Library free bulk detection of explosives – Combining simple sensors for resolving a complicated issue

•Robust, mobile and fully functional prototype of a detector for energetic materials was developed.•The prototype works in a library free manner.•A detection rate of 99,4 % was reached.•The application of custom metal oxide semiconductor gas sensors has the potential of a significant power saving. Based on previous work a robust, mobile and fully functional prototype of a detector for energetic materials was developed. The prototype works in a library free manner – it detects explosives regardless of the analyte’s chemical nature. Based on 170 experiments a detection rate of 99,4 % was reached. The detection algorithm was based on 13 explosive and 4 benign materials. The explosives were chosen to cover most common chemical classes and the benign materials included the ones which could easily be mistaken for explosives either optically or by their chemical constitution. In additional experiments, the possibility of library free and automatized operation was proven. Those experiments were performed in a double-blind mode and resulted in 9 of 10 right assignments (8 energetic materials and one benign) and 1 false positive. Sophisticated modular electronics allows quick exchange of sensors in case of malfunction or for experimental reasons. The application of custom metal oxide semiconductor gas sensors has not only the potential for significant power saving and therefore for making the prototypical detection-device suitable for mobile, battery powered application but additionally shortens the detection procedure runtime remarkably while still maintaining a close to 100 % detection rate, thus bringing the detector prototype one step closer to the market. Additional information about the chemical class of the analyzed substance can also be acquired, which can be a crucial advantage for first responders.