A bioassay is a single step within a microarray experiment. There are 3 types of bioassays. A physical bioassay correspond to wet-lab microarray experimental step. A measured bioassays corresponds to a situation after feature extraction has been performed. A derived bioassay corresponds to data processing experimental steps.

A physical bioassay is created by applying some amount of some biomaterial to a microarray. Bioassay treatment events (e.g., wash, apply blocking agent etc.) transform physical bioassays into new physical bioassays. A particular type of bioassay treatment is image acquisition.