Parallel droplet microfluidics for high throughput cell encapsulation and synthetic microgel generation

Abstract

Cells can be microencapsulated in synthetic hydrogel microspheres (microgels) using droplet microfluidics, but microfluidic devices with a single droplet generating geometry have limited throughput, especially as microgel diameter decreases. Here we demonstrate microencapsulation of human mesenchymal stem cells (hMSCs) in small ( o100 μm diameter) microgels utilizing parallel droplet generators on a two-layer elastomer device, which has 600% increased throughput vs. single-nozzle devices. Distribution of microgel diameters were compared between products of parallel vs. single-nozzle configurations for two square nozzle widths, 35 and 100 μm. Microgels produced on parallel nozzles were equivalent to those produced on single nozzles, with substantially the same polydispersity. Microencapsulation of hMSCs was compared for parallel nozzle devices of each width. Thirty five micrometer wide nozzle devices could be operated at twice the cell concentration of 100 μm wide nozzle devices but produced more empty microgels than predicted by a Poisson distribution. Hundred micrometer wide nozzle devices produced microgels as predicted by a Poisson distribution. Polydispersity of microgels did not increase with the addition of cells for either nozzle width. hMSCs encapsulated on 35 μm wide nozzle devices had reduced viability (~70%) and a corresponding decrease in vascular endothelial growth factor (VEGF) secretion compared to hMSCs cultured on tissue culture (TC) plastic. Encapsulating hMSCs using 100 μm wide nozzle devices mitigated loss of viability and function, as measured by VEGF secretion.

Water Harvesting of Bioinspired Microfibers with Rough Spindle‐Knots from Microfluidics

“…[17] Microfluidic chips with parallel channels have been used to fabricate cell encapsulation and synthetic microgel. [18] Two parallel rectangular nozzles can also be used to study the flow characteristics of two parallel ejected fluids. [19] Here, we propose a novel parallel-nozzles microfluidic method to fabricate bioinspired bead-on-string microfibers (Figure S1e, Supporting Information).…”

Microfluidic Devices in Fabricating Nano or Micromaterials for Biomedical Applications

“…d) Schematic of a droplet‐based MD in generating disk‐like Ca‐alginate hydrogel beads for cell encapsulation and manipulation; the beads with encapsulated cells can be rolled using a thin needle . e) Schematic of parallel MD operation for fabricating microgel with highly loaded human mesenchymal stem cells (hMSCs) . a) Reproduced with permission .…”

Microfluidic formation of highly monodispersed multiple cored droplets using needle‐based system in parallel mode

“…The above‐mentioned limitations severely constrain the applications of glass‐based microfluidic devices, especially in regard of expanding the yields of droplets. The predicament of glass devices could be rectified using glass with PDMS [20, 21] or other materials, such as PMMA [22–24], PDMS [25–35] or PDMS with other materials such as polycarbonate or silicon [36, 37], to fabricate multiple chips or channels to extend the operation feasibility. Among all the materials mentioned, PMMA is cheaper and more robust than glass devices and hundreds of channels could be crafted in a PMMA substrate; however, it is restricted by the manufacturing precision for channels as etching or mechanical machining techniques are commonly used in its fabrication; this may severely impact surface roughness of individual channel, and the formed droplet size has polydispersity with CV in a range of about 3–6% [22–24].…”

“…PDMS microfluidic device can be rapidly replicated from a master mold using soft lithography, and rearranged in a compact system in the form of layers or stacks for enhanced production of droplets. However, they normally have very elaborated designs, examples of which include the tree structures [25, 30, 32], multilevel module with radial arrays [27], the sinoidal shaped main channel intersected by many small shunt channels [33], and millipede structures [31]. These designs can dramatically raise the production rate of droplets to the liter‐scale per day, yet compromising the production accuracy ineluctably.…”