We present, for the first time, a simplified and ultrarapid (~ 1s) approach for synthesis of microbeads with thiol-functionalized surfaces as potential binding sites, whose density can be tuned according to the ratio of two components in the prepolymer. We verify the successful generation of microbeads and their tuneable surface density resulted from different prepolymer off-stoichiometric ratio. This novel approach can be used for bioassays that require rapid surface capture probe binding and customized probe density for suitable bioreactions.