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现时制备微球的方法并不能保证药物以恒速释放，其原因比如微球表面含药较多，对于非溶蚀性微球在释药时增加扩散层，而对于溶蚀性微球则改变其表面积。这样可能需要一种脉冲式释药，而单一聚合物激球不易达到此种释药，多层微球也许会解决。本文提出一步法制备双层微球技术。将两种聚合物选用适宜溶剂分别溶解，将药物均匀分散其中，然后混合，再分散到另一种不相溶溶剂中形成乳剂。将乳剂加温使聚合物溶剂蒸发，产生相分离，使一种聚合物高度均匀地包在另一种聚合物外形成双层徽球。球径约20～1000μm。这种技术还可能用来制备多层微球。
At present, the preparation of microspheres does not guarantee the drug to be released at a constant rate. The reason is that the surface of the microspheres contains more drug, the diffusion layer is increased for the non-erosive microspheres, and the surface area of the microspheres is changed for the erosive microspheres . This may require a pulsatile drug release, which is not easily achieved with a single polymeric balloon and multilayer microspheres may solve the problem. This paper presents a one-step method for the preparation of double-layer microspheres technology. The two polymers were dissolved with appropriate solvents were dissolved, the drug evenly dispersed therein, and then mixed, and then dispersed into another immiscible solvent to form an emulsion. The emulsion is warmed to evaporate the polymer solvent, resulting in phase separation, so that one polymer is highly uniformly coated on top of another polymer to form a double layer emblem. Ball diameter of about 20 ~ 1000μm. This technique may also be used to make multi-layered microspheres.