Figure 3.

a) Image Sequence of the movement of droplet from the enzymatic hydrolysis of phenyl acetate (0.102M) by porcine liver esterase (0.36μM) to produce acetic acid. Droplets are outlined in red in images for clarity. Enzymatic formation of the product leads to an acidification of the droplet and a larger lateral displacement relative to the flow direction. b) Change in pH over time from breakdown of phenyl acetate by porcine liver esterase at 0.89μM solution (red) and at 0.36μM (blue). c) Displacement of droplets along rail as function of time and d) pH