Sweep Heating Thermal Conductivity Detector for 100 ppm Hydrogen Gas Detection

A sweep heating method adopted for the thermal conductivity detector (TCD) is investigated from the viewpoint of a hydrogen (H2) gas sensor. Although our TCD consists of only a 10-μm-diameter platinum (Pt) thin-wire, its low detection limit (LDL) reaches 100 ppm of H2 (0.01%H2; 0.25%LEL). This indicates the excellent detectability of the sweep heating operation. Other sensing properties such as the response to various H2 concentrations and reproducibility are also found to be good. According to a comparison with other TCD-based H2 sensors, the sweep heating operation is found to be an effective way to expand the LDL of TCDs. This allows us to regard the ordinary 10-μm-diameter Pt thin-wire as a highly sensitive gas sensor for detecting 100 ppm of H2. Note that the 100 ppm LDL is comparable to those of the semiconductor H2 sensors and catalytic combustion H2 sensors. In summary, the “sweep heating” operation is a simple yet powerful driving methodology for enhancing TCD detectability. This study facilitates the research and development of TCDs.