Accurate detection of hydrogen gas in vehicle interiors is very important for the future of a fuel cell car. Since this type of gas is highly volatile and flammable, the measurement methods have to be very reliable and precise due to safety reasons. In this paper a thermal conductivity sensor for hydrogen gas detection is presented, exhibiting a lower detection limit of 2000 ppm hydrogen in laboratory air. The sensor element is realized by micro-fabrication techniques on silicon wafers. The heated filament is exposed by a selective wet etching process creating a micro-hotplate on a thin membrane. In order to minimize power consumption, the sensor is operated in pulsed mode. Hydrogen gas detection was carried out using a synthetic gas testbench. Measurements of hydrogen contents ranging from 0% to 4% with an increment of 0.5% were successfully performed for ambient gas temperatures between $-15°$C and $84°$C. Including humidity, high moisture contents have the greatest influence on thermal conductivity. This was predicted in theoretical investigations and confirmed in experiments. For evaluation, both the change in resistance $\mathrm{\Delta }R$ as well as the time constant $\tau$ were taken as sensor output. For both quantities, the previously established theoretical relationship with thermal conductivity could be confirmed.

准确检测车辆内部的氢气对于燃料电池汽车的未来非常重要。由于这类气体具有高挥发性和易燃性，因此出于安全原因，测量方法必须非常可靠和精确。本文介绍了一种用于氢气检测的热导率传感器，该传感器在实验室空气中的氢气检出限较低，为2000 ppm。传感器元件是通过微制造技术在硅片上实现的。加热的灯丝通过选择性湿法刻蚀工艺暴露，从而在薄膜上形成微热板。为了最小化功耗，传感器以脉冲模式运行。使用合成气测试台进行氢气检测。氢含量的测量范围为0％至4％，增量为0。$-15°$C和 $84°$C.包括湿度在内，高水分含量对热导率的影响最大。这在理论研究中得到了预测，并在实验中得到了证实。为了评估，电阻的变化$\mathrm{\Delta }\mathrm{[R}$ 以及时间常数 $\tau$被当作​​传感器输出。对于这两个量，都可以确认先前建立的与导热率的理论关系。