The device utilizes the method of selective withdrawal from a two-layer water-oil system for coating each islet with an aqueous polymeric coat that can be hardened or gelled. Islets together with the aqueous polymer solution are fed by a device that utilizes the principle of hydrodynamic focusing in order to ensure encapsulation of individual islets. The polymer in the aqueous coat is subsequently crosslinked by being exposed to 514 nm light of an argon-ion laser to produce structurally stable microcapsules of controllable thickness of the order of tens of microns. Encapsulated islets are removed from the encapsulation chamber by a valveless micropump and recovered by filtration. The design of this device ensures timely encapsulation of a number of individual islets, adequate for clinical trials, by semipermeable membranes of uniform thickness, which ensure long-term viability and functionality of the islets.

Existing models for selective withdrawal from a two-fluid-layer system through a point sink (Lister, 1989), hydrodynamic focusing (Lee, et al 2001), islet coating (Greener and Middleman, 1975), and valveless pump (Li and Chen, 2003) were used to obtain estimates for the design of the encapsulation chamber and the other components of the device. In parallel an effort has been made to develop a model for selective withdrawal from a two-fluid-layer system with a doublet of a point source and a point sink as in the current device (Hatziavramidis and Pozrikidis, 2007) and the break-up of the composite jets for encapsulation.

The device is currently tried for coating of polystyrene particles of size equal to the average size of the islets, 150 micron. Limited tests are also made to test the efficiency of encapsulation of pancreatic islets in combination with the viability of the encapsulated islets.