Dynamic light-activated control of local chemical concentration in a fluid.

This article reports a method for controlling the chemical concentration in a localized region of a fluid using optoelectrofluidic mechanisms. Optoelectrofluidic fluorescence microscopy (OFM), in which an optoelectrofluidic device is integrated into a conventional fluorescence microscope, allows both modulation and detection of local chemical concentration in an easy and simple way. Here, we present the first experimental investigation of the concentration change of polysaccharides, proteins, and fluorophores, due to the frequency-dependent ac electrokinetics and electrostatic interactions in an optoelectrofluidic device. The dynamic modulation of the local concentration of biomolecules such as dextran and serum albumin was demonstrated in a temporal and spatial manner. This OFM can be a useful tool for controlling the local chemical concentration in several chemical and biological applications.