Battery powered dual-polarity ion detector for trace chemical sensing

Trace chemical detection plays an important role in evaluating environmental hazards as well as benign chemical sources. We have developed a low power dual-polarity ionization-based detector. The detector electronics are operated with a single 9 V battery and provide concentration sensitive voltage outputs. The detection mode can be set manually with the on-board electronics or can be controlled with a microcontroller compatible digital input. The complete assembly and operation of the detector is detailed. The features of the detector make it suitable to be operated as a standalone system or to be integrated as a sub-system into a field-portable analytical platform. The detector can achieve a system step response of ~1.6 s. We performed laboratory measurements with several ionized chemicals using both positive and negative mode. The results showed highly linear responses at trace concentrations as low as 100 ppb.