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from a microfluidic channel 12–15 . While such devices are useful for the precise ejection of

liquids, for example for on-demand droplet printing, ejecting particles within such droplets
may pose additional challenges. For example, particles are not always positioned in the center

of the droplet, making repeatable screening problematic. Further, sheath air used to form
droplets may move either of the two phases faster, causing uneven ejection.

In this report, we demonstrate an approach to dispense buckyball-shaped microscaffolds within

a sheath liquid one-by-one and with high precision into microtiter plates using a newly
developed microfluidic sorting platform (Figure 1). For performance evaluation of the air

pressure-based dispensing method, intactness of the microscaffold constructs was verified by
in-flow fluorescent intensity analysis upstream of the ejector region and was used as a selection

criterion quality control measure. Subsequently, automated deposition of human adipose-
derived stem cells (hASCs) onto the microscaffolds allowed the formation of S-SPHs already

within 24 hours of culture. We introduce for the first time an automated and reproducible

workflow for mass production of building blocks for the converging strategy in TE for a variety
of cell-culture collection vessels including 96-, 384- and even 1536-well plates.

Figure 1: Microfluidic platform schematic for high-throughput, automated fabrication of
scaffolded spheroids (S-SPH). Validated scaffolds, deposited and seeded with primary stem

cells in wells, mature into S-SPH building blocks for TE applications.

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