We present a new biomolecular detection technique performed in microliter droplets freely floating on the surface of perfluorinated oil. The droplets are captured and transported by dielectrophoresis using an electrode chip submerged in the oil. Each droplet serves as a container where microbioassays are performed using the process of agglutination of antibody-coated particles in the presence of analyte. Evaporation leads to the rapid collection of particles in the top portion of droplets. The results are read out by the pattern of unaggregated gold nanoparticles collected on the droplet surface (see Figure). We demonstrate and discuss two formats of microbioassays - GOAgg (Gold Only Agglutination) and GLAgg (Gold Latex Agglutination). The performance of these microbioassays was evaluated by varying analyte concentration, particle concentration and size, number of antigen binding sites per particle, incubation time and rate of particle collection. Microbioassays for Ricin were designed and their performance was compared to the standard hand held assays employed in biological defense. Our droplet microbioassays were found to be 10 times more sensitive in terms of analyte concentration while requiring 100 times less sample volume. We developed a model for the agglutination kinetics and mass transfer process taking place within the droplets, which correlates well with the experimental data. These results could facilitate the development of immunoassays on a chip requiring even smaller sample volumes.