title: Triggered "on/off" micropumps and colloidal photodiode.
abstract: We discuss a set of smart micropumps that sense their surrounding environment and respond accordingly. First we show that crystallites of a photoacid generator function as micropumps in the presence of UV light via diffusiophoresis and can be turned "on/off" in a controlled manner. The pump can be restarted multiple times simply by re-illumination. The electroosmotic component was distinguished from the diffusiophoretic component and compared. We also demonstrate patterning. Second, we show that a polymeric imine can also work as a micropump in acidic environment wherein the velocity can be controlled by controlling the pH and, in turn, the ion gradient; the highest velocities are achieved at the lowest pH. Finally, we combined the photoacid and polyimine pumps to create a colloidal photodiode, where we attain both spatial and temporal control over colloidal transport and obtain amplification along with rectification.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Vinita
authors.initials: V
authors.lastname: Yadav
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.forename: Ryan
authors.initials: R
authors.lastname: Pavlick
authors.forename: Ayusman
authors.initials: A
authors.lastname: Sen