An inexpensive, sensitive device for detecting explosives

A microfluidic, paper-based analytical device (µPAD) — in conjunction with confirmation by a “lab-on-a-chip” analysis — was developed for detection of three explosives (trinitro aromatics) by a team from the University of Technology Sydney (Sydney, Australia; www.uts.edu.au), the University of Lausanne (Switzerland; www.unil.ch), and Florida International University (Miami; www.fiu.edu). A wide range of analytical techniques have been developed for explosives detection, some of them offering high sensitivity and selectivity. However, their long analysis times, high costs and bulky instrumentation limit their use in strategic locations, such as airports or entrances to chemical and other secure facilities. Important advantages of µPADs are low cost, easy storage and disposal, and no requirements for pumps. The fabrication of µPADs involves the construction of patterns of hydrophobic barriers on filter paper, using techniques such as photolithography, plotting, paper cutting, plasma oxidation, inkjet printing and laser treatment. The barriers allow controlled fluid movement that segregates chemical reactions. In the case of this particular application, the µPAD works by monitoring a color…