A paper based microfluidic device for the detection of arsenic using a gold nanosensor

A paper based microfluidic device is fabricated that can rapidly detect very lowconcentrations of As3+ ions using a gold nanosensor, Au-TA-TG. This simple but efficient system develops a visible bluish-black colour precipitate due to the formation of nanoparticle aggregates through transverse diffusive mixing of Au-TA-TG with As3+ ions on a paper substrate. The approach is extremely selective for arsenic with a detection limit of 1.0 ppb, which is lower than the WHO's reference standard for drinking water.