This image shows a periodic table of elements ‘printed’ on a silicon wafer template used for fabricating SEAL (StampEd Assembly of polymer Layers) microparticle arrays. Each square represents a SEAL microparticle capable of being loaded with various cargos. By tuning the molecular weight of the PLGA (poly(lactic-co-glycolic acid)) polymer used to fabricate the microparticles, pulsatile cargo release can be achieved at different time points, ranging from one week to five months. More importantly, through the stabilization technologies we have developed for various vaccines, immune stimulators, and small-molecule drugs, the potential applications of SEAL microparticles are as diverse as the elements in the periodic table. The ultimate goal of this project is to develop a single-injection Hepatitis B vaccine.