text: 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.