Microfluidic devices constructed by a marker pen on a silica gel plate for multiplex assays.

In this report, we describe a simple-to-fabricate microfluidic device constructed on a silica gel plate by a waterproof marker pen. We call it pen-based assay on silica, which was successfully applied to simultaneously analyze multiple targets qualitatively and quantitatively based on colorimetric assays for protein, glucose, and pH value.