Simultaneous visualization of flow fields and oxygen concentrations to unravel transport and metabolic processes in biological systems.

From individual cells to whole organisms, O transport unfolds across micrometer- to millimeter-length scales and can change within milliseconds in response to fluid flows and organismal behavior. The spatiotemporal complexity of these processes makes the accurate assessment of O dynamics via currently available methods difficult or unreliable. Here, we present "sensPIV," a method to simultaneously measure O concentrations and flow fields. By tracking O-sensitive microparticles in flow using imaging technologies that allow for instantaneous referencing, we measured O transport within (1) microfluidic devices, (2) sinking model aggregates, and (3) complex colony-forming corals. Through the use of sensPIV, we find that corals use ciliary movement to link zones of photosynthetic O production to zones of O consumption. SensPIV can potentially be extendable to study flow-organism interactions across many life-science and engineering applications.