Trifurcation microfluidic device for flow layering and controlled diffusive delivery

Purpose: Microfluidic devices allow the controlled layering of flow streams as well as the controlled delivery of solutes into a flow stream.  By sheathing a center blood flow with a viscosity-matched buffer flow on each side, small solutes like calcium ion can rapidly diffuse into the center stream, reaching a near equilibrium distances within about 3 sec of flow and within < 1 cm of flow length. This is particularly useful in conducting coagulation studies with citrated whole blood, once of the most common diagnostic situations found in clinical coagulation labs.  Comsol simulations for any MW solute and solvent viscosity (to dictate diffusivity) are available to define solute penetration into the center stream.

 

Sheathed blood flow.  A strip of collagen/TF was patterned downstream (Y=6 mm) of the trifurcation entrance.  Citrated whole blood was recalcified under flow (600 s-1) with 30 mM Ca2+ buffer.  Platelet (red) and fibrin(ogen) (green) accumulated at the localized injury site, illustrated at the 4.2 min (A), 7.3 min (B), and 10.4 min (C) time points.

Sheathed blood flow. A strip of collagen/TF was patterned downstream (Y=6 mm) of the trifurcation entrance. Citrated whole blood was recalcified under flow (600 s-1) with 30 mM Ca2+ buffer. Platelet (red) and fibrin(ogen) (green) accumulated at the localized injury site, illustrated at the 4.2 min (A), 7.3 min (B), and 10.4 min (C) time points.

Microfluidic device for control delivery of solutes into a flow stream. Citrated whole blood was sheathed with 30 mM calcium buffer (µ=4 cP) at the entrance of the trifurcation design (A).  The sharp gradients between the buffer and blood were illustrated, at the entrance, using FITC dye (B).  The calcium gradients at the trifurcation entrance were simulated using COMSOL (C).

 

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