Spatio-temporally-complex concentration profiles using a tunable chaotic micromixer

The ability to present cells with stimuli that vary in space and time is key for a mechanistic understanding of dynamic processes such as cell migration, growth, adaptation, and differentiation. Microfluidic gradient devices that output multiple concentrations of a given compound exist, but changing the output generally requires a change in flow rates that can be confounding in biological measurements and/or impractical for high-throughput applications. We present chaotic mixers that generate multiple, complex concentration gradients that can be smoothly varied in time without significantly altering the flow rate. (c) 2006 American Institute of Physics.