Transport and collision dynamics in periodic asymmetric obstacle arrays: Rational design of microfluidic rare-cell immunocapture devices

摘要

Microfluidic obstacle arrays have been used in numerous applications, and their ability to sort particles orncapture rare cells from complex samples has broad and impactful applications in biology and medicine. Wenhave investigated the transport and collision dynamics of particles in periodic obstacle arrays to guide thendesign of convective, rather than diffusive, transport-based immunocapture microdevices. Ballistic and fullncomputational fluid dynamics simulations are used to understand the collision modes that evolve in cylindricalnobstacle arrays with various geometries. We identify previously unrecognized collision mode structures andndifferential size-based collision frequencies that emerge from these arrays. Previous descriptions of transversendisplacements that assume unidirectional flow in these obstacle arrays cannot capture mode transitions properlynas these descriptions fail to capture the dependence of the mode transitions on column spacing and the attendantnchange in the flow field. Using these analytical and computational simulations, we elucidate design parametersnthat induce high collision rates for all particles larger than a threshold size or selectively increase collisionnfrequencies for a narrow range of particle sizes within a polydisperse population. Furthermore, we investigatenhowthe particle P´eclet number affects collision dynamics and mode transitions and demonstrate that experimentalnobservations from various obstacle array geometries are well described by our computational model.