The chemical model predicted that localization of a propagating “clot” to a damaged vessel is dependent on shear rate, γ̇: (A) Simplified schematic drawing of the microfluidic device used to test the dependence of “clot” (yellow) propagation through a junction on γ̇. Experimentally, “clotting” of the chemical reaction mixture was initiated in the initiation channel (horizontal) in the absence of flow, and propagation of the “clot” from the initiation channel into the flow channel (vertical) was monitored. (B) When γ̇ in the flow channel was above the threshold γ̇, “clot” propagation remained localized to the initiation channel. (C) When γ̇ in the flow channel was below the threshold γ̇, “clot” propagation did not remain localized to the initiation channel. In panels A–C, black arrows indicate the direction of flow. Adapted with permission from ref 5. Copyright 2004 Wiley-VCH Verlag GmbH & Co. KGaA. (D) Schematic drawing showing the proposed mechanism regulating “clot” propagation. Adapted with permission from ref 5. Copyright 2004 Wiley-VCH Verlag GmbH & Co. KGaA.