Microuidic paper-based analytical devices (mPADs) are an
attractive alternative for chemical analysis in several areas,
including medical diagnostics,1 clinical analysis,2–4 food testing5
and environmental monitoring,6–8 because they are inexpensive,
portable, easy to use, biocompatible and can be easily disposed.
mPADs are obtained by patterning hydrophilic paper with
impermeable barriers that dene ow channels and test
zones.9–11 The hydrophilic cellulose ber network in the ow
channel serves to be a self-priming capillary pump, allowing the
wicking of solution without the need of external pumps. Unlike
traditional analytical methods using cellulosic substrates, such
as litmus paper, mPADs are more efficient for complex chemical
analysis, as well as more advanced sample pretreatment
methods because of the ability to store reagents on the device.