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.