Lab on Paper Sensor for Explosive Materials Detection ^†

Chemical sensors should provide fast and reliable information on an analytes. One possible technology used in contemporary sensor research is the so-called lab on paper, in which appropriate chemical indicators are immobilized on a specially designed paper chip with hydrophilic and hydrophobic paths. The difference in the wettability of the basic material is used to deliver a liquid sample to an appropriate place of the chip via the indicator. The sample is transported by capillary forces. This article presents a new design of a lab-on-paper chemical sensor for the detection of explosive materials. The chemical sensors were based on Whatman chromatography paper, which was covered with a wax layer. A precise wax pattern was deposited using a Xerox wax printer Colorqube 8700. Afterwards, the chromatography paper was heated up to 170 °C for 2 min. In this way, the wax layer penetrates the paper and creates a hydrophobic barrier. A solution of gold nanoparticles (with diameters of 20 nm) was modified using cysteamine. The paper-based chemical sensor was modified using such a solution. The sensing pads were then covered with 0.1 M NaOH solution. The changes in the color of the sensing pad were dependent on the explosive material. The designed sensor was tested with samples of 2,4,6-trinitrotoluene (TNT).