There are many types of methods and technologies available to manufacture microspheres. Simplistically, the processes fall into two broad categories: chemical or physical.
The chemical methods can be categorized as coascervation and polymerization. The latter method is the most widely adopted process to produce the types of polymer microspheres currently used, for example, as solid phase supports in immunological tests and assays. The manufacture of such microspheres involves a chemical reaction (polymerization). A number of processes are available: condensation-, interfacial-, suspension- and emulsion-polymerization. Suspension and emulsion polymerization are the preferred methods for the commercial production of polymer microsphere carrier particles and reference/standard particles for calibration of scientific instruments. In general, emulsion polymerization produces a smaller particle size and a narrower molecular weight distribution. Both methods are aqueous two-phase batch processes. The use of a double emulsion, e.g water-in-oil-in-water (W/O/W), is a variation of the emulsion polymerization method.