Dynamic microarray system with gentle retrieval mechanism for cell-encapsulating hydrogel beads

This paper describes a selective retrieval method for arrayed monodisperse hydrogel beads containing cells. We implemented modifications such as: (i) the incorporation of cavities as nucleation sites, (ii) indirect retrieval using bubble powered jets and (iii) the use of low boiling point fluid in our device to realize a gentle optical-based retrieval method. Parametric studies confirmed that these modifications dramatically reduced both the intensity and duration of applied laser for bubble formation. We also demonstrated for the first time the formation of a bead-based dynamic cell microarray by introducing cell-encapsulating alginate beads into our dynamic microfluidic system, and successfully retrieved an alginate bead from a fluidic trap. Tests with trypan blue revealed that membrane integrity of the encapsulated cells was not compromised by the retrieval process.