Fig. 1.
Microfluidic approach for shear-triggered release of ATP. (A) Schematic of the experimental apparatus (not to scale). A mixture of RBCs and luciferase/luciferin solution are pumped through a microfluidic constriction. (B) Representative experimental measurements of the photon emission rate resulting from the reaction between luciferase/luciferin and ATP, measured versus position along the channel (ℓc = 1,600 μm and wc = 20 μm). The position x = 0 is defined as where the entrance to the constriction is located. The approximate ATP concentration (CATP) converted from the calibration curve (Fig. S1) is shown on the right axis. We focus here only on light collected outside of the constriction; no appreciable signal was measured inside the constriction (Fig. S2). The error bars are reported as the standard error of the mean (n = 5 different measurements). Note that the photon emission rate increases far downstream from the constriction.