Eiser E, Zandstra PW, Kumacheva E. High-throughput generation of hydrogel microbeads with varying elasticity for cell encapsulation. Biomaterials. 2011; 32: 1477-1483.

[155] Zhou K, Li J, Li W, et al. Preparation and magnetic manipulation of Fe3O4/acrylic resin core–shell microspheres. Langmuir. 2023; 39: 11459-11467.

[156] Bian F, Wang H, Sun L, Liu Y, Zhao Y. Quantum-dot-encapsulated core–shell barcode particles from droplet microfluidics. J Mater Chem B. 2018; 6: 7257-7262.

[157] Lee TY, Lee S, Kim YH, et al. Microfluidic fabrication of capsule sensor platform with double-shell structure. Adv Funct Mater. 2019; 29:1902670.

[158] Khan IU, Serra CA, Anton N, et al. Microfluidic conceived drug loaded Janus particles in side-by-side capillaries device. Int J Pharm. 2014; 473: 239-249.

[159] Wu Z, Zheng Y, Lin L, Mao S, Li Z, Lin J-M. Controllable synthesis of multicompartmental particles using 3D microfluidics. Angew Chem Int Ed. 2020; 59: 2225-2229.

[160] Cai Q-W, Ju X-J, Chen C, et al. Fabrication and flow characteristics of monodisperse bullet-shaped microparticles with controllable structures. Chem Eng J. 2019; 370: 925-937.

[161] Xue L, Wang L, Ding X, Sun D, Gu N, Sun J. Soft-template regulation of magnetic microsphere topology from a microfluidic device. Chem Eng Sci. 2025; 305:121106.

[162] Chen L, Xiao Y, Wu Q, et al. Emulsion designer using microfluidic three-dimensional droplet printing in droplet. Small. 2021; 17:2102579.

[163] Qiao D, Hu W, Wang Z, Xie F, Zhang B, Jiang F. Food structuring using microfluidics: updated progress in fundamental principles and structure types. J Food Eng. 2024; 360:111703.

[164] Xu T, Wu Z, Yao H, et al. Evaluation of aconitine cardiotoxicity with a heart-on-a-particle prepared by a microfluidic device. Chem Commun. 2024; 60: 4898-4901.

[165] Zhang L, Chen K, Zhang H, et al. Microfluidic templated multicompartment microgels for 3D encapsulation and pairing of single cells. Small. 2018; 14:1702955.

[166] Hwang DK, Dendukuri D, Doyle PS. Microfluidic-based synthesis of non-spherical magnetic hydrogel microparticles. Lab Chip. 2008; 8: 1640-1647.

[167] Li H, Iyer KS, Bao L, Zhai J, Li JJ. Advances in the development of granular microporous injectable hydrogels with non-spherical microgels and their applications in tissue regeneration. Adv Healthc Mater. 2024; 13:2301597.

[168] Zhu P, Chen R, Zhou C, Aizenberg M, Aizenberg J, Wang L. Bioinspired soft microactuators. Adv Mater. 2021; 33:2008558.

[169] Luo Y, Ma Y, Chen Z, et al. Shape-anisotropic microembolics generated by microfluidic synthesis for transarterial embolization treatment. Adv Healthc Mater. 2022; 11:e2102281.

[170] Ding B, Wang J, Tao S, et al. Fabrication of multi-functional porous microspheres in a modular fashion for the detection, adsorption, and removal of pollutants in wastewater. J Colloid Interface Sci. 2018; 522: 1-9.

[171] Tong T, Hu H, Xie Y, Jin J. Advancements in liquid marbles as an open microfluidic platform: rapid formation, robust manipulation, and revolutionary applications. Droplet. 2025; 4:e160.

[172] van Loo B, ten Den SA, Araújo-Gomes N, et al. Mass production of lumenogenic human embryoid bodies and functional cardiospheres using in-air-generated microcapsules. Nat Commun. 2023; 14: 6685.

[173] Xin S, Chimene D, Garza JE, Gaharwar AK, Alge DL. Clickable PEG hydrogel microspheres as building blocks for 3D bioprinting. Biomater Sci. 2019; 7: 1179-1187.

[174] Yang J, Zhu Y, Wang F, Deng L, Xu X, Cui W. Microfluidic liposomes-anchored microgels as extended delivery platform for treatment of osteoarthritis. Chem Eng J. 2020; 400:126004.

[175] Basiri H, Mohseni SS, Abouei Mehrizi A, et al. Composite microgels for imaging-monitored tracking of the delivery of vascular endothelial growth factor to ischemic muscles. Biomacromolecules. 2021; 22: 5162-5172.

[176] Jiang W, Li M, Chen Z, Leong KW. Cell-laden microfluidic microgels for tissue regeneration. Lab Chip. 2016; 16: 4482-4506.

[177] Liu H, Tao T, Gan Z, et al. Organoid in droplet: production of uniform pancreatic cancer organoids from single cells. Mater Today Bio. 2025; 32:101765.

[178] Caldwell AS, Aguado BA, Anseth KS. Designing microgels for cell culture and controlled assembly of tissue microenvironments. Adv Funct Mater. 2020; 30:1907670.

[179] Major GS, Doan VK, Longoni A, et al. Mapping the microcarrier design pathway to modernise clinical mesenchymal stromal cell expansion. Trends Biotechnol. 2024; 42: 859-876.

[180] Chen AK-L, Reuveny S, Oh SKW. Application of human mesenchymal and pluripotent stem cell microcarrier cultures in cellular therapy: achievements and future direction. Biotechnol Adv. 2013; 31: 1032-1046.

[181] Lei Y, Wang Y, Shen J, et al. Injectable hydrogel microspheres with self-renewable hydration layers alleviate osteoarthritis. Sci Adv. 2022; 8:eabl6449.

[182] Nguyen TPT, Li F, Shrestha S, et al. Cell-laden injectable microgels: current status and future prospects for cartilage regeneration. Biomaterials. 2021; 279:121214.

[183] Xin S, Deo KA, Dai J, et al. Generalizing hydrogel microparticles into a new class of bioinks for extrusion bioprinting. Sci Adv. 2021; 7:eabk3087.

[184] Yin P, Su W, Li T, et al. A modular hydrogel bioink containing microsphere-embedded chondrocytes for 3D-printed multiscale composite scaffolds for cartilage repair. iScience. 2023; 26:107349.

[185] Orbay S, Sanyal R, Sanyal A. Porous microgels for delivery of curcumin: microfluidics-based fabrication and cytotoxicity evaluation. Micromachines. 2023; 14: 1969.

[186] Agrawal G, Agrawal R. Functional microgels: recent advances in their biomedical applications. Small. 2018; 14:1801724.

[187] Chen Z, Song S, Ma J, et al. Fabrication of magnetic core/shell hydrogels via microfluidics for controlled drug delivery. Chem Eng Sci. 2022; 248:117216.

[188] Welling MM, Duszenko N, van Meerbeek MP, et al. Microspheres as a carrier system for therapeutic embolization procedures: achievements and advances. J Clin Med. 2023; 12: 918.

[189] Beh CW, Fu Y, Weiss CR, et al. Microfluidic-prepared, monodisperse, X-ray-visible, embolic microspheres for non-oncological embolization applications. Lab Chip. 2020; 20: 3591-3600.

[190] Dai J, Wang X, Shao C, Liu J, Lian C, Dai H. Microfluidic microspheres loaded with aggregation-induced emission nanomicelles for theranostic applications in osteoarthritis. Adv Healthc Mater. 2025; 15:e03349.

[191] Dharmesh E, Stealey S, Zustiak SP. Microfluidic fabrication and characterization of radiopaque barium sulfate polyethylene glycol-based hydrogel microspheres. FASEB J. 2022; 36:R4312.

[192] Ando M, Tsuchiya M, Itai S, et al. Janus hydrogel microbeads for glucose sensing with pH calibration. Sensors-Basel. 2021; 21: 4829.

[193] Nan L, Zhang H, Weitz DA, Shum HC. Development and future of droplet microfluidics. Lab Chip. 2024; 24: 1135-1153.

[194] Su Y-Y, Pan D-W, Zhang T-X, et al. Wetting-induced interfacial instability: a mechanism for droplet emission at air-liquid interfaces. Sci Adv. 2025; 11:eads1065.

[195] Gan Z, Liu H, Qin X, et al. Microfluidic-assisted pneumatic droplet generators designed for multiscenario biomanufacturing with favorable biocompatibility and extendibility. ACS Biomater Sci Eng. 2024; 10: 6721-6733.

[196] Zhu Z, Chen T, Zhu Y, et al. Programmable pulsed aerodynamic printing for multi-interface composite manufacturing. Matter. 2023; 6: 2034-2051.

[197] Wang J-X, Wang H, Lai H, et al. A machine vision perspective on droplet-based microfluidics. Adv Sci. 2025; 12:2413146.

[198] Liu H, Nan L, Chen F, Zhao Y, Zhao Y. Functions and applications of artificial intelligence in droplet microfluidics. Lab Chip. 2023; 23: 2497-2513.

[199] Shin S, Land OD, Seider WD, Lee J, Lee D. Artificial intelligence-empowered automated double emulsion droplet library generation. Small. 2025; 21:e2412099.

[200] Wang L, Fan L, Filppula AM, Wang Y, Shang L, Zhang H. Spatiotemporal responsive hydrogel microspheres for the treatment of gastric cancer. Aggreg. 2024; 5:e600.

[201] Han Z, Wang F, Xiong W, et al. Precise cell type electrical stimulation therapy via force-electric hydrogel microspheres for cartilage healing. Adv Mater. 2025; 37:2414555.

[202] Shalini KE, Kumari S. 17 - Regulation of hydrogel-based products for biomedical applications. In: R Jayakumar, AK Rajendran, eds. Hydrogel Tissue Analogues. Woodhead Publishing; 2025: 503-513.

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