A miniature pump has at least one controllable expansion-and-contraction chamber, and associated pair of tiny ducts interconnecting a fluid source and destination. The ducts communicate with the chamber(s); an linking tunnel links the ducts. Valves interact with fluid pressures due to expansion and contraction, imposing directionality on flow in the ducts and tunnel. Preferences: making the valve a passive flapper, implanting the pump in a creature, making the source a medication reservoir for supplying the creature; making the source a fuel tank and destination a tiny engine; making the source provide a specimen for assay and destination an observation slide; human or automatic examination of the slide under a microscope (e. g. electron microscope); making the source a reagent and destination a process stream; making the source a colorant and destination a colorant application system. Preferably included is an optical channel with intersecting fluid duct for optically monitoring pumped fluid.