We also considered a number of communication paradigms that are unique to the capabilities of MEMS devices. For example, MEMS sensors are capable of detecting even very small concentrations of certain chemicals. By having each MEMS 'dandelion' release a small amount of signal chemical when it detects a local event (such as presence of a biochem warfare agent), collections of particles could use the concentration level of the signal chemical to decide whether their readings are correlated, e.g. whether a regional event is occurring that justifies the high cost of communicating to headquarters.