Depending on the general substrate on which the assay principle is applied:
#Bioassay: when the response is biological activity of live objects. Examples include
##in vivo, whole organism (e.g. mouse or other subject injected with a drug)
##ex vivo body part (e.g. leg of a frog)
##ex vivo organ (e.g. heart of a dog)
##ex vivo part of an organ (e.g. a segment of an intestine).
##tissue (e.g. limulus lysate)
##cell (e.g. platelets)
#Ligand binding assay when a ligand (usually a small molecule) binds a receptor (usually a large protein).
#Immunoassay when the response is an antigen antibody binding type reaction.