An Enclosed Paper Microfluidic Chip as a Sample Preconcentrator Based on Ion Concentration Polarization.Sensitivity is an essential consideration for microfluidic paper-based analytical devices (μPADs) when these devices are used for low concentration sample detection.  Very recently, ion concentration polarization (ICP)-based μPADs are emerging as novel tools for bio-sample preconcentration.  This paper chip is fabricated by a Parafilm embedding technique and holds many advantages over traditional open-channel μPADs, which usually suffer from sample contamination and evaporation problems. 
μPADs
An Enclosed Paper Microfluidic Chip as a Sample Preconcentrator Based on Ion Concentration Polarization.Sensitivity is an essential consideration for microfluidic paper-based analytical devices (μPADs) when these devices are used for low concentration sample detection.  Very recently, ion concentration polarization (ICP)-based μPADs are emerging as novel tools for bio-sample preconcentration.  In this study, we develop an enclosed paper-based microfluidic platform as a preconcentrator based on the ICP effect.  The experiment results show that more than 100-fold concentration enhancement can be achieved in the enclosed paper device, which is comparable with most reported paper-based ICP devices.  Additionally, other improved ICP performance has been observed on the enclosed device, including better concentration plug profile, increased concentration durability.
ICP
This paper chip is fabricated by a Parafilm embedding technique and holds many advantages over traditional open-channel μPADs, which usually suffer from sample contamination and evaporation problems. 
Parafilm