Apparatus having a biphasic spray head for entrapping biological material in a hydrophilic gel

Biological material is entrapped in a hydrophilic gel by using an apparatus containing a biphasic spray head. In a preferred embodiment, mammalian cells are mixed with a solution of alginate to form a mixture and the mixture is fed to a biphasic spray head where the mixture passes through a nozzle surrounded by an annular passageway through which air is passed. Droplets of the mixture are formed at the tip of the nozzle and air passing through the passageway frees the droplets from the tip and propels them into the atmosphere in the form of fine spherical droplets. The droplets then contact a solution of divalent cation such as calcium chloride which gels the alginate. Preferably, the nozzle has an inner diameter of between about 0.006'' and 0.016'' and is beveled at an angle between about 15 DEG and 30 DEG to form a conical tip.